1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2012 Alexander Block.  All rights reserved.
   4 */
   5
   6#include <linux/bsearch.h>
   7#include <linux/fs.h>
   8#include <linux/file.h>
   9#include <linux/sort.h>
  10#include <linux/mount.h>
  11#include <linux/xattr.h>
  12#include <linux/posix_acl_xattr.h>
  13#include <linux/radix-tree.h>
  14#include <linux/vmalloc.h>
  15#include <linux/string.h>
  16#include <linux/compat.h>
  17#include <linux/crc32c.h>
  18#include <linux/fsverity.h>
  19
  20#include "send.h"
  21#include "ctree.h"
  22#include "backref.h"
  23#include "locking.h"
  24#include "disk-io.h"
  25#include "btrfs_inode.h"
  26#include "transaction.h"
  27#include "compression.h"
  28#include "xattr.h"
  29#include "print-tree.h"
  30#include "accessors.h"
  31#include "dir-item.h"
  32#include "file-item.h"
  33#include "ioctl.h"
  34#include "verity.h"
  35#include "lru_cache.h"
  36
  37/*
  38 * Maximum number of references an extent can have in order for us to attempt to
  39 * issue clone operations instead of write operations. This currently exists to
  40 * avoid hitting limitations of the backreference walking code (taking a lot of
  41 * time and using too much memory for extents with large number of references).
  42 */
  43#define SEND_MAX_EXTENT_REFS	1024
  44
  45/*
  46 * A fs_path is a helper to dynamically build path names with unknown size.
  47 * It reallocates the internal buffer on demand.
  48 * It allows fast adding of path elements on the right side (normal path) and
  49 * fast adding to the left side (reversed path). A reversed path can also be
  50 * unreversed if needed.
  51 */
  52struct fs_path {
  53	union {
  54		struct {
  55			char *start;
  56			char *end;
  57
  58			char *buf;
  59			unsigned short buf_len:15;
  60			unsigned short reversed:1;
  61			char inline_buf[];
  62		};
  63		/*
  64		 * Average path length does not exceed 200 bytes, we'll have
  65		 * better packing in the slab and higher chance to satisfy
  66		 * a allocation later during send.
  67		 */
  68		char pad[256];
  69	};
  70};
  71#define FS_PATH_INLINE_SIZE \
  72	(sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
  73
  74
  75/* reused for each extent */
  76struct clone_root {
  77	struct btrfs_root *root;
  78	u64 ino;
  79	u64 offset;
  80	u64 num_bytes;
  81	bool found_ref;
  82};
  83
  84#define SEND_MAX_NAME_CACHE_SIZE			256
  85
  86/*
  87 * Limit the root_ids array of struct backref_cache_entry to 17 elements.
  88 * This makes the size of a cache entry to be exactly 192 bytes on x86_64, which
  89 * can be satisfied from the kmalloc-192 slab, without wasting any space.
  90 * The most common case is to have a single root for cloning, which corresponds
  91 * to the send root. Having the user specify more than 16 clone roots is not
  92 * common, and in such rare cases we simply don't use caching if the number of
  93 * cloning roots that lead down to a leaf is more than 17.
  94 */
  95#define SEND_MAX_BACKREF_CACHE_ROOTS			17
  96
  97/*
  98 * Max number of entries in the cache.
  99 * With SEND_MAX_BACKREF_CACHE_ROOTS as 17, the size in bytes, excluding
 100 * maple tree's internal nodes, is 24K.
 101 */
 102#define SEND_MAX_BACKREF_CACHE_SIZE 128
 103
 104/*
 105 * A backref cache entry maps a leaf to a list of IDs of roots from which the
 106 * leaf is accessible and we can use for clone operations.
 107 * With SEND_MAX_BACKREF_CACHE_ROOTS as 12, each cache entry is 128 bytes (on
 108 * x86_64).
 109 */
 110struct backref_cache_entry {
 111	struct btrfs_lru_cache_entry entry;
 112	u64 root_ids[SEND_MAX_BACKREF_CACHE_ROOTS];
 113	/* Number of valid elements in the root_ids array. */
 114	int num_roots;
 115};
 116
 117/* See the comment at lru_cache.h about struct btrfs_lru_cache_entry. */
 118static_assert(offsetof(struct backref_cache_entry, entry) == 0);
 119
 120/*
 121 * Max number of entries in the cache that stores directories that were already
 122 * created. The cache uses raw struct btrfs_lru_cache_entry entries, so it uses
 123 * at most 4096 bytes - sizeof(struct btrfs_lru_cache_entry) is 48 bytes, but
 124 * the kmalloc-64 slab is used, so we get 4096 bytes (64 bytes * 64).
 125 */
 126#define SEND_MAX_DIR_CREATED_CACHE_SIZE			64
 127
 128/*
 129 * Max number of entries in the cache that stores directories that were already
 130 * created. The cache uses raw struct btrfs_lru_cache_entry entries, so it uses
 131 * at most 4096 bytes - sizeof(struct btrfs_lru_cache_entry) is 48 bytes, but
 132 * the kmalloc-64 slab is used, so we get 4096 bytes (64 bytes * 64).
 133 */
 134#define SEND_MAX_DIR_UTIMES_CACHE_SIZE			64
 135
 136struct send_ctx {
 137	struct file *send_filp;
 138	loff_t send_off;
 139	char *send_buf;
 140	u32 send_size;
 141	u32 send_max_size;
 142	/*
 143	 * Whether BTRFS_SEND_A_DATA attribute was already added to current
 144	 * command (since protocol v2, data must be the last attribute).
 145	 */
 146	bool put_data;
 147	struct page **send_buf_pages;
 148	u64 flags;	/* 'flags' member of btrfs_ioctl_send_args is u64 */
 149	/* Protocol version compatibility requested */
 150	u32 proto;
 151
 152	struct btrfs_root *send_root;
 153	struct btrfs_root *parent_root;
 154	struct clone_root *clone_roots;
 155	int clone_roots_cnt;
 156
 157	/* current state of the compare_tree call */
 158	struct btrfs_path *left_path;
 159	struct btrfs_path *right_path;
 160	struct btrfs_key *cmp_key;
 161
 162	/*
 163	 * Keep track of the generation of the last transaction that was used
 164	 * for relocating a block group. This is periodically checked in order
 165	 * to detect if a relocation happened since the last check, so that we
 166	 * don't operate on stale extent buffers for nodes (level >= 1) or on
 167	 * stale disk_bytenr values of file extent items.
 168	 */
 169	u64 last_reloc_trans;
 170
 171	/*
 172	 * infos of the currently processed inode. In case of deleted inodes,
 173	 * these are the values from the deleted inode.
 174	 */
 175	u64 cur_ino;
 176	u64 cur_inode_gen;
 177	u64 cur_inode_size;
 178	u64 cur_inode_mode;
 179	u64 cur_inode_rdev;
 180	u64 cur_inode_last_extent;
 181	u64 cur_inode_next_write_offset;
 182	bool cur_inode_new;
 183	bool cur_inode_new_gen;
 184	bool cur_inode_deleted;
 185	bool ignore_cur_inode;
 186	bool cur_inode_needs_verity;
 187	void *verity_descriptor;
 188
 189	u64 send_progress;
 190
 191	struct list_head new_refs;
 192	struct list_head deleted_refs;
 193
 194	struct btrfs_lru_cache name_cache;
 195
 196	/*
 197	 * The inode we are currently processing. It's not NULL only when we
 198	 * need to issue write commands for data extents from this inode.
 199	 */
 200	struct inode *cur_inode;
 201	struct file_ra_state ra;
 202	u64 page_cache_clear_start;
 203	bool clean_page_cache;
 204
 205	/*
 206	 * We process inodes by their increasing order, so if before an
 207	 * incremental send we reverse the parent/child relationship of
 208	 * directories such that a directory with a lower inode number was
 209	 * the parent of a directory with a higher inode number, and the one
 210	 * becoming the new parent got renamed too, we can't rename/move the
 211	 * directory with lower inode number when we finish processing it - we
 212	 * must process the directory with higher inode number first, then
 213	 * rename/move it and then rename/move the directory with lower inode
 214	 * number. Example follows.
 215	 *
 216	 * Tree state when the first send was performed:
 217	 *
 218	 * .
 219	 * |-- a                   (ino 257)
 220	 *     |-- b               (ino 258)
 221	 *         |
 222	 *         |
 223	 *         |-- c           (ino 259)
 224	 *         |   |-- d       (ino 260)
 225	 *         |
 226	 *         |-- c2          (ino 261)
 227	 *
 228	 * Tree state when the second (incremental) send is performed:
 229	 *
 230	 * .
 231	 * |-- a                   (ino 257)
 232	 *     |-- b               (ino 258)
 233	 *         |-- c2          (ino 261)
 234	 *             |-- d2      (ino 260)
 235	 *                 |-- cc  (ino 259)
 236	 *
 237	 * The sequence of steps that lead to the second state was:
 238	 *
 239	 * mv /a/b/c/d /a/b/c2/d2
 240	 * mv /a/b/c /a/b/c2/d2/cc
 241	 *
 242	 * "c" has lower inode number, but we can't move it (2nd mv operation)
 243	 * before we move "d", which has higher inode number.
 244	 *
 245	 * So we just memorize which move/rename operations must be performed
 246	 * later when their respective parent is processed and moved/renamed.
 247	 */
 248
 249	/* Indexed by parent directory inode number. */
 250	struct rb_root pending_dir_moves;
 251
 252	/*
 253	 * Reverse index, indexed by the inode number of a directory that
 254	 * is waiting for the move/rename of its immediate parent before its
 255	 * own move/rename can be performed.
 256	 */
 257	struct rb_root waiting_dir_moves;
 258
 259	/*
 260	 * A directory that is going to be rm'ed might have a child directory
 261	 * which is in the pending directory moves index above. In this case,
 262	 * the directory can only be removed after the move/rename of its child
 263	 * is performed. Example:
 264	 *
 265	 * Parent snapshot:
 266	 *
 267	 * .                        (ino 256)
 268	 * |-- a/                   (ino 257)
 269	 *     |-- b/               (ino 258)
 270	 *         |-- c/           (ino 259)
 271	 *         |   |-- x/       (ino 260)
 272	 *         |
 273	 *         |-- y/           (ino 261)
 274	 *
 275	 * Send snapshot:
 276	 *
 277	 * .                        (ino 256)
 278	 * |-- a/                   (ino 257)
 279	 *     |-- b/               (ino 258)
 280	 *         |-- YY/          (ino 261)
 281	 *              |-- x/      (ino 260)
 282	 *
 283	 * Sequence of steps that lead to the send snapshot:
 284	 * rm -f /a/b/c/foo.txt
 285	 * mv /a/b/y /a/b/YY
 286	 * mv /a/b/c/x /a/b/YY
 287	 * rmdir /a/b/c
 288	 *
 289	 * When the child is processed, its move/rename is delayed until its
 290	 * parent is processed (as explained above), but all other operations
 291	 * like update utimes, chown, chgrp, etc, are performed and the paths
 292	 * that it uses for those operations must use the orphanized name of
 293	 * its parent (the directory we're going to rm later), so we need to
 294	 * memorize that name.
 295	 *
 296	 * Indexed by the inode number of the directory to be deleted.
 297	 */
 298	struct rb_root orphan_dirs;
 299
 300	struct rb_root rbtree_new_refs;
 301	struct rb_root rbtree_deleted_refs;
 302
 303	struct btrfs_lru_cache backref_cache;
 304	u64 backref_cache_last_reloc_trans;
 305
 306	struct btrfs_lru_cache dir_created_cache;
 307	struct btrfs_lru_cache dir_utimes_cache;
 308};
 309
 310struct pending_dir_move {
 311	struct rb_node node;
 312	struct list_head list;
 313	u64 parent_ino;
 314	u64 ino;
 315	u64 gen;
 316	struct list_head update_refs;
 317};
 318
 319struct waiting_dir_move {
 320	struct rb_node node;
 321	u64 ino;
 322	/*
 323	 * There might be some directory that could not be removed because it
 324	 * was waiting for this directory inode to be moved first. Therefore
 325	 * after this directory is moved, we can try to rmdir the ino rmdir_ino.
 326	 */
 327	u64 rmdir_ino;
 328	u64 rmdir_gen;
 329	bool orphanized;
 330};
 331
 332struct orphan_dir_info {
 333	struct rb_node node;
 334	u64 ino;
 335	u64 gen;
 336	u64 last_dir_index_offset;
 337	u64 dir_high_seq_ino;
 338};
 339
 340struct name_cache_entry {
 341	/*
 342	 * The key in the entry is an inode number, and the generation matches
 343	 * the inode's generation.
 344	 */
 345	struct btrfs_lru_cache_entry entry;
 346	u64 parent_ino;
 347	u64 parent_gen;
 348	int ret;
 349	int need_later_update;
 
 350	int name_len;
 351	char name[];
 
 352};
 353
 354/* See the comment at lru_cache.h about struct btrfs_lru_cache_entry. */
 355static_assert(offsetof(struct name_cache_entry, entry) == 0);
 356
 357#define ADVANCE							1
 358#define ADVANCE_ONLY_NEXT					-1
 359
 360enum btrfs_compare_tree_result {
 361	BTRFS_COMPARE_TREE_NEW,
 362	BTRFS_COMPARE_TREE_DELETED,
 363	BTRFS_COMPARE_TREE_CHANGED,
 364	BTRFS_COMPARE_TREE_SAME,
 365};
 366
 367__cold
 368static void inconsistent_snapshot_error(struct send_ctx *sctx,
 369					enum btrfs_compare_tree_result result,
 370					const char *what)
 371{
 372	const char *result_string;
 373
 374	switch (result) {
 375	case BTRFS_COMPARE_TREE_NEW:
 376		result_string = "new";
 377		break;
 378	case BTRFS_COMPARE_TREE_DELETED:
 379		result_string = "deleted";
 380		break;
 381	case BTRFS_COMPARE_TREE_CHANGED:
 382		result_string = "updated";
 383		break;
 384	case BTRFS_COMPARE_TREE_SAME:
 385		ASSERT(0);
 386		result_string = "unchanged";
 387		break;
 388	default:
 389		ASSERT(0);
 390		result_string = "unexpected";
 391	}
 392
 393	btrfs_err(sctx->send_root->fs_info,
 394		  "Send: inconsistent snapshot, found %s %s for inode %llu without updated inode item, send root is %llu, parent root is %llu",
 395		  result_string, what, sctx->cmp_key->objectid,
 396		  sctx->send_root->root_key.objectid,
 397		  (sctx->parent_root ?
 398		   sctx->parent_root->root_key.objectid : 0));
 399}
 400
 401__maybe_unused
 402static bool proto_cmd_ok(const struct send_ctx *sctx, int cmd)
 403{
 404	switch (sctx->proto) {
 405	case 1:	 return cmd <= BTRFS_SEND_C_MAX_V1;
 406	case 2:	 return cmd <= BTRFS_SEND_C_MAX_V2;
 407	case 3:	 return cmd <= BTRFS_SEND_C_MAX_V3;
 408	default: return false;
 409	}
 410}
 411
 412static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
 413
 414static struct waiting_dir_move *
 415get_waiting_dir_move(struct send_ctx *sctx, u64 ino);
 416
 417static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen);
 418
 419static int need_send_hole(struct send_ctx *sctx)
 420{
 421	return (sctx->parent_root && !sctx->cur_inode_new &&
 422		!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted &&
 423		S_ISREG(sctx->cur_inode_mode));
 424}
 425
 426static void fs_path_reset(struct fs_path *p)
 427{
 428	if (p->reversed) {
 429		p->start = p->buf + p->buf_len - 1;
 430		p->end = p->start;
 431		*p->start = 0;
 432	} else {
 433		p->start = p->buf;
 434		p->end = p->start;
 435		*p->start = 0;
 436	}
 437}
 438
 439static struct fs_path *fs_path_alloc(void)
 440{
 441	struct fs_path *p;
 442
 443	p = kmalloc(sizeof(*p), GFP_KERNEL);
 444	if (!p)
 445		return NULL;
 446	p->reversed = 0;
 447	p->buf = p->inline_buf;
 448	p->buf_len = FS_PATH_INLINE_SIZE;
 449	fs_path_reset(p);
 450	return p;
 451}
 452
 453static struct fs_path *fs_path_alloc_reversed(void)
 454{
 455	struct fs_path *p;
 456
 457	p = fs_path_alloc();
 458	if (!p)
 459		return NULL;
 460	p->reversed = 1;
 461	fs_path_reset(p);
 462	return p;
 463}
 464
 465static void fs_path_free(struct fs_path *p)
 466{
 467	if (!p)
 468		return;
 469	if (p->buf != p->inline_buf)
 470		kfree(p->buf);
 471	kfree(p);
 472}
 473
 474static int fs_path_len(struct fs_path *p)
 475{
 476	return p->end - p->start;
 477}
 478
 479static int fs_path_ensure_buf(struct fs_path *p, int len)
 480{
 481	char *tmp_buf;
 482	int path_len;
 483	int old_buf_len;
 484
 485	len++;
 486
 487	if (p->buf_len >= len)
 488		return 0;
 489
 490	if (len > PATH_MAX) {
 491		WARN_ON(1);
 492		return -ENOMEM;
 493	}
 494
 495	path_len = p->end - p->start;
 496	old_buf_len = p->buf_len;
 497
 498	/*
 499	 * Allocate to the next largest kmalloc bucket size, to let
 500	 * the fast path happen most of the time.
 501	 */
 502	len = kmalloc_size_roundup(len);
 503	/*
 504	 * First time the inline_buf does not suffice
 505	 */
 506	if (p->buf == p->inline_buf) {
 507		tmp_buf = kmalloc(len, GFP_KERNEL);
 508		if (tmp_buf)
 509			memcpy(tmp_buf, p->buf, old_buf_len);
 510	} else {
 511		tmp_buf = krealloc(p->buf, len, GFP_KERNEL);
 512	}
 513	if (!tmp_buf)
 514		return -ENOMEM;
 515	p->buf = tmp_buf;
 516	p->buf_len = len;
 517
 518	if (p->reversed) {
 519		tmp_buf = p->buf + old_buf_len - path_len - 1;
 520		p->end = p->buf + p->buf_len - 1;
 521		p->start = p->end - path_len;
 522		memmove(p->start, tmp_buf, path_len + 1);
 523	} else {
 524		p->start = p->buf;
 525		p->end = p->start + path_len;
 526	}
 527	return 0;
 528}
 529
 530static int fs_path_prepare_for_add(struct fs_path *p, int name_len,
 531				   char **prepared)
 532{
 533	int ret;
 534	int new_len;
 535
 536	new_len = p->end - p->start + name_len;
 537	if (p->start != p->end)
 538		new_len++;
 539	ret = fs_path_ensure_buf(p, new_len);
 540	if (ret < 0)
 541		goto out;
 542
 543	if (p->reversed) {
 544		if (p->start != p->end)
 545			*--p->start = '/';
 546		p->start -= name_len;
 547		*prepared = p->start;
 548	} else {
 549		if (p->start != p->end)
 550			*p->end++ = '/';
 551		*prepared = p->end;
 552		p->end += name_len;
 553		*p->end = 0;
 554	}
 555
 556out:
 557	return ret;
 558}
 559
 560static int fs_path_add(struct fs_path *p, const char *name, int name_len)
 561{
 562	int ret;
 563	char *prepared;
 564
 565	ret = fs_path_prepare_for_add(p, name_len, &prepared);
 566	if (ret < 0)
 567		goto out;
 568	memcpy(prepared, name, name_len);
 569
 570out:
 571	return ret;
 572}
 573
 574static int fs_path_add_path(struct fs_path *p, struct fs_path *p2)
 575{
 576	int ret;
 577	char *prepared;
 578
 579	ret = fs_path_prepare_for_add(p, p2->end - p2->start, &prepared);
 580	if (ret < 0)
 581		goto out;
 582	memcpy(prepared, p2->start, p2->end - p2->start);
 583
 584out:
 585	return ret;
 586}
 587
 588static int fs_path_add_from_extent_buffer(struct fs_path *p,
 589					  struct extent_buffer *eb,
 590					  unsigned long off, int len)
 591{
 592	int ret;
 593	char *prepared;
 594
 595	ret = fs_path_prepare_for_add(p, len, &prepared);
 596	if (ret < 0)
 597		goto out;
 598
 599	read_extent_buffer(eb, prepared, off, len);
 600
 601out:
 602	return ret;
 603}
 604
 605static int fs_path_copy(struct fs_path *p, struct fs_path *from)
 606{
 607	p->reversed = from->reversed;
 608	fs_path_reset(p);
 609
 610	return fs_path_add_path(p, from);
 611}
 612
 613static void fs_path_unreverse(struct fs_path *p)
 614{
 615	char *tmp;
 616	int len;
 617
 618	if (!p->reversed)
 619		return;
 620
 621	tmp = p->start;
 622	len = p->end - p->start;
 623	p->start = p->buf;
 624	p->end = p->start + len;
 625	memmove(p->start, tmp, len + 1);
 626	p->reversed = 0;
 627}
 628
 629static struct btrfs_path *alloc_path_for_send(void)
 630{
 631	struct btrfs_path *path;
 632
 633	path = btrfs_alloc_path();
 634	if (!path)
 635		return NULL;
 636	path->search_commit_root = 1;
 637	path->skip_locking = 1;
 638	path->need_commit_sem = 1;
 639	return path;
 640}
 641
 642static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
 643{
 644	int ret;
 645	u32 pos = 0;
 646
 647	while (pos < len) {
 648		ret = kernel_write(filp, buf + pos, len - pos, off);
 649		if (ret < 0)
 650			return ret;
 651		if (ret == 0)
 652			return -EIO;
 653		pos += ret;
 654	}
 655
 656	return 0;
 657}
 658
 659static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
 660{
 661	struct btrfs_tlv_header *hdr;
 662	int total_len = sizeof(*hdr) + len;
 663	int left = sctx->send_max_size - sctx->send_size;
 664
 665	if (WARN_ON_ONCE(sctx->put_data))
 666		return -EINVAL;
 667
 668	if (unlikely(left < total_len))
 669		return -EOVERFLOW;
 670
 671	hdr = (struct btrfs_tlv_header *) (sctx->send_buf + sctx->send_size);
 672	put_unaligned_le16(attr, &hdr->tlv_type);
 673	put_unaligned_le16(len, &hdr->tlv_len);
 674	memcpy(hdr + 1, data, len);
 675	sctx->send_size += total_len;
 676
 677	return 0;
 678}
 679
 680#define TLV_PUT_DEFINE_INT(bits) \
 681	static int tlv_put_u##bits(struct send_ctx *sctx,	 	\
 682			u##bits attr, u##bits value)			\
 683	{								\
 684		__le##bits __tmp = cpu_to_le##bits(value);		\
 685		return tlv_put(sctx, attr, &__tmp, sizeof(__tmp));	\
 686	}
 687
 688TLV_PUT_DEFINE_INT(8)
 689TLV_PUT_DEFINE_INT(32)
 690TLV_PUT_DEFINE_INT(64)
 691
 692static int tlv_put_string(struct send_ctx *sctx, u16 attr,
 693			  const char *str, int len)
 694{
 695	if (len == -1)
 696		len = strlen(str);
 697	return tlv_put(sctx, attr, str, len);
 698}
 699
 700static int tlv_put_uuid(struct send_ctx *sctx, u16 attr,
 701			const u8 *uuid)
 702{
 703	return tlv_put(sctx, attr, uuid, BTRFS_UUID_SIZE);
 704}
 705
 706static int tlv_put_btrfs_timespec(struct send_ctx *sctx, u16 attr,
 707				  struct extent_buffer *eb,
 708				  struct btrfs_timespec *ts)
 709{
 710	struct btrfs_timespec bts;
 711	read_extent_buffer(eb, &bts, (unsigned long)ts, sizeof(bts));
 712	return tlv_put(sctx, attr, &bts, sizeof(bts));
 713}
 714
 715
 716#define TLV_PUT(sctx, attrtype, data, attrlen) \
 717	do { \
 718		ret = tlv_put(sctx, attrtype, data, attrlen); \
 719		if (ret < 0) \
 720			goto tlv_put_failure; \
 721	} while (0)
 722
 723#define TLV_PUT_INT(sctx, attrtype, bits, value) \
 724	do { \
 725		ret = tlv_put_u##bits(sctx, attrtype, value); \
 726		if (ret < 0) \
 727			goto tlv_put_failure; \
 728	} while (0)
 729
 730#define TLV_PUT_U8(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 8, data)
 731#define TLV_PUT_U16(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 16, data)
 732#define TLV_PUT_U32(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 32, data)
 733#define TLV_PUT_U64(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 64, data)
 734#define TLV_PUT_STRING(sctx, attrtype, str, len) \
 735	do { \
 736		ret = tlv_put_string(sctx, attrtype, str, len); \
 737		if (ret < 0) \
 738			goto tlv_put_failure; \
 739	} while (0)
 740#define TLV_PUT_PATH(sctx, attrtype, p) \
 741	do { \
 742		ret = tlv_put_string(sctx, attrtype, p->start, \
 743			p->end - p->start); \
 744		if (ret < 0) \
 745			goto tlv_put_failure; \
 746	} while(0)
 747#define TLV_PUT_UUID(sctx, attrtype, uuid) \
 748	do { \
 749		ret = tlv_put_uuid(sctx, attrtype, uuid); \
 750		if (ret < 0) \
 751			goto tlv_put_failure; \
 752	} while (0)
 753#define TLV_PUT_BTRFS_TIMESPEC(sctx, attrtype, eb, ts) \
 754	do { \
 755		ret = tlv_put_btrfs_timespec(sctx, attrtype, eb, ts); \
 756		if (ret < 0) \
 757			goto tlv_put_failure; \
 758	} while (0)
 759
 760static int send_header(struct send_ctx *sctx)
 761{
 762	struct btrfs_stream_header hdr;
 763
 764	strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
 765	hdr.version = cpu_to_le32(sctx->proto);
 766	return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
 767					&sctx->send_off);
 768}
 769
 770/*
 771 * For each command/item we want to send to userspace, we call this function.
 772 */
 773static int begin_cmd(struct send_ctx *sctx, int cmd)
 774{
 775	struct btrfs_cmd_header *hdr;
 776
 777	if (WARN_ON(!sctx->send_buf))
 778		return -EINVAL;
 779
 780	BUG_ON(sctx->send_size);
 
 
 
 
 
 781
 782	sctx->send_size += sizeof(*hdr);
 783	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
 784	put_unaligned_le16(cmd, &hdr->cmd);
 785
 786	return 0;
 787}
 788
 789static int send_cmd(struct send_ctx *sctx)
 790{
 791	int ret;
 792	struct btrfs_cmd_header *hdr;
 793	u32 crc;
 794
 795	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
 796	put_unaligned_le32(sctx->send_size - sizeof(*hdr), &hdr->len);
 797	put_unaligned_le32(0, &hdr->crc);
 798
 799	crc = crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
 800	put_unaligned_le32(crc, &hdr->crc);
 801
 802	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
 803					&sctx->send_off);
 804
 805	sctx->send_size = 0;
 806	sctx->put_data = false;
 807
 808	return ret;
 809}
 810
 811/*
 812 * Sends a move instruction to user space
 813 */
 814static int send_rename(struct send_ctx *sctx,
 815		     struct fs_path *from, struct fs_path *to)
 816{
 817	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
 818	int ret;
 819
 820	btrfs_debug(fs_info, "send_rename %s -> %s", from->start, to->start);
 821
 822	ret = begin_cmd(sctx, BTRFS_SEND_C_RENAME);
 823	if (ret < 0)
 824		goto out;
 825
 826	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, from);
 827	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_TO, to);
 828
 829	ret = send_cmd(sctx);
 830
 831tlv_put_failure:
 832out:
 833	return ret;
 834}
 835
 836/*
 837 * Sends a link instruction to user space
 838 */
 839static int send_link(struct send_ctx *sctx,
 840		     struct fs_path *path, struct fs_path *lnk)
 841{
 842	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
 843	int ret;
 844
 845	btrfs_debug(fs_info, "send_link %s -> %s", path->start, lnk->start);
 846
 847	ret = begin_cmd(sctx, BTRFS_SEND_C_LINK);
 848	if (ret < 0)
 849		goto out;
 850
 851	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
 852	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, lnk);
 853
 854	ret = send_cmd(sctx);
 855
 856tlv_put_failure:
 857out:
 858	return ret;
 859}
 860
 861/*
 862 * Sends an unlink instruction to user space
 863 */
 864static int send_unlink(struct send_ctx *sctx, struct fs_path *path)
 865{
 866	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
 867	int ret;
 868
 869	btrfs_debug(fs_info, "send_unlink %s", path->start);
 870
 871	ret = begin_cmd(sctx, BTRFS_SEND_C_UNLINK);
 872	if (ret < 0)
 873		goto out;
 874
 875	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
 876
 877	ret = send_cmd(sctx);
 878
 879tlv_put_failure:
 880out:
 881	return ret;
 882}
 883
 884/*
 885 * Sends a rmdir instruction to user space
 886 */
 887static int send_rmdir(struct send_ctx *sctx, struct fs_path *path)
 888{
 889	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
 890	int ret;
 891
 892	btrfs_debug(fs_info, "send_rmdir %s", path->start);
 893
 894	ret = begin_cmd(sctx, BTRFS_SEND_C_RMDIR);
 895	if (ret < 0)
 896		goto out;
 897
 898	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
 899
 900	ret = send_cmd(sctx);
 901
 902tlv_put_failure:
 903out:
 904	return ret;
 905}
 906
 907struct btrfs_inode_info {
 908	u64 size;
 909	u64 gen;
 910	u64 mode;
 911	u64 uid;
 912	u64 gid;
 913	u64 rdev;
 914	u64 fileattr;
 915	u64 nlink;
 916};
 917
 918/*
 919 * Helper function to retrieve some fields from an inode item.
 920 */
 921static int get_inode_info(struct btrfs_root *root, u64 ino,
 922			  struct btrfs_inode_info *info)
 923{
 924	int ret;
 925	struct btrfs_path *path;
 926	struct btrfs_inode_item *ii;
 927	struct btrfs_key key;
 928
 929	path = alloc_path_for_send();
 930	if (!path)
 931		return -ENOMEM;
 932
 933	key.objectid = ino;
 934	key.type = BTRFS_INODE_ITEM_KEY;
 935	key.offset = 0;
 936	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 937	if (ret) {
 938		if (ret > 0)
 939			ret = -ENOENT;
 940		goto out;
 941	}
 942
 943	if (!info)
 944		goto out;
 945
 946	ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
 947			struct btrfs_inode_item);
 948	info->size = btrfs_inode_size(path->nodes[0], ii);
 949	info->gen = btrfs_inode_generation(path->nodes[0], ii);
 950	info->mode = btrfs_inode_mode(path->nodes[0], ii);
 951	info->uid = btrfs_inode_uid(path->nodes[0], ii);
 952	info->gid = btrfs_inode_gid(path->nodes[0], ii);
 953	info->rdev = btrfs_inode_rdev(path->nodes[0], ii);
 954	info->nlink = btrfs_inode_nlink(path->nodes[0], ii);
 955	/*
 956	 * Transfer the unchanged u64 value of btrfs_inode_item::flags, that's
 957	 * otherwise logically split to 32/32 parts.
 958	 */
 959	info->fileattr = btrfs_inode_flags(path->nodes[0], ii);
 960
 961out:
 962	btrfs_free_path(path);
 963	return ret;
 964}
 965
 966static int get_inode_gen(struct btrfs_root *root, u64 ino, u64 *gen)
 967{
 968	int ret;
 969	struct btrfs_inode_info info = { 0 };
 970
 971	ASSERT(gen);
 972
 973	ret = get_inode_info(root, ino, &info);
 974	*gen = info.gen;
 975	return ret;
 976}
 977
 978typedef int (*iterate_inode_ref_t)(int num, u64 dir, int index,
 979				   struct fs_path *p,
 980				   void *ctx);
 981
 982/*
 983 * Helper function to iterate the entries in ONE btrfs_inode_ref or
 984 * btrfs_inode_extref.
 985 * The iterate callback may return a non zero value to stop iteration. This can
 986 * be a negative value for error codes or 1 to simply stop it.
 987 *
 988 * path must point to the INODE_REF or INODE_EXTREF when called.
 989 */
 990static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
 991			     struct btrfs_key *found_key, int resolve,
 992			     iterate_inode_ref_t iterate, void *ctx)
 993{
 994	struct extent_buffer *eb = path->nodes[0];
 995	struct btrfs_inode_ref *iref;
 996	struct btrfs_inode_extref *extref;
 997	struct btrfs_path *tmp_path;
 998	struct fs_path *p;
 999	u32 cur = 0;
1000	u32 total;
1001	int slot = path->slots[0];
1002	u32 name_len;
1003	char *start;
1004	int ret = 0;
1005	int num = 0;
1006	int index;
1007	u64 dir;
1008	unsigned long name_off;
1009	unsigned long elem_size;
1010	unsigned long ptr;
1011
1012	p = fs_path_alloc_reversed();
1013	if (!p)
1014		return -ENOMEM;
1015
1016	tmp_path = alloc_path_for_send();
1017	if (!tmp_path) {
1018		fs_path_free(p);
1019		return -ENOMEM;
1020	}
1021
1022
1023	if (found_key->type == BTRFS_INODE_REF_KEY) {
1024		ptr = (unsigned long)btrfs_item_ptr(eb, slot,
1025						    struct btrfs_inode_ref);
1026		total = btrfs_item_size(eb, slot);
1027		elem_size = sizeof(*iref);
1028	} else {
1029		ptr = btrfs_item_ptr_offset(eb, slot);
1030		total = btrfs_item_size(eb, slot);
1031		elem_size = sizeof(*extref);
1032	}
1033
1034	while (cur < total) {
1035		fs_path_reset(p);
1036
1037		if (found_key->type == BTRFS_INODE_REF_KEY) {
1038			iref = (struct btrfs_inode_ref *)(ptr + cur);
1039			name_len = btrfs_inode_ref_name_len(eb, iref);
1040			name_off = (unsigned long)(iref + 1);
1041			index = btrfs_inode_ref_index(eb, iref);
1042			dir = found_key->offset;
1043		} else {
1044			extref = (struct btrfs_inode_extref *)(ptr + cur);
1045			name_len = btrfs_inode_extref_name_len(eb, extref);
1046			name_off = (unsigned long)&extref->name;
1047			index = btrfs_inode_extref_index(eb, extref);
1048			dir = btrfs_inode_extref_parent(eb, extref);
1049		}
1050
1051		if (resolve) {
1052			start = btrfs_ref_to_path(root, tmp_path, name_len,
1053						  name_off, eb, dir,
1054						  p->buf, p->buf_len);
1055			if (IS_ERR(start)) {
1056				ret = PTR_ERR(start);
1057				goto out;
1058			}
1059			if (start < p->buf) {
1060				/* overflow , try again with larger buffer */
1061				ret = fs_path_ensure_buf(p,
1062						p->buf_len + p->buf - start);
1063				if (ret < 0)
1064					goto out;
1065				start = btrfs_ref_to_path(root, tmp_path,
1066							  name_len, name_off,
1067							  eb, dir,
1068							  p->buf, p->buf_len);
1069				if (IS_ERR(start)) {
1070					ret = PTR_ERR(start);
1071					goto out;
1072				}
1073				BUG_ON(start < p->buf);
 
 
 
 
 
 
 
 
1074			}
1075			p->start = start;
1076		} else {
1077			ret = fs_path_add_from_extent_buffer(p, eb, name_off,
1078							     name_len);
1079			if (ret < 0)
1080				goto out;
1081		}
1082
1083		cur += elem_size + name_len;
1084		ret = iterate(num, dir, index, p, ctx);
1085		if (ret)
1086			goto out;
1087		num++;
1088	}
1089
1090out:
1091	btrfs_free_path(tmp_path);
1092	fs_path_free(p);
1093	return ret;
1094}
1095
1096typedef int (*iterate_dir_item_t)(int num, struct btrfs_key *di_key,
1097				  const char *name, int name_len,
1098				  const char *data, int data_len,
1099				  void *ctx);
1100
1101/*
1102 * Helper function to iterate the entries in ONE btrfs_dir_item.
1103 * The iterate callback may return a non zero value to stop iteration. This can
1104 * be a negative value for error codes or 1 to simply stop it.
1105 *
1106 * path must point to the dir item when called.
1107 */
1108static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
1109			    iterate_dir_item_t iterate, void *ctx)
1110{
1111	int ret = 0;
1112	struct extent_buffer *eb;
1113	struct btrfs_dir_item *di;
1114	struct btrfs_key di_key;
1115	char *buf = NULL;
1116	int buf_len;
1117	u32 name_len;
1118	u32 data_len;
1119	u32 cur;
1120	u32 len;
1121	u32 total;
1122	int slot;
1123	int num;
1124
1125	/*
1126	 * Start with a small buffer (1 page). If later we end up needing more
1127	 * space, which can happen for xattrs on a fs with a leaf size greater
1128	 * then the page size, attempt to increase the buffer. Typically xattr
1129	 * values are small.
1130	 */
1131	buf_len = PATH_MAX;
1132	buf = kmalloc(buf_len, GFP_KERNEL);
1133	if (!buf) {
1134		ret = -ENOMEM;
1135		goto out;
1136	}
1137
1138	eb = path->nodes[0];
1139	slot = path->slots[0];
1140	di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
1141	cur = 0;
1142	len = 0;
1143	total = btrfs_item_size(eb, slot);
1144
1145	num = 0;
1146	while (cur < total) {
1147		name_len = btrfs_dir_name_len(eb, di);
1148		data_len = btrfs_dir_data_len(eb, di);
1149		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
1150
1151		if (btrfs_dir_ftype(eb, di) == BTRFS_FT_XATTR) {
1152			if (name_len > XATTR_NAME_MAX) {
1153				ret = -ENAMETOOLONG;
1154				goto out;
1155			}
1156			if (name_len + data_len >
1157					BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
1158				ret = -E2BIG;
1159				goto out;
1160			}
1161		} else {
1162			/*
1163			 * Path too long
1164			 */
1165			if (name_len + data_len > PATH_MAX) {
1166				ret = -ENAMETOOLONG;
1167				goto out;
1168			}
1169		}
1170
1171		if (name_len + data_len > buf_len) {
1172			buf_len = name_len + data_len;
1173			if (is_vmalloc_addr(buf)) {
1174				vfree(buf);
1175				buf = NULL;
1176			} else {
1177				char *tmp = krealloc(buf, buf_len,
1178						GFP_KERNEL | __GFP_NOWARN);
1179
1180				if (!tmp)
1181					kfree(buf);
1182				buf = tmp;
1183			}
1184			if (!buf) {
1185				buf = kvmalloc(buf_len, GFP_KERNEL);
1186				if (!buf) {
1187					ret = -ENOMEM;
1188					goto out;
1189				}
1190			}
1191		}
1192
1193		read_extent_buffer(eb, buf, (unsigned long)(di + 1),
1194				name_len + data_len);
1195
1196		len = sizeof(*di) + name_len + data_len;
1197		di = (struct btrfs_dir_item *)((char *)di + len);
1198		cur += len;
1199
1200		ret = iterate(num, &di_key, buf, name_len, buf + name_len,
1201			      data_len, ctx);
1202		if (ret < 0)
1203			goto out;
1204		if (ret) {
1205			ret = 0;
1206			goto out;
1207		}
1208
1209		num++;
1210	}
1211
1212out:
1213	kvfree(buf);
1214	return ret;
1215}
1216
1217static int __copy_first_ref(int num, u64 dir, int index,
1218			    struct fs_path *p, void *ctx)
1219{
1220	int ret;
1221	struct fs_path *pt = ctx;
1222
1223	ret = fs_path_copy(pt, p);
1224	if (ret < 0)
1225		return ret;
1226
1227	/* we want the first only */
1228	return 1;
1229}
1230
1231/*
1232 * Retrieve the first path of an inode. If an inode has more then one
1233 * ref/hardlink, this is ignored.
1234 */
1235static int get_inode_path(struct btrfs_root *root,
1236			  u64 ino, struct fs_path *path)
1237{
1238	int ret;
1239	struct btrfs_key key, found_key;
1240	struct btrfs_path *p;
1241
1242	p = alloc_path_for_send();
1243	if (!p)
1244		return -ENOMEM;
1245
1246	fs_path_reset(path);
1247
1248	key.objectid = ino;
1249	key.type = BTRFS_INODE_REF_KEY;
1250	key.offset = 0;
1251
1252	ret = btrfs_search_slot_for_read(root, &key, p, 1, 0);
1253	if (ret < 0)
1254		goto out;
1255	if (ret) {
1256		ret = 1;
1257		goto out;
1258	}
1259	btrfs_item_key_to_cpu(p->nodes[0], &found_key, p->slots[0]);
1260	if (found_key.objectid != ino ||
1261	    (found_key.type != BTRFS_INODE_REF_KEY &&
1262	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
1263		ret = -ENOENT;
1264		goto out;
1265	}
1266
1267	ret = iterate_inode_ref(root, p, &found_key, 1,
1268				__copy_first_ref, path);
1269	if (ret < 0)
1270		goto out;
1271	ret = 0;
1272
1273out:
1274	btrfs_free_path(p);
1275	return ret;
1276}
1277
1278struct backref_ctx {
1279	struct send_ctx *sctx;
1280
1281	/* number of total found references */
1282	u64 found;
1283
1284	/*
1285	 * used for clones found in send_root. clones found behind cur_objectid
1286	 * and cur_offset are not considered as allowed clones.
1287	 */
1288	u64 cur_objectid;
1289	u64 cur_offset;
1290
1291	/* may be truncated in case it's the last extent in a file */
1292	u64 extent_len;
1293
1294	/* The bytenr the file extent item we are processing refers to. */
1295	u64 bytenr;
1296	/* The owner (root id) of the data backref for the current extent. */
1297	u64 backref_owner;
1298	/* The offset of the data backref for the current extent. */
1299	u64 backref_offset;
1300};
1301
1302static int __clone_root_cmp_bsearch(const void *key, const void *elt)
1303{
1304	u64 root = (u64)(uintptr_t)key;
1305	const struct clone_root *cr = elt;
1306
1307	if (root < cr->root->root_key.objectid)
1308		return -1;
1309	if (root > cr->root->root_key.objectid)
1310		return 1;
1311	return 0;
1312}
1313
1314static int __clone_root_cmp_sort(const void *e1, const void *e2)
1315{
1316	const struct clone_root *cr1 = e1;
1317	const struct clone_root *cr2 = e2;
1318
1319	if (cr1->root->root_key.objectid < cr2->root->root_key.objectid)
1320		return -1;
1321	if (cr1->root->root_key.objectid > cr2->root->root_key.objectid)
1322		return 1;
1323	return 0;
1324}
1325
1326/*
1327 * Called for every backref that is found for the current extent.
1328 * Results are collected in sctx->clone_roots->ino/offset.
1329 */
1330static int iterate_backrefs(u64 ino, u64 offset, u64 num_bytes, u64 root_id,
1331			    void *ctx_)
1332{
1333	struct backref_ctx *bctx = ctx_;
1334	struct clone_root *clone_root;
1335
1336	/* First check if the root is in the list of accepted clone sources */
1337	clone_root = bsearch((void *)(uintptr_t)root_id, bctx->sctx->clone_roots,
1338			     bctx->sctx->clone_roots_cnt,
1339			     sizeof(struct clone_root),
1340			     __clone_root_cmp_bsearch);
1341	if (!clone_root)
1342		return 0;
1343
1344	/* This is our own reference, bail out as we can't clone from it. */
1345	if (clone_root->root == bctx->sctx->send_root &&
1346	    ino == bctx->cur_objectid &&
1347	    offset == bctx->cur_offset)
1348		return 0;
1349
1350	/*
1351	 * Make sure we don't consider clones from send_root that are
1352	 * behind the current inode/offset.
1353	 */
1354	if (clone_root->root == bctx->sctx->send_root) {
1355		/*
1356		 * If the source inode was not yet processed we can't issue a
1357		 * clone operation, as the source extent does not exist yet at
1358		 * the destination of the stream.
1359		 */
1360		if (ino > bctx->cur_objectid)
1361			return 0;
1362		/*
1363		 * We clone from the inode currently being sent as long as the
1364		 * source extent is already processed, otherwise we could try
1365		 * to clone from an extent that does not exist yet at the
1366		 * destination of the stream.
1367		 */
1368		if (ino == bctx->cur_objectid &&
1369		    offset + bctx->extent_len >
1370		    bctx->sctx->cur_inode_next_write_offset)
1371			return 0;
1372	}
1373
1374	bctx->found++;
1375	clone_root->found_ref = true;
1376
1377	/*
1378	 * If the given backref refers to a file extent item with a larger
1379	 * number of bytes than what we found before, use the new one so that
1380	 * we clone more optimally and end up doing less writes and getting
1381	 * less exclusive, non-shared extents at the destination.
1382	 */
1383	if (num_bytes > clone_root->num_bytes) {
1384		clone_root->ino = ino;
1385		clone_root->offset = offset;
1386		clone_root->num_bytes = num_bytes;
1387
1388		/*
1389		 * Found a perfect candidate, so there's no need to continue
1390		 * backref walking.
1391		 */
1392		if (num_bytes >= bctx->extent_len)
1393			return BTRFS_ITERATE_EXTENT_INODES_STOP;
1394	}
1395
1396	return 0;
1397}
1398
1399static bool lookup_backref_cache(u64 leaf_bytenr, void *ctx,
1400				 const u64 **root_ids_ret, int *root_count_ret)
1401{
1402	struct backref_ctx *bctx = ctx;
1403	struct send_ctx *sctx = bctx->sctx;
1404	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
1405	const u64 key = leaf_bytenr >> fs_info->sectorsize_bits;
1406	struct btrfs_lru_cache_entry *raw_entry;
1407	struct backref_cache_entry *entry;
1408
1409	if (btrfs_lru_cache_size(&sctx->backref_cache) == 0)
1410		return false;
1411
1412	/*
1413	 * If relocation happened since we first filled the cache, then we must
1414	 * empty the cache and can not use it, because even though we operate on
1415	 * read-only roots, their leaves and nodes may have been reallocated and
1416	 * now be used for different nodes/leaves of the same tree or some other
1417	 * tree.
1418	 *
1419	 * We are called from iterate_extent_inodes() while either holding a
1420	 * transaction handle or holding fs_info->commit_root_sem, so no need
1421	 * to take any lock here.
1422	 */
1423	if (fs_info->last_reloc_trans > sctx->backref_cache_last_reloc_trans) {
1424		btrfs_lru_cache_clear(&sctx->backref_cache);
1425		return false;
1426	}
1427
1428	raw_entry = btrfs_lru_cache_lookup(&sctx->backref_cache, key, 0);
1429	if (!raw_entry)
1430		return false;
1431
1432	entry = container_of(raw_entry, struct backref_cache_entry, entry);
1433	*root_ids_ret = entry->root_ids;
1434	*root_count_ret = entry->num_roots;
1435
1436	return true;
1437}
1438
1439static void store_backref_cache(u64 leaf_bytenr, const struct ulist *root_ids,
1440				void *ctx)
1441{
1442	struct backref_ctx *bctx = ctx;
1443	struct send_ctx *sctx = bctx->sctx;
1444	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
1445	struct backref_cache_entry *new_entry;
1446	struct ulist_iterator uiter;
1447	struct ulist_node *node;
1448	int ret;
1449
1450	/*
1451	 * We're called while holding a transaction handle or while holding
1452	 * fs_info->commit_root_sem (at iterate_extent_inodes()), so must do a
1453	 * NOFS allocation.
1454	 */
1455	new_entry = kmalloc(sizeof(struct backref_cache_entry), GFP_NOFS);
1456	/* No worries, cache is optional. */
1457	if (!new_entry)
1458		return;
1459
1460	new_entry->entry.key = leaf_bytenr >> fs_info->sectorsize_bits;
1461	new_entry->entry.gen = 0;
1462	new_entry->num_roots = 0;
1463	ULIST_ITER_INIT(&uiter);
1464	while ((node = ulist_next(root_ids, &uiter)) != NULL) {
1465		const u64 root_id = node->val;
1466		struct clone_root *root;
1467
1468		root = bsearch((void *)(uintptr_t)root_id, sctx->clone_roots,
1469			       sctx->clone_roots_cnt, sizeof(struct clone_root),
1470			       __clone_root_cmp_bsearch);
1471		if (!root)
1472			continue;
1473
1474		/* Too many roots, just exit, no worries as caching is optional. */
1475		if (new_entry->num_roots >= SEND_MAX_BACKREF_CACHE_ROOTS) {
1476			kfree(new_entry);
1477			return;
1478		}
1479
1480		new_entry->root_ids[new_entry->num_roots] = root_id;
1481		new_entry->num_roots++;
1482	}
1483
1484	/*
1485	 * We may have not added any roots to the new cache entry, which means
1486	 * none of the roots is part of the list of roots from which we are
1487	 * allowed to clone. Cache the new entry as it's still useful to avoid
1488	 * backref walking to determine which roots have a path to the leaf.
1489	 *
1490	 * Also use GFP_NOFS because we're called while holding a transaction
1491	 * handle or while holding fs_info->commit_root_sem.
1492	 */
1493	ret = btrfs_lru_cache_store(&sctx->backref_cache, &new_entry->entry,
1494				    GFP_NOFS);
1495	ASSERT(ret == 0 || ret == -ENOMEM);
1496	if (ret) {
1497		/* Caching is optional, no worries. */
1498		kfree(new_entry);
1499		return;
1500	}
1501
1502	/*
1503	 * We are called from iterate_extent_inodes() while either holding a
1504	 * transaction handle or holding fs_info->commit_root_sem, so no need
1505	 * to take any lock here.
1506	 */
1507	if (btrfs_lru_cache_size(&sctx->backref_cache) == 1)
1508		sctx->backref_cache_last_reloc_trans = fs_info->last_reloc_trans;
1509}
1510
1511static int check_extent_item(u64 bytenr, const struct btrfs_extent_item *ei,
1512			     const struct extent_buffer *leaf, void *ctx)
1513{
1514	const u64 refs = btrfs_extent_refs(leaf, ei);
1515	const struct backref_ctx *bctx = ctx;
1516	const struct send_ctx *sctx = bctx->sctx;
1517
1518	if (bytenr == bctx->bytenr) {
1519		const u64 flags = btrfs_extent_flags(leaf, ei);
1520
1521		if (WARN_ON(flags & BTRFS_EXTENT_FLAG_TREE_BLOCK))
1522			return -EUCLEAN;
1523
1524		/*
1525		 * If we have only one reference and only the send root as a
1526		 * clone source - meaning no clone roots were given in the
1527		 * struct btrfs_ioctl_send_args passed to the send ioctl - then
1528		 * it's our reference and there's no point in doing backref
1529		 * walking which is expensive, so exit early.
1530		 */
1531		if (refs == 1 && sctx->clone_roots_cnt == 1)
1532			return -ENOENT;
1533	}
1534
1535	/*
1536	 * Backreference walking (iterate_extent_inodes() below) is currently
1537	 * too expensive when an extent has a large number of references, both
1538	 * in time spent and used memory. So for now just fallback to write
1539	 * operations instead of clone operations when an extent has more than
1540	 * a certain amount of references.
1541	 */
1542	if (refs > SEND_MAX_EXTENT_REFS)
1543		return -ENOENT;
1544
1545	return 0;
1546}
1547
1548static bool skip_self_data_ref(u64 root, u64 ino, u64 offset, void *ctx)
1549{
1550	const struct backref_ctx *bctx = ctx;
1551
1552	if (ino == bctx->cur_objectid &&
1553	    root == bctx->backref_owner &&
1554	    offset == bctx->backref_offset)
1555		return true;
1556
1557	return false;
1558}
1559
1560/*
1561 * Given an inode, offset and extent item, it finds a good clone for a clone
1562 * instruction. Returns -ENOENT when none could be found. The function makes
1563 * sure that the returned clone is usable at the point where sending is at the
1564 * moment. This means, that no clones are accepted which lie behind the current
1565 * inode+offset.
1566 *
1567 * path must point to the extent item when called.
1568 */
1569static int find_extent_clone(struct send_ctx *sctx,
1570			     struct btrfs_path *path,
1571			     u64 ino, u64 data_offset,
1572			     u64 ino_size,
1573			     struct clone_root **found)
1574{
1575	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
1576	int ret;
1577	int extent_type;
1578	u64 logical;
1579	u64 disk_byte;
1580	u64 num_bytes;
1581	struct btrfs_file_extent_item *fi;
1582	struct extent_buffer *eb = path->nodes[0];
1583	struct backref_ctx backref_ctx = { 0 };
1584	struct btrfs_backref_walk_ctx backref_walk_ctx = { 0 };
1585	struct clone_root *cur_clone_root;
1586	int compressed;
1587	u32 i;
1588
1589	/*
1590	 * With fallocate we can get prealloc extents beyond the inode's i_size,
1591	 * so we don't do anything here because clone operations can not clone
1592	 * to a range beyond i_size without increasing the i_size of the
1593	 * destination inode.
1594	 */
1595	if (data_offset >= ino_size)
1596		return 0;
1597
1598	fi = btrfs_item_ptr(eb, path->slots[0], struct btrfs_file_extent_item);
1599	extent_type = btrfs_file_extent_type(eb, fi);
1600	if (extent_type == BTRFS_FILE_EXTENT_INLINE)
1601		return -ENOENT;
1602
1603	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
1604	if (disk_byte == 0)
1605		return -ENOENT;
1606
1607	compressed = btrfs_file_extent_compression(eb, fi);
1608	num_bytes = btrfs_file_extent_num_bytes(eb, fi);
1609	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
1610
1611	/*
1612	 * Setup the clone roots.
1613	 */
1614	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1615		cur_clone_root = sctx->clone_roots + i;
1616		cur_clone_root->ino = (u64)-1;
1617		cur_clone_root->offset = 0;
1618		cur_clone_root->num_bytes = 0;
1619		cur_clone_root->found_ref = false;
1620	}
1621
1622	backref_ctx.sctx = sctx;
1623	backref_ctx.cur_objectid = ino;
1624	backref_ctx.cur_offset = data_offset;
1625	backref_ctx.bytenr = disk_byte;
1626	/*
1627	 * Use the header owner and not the send root's id, because in case of a
1628	 * snapshot we can have shared subtrees.
1629	 */
1630	backref_ctx.backref_owner = btrfs_header_owner(eb);
1631	backref_ctx.backref_offset = data_offset - btrfs_file_extent_offset(eb, fi);
1632
1633	/*
1634	 * The last extent of a file may be too large due to page alignment.
1635	 * We need to adjust extent_len in this case so that the checks in
1636	 * iterate_backrefs() work.
1637	 */
1638	if (data_offset + num_bytes >= ino_size)
1639		backref_ctx.extent_len = ino_size - data_offset;
1640	else
1641		backref_ctx.extent_len = num_bytes;
1642
1643	/*
1644	 * Now collect all backrefs.
1645	 */
1646	backref_walk_ctx.bytenr = disk_byte;
1647	if (compressed == BTRFS_COMPRESS_NONE)
1648		backref_walk_ctx.extent_item_pos = btrfs_file_extent_offset(eb, fi);
1649	backref_walk_ctx.fs_info = fs_info;
1650	backref_walk_ctx.cache_lookup = lookup_backref_cache;
1651	backref_walk_ctx.cache_store = store_backref_cache;
1652	backref_walk_ctx.indirect_ref_iterator = iterate_backrefs;
1653	backref_walk_ctx.check_extent_item = check_extent_item;
1654	backref_walk_ctx.user_ctx = &backref_ctx;
1655
1656	/*
1657	 * If have a single clone root, then it's the send root and we can tell
1658	 * the backref walking code to skip our own backref and not resolve it,
1659	 * since we can not use it for cloning - the source and destination
1660	 * ranges can't overlap and in case the leaf is shared through a subtree
1661	 * due to snapshots, we can't use those other roots since they are not
1662	 * in the list of clone roots.
1663	 */
1664	if (sctx->clone_roots_cnt == 1)
1665		backref_walk_ctx.skip_data_ref = skip_self_data_ref;
1666
1667	ret = iterate_extent_inodes(&backref_walk_ctx, true, iterate_backrefs,
1668				    &backref_ctx);
1669	if (ret < 0)
1670		return ret;
1671
1672	down_read(&fs_info->commit_root_sem);
1673	if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
1674		/*
1675		 * A transaction commit for a transaction in which block group
1676		 * relocation was done just happened.
1677		 * The disk_bytenr of the file extent item we processed is
1678		 * possibly stale, referring to the extent's location before
1679		 * relocation. So act as if we haven't found any clone sources
1680		 * and fallback to write commands, which will read the correct
1681		 * data from the new extent location. Otherwise we will fail
1682		 * below because we haven't found our own back reference or we
1683		 * could be getting incorrect sources in case the old extent
1684		 * was already reallocated after the relocation.
1685		 */
1686		up_read(&fs_info->commit_root_sem);
1687		return -ENOENT;
1688	}
1689	up_read(&fs_info->commit_root_sem);
1690
1691	btrfs_debug(fs_info,
1692		    "find_extent_clone: data_offset=%llu, ino=%llu, num_bytes=%llu, logical=%llu",
1693		    data_offset, ino, num_bytes, logical);
1694
1695	if (!backref_ctx.found) {
1696		btrfs_debug(fs_info, "no clones found");
1697		return -ENOENT;
1698	}
1699
1700	cur_clone_root = NULL;
1701	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1702		struct clone_root *clone_root = &sctx->clone_roots[i];
1703
1704		if (!clone_root->found_ref)
1705			continue;
1706
1707		/*
1708		 * Choose the root from which we can clone more bytes, to
1709		 * minimize write operations and therefore have more extent
1710		 * sharing at the destination (the same as in the source).
1711		 */
1712		if (!cur_clone_root ||
1713		    clone_root->num_bytes > cur_clone_root->num_bytes) {
1714			cur_clone_root = clone_root;
1715
1716			/*
1717			 * We found an optimal clone candidate (any inode from
1718			 * any root is fine), so we're done.
1719			 */
1720			if (clone_root->num_bytes >= backref_ctx.extent_len)
1721				break;
1722		}
1723	}
1724
1725	if (cur_clone_root) {
1726		*found = cur_clone_root;
1727		ret = 0;
1728	} else {
1729		ret = -ENOENT;
1730	}
1731
1732	return ret;
1733}
1734
1735static int read_symlink(struct btrfs_root *root,
1736			u64 ino,
1737			struct fs_path *dest)
1738{
1739	int ret;
1740	struct btrfs_path *path;
1741	struct btrfs_key key;
1742	struct btrfs_file_extent_item *ei;
1743	u8 type;
1744	u8 compression;
1745	unsigned long off;
1746	int len;
1747
1748	path = alloc_path_for_send();
1749	if (!path)
1750		return -ENOMEM;
1751
1752	key.objectid = ino;
1753	key.type = BTRFS_EXTENT_DATA_KEY;
1754	key.offset = 0;
1755	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1756	if (ret < 0)
1757		goto out;
1758	if (ret) {
1759		/*
1760		 * An empty symlink inode. Can happen in rare error paths when
1761		 * creating a symlink (transaction committed before the inode
1762		 * eviction handler removed the symlink inode items and a crash
1763		 * happened in between or the subvol was snapshoted in between).
1764		 * Print an informative message to dmesg/syslog so that the user
1765		 * can delete the symlink.
1766		 */
1767		btrfs_err(root->fs_info,
1768			  "Found empty symlink inode %llu at root %llu",
1769			  ino, root->root_key.objectid);
1770		ret = -EIO;
1771		goto out;
1772	}
1773
1774	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
1775			struct btrfs_file_extent_item);
1776	type = btrfs_file_extent_type(path->nodes[0], ei);
1777	if (unlikely(type != BTRFS_FILE_EXTENT_INLINE)) {
1778		ret = -EUCLEAN;
1779		btrfs_crit(root->fs_info,
1780"send: found symlink extent that is not inline, ino %llu root %llu extent type %d",
1781			   ino, btrfs_root_id(root), type);
1782		goto out;
1783	}
1784	compression = btrfs_file_extent_compression(path->nodes[0], ei);
1785	if (unlikely(compression != BTRFS_COMPRESS_NONE)) {
1786		ret = -EUCLEAN;
1787		btrfs_crit(root->fs_info,
1788"send: found symlink extent with compression, ino %llu root %llu compression type %d",
1789			   ino, btrfs_root_id(root), compression);
1790		goto out;
1791	}
1792
1793	off = btrfs_file_extent_inline_start(ei);
1794	len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);
1795
1796	ret = fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
1797
1798out:
1799	btrfs_free_path(path);
1800	return ret;
1801}
1802
1803/*
1804 * Helper function to generate a file name that is unique in the root of
1805 * send_root and parent_root. This is used to generate names for orphan inodes.
1806 */
1807static int gen_unique_name(struct send_ctx *sctx,
1808			   u64 ino, u64 gen,
1809			   struct fs_path *dest)
1810{
1811	int ret = 0;
1812	struct btrfs_path *path;
1813	struct btrfs_dir_item *di;
1814	char tmp[64];
1815	int len;
1816	u64 idx = 0;
1817
1818	path = alloc_path_for_send();
1819	if (!path)
1820		return -ENOMEM;
1821
1822	while (1) {
1823		struct fscrypt_str tmp_name;
1824
1825		len = snprintf(tmp, sizeof(tmp), "o%llu-%llu-%llu",
1826				ino, gen, idx);
1827		ASSERT(len < sizeof(tmp));
1828		tmp_name.name = tmp;
1829		tmp_name.len = strlen(tmp);
1830
1831		di = btrfs_lookup_dir_item(NULL, sctx->send_root,
1832				path, BTRFS_FIRST_FREE_OBJECTID,
1833				&tmp_name, 0);
1834		btrfs_release_path(path);
1835		if (IS_ERR(di)) {
1836			ret = PTR_ERR(di);
1837			goto out;
1838		}
1839		if (di) {
1840			/* not unique, try again */
1841			idx++;
1842			continue;
1843		}
1844
1845		if (!sctx->parent_root) {
1846			/* unique */
1847			ret = 0;
1848			break;
1849		}
1850
1851		di = btrfs_lookup_dir_item(NULL, sctx->parent_root,
1852				path, BTRFS_FIRST_FREE_OBJECTID,
1853				&tmp_name, 0);
1854		btrfs_release_path(path);
1855		if (IS_ERR(di)) {
1856			ret = PTR_ERR(di);
1857			goto out;
1858		}
1859		if (di) {
1860			/* not unique, try again */
1861			idx++;
1862			continue;
1863		}
1864		/* unique */
1865		break;
1866	}
1867
1868	ret = fs_path_add(dest, tmp, strlen(tmp));
1869
1870out:
1871	btrfs_free_path(path);
1872	return ret;
1873}
1874
1875enum inode_state {
1876	inode_state_no_change,
1877	inode_state_will_create,
1878	inode_state_did_create,
1879	inode_state_will_delete,
1880	inode_state_did_delete,
1881};
1882
1883static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen,
1884			       u64 *send_gen, u64 *parent_gen)
1885{
1886	int ret;
1887	int left_ret;
1888	int right_ret;
1889	u64 left_gen;
1890	u64 right_gen = 0;
1891	struct btrfs_inode_info info;
1892
1893	ret = get_inode_info(sctx->send_root, ino, &info);
1894	if (ret < 0 && ret != -ENOENT)
1895		goto out;
1896	left_ret = (info.nlink == 0) ? -ENOENT : ret;
1897	left_gen = info.gen;
1898	if (send_gen)
1899		*send_gen = ((left_ret == -ENOENT) ? 0 : info.gen);
1900
1901	if (!sctx->parent_root) {
1902		right_ret = -ENOENT;
1903	} else {
1904		ret = get_inode_info(sctx->parent_root, ino, &info);
1905		if (ret < 0 && ret != -ENOENT)
1906			goto out;
1907		right_ret = (info.nlink == 0) ? -ENOENT : ret;
1908		right_gen = info.gen;
1909		if (parent_gen)
1910			*parent_gen = ((right_ret == -ENOENT) ? 0 : info.gen);
1911	}
1912
1913	if (!left_ret && !right_ret) {
1914		if (left_gen == gen && right_gen == gen) {
1915			ret = inode_state_no_change;
1916		} else if (left_gen == gen) {
1917			if (ino < sctx->send_progress)
1918				ret = inode_state_did_create;
1919			else
1920				ret = inode_state_will_create;
1921		} else if (right_gen == gen) {
1922			if (ino < sctx->send_progress)
1923				ret = inode_state_did_delete;
1924			else
1925				ret = inode_state_will_delete;
1926		} else  {
1927			ret = -ENOENT;
1928		}
1929	} else if (!left_ret) {
1930		if (left_gen == gen) {
1931			if (ino < sctx->send_progress)
1932				ret = inode_state_did_create;
1933			else
1934				ret = inode_state_will_create;
1935		} else {
1936			ret = -ENOENT;
1937		}
1938	} else if (!right_ret) {
1939		if (right_gen == gen) {
1940			if (ino < sctx->send_progress)
1941				ret = inode_state_did_delete;
1942			else
1943				ret = inode_state_will_delete;
1944		} else {
1945			ret = -ENOENT;
1946		}
1947	} else {
1948		ret = -ENOENT;
1949	}
1950
1951out:
1952	return ret;
1953}
1954
1955static int is_inode_existent(struct send_ctx *sctx, u64 ino, u64 gen,
1956			     u64 *send_gen, u64 *parent_gen)
1957{
1958	int ret;
1959
1960	if (ino == BTRFS_FIRST_FREE_OBJECTID)
1961		return 1;
1962
1963	ret = get_cur_inode_state(sctx, ino, gen, send_gen, parent_gen);
1964	if (ret < 0)
1965		goto out;
1966
1967	if (ret == inode_state_no_change ||
1968	    ret == inode_state_did_create ||
1969	    ret == inode_state_will_delete)
1970		ret = 1;
1971	else
1972		ret = 0;
1973
1974out:
1975	return ret;
1976}
1977
1978/*
1979 * Helper function to lookup a dir item in a dir.
1980 */
1981static int lookup_dir_item_inode(struct btrfs_root *root,
1982				 u64 dir, const char *name, int name_len,
1983				 u64 *found_inode)
1984{
1985	int ret = 0;
1986	struct btrfs_dir_item *di;
1987	struct btrfs_key key;
1988	struct btrfs_path *path;
1989	struct fscrypt_str name_str = FSTR_INIT((char *)name, name_len);
1990
1991	path = alloc_path_for_send();
1992	if (!path)
1993		return -ENOMEM;
1994
1995	di = btrfs_lookup_dir_item(NULL, root, path, dir, &name_str, 0);
1996	if (IS_ERR_OR_NULL(di)) {
1997		ret = di ? PTR_ERR(di) : -ENOENT;
1998		goto out;
1999	}
2000	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
2001	if (key.type == BTRFS_ROOT_ITEM_KEY) {
2002		ret = -ENOENT;
2003		goto out;
2004	}
2005	*found_inode = key.objectid;
2006
2007out:
2008	btrfs_free_path(path);
2009	return ret;
2010}
2011
2012/*
2013 * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir,
2014 * generation of the parent dir and the name of the dir entry.
2015 */
2016static int get_first_ref(struct btrfs_root *root, u64 ino,
2017			 u64 *dir, u64 *dir_gen, struct fs_path *name)
2018{
2019	int ret;
2020	struct btrfs_key key;
2021	struct btrfs_key found_key;
2022	struct btrfs_path *path;
2023	int len;
2024	u64 parent_dir;
2025
2026	path = alloc_path_for_send();
2027	if (!path)
2028		return -ENOMEM;
2029
2030	key.objectid = ino;
2031	key.type = BTRFS_INODE_REF_KEY;
2032	key.offset = 0;
2033
2034	ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
2035	if (ret < 0)
2036		goto out;
2037	if (!ret)
2038		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
2039				path->slots[0]);
2040	if (ret || found_key.objectid != ino ||
2041	    (found_key.type != BTRFS_INODE_REF_KEY &&
2042	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
2043		ret = -ENOENT;
2044		goto out;
2045	}
2046
2047	if (found_key.type == BTRFS_INODE_REF_KEY) {
2048		struct btrfs_inode_ref *iref;
2049		iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
2050				      struct btrfs_inode_ref);
2051		len = btrfs_inode_ref_name_len(path->nodes[0], iref);
2052		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
2053						     (unsigned long)(iref + 1),
2054						     len);
2055		parent_dir = found_key.offset;
2056	} else {
2057		struct btrfs_inode_extref *extref;
2058		extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
2059					struct btrfs_inode_extref);
2060		len = btrfs_inode_extref_name_len(path->nodes[0], extref);
2061		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
2062					(unsigned long)&extref->name, len);
2063		parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
2064	}
2065	if (ret < 0)
2066		goto out;
2067	btrfs_release_path(path);
2068
2069	if (dir_gen) {
2070		ret = get_inode_gen(root, parent_dir, dir_gen);
2071		if (ret < 0)
2072			goto out;
2073	}
2074
2075	*dir = parent_dir;
2076
2077out:
2078	btrfs_free_path(path);
2079	return ret;
2080}
2081
2082static int is_first_ref(struct btrfs_root *root,
2083			u64 ino, u64 dir,
2084			const char *name, int name_len)
2085{
2086	int ret;
2087	struct fs_path *tmp_name;
2088	u64 tmp_dir;
2089
2090	tmp_name = fs_path_alloc();
2091	if (!tmp_name)
2092		return -ENOMEM;
2093
2094	ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
2095	if (ret < 0)
2096		goto out;
2097
2098	if (dir != tmp_dir || name_len != fs_path_len(tmp_name)) {
2099		ret = 0;
2100		goto out;
2101	}
2102
2103	ret = !memcmp(tmp_name->start, name, name_len);
2104
2105out:
2106	fs_path_free(tmp_name);
2107	return ret;
2108}
2109
2110/*
2111 * Used by process_recorded_refs to determine if a new ref would overwrite an
2112 * already existing ref. In case it detects an overwrite, it returns the
2113 * inode/gen in who_ino/who_gen.
2114 * When an overwrite is detected, process_recorded_refs does proper orphanizing
2115 * to make sure later references to the overwritten inode are possible.
2116 * Orphanizing is however only required for the first ref of an inode.
2117 * process_recorded_refs does an additional is_first_ref check to see if
2118 * orphanizing is really required.
2119 */
2120static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
2121			      const char *name, int name_len,
2122			      u64 *who_ino, u64 *who_gen, u64 *who_mode)
2123{
2124	int ret;
2125	u64 parent_root_dir_gen;
2126	u64 other_inode = 0;
2127	struct btrfs_inode_info info;
2128
2129	if (!sctx->parent_root)
2130		return 0;
2131
2132	ret = is_inode_existent(sctx, dir, dir_gen, NULL, &parent_root_dir_gen);
2133	if (ret <= 0)
2134		return 0;
2135
2136	/*
2137	 * If we have a parent root we need to verify that the parent dir was
2138	 * not deleted and then re-created, if it was then we have no overwrite
2139	 * and we can just unlink this entry.
2140	 *
2141	 * @parent_root_dir_gen was set to 0 if the inode does not exist in the
2142	 * parent root.
2143	 */
2144	if (sctx->parent_root && dir != BTRFS_FIRST_FREE_OBJECTID &&
2145	    parent_root_dir_gen != dir_gen)
2146		return 0;
2147
2148	ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
2149				    &other_inode);
2150	if (ret == -ENOENT)
2151		return 0;
2152	else if (ret < 0)
2153		return ret;
2154
2155	/*
2156	 * Check if the overwritten ref was already processed. If yes, the ref
2157	 * was already unlinked/moved, so we can safely assume that we will not
2158	 * overwrite anything at this point in time.
2159	 */
2160	if (other_inode > sctx->send_progress ||
2161	    is_waiting_for_move(sctx, other_inode)) {
2162		ret = get_inode_info(sctx->parent_root, other_inode, &info);
2163		if (ret < 0)
2164			return ret;
2165
2166		*who_ino = other_inode;
2167		*who_gen = info.gen;
2168		*who_mode = info.mode;
2169		return 1;
2170	}
2171
2172	return 0;
2173}
2174
2175/*
2176 * Checks if the ref was overwritten by an already processed inode. This is
2177 * used by __get_cur_name_and_parent to find out if the ref was orphanized and
2178 * thus the orphan name needs be used.
2179 * process_recorded_refs also uses it to avoid unlinking of refs that were
2180 * overwritten.
2181 */
2182static int did_overwrite_ref(struct send_ctx *sctx,
2183			    u64 dir, u64 dir_gen,
2184			    u64 ino, u64 ino_gen,
2185			    const char *name, int name_len)
2186{
2187	int ret;
2188	u64 ow_inode;
2189	u64 ow_gen = 0;
2190	u64 send_root_dir_gen;
2191
2192	if (!sctx->parent_root)
2193		return 0;
2194
2195	ret = is_inode_existent(sctx, dir, dir_gen, &send_root_dir_gen, NULL);
2196	if (ret <= 0)
2197		return ret;
2198
2199	/*
2200	 * @send_root_dir_gen was set to 0 if the inode does not exist in the
2201	 * send root.
2202	 */
2203	if (dir != BTRFS_FIRST_FREE_OBJECTID && send_root_dir_gen != dir_gen)
2204		return 0;
2205
2206	/* check if the ref was overwritten by another ref */
2207	ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
2208				    &ow_inode);
2209	if (ret == -ENOENT) {
2210		/* was never and will never be overwritten */
2211		return 0;
2212	} else if (ret < 0) {
2213		return ret;
2214	}
2215
2216	if (ow_inode == ino) {
2217		ret = get_inode_gen(sctx->send_root, ow_inode, &ow_gen);
2218		if (ret < 0)
2219			return ret;
2220
2221		/* It's the same inode, so no overwrite happened. */
2222		if (ow_gen == ino_gen)
2223			return 0;
2224	}
2225
2226	/*
2227	 * We know that it is or will be overwritten. Check this now.
2228	 * The current inode being processed might have been the one that caused
2229	 * inode 'ino' to be orphanized, therefore check if ow_inode matches
2230	 * the current inode being processed.
2231	 */
2232	if (ow_inode < sctx->send_progress)
2233		return 1;
2234
2235	if (ino != sctx->cur_ino && ow_inode == sctx->cur_ino) {
2236		if (ow_gen == 0) {
2237			ret = get_inode_gen(sctx->send_root, ow_inode, &ow_gen);
2238			if (ret < 0)
2239				return ret;
2240		}
2241		if (ow_gen == sctx->cur_inode_gen)
2242			return 1;
2243	}
2244
2245	return 0;
2246}
2247
2248/*
2249 * Same as did_overwrite_ref, but also checks if it is the first ref of an inode
2250 * that got overwritten. This is used by process_recorded_refs to determine
2251 * if it has to use the path as returned by get_cur_path or the orphan name.
2252 */
2253static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen)
2254{
2255	int ret = 0;
2256	struct fs_path *name = NULL;
2257	u64 dir;
2258	u64 dir_gen;
2259
2260	if (!sctx->parent_root)
2261		goto out;
2262
2263	name = fs_path_alloc();
2264	if (!name)
2265		return -ENOMEM;
2266
2267	ret = get_first_ref(sctx->parent_root, ino, &dir, &dir_gen, name);
2268	if (ret < 0)
2269		goto out;
2270
2271	ret = did_overwrite_ref(sctx, dir, dir_gen, ino, gen,
2272			name->start, fs_path_len(name));
2273
2274out:
2275	fs_path_free(name);
2276	return ret;
2277}
2278
2279static inline struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
2280							 u64 ino, u64 gen)
2281{
2282	struct btrfs_lru_cache_entry *entry;
2283
2284	entry = btrfs_lru_cache_lookup(&sctx->name_cache, ino, gen);
2285	if (!entry)
2286		return NULL;
2287
2288	return container_of(entry, struct name_cache_entry, entry);
2289}
2290
2291/*
2292 * Used by get_cur_path for each ref up to the root.
2293 * Returns 0 if it succeeded.
2294 * Returns 1 if the inode is not existent or got overwritten. In that case, the
2295 * name is an orphan name. This instructs get_cur_path to stop iterating. If 1
2296 * is returned, parent_ino/parent_gen are not guaranteed to be valid.
2297 * Returns <0 in case of error.
2298 */
2299static int __get_cur_name_and_parent(struct send_ctx *sctx,
2300				     u64 ino, u64 gen,
2301				     u64 *parent_ino,
2302				     u64 *parent_gen,
2303				     struct fs_path *dest)
2304{
2305	int ret;
2306	int nce_ret;
2307	struct name_cache_entry *nce;
2308
2309	/*
2310	 * First check if we already did a call to this function with the same
2311	 * ino/gen. If yes, check if the cache entry is still up-to-date. If yes
2312	 * return the cached result.
2313	 */
2314	nce = name_cache_search(sctx, ino, gen);
2315	if (nce) {
2316		if (ino < sctx->send_progress && nce->need_later_update) {
2317			btrfs_lru_cache_remove(&sctx->name_cache, &nce->entry);
2318			nce = NULL;
2319		} else {
2320			*parent_ino = nce->parent_ino;
2321			*parent_gen = nce->parent_gen;
2322			ret = fs_path_add(dest, nce->name, nce->name_len);
2323			if (ret < 0)
2324				goto out;
2325			ret = nce->ret;
2326			goto out;
2327		}
2328	}
2329
2330	/*
2331	 * If the inode is not existent yet, add the orphan name and return 1.
2332	 * This should only happen for the parent dir that we determine in
2333	 * record_new_ref_if_needed().
2334	 */
2335	ret = is_inode_existent(sctx, ino, gen, NULL, NULL);
2336	if (ret < 0)
2337		goto out;
2338
2339	if (!ret) {
2340		ret = gen_unique_name(sctx, ino, gen, dest);
2341		if (ret < 0)
2342			goto out;
2343		ret = 1;
2344		goto out_cache;
2345	}
2346
2347	/*
2348	 * Depending on whether the inode was already processed or not, use
2349	 * send_root or parent_root for ref lookup.
2350	 */
2351	if (ino < sctx->send_progress)
2352		ret = get_first_ref(sctx->send_root, ino,
2353				    parent_ino, parent_gen, dest);
2354	else
2355		ret = get_first_ref(sctx->parent_root, ino,
2356				    parent_ino, parent_gen, dest);
2357	if (ret < 0)
2358		goto out;
2359
2360	/*
2361	 * Check if the ref was overwritten by an inode's ref that was processed
2362	 * earlier. If yes, treat as orphan and return 1.
2363	 */
2364	ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen,
2365			dest->start, dest->end - dest->start);
2366	if (ret < 0)
2367		goto out;
2368	if (ret) {
2369		fs_path_reset(dest);
2370		ret = gen_unique_name(sctx, ino, gen, dest);
2371		if (ret < 0)
2372			goto out;
2373		ret = 1;
2374	}
2375
2376out_cache:
2377	/*
2378	 * Store the result of the lookup in the name cache.
2379	 */
2380	nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_KERNEL);
2381	if (!nce) {
2382		ret = -ENOMEM;
2383		goto out;
2384	}
2385
2386	nce->entry.key = ino;
2387	nce->entry.gen = gen;
2388	nce->parent_ino = *parent_ino;
2389	nce->parent_gen = *parent_gen;
2390	nce->name_len = fs_path_len(dest);
2391	nce->ret = ret;
2392	strcpy(nce->name, dest->start);
2393
2394	if (ino < sctx->send_progress)
2395		nce->need_later_update = 0;
2396	else
2397		nce->need_later_update = 1;
2398
2399	nce_ret = btrfs_lru_cache_store(&sctx->name_cache, &nce->entry, GFP_KERNEL);
2400	if (nce_ret < 0) {
2401		kfree(nce);
2402		ret = nce_ret;
2403	}
2404
2405out:
2406	return ret;
2407}
2408
2409/*
2410 * Magic happens here. This function returns the first ref to an inode as it
2411 * would look like while receiving the stream at this point in time.
2412 * We walk the path up to the root. For every inode in between, we check if it
2413 * was already processed/sent. If yes, we continue with the parent as found
2414 * in send_root. If not, we continue with the parent as found in parent_root.
2415 * If we encounter an inode that was deleted at this point in time, we use the
2416 * inodes "orphan" name instead of the real name and stop. Same with new inodes
2417 * that were not created yet and overwritten inodes/refs.
2418 *
2419 * When do we have orphan inodes:
2420 * 1. When an inode is freshly created and thus no valid refs are available yet
2421 * 2. When a directory lost all it's refs (deleted) but still has dir items
2422 *    inside which were not processed yet (pending for move/delete). If anyone
2423 *    tried to get the path to the dir items, it would get a path inside that
2424 *    orphan directory.
2425 * 3. When an inode is moved around or gets new links, it may overwrite the ref
2426 *    of an unprocessed inode. If in that case the first ref would be
2427 *    overwritten, the overwritten inode gets "orphanized". Later when we
2428 *    process this overwritten inode, it is restored at a new place by moving
2429 *    the orphan inode.
2430 *
2431 * sctx->send_progress tells this function at which point in time receiving
2432 * would be.
2433 */
2434static int get_cur_path(struct send_ctx *sctx, u64 ino, u64 gen,
2435			struct fs_path *dest)
2436{
2437	int ret = 0;
2438	struct fs_path *name = NULL;
2439	u64 parent_inode = 0;
2440	u64 parent_gen = 0;
2441	int stop = 0;
2442
2443	name = fs_path_alloc();
2444	if (!name) {
2445		ret = -ENOMEM;
2446		goto out;
2447	}
2448
2449	dest->reversed = 1;
2450	fs_path_reset(dest);
2451
2452	while (!stop && ino != BTRFS_FIRST_FREE_OBJECTID) {
2453		struct waiting_dir_move *wdm;
2454
2455		fs_path_reset(name);
2456
2457		if (is_waiting_for_rm(sctx, ino, gen)) {
2458			ret = gen_unique_name(sctx, ino, gen, name);
2459			if (ret < 0)
2460				goto out;
2461			ret = fs_path_add_path(dest, name);
2462			break;
2463		}
2464
2465		wdm = get_waiting_dir_move(sctx, ino);
2466		if (wdm && wdm->orphanized) {
2467			ret = gen_unique_name(sctx, ino, gen, name);
2468			stop = 1;
2469		} else if (wdm) {
2470			ret = get_first_ref(sctx->parent_root, ino,
2471					    &parent_inode, &parent_gen, name);
2472		} else {
2473			ret = __get_cur_name_and_parent(sctx, ino, gen,
2474							&parent_inode,
2475							&parent_gen, name);
2476			if (ret)
2477				stop = 1;
2478		}
2479
2480		if (ret < 0)
2481			goto out;
2482
2483		ret = fs_path_add_path(dest, name);
2484		if (ret < 0)
2485			goto out;
2486
2487		ino = parent_inode;
2488		gen = parent_gen;
2489	}
2490
2491out:
2492	fs_path_free(name);
2493	if (!ret)
2494		fs_path_unreverse(dest);
2495	return ret;
2496}
2497
2498/*
2499 * Sends a BTRFS_SEND_C_SUBVOL command/item to userspace
2500 */
2501static int send_subvol_begin(struct send_ctx *sctx)
2502{
2503	int ret;
2504	struct btrfs_root *send_root = sctx->send_root;
2505	struct btrfs_root *parent_root = sctx->parent_root;
2506	struct btrfs_path *path;
2507	struct btrfs_key key;
2508	struct btrfs_root_ref *ref;
2509	struct extent_buffer *leaf;
2510	char *name = NULL;
2511	int namelen;
2512
2513	path = btrfs_alloc_path();
2514	if (!path)
2515		return -ENOMEM;
2516
2517	name = kmalloc(BTRFS_PATH_NAME_MAX, GFP_KERNEL);
2518	if (!name) {
2519		btrfs_free_path(path);
2520		return -ENOMEM;
2521	}
2522
2523	key.objectid = send_root->root_key.objectid;
2524	key.type = BTRFS_ROOT_BACKREF_KEY;
2525	key.offset = 0;
2526
2527	ret = btrfs_search_slot_for_read(send_root->fs_info->tree_root,
2528				&key, path, 1, 0);
2529	if (ret < 0)
2530		goto out;
2531	if (ret) {
2532		ret = -ENOENT;
2533		goto out;
2534	}
2535
2536	leaf = path->nodes[0];
2537	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2538	if (key.type != BTRFS_ROOT_BACKREF_KEY ||
2539	    key.objectid != send_root->root_key.objectid) {
2540		ret = -ENOENT;
2541		goto out;
2542	}
2543	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
2544	namelen = btrfs_root_ref_name_len(leaf, ref);
2545	read_extent_buffer(leaf, name, (unsigned long)(ref + 1), namelen);
2546	btrfs_release_path(path);
2547
2548	if (parent_root) {
2549		ret = begin_cmd(sctx, BTRFS_SEND_C_SNAPSHOT);
2550		if (ret < 0)
2551			goto out;
2552	} else {
2553		ret = begin_cmd(sctx, BTRFS_SEND_C_SUBVOL);
2554		if (ret < 0)
2555			goto out;
2556	}
2557
2558	TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen);
2559
2560	if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid))
2561		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2562			    sctx->send_root->root_item.received_uuid);
2563	else
2564		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2565			    sctx->send_root->root_item.uuid);
2566
2567	TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
2568		    btrfs_root_ctransid(&sctx->send_root->root_item));
2569	if (parent_root) {
2570		if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
2571			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2572				     parent_root->root_item.received_uuid);
2573		else
2574			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2575				     parent_root->root_item.uuid);
2576		TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
2577			    btrfs_root_ctransid(&sctx->parent_root->root_item));
2578	}
2579
2580	ret = send_cmd(sctx);
2581
2582tlv_put_failure:
2583out:
2584	btrfs_free_path(path);
2585	kfree(name);
2586	return ret;
2587}
2588
2589static int send_truncate(struct send_ctx *sctx, u64 ino, u64 gen, u64 size)
2590{
2591	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2592	int ret = 0;
2593	struct fs_path *p;
2594
2595	btrfs_debug(fs_info, "send_truncate %llu size=%llu", ino, size);
2596
2597	p = fs_path_alloc();
2598	if (!p)
2599		return -ENOMEM;
2600
2601	ret = begin_cmd(sctx, BTRFS_SEND_C_TRUNCATE);
2602	if (ret < 0)
2603		goto out;
2604
2605	ret = get_cur_path(sctx, ino, gen, p);
2606	if (ret < 0)
2607		goto out;
2608	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2609	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, size);
2610
2611	ret = send_cmd(sctx);
2612
2613tlv_put_failure:
2614out:
2615	fs_path_free(p);
2616	return ret;
2617}
2618
2619static int send_chmod(struct send_ctx *sctx, u64 ino, u64 gen, u64 mode)
2620{
2621	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2622	int ret = 0;
2623	struct fs_path *p;
2624
2625	btrfs_debug(fs_info, "send_chmod %llu mode=%llu", ino, mode);
2626
2627	p = fs_path_alloc();
2628	if (!p)
2629		return -ENOMEM;
2630
2631	ret = begin_cmd(sctx, BTRFS_SEND_C_CHMOD);
2632	if (ret < 0)
2633		goto out;
2634
2635	ret = get_cur_path(sctx, ino, gen, p);
2636	if (ret < 0)
2637		goto out;
2638	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2639	TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode & 07777);
2640
2641	ret = send_cmd(sctx);
2642
2643tlv_put_failure:
2644out:
2645	fs_path_free(p);
2646	return ret;
2647}
2648
2649static int send_fileattr(struct send_ctx *sctx, u64 ino, u64 gen, u64 fileattr)
2650{
2651	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2652	int ret = 0;
2653	struct fs_path *p;
2654
2655	if (sctx->proto < 2)
2656		return 0;
2657
2658	btrfs_debug(fs_info, "send_fileattr %llu fileattr=%llu", ino, fileattr);
2659
2660	p = fs_path_alloc();
2661	if (!p)
2662		return -ENOMEM;
2663
2664	ret = begin_cmd(sctx, BTRFS_SEND_C_FILEATTR);
2665	if (ret < 0)
2666		goto out;
2667
2668	ret = get_cur_path(sctx, ino, gen, p);
2669	if (ret < 0)
2670		goto out;
2671	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2672	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILEATTR, fileattr);
2673
2674	ret = send_cmd(sctx);
2675
2676tlv_put_failure:
2677out:
2678	fs_path_free(p);
2679	return ret;
2680}
2681
2682static int send_chown(struct send_ctx *sctx, u64 ino, u64 gen, u64 uid, u64 gid)
2683{
2684	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2685	int ret = 0;
2686	struct fs_path *p;
2687
2688	btrfs_debug(fs_info, "send_chown %llu uid=%llu, gid=%llu",
2689		    ino, uid, gid);
2690
2691	p = fs_path_alloc();
2692	if (!p)
2693		return -ENOMEM;
2694
2695	ret = begin_cmd(sctx, BTRFS_SEND_C_CHOWN);
2696	if (ret < 0)
2697		goto out;
2698
2699	ret = get_cur_path(sctx, ino, gen, p);
2700	if (ret < 0)
2701		goto out;
2702	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2703	TLV_PUT_U64(sctx, BTRFS_SEND_A_UID, uid);
2704	TLV_PUT_U64(sctx, BTRFS_SEND_A_GID, gid);
2705
2706	ret = send_cmd(sctx);
2707
2708tlv_put_failure:
2709out:
2710	fs_path_free(p);
2711	return ret;
2712}
2713
2714static int send_utimes(struct send_ctx *sctx, u64 ino, u64 gen)
2715{
2716	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2717	int ret = 0;
2718	struct fs_path *p = NULL;
2719	struct btrfs_inode_item *ii;
2720	struct btrfs_path *path = NULL;
2721	struct extent_buffer *eb;
2722	struct btrfs_key key;
2723	int slot;
2724
2725	btrfs_debug(fs_info, "send_utimes %llu", ino);
2726
2727	p = fs_path_alloc();
2728	if (!p)
2729		return -ENOMEM;
2730
2731	path = alloc_path_for_send();
2732	if (!path) {
2733		ret = -ENOMEM;
2734		goto out;
2735	}
2736
2737	key.objectid = ino;
2738	key.type = BTRFS_INODE_ITEM_KEY;
2739	key.offset = 0;
2740	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
2741	if (ret > 0)
2742		ret = -ENOENT;
2743	if (ret < 0)
2744		goto out;
2745
2746	eb = path->nodes[0];
2747	slot = path->slots[0];
2748	ii = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
2749
2750	ret = begin_cmd(sctx, BTRFS_SEND_C_UTIMES);
2751	if (ret < 0)
2752		goto out;
2753
2754	ret = get_cur_path(sctx, ino, gen, p);
2755	if (ret < 0)
2756		goto out;
2757	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2758	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_ATIME, eb, &ii->atime);
2759	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_MTIME, eb, &ii->mtime);
2760	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, &ii->ctime);
2761	if (sctx->proto >= 2)
2762		TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_OTIME, eb, &ii->otime);
2763
2764	ret = send_cmd(sctx);
2765
2766tlv_put_failure:
2767out:
2768	fs_path_free(p);
2769	btrfs_free_path(path);
2770	return ret;
2771}
2772
2773/*
2774 * If the cache is full, we can't remove entries from it and do a call to
2775 * send_utimes() for each respective inode, because we might be finishing
2776 * processing an inode that is a directory and it just got renamed, and existing
2777 * entries in the cache may refer to inodes that have the directory in their
2778 * full path - in which case we would generate outdated paths (pre-rename)
2779 * for the inodes that the cache entries point to. Instead of prunning the
2780 * cache when inserting, do it after we finish processing each inode at
2781 * finish_inode_if_needed().
2782 */
2783static int cache_dir_utimes(struct send_ctx *sctx, u64 dir, u64 gen)
2784{
2785	struct btrfs_lru_cache_entry *entry;
2786	int ret;
2787
2788	entry = btrfs_lru_cache_lookup(&sctx->dir_utimes_cache, dir, gen);
2789	if (entry != NULL)
2790		return 0;
2791
2792	/* Caching is optional, don't fail if we can't allocate memory. */
2793	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
2794	if (!entry)
2795		return send_utimes(sctx, dir, gen);
2796
2797	entry->key = dir;
2798	entry->gen = gen;
2799
2800	ret = btrfs_lru_cache_store(&sctx->dir_utimes_cache, entry, GFP_KERNEL);
2801	ASSERT(ret != -EEXIST);
2802	if (ret) {
2803		kfree(entry);
2804		return send_utimes(sctx, dir, gen);
2805	}
2806
2807	return 0;
2808}
2809
2810static int trim_dir_utimes_cache(struct send_ctx *sctx)
2811{
2812	while (btrfs_lru_cache_size(&sctx->dir_utimes_cache) >
2813	       SEND_MAX_DIR_UTIMES_CACHE_SIZE) {
2814		struct btrfs_lru_cache_entry *lru;
2815		int ret;
2816
2817		lru = btrfs_lru_cache_lru_entry(&sctx->dir_utimes_cache);
2818		ASSERT(lru != NULL);
2819
2820		ret = send_utimes(sctx, lru->key, lru->gen);
2821		if (ret)
2822			return ret;
2823
2824		btrfs_lru_cache_remove(&sctx->dir_utimes_cache, lru);
2825	}
2826
2827	return 0;
2828}
2829
2830/*
2831 * Sends a BTRFS_SEND_C_MKXXX or SYMLINK command to user space. We don't have
2832 * a valid path yet because we did not process the refs yet. So, the inode
2833 * is created as orphan.
2834 */
2835static int send_create_inode(struct send_ctx *sctx, u64 ino)
2836{
2837	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2838	int ret = 0;
2839	struct fs_path *p;
2840	int cmd;
2841	struct btrfs_inode_info info;
2842	u64 gen;
2843	u64 mode;
2844	u64 rdev;
2845
2846	btrfs_debug(fs_info, "send_create_inode %llu", ino);
2847
2848	p = fs_path_alloc();
2849	if (!p)
2850		return -ENOMEM;
2851
2852	if (ino != sctx->cur_ino) {
2853		ret = get_inode_info(sctx->send_root, ino, &info);
2854		if (ret < 0)
2855			goto out;
2856		gen = info.gen;
2857		mode = info.mode;
2858		rdev = info.rdev;
2859	} else {
2860		gen = sctx->cur_inode_gen;
2861		mode = sctx->cur_inode_mode;
2862		rdev = sctx->cur_inode_rdev;
2863	}
2864
2865	if (S_ISREG(mode)) {
2866		cmd = BTRFS_SEND_C_MKFILE;
2867	} else if (S_ISDIR(mode)) {
2868		cmd = BTRFS_SEND_C_MKDIR;
2869	} else if (S_ISLNK(mode)) {
2870		cmd = BTRFS_SEND_C_SYMLINK;
2871	} else if (S_ISCHR(mode) || S_ISBLK(mode)) {
2872		cmd = BTRFS_SEND_C_MKNOD;
2873	} else if (S_ISFIFO(mode)) {
2874		cmd = BTRFS_SEND_C_MKFIFO;
2875	} else if (S_ISSOCK(mode)) {
2876		cmd = BTRFS_SEND_C_MKSOCK;
2877	} else {
2878		btrfs_warn(sctx->send_root->fs_info, "unexpected inode type %o",
2879				(int)(mode & S_IFMT));
2880		ret = -EOPNOTSUPP;
2881		goto out;
2882	}
2883
2884	ret = begin_cmd(sctx, cmd);
2885	if (ret < 0)
2886		goto out;
2887
2888	ret = gen_unique_name(sctx, ino, gen, p);
2889	if (ret < 0)
2890		goto out;
2891
2892	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2893	TLV_PUT_U64(sctx, BTRFS_SEND_A_INO, ino);
2894
2895	if (S_ISLNK(mode)) {
2896		fs_path_reset(p);
2897		ret = read_symlink(sctx->send_root, ino, p);
2898		if (ret < 0)
2899			goto out;
2900		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, p);
2901	} else if (S_ISCHR(mode) || S_ISBLK(mode) ||
2902		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
2903		TLV_PUT_U64(sctx, BTRFS_SEND_A_RDEV, new_encode_dev(rdev));
2904		TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode);
2905	}
2906
2907	ret = send_cmd(sctx);
2908	if (ret < 0)
2909		goto out;
2910
2911
2912tlv_put_failure:
2913out:
2914	fs_path_free(p);
2915	return ret;
2916}
2917
2918static void cache_dir_created(struct send_ctx *sctx, u64 dir)
2919{
2920	struct btrfs_lru_cache_entry *entry;
2921	int ret;
2922
2923	/* Caching is optional, ignore any failures. */
2924	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
2925	if (!entry)
2926		return;
2927
2928	entry->key = dir;
2929	entry->gen = 0;
2930	ret = btrfs_lru_cache_store(&sctx->dir_created_cache, entry, GFP_KERNEL);
2931	if (ret < 0)
2932		kfree(entry);
2933}
2934
2935/*
2936 * We need some special handling for inodes that get processed before the parent
2937 * directory got created. See process_recorded_refs for details.
2938 * This function does the check if we already created the dir out of order.
2939 */
2940static int did_create_dir(struct send_ctx *sctx, u64 dir)
2941{
2942	int ret = 0;
2943	int iter_ret = 0;
2944	struct btrfs_path *path = NULL;
2945	struct btrfs_key key;
2946	struct btrfs_key found_key;
2947	struct btrfs_key di_key;
2948	struct btrfs_dir_item *di;
2949
2950	if (btrfs_lru_cache_lookup(&sctx->dir_created_cache, dir, 0))
2951		return 1;
2952
2953	path = alloc_path_for_send();
2954	if (!path)
2955		return -ENOMEM;
2956
2957	key.objectid = dir;
2958	key.type = BTRFS_DIR_INDEX_KEY;
2959	key.offset = 0;
2960
2961	btrfs_for_each_slot(sctx->send_root, &key, &found_key, path, iter_ret) {
2962		struct extent_buffer *eb = path->nodes[0];
2963
2964		if (found_key.objectid != key.objectid ||
2965		    found_key.type != key.type) {
2966			ret = 0;
2967			break;
2968		}
2969
2970		di = btrfs_item_ptr(eb, path->slots[0], struct btrfs_dir_item);
2971		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
2972
2973		if (di_key.type != BTRFS_ROOT_ITEM_KEY &&
2974		    di_key.objectid < sctx->send_progress) {
2975			ret = 1;
2976			cache_dir_created(sctx, dir);
2977			break;
2978		}
2979	}
2980	/* Catch error found during iteration */
2981	if (iter_ret < 0)
2982		ret = iter_ret;
2983
2984	btrfs_free_path(path);
2985	return ret;
2986}
2987
2988/*
2989 * Only creates the inode if it is:
2990 * 1. Not a directory
2991 * 2. Or a directory which was not created already due to out of order
2992 *    directories. See did_create_dir and process_recorded_refs for details.
2993 */
2994static int send_create_inode_if_needed(struct send_ctx *sctx)
2995{
2996	int ret;
2997
2998	if (S_ISDIR(sctx->cur_inode_mode)) {
2999		ret = did_create_dir(sctx, sctx->cur_ino);
3000		if (ret < 0)
3001			return ret;
3002		else if (ret > 0)
3003			return 0;
3004	}
3005
3006	ret = send_create_inode(sctx, sctx->cur_ino);
3007
3008	if (ret == 0 && S_ISDIR(sctx->cur_inode_mode))
3009		cache_dir_created(sctx, sctx->cur_ino);
3010
3011	return ret;
3012}
3013
3014struct recorded_ref {
3015	struct list_head list;
3016	char *name;
3017	struct fs_path *full_path;
3018	u64 dir;
3019	u64 dir_gen;
3020	int name_len;
3021	struct rb_node node;
3022	struct rb_root *root;
3023};
3024
3025static struct recorded_ref *recorded_ref_alloc(void)
3026{
3027	struct recorded_ref *ref;
3028
3029	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
3030	if (!ref)
3031		return NULL;
3032	RB_CLEAR_NODE(&ref->node);
3033	INIT_LIST_HEAD(&ref->list);
3034	return ref;
3035}
3036
3037static void recorded_ref_free(struct recorded_ref *ref)
3038{
3039	if (!ref)
3040		return;
3041	if (!RB_EMPTY_NODE(&ref->node))
3042		rb_erase(&ref->node, ref->root);
3043	list_del(&ref->list);
3044	fs_path_free(ref->full_path);
3045	kfree(ref);
3046}
3047
3048static void set_ref_path(struct recorded_ref *ref, struct fs_path *path)
3049{
3050	ref->full_path = path;
3051	ref->name = (char *)kbasename(ref->full_path->start);
3052	ref->name_len = ref->full_path->end - ref->name;
3053}
3054
3055static int dup_ref(struct recorded_ref *ref, struct list_head *list)
3056{
3057	struct recorded_ref *new;
3058
3059	new = recorded_ref_alloc();
3060	if (!new)
3061		return -ENOMEM;
3062
3063	new->dir = ref->dir;
3064	new->dir_gen = ref->dir_gen;
3065	list_add_tail(&new->list, list);
3066	return 0;
3067}
3068
3069static void __free_recorded_refs(struct list_head *head)
3070{
3071	struct recorded_ref *cur;
3072
3073	while (!list_empty(head)) {
3074		cur = list_entry(head->next, struct recorded_ref, list);
3075		recorded_ref_free(cur);
3076	}
3077}
3078
3079static void free_recorded_refs(struct send_ctx *sctx)
3080{
3081	__free_recorded_refs(&sctx->new_refs);
3082	__free_recorded_refs(&sctx->deleted_refs);
3083}
3084
3085/*
3086 * Renames/moves a file/dir to its orphan name. Used when the first
3087 * ref of an unprocessed inode gets overwritten and for all non empty
3088 * directories.
3089 */
3090static int orphanize_inode(struct send_ctx *sctx, u64 ino, u64 gen,
3091			  struct fs_path *path)
3092{
3093	int ret;
3094	struct fs_path *orphan;
3095
3096	orphan = fs_path_alloc();
3097	if (!orphan)
3098		return -ENOMEM;
3099
3100	ret = gen_unique_name(sctx, ino, gen, orphan);
3101	if (ret < 0)
3102		goto out;
3103
3104	ret = send_rename(sctx, path, orphan);
3105
3106out:
3107	fs_path_free(orphan);
3108	return ret;
3109}
3110
3111static struct orphan_dir_info *add_orphan_dir_info(struct send_ctx *sctx,
3112						   u64 dir_ino, u64 dir_gen)
3113{
3114	struct rb_node **p = &sctx->orphan_dirs.rb_node;
3115	struct rb_node *parent = NULL;
3116	struct orphan_dir_info *entry, *odi;
3117
3118	while (*p) {
3119		parent = *p;
3120		entry = rb_entry(parent, struct orphan_dir_info, node);
3121		if (dir_ino < entry->ino)
3122			p = &(*p)->rb_left;
3123		else if (dir_ino > entry->ino)
3124			p = &(*p)->rb_right;
3125		else if (dir_gen < entry->gen)
3126			p = &(*p)->rb_left;
3127		else if (dir_gen > entry->gen)
3128			p = &(*p)->rb_right;
3129		else
3130			return entry;
3131	}
3132
3133	odi = kmalloc(sizeof(*odi), GFP_KERNEL);
3134	if (!odi)
3135		return ERR_PTR(-ENOMEM);
3136	odi->ino = dir_ino;
3137	odi->gen = dir_gen;
3138	odi->last_dir_index_offset = 0;
3139	odi->dir_high_seq_ino = 0;
3140
3141	rb_link_node(&odi->node, parent, p);
3142	rb_insert_color(&odi->node, &sctx->orphan_dirs);
3143	return odi;
3144}
3145
3146static struct orphan_dir_info *get_orphan_dir_info(struct send_ctx *sctx,
3147						   u64 dir_ino, u64 gen)
3148{
3149	struct rb_node *n = sctx->orphan_dirs.rb_node;
3150	struct orphan_dir_info *entry;
3151
3152	while (n) {
3153		entry = rb_entry(n, struct orphan_dir_info, node);
3154		if (dir_ino < entry->ino)
3155			n = n->rb_left;
3156		else if (dir_ino > entry->ino)
3157			n = n->rb_right;
3158		else if (gen < entry->gen)
3159			n = n->rb_left;
3160		else if (gen > entry->gen)
3161			n = n->rb_right;
3162		else
3163			return entry;
3164	}
3165	return NULL;
3166}
3167
3168static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen)
3169{
3170	struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino, gen);
3171
3172	return odi != NULL;
3173}
3174
3175static void free_orphan_dir_info(struct send_ctx *sctx,
3176				 struct orphan_dir_info *odi)
3177{
3178	if (!odi)
3179		return;
3180	rb_erase(&odi->node, &sctx->orphan_dirs);
3181	kfree(odi);
3182}
3183
3184/*
3185 * Returns 1 if a directory can be removed at this point in time.
3186 * We check this by iterating all dir items and checking if the inode behind
3187 * the dir item was already processed.
3188 */
3189static int can_rmdir(struct send_ctx *sctx, u64 dir, u64 dir_gen)
3190{
3191	int ret = 0;
3192	int iter_ret = 0;
3193	struct btrfs_root *root = sctx->parent_root;
3194	struct btrfs_path *path;
3195	struct btrfs_key key;
3196	struct btrfs_key found_key;
3197	struct btrfs_key loc;
3198	struct btrfs_dir_item *di;
3199	struct orphan_dir_info *odi = NULL;
3200	u64 dir_high_seq_ino = 0;
3201	u64 last_dir_index_offset = 0;
3202
3203	/*
3204	 * Don't try to rmdir the top/root subvolume dir.
3205	 */
3206	if (dir == BTRFS_FIRST_FREE_OBJECTID)
3207		return 0;
3208
3209	odi = get_orphan_dir_info(sctx, dir, dir_gen);
3210	if (odi && sctx->cur_ino < odi->dir_high_seq_ino)
3211		return 0;
3212
3213	path = alloc_path_for_send();
3214	if (!path)
3215		return -ENOMEM;
3216
3217	if (!odi) {
3218		/*
3219		 * Find the inode number associated with the last dir index
3220		 * entry. This is very likely the inode with the highest number
3221		 * of all inodes that have an entry in the directory. We can
3222		 * then use it to avoid future calls to can_rmdir(), when
3223		 * processing inodes with a lower number, from having to search
3224		 * the parent root b+tree for dir index keys.
3225		 */
3226		key.objectid = dir;
3227		key.type = BTRFS_DIR_INDEX_KEY;
3228		key.offset = (u64)-1;
3229
3230		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3231		if (ret < 0) {
3232			goto out;
3233		} else if (ret > 0) {
3234			/* Can't happen, the root is never empty. */
3235			ASSERT(path->slots[0] > 0);
3236			if (WARN_ON(path->slots[0] == 0)) {
3237				ret = -EUCLEAN;
3238				goto out;
3239			}
3240			path->slots[0]--;
3241		}
3242
3243		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
3244		if (key.objectid != dir || key.type != BTRFS_DIR_INDEX_KEY) {
3245			/* No index keys, dir can be removed. */
3246			ret = 1;
3247			goto out;
3248		}
3249
3250		di = btrfs_item_ptr(path->nodes[0], path->slots[0],
3251				    struct btrfs_dir_item);
3252		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
3253		dir_high_seq_ino = loc.objectid;
3254		if (sctx->cur_ino < dir_high_seq_ino) {
3255			ret = 0;
3256			goto out;
3257		}
3258
3259		btrfs_release_path(path);
3260	}
3261
3262	key.objectid = dir;
3263	key.type = BTRFS_DIR_INDEX_KEY;
3264	key.offset = (odi ? odi->last_dir_index_offset : 0);
3265
3266	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
3267		struct waiting_dir_move *dm;
3268
3269		if (found_key.objectid != key.objectid ||
3270		    found_key.type != key.type)
3271			break;
3272
3273		di = btrfs_item_ptr(path->nodes[0], path->slots[0],
3274				struct btrfs_dir_item);
3275		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
3276
3277		dir_high_seq_ino = max(dir_high_seq_ino, loc.objectid);
3278		last_dir_index_offset = found_key.offset;
3279
3280		dm = get_waiting_dir_move(sctx, loc.objectid);
3281		if (dm) {
3282			dm->rmdir_ino = dir;
3283			dm->rmdir_gen = dir_gen;
3284			ret = 0;
3285			goto out;
3286		}
3287
3288		if (loc.objectid > sctx->cur_ino) {
3289			ret = 0;
3290			goto out;
3291		}
3292	}
3293	if (iter_ret < 0) {
3294		ret = iter_ret;
3295		goto out;
3296	}
3297	free_orphan_dir_info(sctx, odi);
3298
3299	ret = 1;
3300
3301out:
3302	btrfs_free_path(path);
3303
3304	if (ret)
3305		return ret;
3306
3307	if (!odi) {
3308		odi = add_orphan_dir_info(sctx, dir, dir_gen);
3309		if (IS_ERR(odi))
3310			return PTR_ERR(odi);
3311
3312		odi->gen = dir_gen;
3313	}
3314
3315	odi->last_dir_index_offset = last_dir_index_offset;
3316	odi->dir_high_seq_ino = max(odi->dir_high_seq_ino, dir_high_seq_ino);
3317
3318	return 0;
3319}
3320
3321static int is_waiting_for_move(struct send_ctx *sctx, u64 ino)
3322{
3323	struct waiting_dir_move *entry = get_waiting_dir_move(sctx, ino);
3324
3325	return entry != NULL;
3326}
3327
3328static int add_waiting_dir_move(struct send_ctx *sctx, u64 ino, bool orphanized)
3329{
3330	struct rb_node **p = &sctx->waiting_dir_moves.rb_node;
3331	struct rb_node *parent = NULL;
3332	struct waiting_dir_move *entry, *dm;
3333
3334	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
3335	if (!dm)
3336		return -ENOMEM;
3337	dm->ino = ino;
3338	dm->rmdir_ino = 0;
3339	dm->rmdir_gen = 0;
3340	dm->orphanized = orphanized;
3341
3342	while (*p) {
3343		parent = *p;
3344		entry = rb_entry(parent, struct waiting_dir_move, node);
3345		if (ino < entry->ino) {
3346			p = &(*p)->rb_left;
3347		} else if (ino > entry->ino) {
3348			p = &(*p)->rb_right;
3349		} else {
3350			kfree(dm);
3351			return -EEXIST;
3352		}
3353	}
3354
3355	rb_link_node(&dm->node, parent, p);
3356	rb_insert_color(&dm->node, &sctx->waiting_dir_moves);
3357	return 0;
3358}
3359
3360static struct waiting_dir_move *
3361get_waiting_dir_move(struct send_ctx *sctx, u64 ino)
3362{
3363	struct rb_node *n = sctx->waiting_dir_moves.rb_node;
3364	struct waiting_dir_move *entry;
3365
3366	while (n) {
3367		entry = rb_entry(n, struct waiting_dir_move, node);
3368		if (ino < entry->ino)
3369			n = n->rb_left;
3370		else if (ino > entry->ino)
3371			n = n->rb_right;
3372		else
3373			return entry;
3374	}
3375	return NULL;
3376}
3377
3378static void free_waiting_dir_move(struct send_ctx *sctx,
3379				  struct waiting_dir_move *dm)
3380{
3381	if (!dm)
3382		return;
3383	rb_erase(&dm->node, &sctx->waiting_dir_moves);
3384	kfree(dm);
3385}
3386
3387static int add_pending_dir_move(struct send_ctx *sctx,
3388				u64 ino,
3389				u64 ino_gen,
3390				u64 parent_ino,
3391				struct list_head *new_refs,
3392				struct list_head *deleted_refs,
3393				const bool is_orphan)
3394{
3395	struct rb_node **p = &sctx->pending_dir_moves.rb_node;
3396	struct rb_node *parent = NULL;
3397	struct pending_dir_move *entry = NULL, *pm;
3398	struct recorded_ref *cur;
3399	int exists = 0;
3400	int ret;
3401
3402	pm = kmalloc(sizeof(*pm), GFP_KERNEL);
3403	if (!pm)
3404		return -ENOMEM;
3405	pm->parent_ino = parent_ino;
3406	pm->ino = ino;
3407	pm->gen = ino_gen;
3408	INIT_LIST_HEAD(&pm->list);
3409	INIT_LIST_HEAD(&pm->update_refs);
3410	RB_CLEAR_NODE(&pm->node);
3411
3412	while (*p) {
3413		parent = *p;
3414		entry = rb_entry(parent, struct pending_dir_move, node);
3415		if (parent_ino < entry->parent_ino) {
3416			p = &(*p)->rb_left;
3417		} else if (parent_ino > entry->parent_ino) {
3418			p = &(*p)->rb_right;
3419		} else {
3420			exists = 1;
3421			break;
3422		}
3423	}
3424
3425	list_for_each_entry(cur, deleted_refs, list) {
3426		ret = dup_ref(cur, &pm->update_refs);
3427		if (ret < 0)
3428			goto out;
3429	}
3430	list_for_each_entry(cur, new_refs, list) {
3431		ret = dup_ref(cur, &pm->update_refs);
3432		if (ret < 0)
3433			goto out;
3434	}
3435
3436	ret = add_waiting_dir_move(sctx, pm->ino, is_orphan);
3437	if (ret)
3438		goto out;
3439
3440	if (exists) {
3441		list_add_tail(&pm->list, &entry->list);
3442	} else {
3443		rb_link_node(&pm->node, parent, p);
3444		rb_insert_color(&pm->node, &sctx->pending_dir_moves);
3445	}
3446	ret = 0;
3447out:
3448	if (ret) {
3449		__free_recorded_refs(&pm->update_refs);
3450		kfree(pm);
3451	}
3452	return ret;
3453}
3454
3455static struct pending_dir_move *get_pending_dir_moves(struct send_ctx *sctx,
3456						      u64 parent_ino)
3457{
3458	struct rb_node *n = sctx->pending_dir_moves.rb_node;
3459	struct pending_dir_move *entry;
3460
3461	while (n) {
3462		entry = rb_entry(n, struct pending_dir_move, node);
3463		if (parent_ino < entry->parent_ino)
3464			n = n->rb_left;
3465		else if (parent_ino > entry->parent_ino)
3466			n = n->rb_right;
3467		else
3468			return entry;
3469	}
3470	return NULL;
3471}
3472
3473static int path_loop(struct send_ctx *sctx, struct fs_path *name,
3474		     u64 ino, u64 gen, u64 *ancestor_ino)
3475{
3476	int ret = 0;
3477	u64 parent_inode = 0;
3478	u64 parent_gen = 0;
3479	u64 start_ino = ino;
3480
3481	*ancestor_ino = 0;
3482	while (ino != BTRFS_FIRST_FREE_OBJECTID) {
3483		fs_path_reset(name);
3484
3485		if (is_waiting_for_rm(sctx, ino, gen))
3486			break;
3487		if (is_waiting_for_move(sctx, ino)) {
3488			if (*ancestor_ino == 0)
3489				*ancestor_ino = ino;
3490			ret = get_first_ref(sctx->parent_root, ino,
3491					    &parent_inode, &parent_gen, name);
3492		} else {
3493			ret = __get_cur_name_and_parent(sctx, ino, gen,
3494							&parent_inode,
3495							&parent_gen, name);
3496			if (ret > 0) {
3497				ret = 0;
3498				break;
3499			}
3500		}
3501		if (ret < 0)
3502			break;
3503		if (parent_inode == start_ino) {
3504			ret = 1;
3505			if (*ancestor_ino == 0)
3506				*ancestor_ino = ino;
3507			break;
3508		}
3509		ino = parent_inode;
3510		gen = parent_gen;
3511	}
3512	return ret;
3513}
3514
3515static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
3516{
3517	struct fs_path *from_path = NULL;
3518	struct fs_path *to_path = NULL;
3519	struct fs_path *name = NULL;
3520	u64 orig_progress = sctx->send_progress;
3521	struct recorded_ref *cur;
3522	u64 parent_ino, parent_gen;
3523	struct waiting_dir_move *dm = NULL;
3524	u64 rmdir_ino = 0;
3525	u64 rmdir_gen;
3526	u64 ancestor;
3527	bool is_orphan;
3528	int ret;
3529
3530	name = fs_path_alloc();
3531	from_path = fs_path_alloc();
3532	if (!name || !from_path) {
3533		ret = -ENOMEM;
3534		goto out;
3535	}
3536
3537	dm = get_waiting_dir_move(sctx, pm->ino);
3538	ASSERT(dm);
3539	rmdir_ino = dm->rmdir_ino;
3540	rmdir_gen = dm->rmdir_gen;
3541	is_orphan = dm->orphanized;
3542	free_waiting_dir_move(sctx, dm);
3543
3544	if (is_orphan) {
3545		ret = gen_unique_name(sctx, pm->ino,
3546				      pm->gen, from_path);
3547	} else {
3548		ret = get_first_ref(sctx->parent_root, pm->ino,
3549				    &parent_ino, &parent_gen, name);
3550		if (ret < 0)
3551			goto out;
3552		ret = get_cur_path(sctx, parent_ino, parent_gen,
3553				   from_path);
3554		if (ret < 0)
3555			goto out;
3556		ret = fs_path_add_path(from_path, name);
3557	}
3558	if (ret < 0)
3559		goto out;
3560
3561	sctx->send_progress = sctx->cur_ino + 1;
3562	ret = path_loop(sctx, name, pm->ino, pm->gen, &ancestor);
3563	if (ret < 0)
3564		goto out;
3565	if (ret) {
3566		LIST_HEAD(deleted_refs);
3567		ASSERT(ancestor > BTRFS_FIRST_FREE_OBJECTID);
3568		ret = add_pending_dir_move(sctx, pm->ino, pm->gen, ancestor,
3569					   &pm->update_refs, &deleted_refs,
3570					   is_orphan);
3571		if (ret < 0)
3572			goto out;
3573		if (rmdir_ino) {
3574			dm = get_waiting_dir_move(sctx, pm->ino);
3575			ASSERT(dm);
3576			dm->rmdir_ino = rmdir_ino;
3577			dm->rmdir_gen = rmdir_gen;
3578		}
3579		goto out;
3580	}
3581	fs_path_reset(name);
3582	to_path = name;
3583	name = NULL;
3584	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
3585	if (ret < 0)
3586		goto out;
3587
3588	ret = send_rename(sctx, from_path, to_path);
3589	if (ret < 0)
3590		goto out;
3591
3592	if (rmdir_ino) {
3593		struct orphan_dir_info *odi;
3594		u64 gen;
3595
3596		odi = get_orphan_dir_info(sctx, rmdir_ino, rmdir_gen);
3597		if (!odi) {
3598			/* already deleted */
3599			goto finish;
3600		}
3601		gen = odi->gen;
3602
3603		ret = can_rmdir(sctx, rmdir_ino, gen);
3604		if (ret < 0)
3605			goto out;
3606		if (!ret)
3607			goto finish;
3608
3609		name = fs_path_alloc();
3610		if (!name) {
3611			ret = -ENOMEM;
3612			goto out;
3613		}
3614		ret = get_cur_path(sctx, rmdir_ino, gen, name);
3615		if (ret < 0)
3616			goto out;
3617		ret = send_rmdir(sctx, name);
3618		if (ret < 0)
3619			goto out;
3620	}
3621
3622finish:
3623	ret = cache_dir_utimes(sctx, pm->ino, pm->gen);
3624	if (ret < 0)
3625		goto out;
3626
3627	/*
3628	 * After rename/move, need to update the utimes of both new parent(s)
3629	 * and old parent(s).
3630	 */
3631	list_for_each_entry(cur, &pm->update_refs, list) {
3632		/*
3633		 * The parent inode might have been deleted in the send snapshot
3634		 */
3635		ret = get_inode_info(sctx->send_root, cur->dir, NULL);
3636		if (ret == -ENOENT) {
3637			ret = 0;
3638			continue;
3639		}
3640		if (ret < 0)
3641			goto out;
3642
3643		ret = cache_dir_utimes(sctx, cur->dir, cur->dir_gen);
3644		if (ret < 0)
3645			goto out;
3646	}
3647
3648out:
3649	fs_path_free(name);
3650	fs_path_free(from_path);
3651	fs_path_free(to_path);
3652	sctx->send_progress = orig_progress;
3653
3654	return ret;
3655}
3656
3657static void free_pending_move(struct send_ctx *sctx, struct pending_dir_move *m)
3658{
3659	if (!list_empty(&m->list))
3660		list_del(&m->list);
3661	if (!RB_EMPTY_NODE(&m->node))
3662		rb_erase(&m->node, &sctx->pending_dir_moves);
3663	__free_recorded_refs(&m->update_refs);
3664	kfree(m);
3665}
3666
3667static void tail_append_pending_moves(struct send_ctx *sctx,
3668				      struct pending_dir_move *moves,
3669				      struct list_head *stack)
3670{
3671	if (list_empty(&moves->list)) {
3672		list_add_tail(&moves->list, stack);
3673	} else {
3674		LIST_HEAD(list);
3675		list_splice_init(&moves->list, &list);
3676		list_add_tail(&moves->list, stack);
3677		list_splice_tail(&list, stack);
3678	}
3679	if (!RB_EMPTY_NODE(&moves->node)) {
3680		rb_erase(&moves->node, &sctx->pending_dir_moves);
3681		RB_CLEAR_NODE(&moves->node);
3682	}
3683}
3684
3685static int apply_children_dir_moves(struct send_ctx *sctx)
3686{
3687	struct pending_dir_move *pm;
3688	LIST_HEAD(stack);
3689	u64 parent_ino = sctx->cur_ino;
3690	int ret = 0;
3691
3692	pm = get_pending_dir_moves(sctx, parent_ino);
3693	if (!pm)
3694		return 0;
3695
3696	tail_append_pending_moves(sctx, pm, &stack);
3697
3698	while (!list_empty(&stack)) {
3699		pm = list_first_entry(&stack, struct pending_dir_move, list);
3700		parent_ino = pm->ino;
3701		ret = apply_dir_move(sctx, pm);
3702		free_pending_move(sctx, pm);
3703		if (ret)
3704			goto out;
3705		pm = get_pending_dir_moves(sctx, parent_ino);
3706		if (pm)
3707			tail_append_pending_moves(sctx, pm, &stack);
3708	}
3709	return 0;
3710
3711out:
3712	while (!list_empty(&stack)) {
3713		pm = list_first_entry(&stack, struct pending_dir_move, list);
3714		free_pending_move(sctx, pm);
3715	}
3716	return ret;
3717}
3718
3719/*
3720 * We might need to delay a directory rename even when no ancestor directory
3721 * (in the send root) with a higher inode number than ours (sctx->cur_ino) was
3722 * renamed. This happens when we rename a directory to the old name (the name
3723 * in the parent root) of some other unrelated directory that got its rename
3724 * delayed due to some ancestor with higher number that got renamed.
3725 *
3726 * Example:
3727 *
3728 * Parent snapshot:
3729 * .                                       (ino 256)
3730 * |---- a/                                (ino 257)
3731 * |     |---- file                        (ino 260)
3732 * |
3733 * |---- b/                                (ino 258)
3734 * |---- c/                                (ino 259)
3735 *
3736 * Send snapshot:
3737 * .                                       (ino 256)
3738 * |---- a/                                (ino 258)
3739 * |---- x/                                (ino 259)
3740 *       |---- y/                          (ino 257)
3741 *             |----- file                 (ino 260)
3742 *
3743 * Here we can not rename 258 from 'b' to 'a' without the rename of inode 257
3744 * from 'a' to 'x/y' happening first, which in turn depends on the rename of
3745 * inode 259 from 'c' to 'x'. So the order of rename commands the send stream
3746 * must issue is:
3747 *
3748 * 1 - rename 259 from 'c' to 'x'
3749 * 2 - rename 257 from 'a' to 'x/y'
3750 * 3 - rename 258 from 'b' to 'a'
3751 *
3752 * Returns 1 if the rename of sctx->cur_ino needs to be delayed, 0 if it can
3753 * be done right away and < 0 on error.
3754 */
3755static int wait_for_dest_dir_move(struct send_ctx *sctx,
3756				  struct recorded_ref *parent_ref,
3757				  const bool is_orphan)
3758{
3759	struct btrfs_fs_info *fs_info = sctx->parent_root->fs_info;
3760	struct btrfs_path *path;
3761	struct btrfs_key key;
3762	struct btrfs_key di_key;
3763	struct btrfs_dir_item *di;
3764	u64 left_gen;
3765	u64 right_gen;
3766	int ret = 0;
3767	struct waiting_dir_move *wdm;
3768
3769	if (RB_EMPTY_ROOT(&sctx->waiting_dir_moves))
3770		return 0;
3771
3772	path = alloc_path_for_send();
3773	if (!path)
3774		return -ENOMEM;
3775
3776	key.objectid = parent_ref->dir;
3777	key.type = BTRFS_DIR_ITEM_KEY;
3778	key.offset = btrfs_name_hash(parent_ref->name, parent_ref->name_len);
3779
3780	ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
3781	if (ret < 0) {
3782		goto out;
3783	} else if (ret > 0) {
3784		ret = 0;
3785		goto out;
3786	}
3787
3788	di = btrfs_match_dir_item_name(fs_info, path, parent_ref->name,
3789				       parent_ref->name_len);
3790	if (!di) {
3791		ret = 0;
3792		goto out;
3793	}
3794	/*
3795	 * di_key.objectid has the number of the inode that has a dentry in the
3796	 * parent directory with the same name that sctx->cur_ino is being
3797	 * renamed to. We need to check if that inode is in the send root as
3798	 * well and if it is currently marked as an inode with a pending rename,
3799	 * if it is, we need to delay the rename of sctx->cur_ino as well, so
3800	 * that it happens after that other inode is renamed.
3801	 */
3802	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &di_key);
3803	if (di_key.type != BTRFS_INODE_ITEM_KEY) {
3804		ret = 0;
3805		goto out;
3806	}
3807
3808	ret = get_inode_gen(sctx->parent_root, di_key.objectid, &left_gen);
3809	if (ret < 0)
3810		goto out;
3811	ret = get_inode_gen(sctx->send_root, di_key.objectid, &right_gen);
3812	if (ret < 0) {
3813		if (ret == -ENOENT)
3814			ret = 0;
3815		goto out;
3816	}
3817
3818	/* Different inode, no need to delay the rename of sctx->cur_ino */
3819	if (right_gen != left_gen) {
3820		ret = 0;
3821		goto out;
3822	}
3823
3824	wdm = get_waiting_dir_move(sctx, di_key.objectid);
3825	if (wdm && !wdm->orphanized) {
3826		ret = add_pending_dir_move(sctx,
3827					   sctx->cur_ino,
3828					   sctx->cur_inode_gen,
3829					   di_key.objectid,
3830					   &sctx->new_refs,
3831					   &sctx->deleted_refs,
3832					   is_orphan);
3833		if (!ret)
3834			ret = 1;
3835	}
3836out:
3837	btrfs_free_path(path);
3838	return ret;
3839}
3840
3841/*
3842 * Check if inode ino2, or any of its ancestors, is inode ino1.
3843 * Return 1 if true, 0 if false and < 0 on error.
3844 */
3845static int check_ino_in_path(struct btrfs_root *root,
3846			     const u64 ino1,
3847			     const u64 ino1_gen,
3848			     const u64 ino2,
3849			     const u64 ino2_gen,
3850			     struct fs_path *fs_path)
3851{
3852	u64 ino = ino2;
3853
3854	if (ino1 == ino2)
3855		return ino1_gen == ino2_gen;
3856
3857	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3858		u64 parent;
3859		u64 parent_gen;
3860		int ret;
3861
3862		fs_path_reset(fs_path);
3863		ret = get_first_ref(root, ino, &parent, &parent_gen, fs_path);
3864		if (ret < 0)
3865			return ret;
3866		if (parent == ino1)
3867			return parent_gen == ino1_gen;
3868		ino = parent;
3869	}
3870	return 0;
3871}
3872
3873/*
3874 * Check if inode ino1 is an ancestor of inode ino2 in the given root for any
3875 * possible path (in case ino2 is not a directory and has multiple hard links).
3876 * Return 1 if true, 0 if false and < 0 on error.
3877 */
3878static int is_ancestor(struct btrfs_root *root,
3879		       const u64 ino1,
3880		       const u64 ino1_gen,
3881		       const u64 ino2,
3882		       struct fs_path *fs_path)
3883{
3884	bool free_fs_path = false;
3885	int ret = 0;
3886	int iter_ret = 0;
3887	struct btrfs_path *path = NULL;
3888	struct btrfs_key key;
3889
3890	if (!fs_path) {
3891		fs_path = fs_path_alloc();
3892		if (!fs_path)
3893			return -ENOMEM;
3894		free_fs_path = true;
3895	}
3896
3897	path = alloc_path_for_send();
3898	if (!path) {
3899		ret = -ENOMEM;
3900		goto out;
3901	}
3902
3903	key.objectid = ino2;
3904	key.type = BTRFS_INODE_REF_KEY;
3905	key.offset = 0;
3906
3907	btrfs_for_each_slot(root, &key, &key, path, iter_ret) {
3908		struct extent_buffer *leaf = path->nodes[0];
3909		int slot = path->slots[0];
3910		u32 cur_offset = 0;
3911		u32 item_size;
3912
3913		if (key.objectid != ino2)
3914			break;
3915		if (key.type != BTRFS_INODE_REF_KEY &&
3916		    key.type != BTRFS_INODE_EXTREF_KEY)
3917			break;
3918
3919		item_size = btrfs_item_size(leaf, slot);
3920		while (cur_offset < item_size) {
3921			u64 parent;
3922			u64 parent_gen;
3923
3924			if (key.type == BTRFS_INODE_EXTREF_KEY) {
3925				unsigned long ptr;
3926				struct btrfs_inode_extref *extref;
3927
3928				ptr = btrfs_item_ptr_offset(leaf, slot);
3929				extref = (struct btrfs_inode_extref *)
3930					(ptr + cur_offset);
3931				parent = btrfs_inode_extref_parent(leaf,
3932								   extref);
3933				cur_offset += sizeof(*extref);
3934				cur_offset += btrfs_inode_extref_name_len(leaf,
3935								  extref);
3936			} else {
3937				parent = key.offset;
3938				cur_offset = item_size;
3939			}
3940
3941			ret = get_inode_gen(root, parent, &parent_gen);
3942			if (ret < 0)
3943				goto out;
3944			ret = check_ino_in_path(root, ino1, ino1_gen,
3945						parent, parent_gen, fs_path);
3946			if (ret)
3947				goto out;
3948		}
3949	}
3950	ret = 0;
3951	if (iter_ret < 0)
3952		ret = iter_ret;
3953
3954out:
3955	btrfs_free_path(path);
3956	if (free_fs_path)
3957		fs_path_free(fs_path);
3958	return ret;
3959}
3960
3961static int wait_for_parent_move(struct send_ctx *sctx,
3962				struct recorded_ref *parent_ref,
3963				const bool is_orphan)
3964{
3965	int ret = 0;
3966	u64 ino = parent_ref->dir;
3967	u64 ino_gen = parent_ref->dir_gen;
3968	u64 parent_ino_before, parent_ino_after;
3969	struct fs_path *path_before = NULL;
3970	struct fs_path *path_after = NULL;
3971	int len1, len2;
3972
3973	path_after = fs_path_alloc();
3974	path_before = fs_path_alloc();
3975	if (!path_after || !path_before) {
3976		ret = -ENOMEM;
3977		goto out;
3978	}
3979
3980	/*
3981	 * Our current directory inode may not yet be renamed/moved because some
3982	 * ancestor (immediate or not) has to be renamed/moved first. So find if
3983	 * such ancestor exists and make sure our own rename/move happens after
3984	 * that ancestor is processed to avoid path build infinite loops (done
3985	 * at get_cur_path()).
3986	 */
3987	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3988		u64 parent_ino_after_gen;
3989
3990		if (is_waiting_for_move(sctx, ino)) {
3991			/*
3992			 * If the current inode is an ancestor of ino in the
3993			 * parent root, we need to delay the rename of the
3994			 * current inode, otherwise don't delayed the rename
3995			 * because we can end up with a circular dependency
3996			 * of renames, resulting in some directories never
3997			 * getting the respective rename operations issued in
3998			 * the send stream or getting into infinite path build
3999			 * loops.
4000			 */
4001			ret = is_ancestor(sctx->parent_root,
4002					  sctx->cur_ino, sctx->cur_inode_gen,
4003					  ino, path_before);
4004			if (ret)
4005				break;
4006		}
4007
4008		fs_path_reset(path_before);
4009		fs_path_reset(path_after);
4010
4011		ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
4012				    &parent_ino_after_gen, path_after);
4013		if (ret < 0)
4014			goto out;
4015		ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
4016				    NULL, path_before);
4017		if (ret < 0 && ret != -ENOENT) {
4018			goto out;
4019		} else if (ret == -ENOENT) {
4020			ret = 0;
4021			break;
4022		}
4023
4024		len1 = fs_path_len(path_before);
4025		len2 = fs_path_len(path_after);
4026		if (ino > sctx->cur_ino &&
4027		    (parent_ino_before != parent_ino_after || len1 != len2 ||
4028		     memcmp(path_before->start, path_after->start, len1))) {
4029			u64 parent_ino_gen;
4030
4031			ret = get_inode_gen(sctx->parent_root, ino, &parent_ino_gen);
4032			if (ret < 0)
4033				goto out;
4034			if (ino_gen == parent_ino_gen) {
4035				ret = 1;
4036				break;
4037			}
4038		}
4039		ino = parent_ino_after;
4040		ino_gen = parent_ino_after_gen;
4041	}
4042
4043out:
4044	fs_path_free(path_before);
4045	fs_path_free(path_after);
4046
4047	if (ret == 1) {
4048		ret = add_pending_dir_move(sctx,
4049					   sctx->cur_ino,
4050					   sctx->cur_inode_gen,
4051					   ino,
4052					   &sctx->new_refs,
4053					   &sctx->deleted_refs,
4054					   is_orphan);
4055		if (!ret)
4056			ret = 1;
4057	}
4058
4059	return ret;
4060}
4061
4062static int update_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
4063{
4064	int ret;
4065	struct fs_path *new_path;
4066
4067	/*
4068	 * Our reference's name member points to its full_path member string, so
4069	 * we use here a new path.
4070	 */
4071	new_path = fs_path_alloc();
4072	if (!new_path)
4073		return -ENOMEM;
4074
4075	ret = get_cur_path(sctx, ref->dir, ref->dir_gen, new_path);
4076	if (ret < 0) {
4077		fs_path_free(new_path);
4078		return ret;
4079	}
4080	ret = fs_path_add(new_path, ref->name, ref->name_len);
4081	if (ret < 0) {
4082		fs_path_free(new_path);
4083		return ret;
4084	}
4085
4086	fs_path_free(ref->full_path);
4087	set_ref_path(ref, new_path);
4088
4089	return 0;
4090}
4091
4092/*
4093 * When processing the new references for an inode we may orphanize an existing
4094 * directory inode because its old name conflicts with one of the new references
4095 * of the current inode. Later, when processing another new reference of our
4096 * inode, we might need to orphanize another inode, but the path we have in the
4097 * reference reflects the pre-orphanization name of the directory we previously
4098 * orphanized. For example:
4099 *
4100 * parent snapshot looks like:
4101 *
4102 * .                                     (ino 256)
4103 * |----- f1                             (ino 257)
4104 * |----- f2                             (ino 258)
4105 * |----- d1/                            (ino 259)
4106 *        |----- d2/                     (ino 260)
4107 *
4108 * send snapshot looks like:
4109 *
4110 * .                                     (ino 256)
4111 * |----- d1                             (ino 258)
4112 * |----- f2/                            (ino 259)
4113 *        |----- f2_link/                (ino 260)
4114 *        |       |----- f1              (ino 257)
4115 *        |
4116 *        |----- d2                      (ino 258)
4117 *
4118 * When processing inode 257 we compute the name for inode 259 as "d1", and we
4119 * cache it in the name cache. Later when we start processing inode 258, when
4120 * collecting all its new references we set a full path of "d1/d2" for its new
4121 * reference with name "d2". When we start processing the new references we
4122 * start by processing the new reference with name "d1", and this results in
4123 * orphanizing inode 259, since its old reference causes a conflict. Then we
4124 * move on the next new reference, with name "d2", and we find out we must
4125 * orphanize inode 260, as its old reference conflicts with ours - but for the
4126 * orphanization we use a source path corresponding to the path we stored in the
4127 * new reference, which is "d1/d2" and not "o259-6-0/d2" - this makes the
4128 * receiver fail since the path component "d1/" no longer exists, it was renamed
4129 * to "o259-6-0/" when processing the previous new reference. So in this case we
4130 * must recompute the path in the new reference and use it for the new
4131 * orphanization operation.
4132 */
4133static int refresh_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
4134{
4135	char *name;
4136	int ret;
4137
4138	name = kmemdup(ref->name, ref->name_len, GFP_KERNEL);
4139	if (!name)
4140		return -ENOMEM;
4141
4142	fs_path_reset(ref->full_path);
4143	ret = get_cur_path(sctx, ref->dir, ref->dir_gen, ref->full_path);
4144	if (ret < 0)
4145		goto out;
4146
4147	ret = fs_path_add(ref->full_path, name, ref->name_len);
4148	if (ret < 0)
4149		goto out;
4150
4151	/* Update the reference's base name pointer. */
4152	set_ref_path(ref, ref->full_path);
4153out:
4154	kfree(name);
4155	return ret;
4156}
4157
4158/*
4159 * This does all the move/link/unlink/rmdir magic.
4160 */
4161static int process_recorded_refs(struct send_ctx *sctx, int *pending_move)
4162{
4163	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
4164	int ret = 0;
4165	struct recorded_ref *cur;
4166	struct recorded_ref *cur2;
4167	LIST_HEAD(check_dirs);
4168	struct fs_path *valid_path = NULL;
4169	u64 ow_inode = 0;
4170	u64 ow_gen;
4171	u64 ow_mode;
4172	int did_overwrite = 0;
4173	int is_orphan = 0;
4174	u64 last_dir_ino_rm = 0;
4175	bool can_rename = true;
4176	bool orphanized_dir = false;
4177	bool orphanized_ancestor = false;
4178
4179	btrfs_debug(fs_info, "process_recorded_refs %llu", sctx->cur_ino);
4180
4181	/*
4182	 * This should never happen as the root dir always has the same ref
4183	 * which is always '..'
4184	 */
4185	BUG_ON(sctx->cur_ino <= BTRFS_FIRST_FREE_OBJECTID);
 
 
 
 
 
 
4186
4187	valid_path = fs_path_alloc();
4188	if (!valid_path) {
4189		ret = -ENOMEM;
4190		goto out;
4191	}
4192
4193	/*
4194	 * First, check if the first ref of the current inode was overwritten
4195	 * before. If yes, we know that the current inode was already orphanized
4196	 * and thus use the orphan name. If not, we can use get_cur_path to
4197	 * get the path of the first ref as it would like while receiving at
4198	 * this point in time.
4199	 * New inodes are always orphan at the beginning, so force to use the
4200	 * orphan name in this case.
4201	 * The first ref is stored in valid_path and will be updated if it
4202	 * gets moved around.
4203	 */
4204	if (!sctx->cur_inode_new) {
4205		ret = did_overwrite_first_ref(sctx, sctx->cur_ino,
4206				sctx->cur_inode_gen);
4207		if (ret < 0)
4208			goto out;
4209		if (ret)
4210			did_overwrite = 1;
4211	}
4212	if (sctx->cur_inode_new || did_overwrite) {
4213		ret = gen_unique_name(sctx, sctx->cur_ino,
4214				sctx->cur_inode_gen, valid_path);
4215		if (ret < 0)
4216			goto out;
4217		is_orphan = 1;
4218	} else {
4219		ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
4220				valid_path);
4221		if (ret < 0)
4222			goto out;
4223	}
4224
4225	/*
4226	 * Before doing any rename and link operations, do a first pass on the
4227	 * new references to orphanize any unprocessed inodes that may have a
4228	 * reference that conflicts with one of the new references of the current
4229	 * inode. This needs to happen first because a new reference may conflict
4230	 * with the old reference of a parent directory, so we must make sure
4231	 * that the path used for link and rename commands don't use an
4232	 * orphanized name when an ancestor was not yet orphanized.
4233	 *
4234	 * Example:
4235	 *
4236	 * Parent snapshot:
4237	 *
4238	 * .                                                      (ino 256)
4239	 * |----- testdir/                                        (ino 259)
4240	 * |          |----- a                                    (ino 257)
4241	 * |
4242	 * |----- b                                               (ino 258)
4243	 *
4244	 * Send snapshot:
4245	 *
4246	 * .                                                      (ino 256)
4247	 * |----- testdir_2/                                      (ino 259)
4248	 * |          |----- a                                    (ino 260)
4249	 * |
4250	 * |----- testdir                                         (ino 257)
4251	 * |----- b                                               (ino 257)
4252	 * |----- b2                                              (ino 258)
4253	 *
4254	 * Processing the new reference for inode 257 with name "b" may happen
4255	 * before processing the new reference with name "testdir". If so, we
4256	 * must make sure that by the time we send a link command to create the
4257	 * hard link "b", inode 259 was already orphanized, since the generated
4258	 * path in "valid_path" already contains the orphanized name for 259.
4259	 * We are processing inode 257, so only later when processing 259 we do
4260	 * the rename operation to change its temporary (orphanized) name to
4261	 * "testdir_2".
4262	 */
4263	list_for_each_entry(cur, &sctx->new_refs, list) {
4264		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen, NULL, NULL);
4265		if (ret < 0)
4266			goto out;
4267		if (ret == inode_state_will_create)
4268			continue;
4269
4270		/*
4271		 * Check if this new ref would overwrite the first ref of another
4272		 * unprocessed inode. If yes, orphanize the overwritten inode.
4273		 * If we find an overwritten ref that is not the first ref,
4274		 * simply unlink it.
4275		 */
4276		ret = will_overwrite_ref(sctx, cur->dir, cur->dir_gen,
4277				cur->name, cur->name_len,
4278				&ow_inode, &ow_gen, &ow_mode);
4279		if (ret < 0)
4280			goto out;
4281		if (ret) {
4282			ret = is_first_ref(sctx->parent_root,
4283					   ow_inode, cur->dir, cur->name,
4284					   cur->name_len);
4285			if (ret < 0)
4286				goto out;
4287			if (ret) {
4288				struct name_cache_entry *nce;
4289				struct waiting_dir_move *wdm;
4290
4291				if (orphanized_dir) {
4292					ret = refresh_ref_path(sctx, cur);
4293					if (ret < 0)
4294						goto out;
4295				}
4296
4297				ret = orphanize_inode(sctx, ow_inode, ow_gen,
4298						cur->full_path);
4299				if (ret < 0)
4300					goto out;
4301				if (S_ISDIR(ow_mode))
4302					orphanized_dir = true;
4303
4304				/*
4305				 * If ow_inode has its rename operation delayed
4306				 * make sure that its orphanized name is used in
4307				 * the source path when performing its rename
4308				 * operation.
4309				 */
4310				wdm = get_waiting_dir_move(sctx, ow_inode);
4311				if (wdm)
4312					wdm->orphanized = true;
4313
4314				/*
4315				 * Make sure we clear our orphanized inode's
4316				 * name from the name cache. This is because the
4317				 * inode ow_inode might be an ancestor of some
4318				 * other inode that will be orphanized as well
4319				 * later and has an inode number greater than
4320				 * sctx->send_progress. We need to prevent
4321				 * future name lookups from using the old name
4322				 * and get instead the orphan name.
4323				 */
4324				nce = name_cache_search(sctx, ow_inode, ow_gen);
4325				if (nce)
4326					btrfs_lru_cache_remove(&sctx->name_cache,
4327							       &nce->entry);
4328
4329				/*
4330				 * ow_inode might currently be an ancestor of
4331				 * cur_ino, therefore compute valid_path (the
4332				 * current path of cur_ino) again because it
4333				 * might contain the pre-orphanization name of
4334				 * ow_inode, which is no longer valid.
4335				 */
4336				ret = is_ancestor(sctx->parent_root,
4337						  ow_inode, ow_gen,
4338						  sctx->cur_ino, NULL);
4339				if (ret > 0) {
4340					orphanized_ancestor = true;
4341					fs_path_reset(valid_path);
4342					ret = get_cur_path(sctx, sctx->cur_ino,
4343							   sctx->cur_inode_gen,
4344							   valid_path);
4345				}
4346				if (ret < 0)
4347					goto out;
4348			} else {
4349				/*
4350				 * If we previously orphanized a directory that
4351				 * collided with a new reference that we already
4352				 * processed, recompute the current path because
4353				 * that directory may be part of the path.
4354				 */
4355				if (orphanized_dir) {
4356					ret = refresh_ref_path(sctx, cur);
4357					if (ret < 0)
4358						goto out;
4359				}
4360				ret = send_unlink(sctx, cur->full_path);
4361				if (ret < 0)
4362					goto out;
4363			}
4364		}
4365
4366	}
4367
4368	list_for_each_entry(cur, &sctx->new_refs, list) {
4369		/*
4370		 * We may have refs where the parent directory does not exist
4371		 * yet. This happens if the parent directories inum is higher
4372		 * than the current inum. To handle this case, we create the
4373		 * parent directory out of order. But we need to check if this
4374		 * did already happen before due to other refs in the same dir.
4375		 */
4376		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen, NULL, NULL);
4377		if (ret < 0)
4378			goto out;
4379		if (ret == inode_state_will_create) {
4380			ret = 0;
4381			/*
4382			 * First check if any of the current inodes refs did
4383			 * already create the dir.
4384			 */
4385			list_for_each_entry(cur2, &sctx->new_refs, list) {
4386				if (cur == cur2)
4387					break;
4388				if (cur2->dir == cur->dir) {
4389					ret = 1;
4390					break;
4391				}
4392			}
4393
4394			/*
4395			 * If that did not happen, check if a previous inode
4396			 * did already create the dir.
4397			 */
4398			if (!ret)
4399				ret = did_create_dir(sctx, cur->dir);
4400			if (ret < 0)
4401				goto out;
4402			if (!ret) {
4403				ret = send_create_inode(sctx, cur->dir);
4404				if (ret < 0)
4405					goto out;
4406				cache_dir_created(sctx, cur->dir);
4407			}
4408		}
4409
4410		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root) {
4411			ret = wait_for_dest_dir_move(sctx, cur, is_orphan);
4412			if (ret < 0)
4413				goto out;
4414			if (ret == 1) {
4415				can_rename = false;
4416				*pending_move = 1;
4417			}
4418		}
4419
4420		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root &&
4421		    can_rename) {
4422			ret = wait_for_parent_move(sctx, cur, is_orphan);
4423			if (ret < 0)
4424				goto out;
4425			if (ret == 1) {
4426				can_rename = false;
4427				*pending_move = 1;
4428			}
4429		}
4430
4431		/*
4432		 * link/move the ref to the new place. If we have an orphan
4433		 * inode, move it and update valid_path. If not, link or move
4434		 * it depending on the inode mode.
4435		 */
4436		if (is_orphan && can_rename) {
4437			ret = send_rename(sctx, valid_path, cur->full_path);
4438			if (ret < 0)
4439				goto out;
4440			is_orphan = 0;
4441			ret = fs_path_copy(valid_path, cur->full_path);
4442			if (ret < 0)
4443				goto out;
4444		} else if (can_rename) {
4445			if (S_ISDIR(sctx->cur_inode_mode)) {
4446				/*
4447				 * Dirs can't be linked, so move it. For moved
4448				 * dirs, we always have one new and one deleted
4449				 * ref. The deleted ref is ignored later.
4450				 */
4451				ret = send_rename(sctx, valid_path,
4452						  cur->full_path);
4453				if (!ret)
4454					ret = fs_path_copy(valid_path,
4455							   cur->full_path);
4456				if (ret < 0)
4457					goto out;
4458			} else {
4459				/*
4460				 * We might have previously orphanized an inode
4461				 * which is an ancestor of our current inode,
4462				 * so our reference's full path, which was
4463				 * computed before any such orphanizations, must
4464				 * be updated.
4465				 */
4466				if (orphanized_dir) {
4467					ret = update_ref_path(sctx, cur);
4468					if (ret < 0)
4469						goto out;
4470				}
4471				ret = send_link(sctx, cur->full_path,
4472						valid_path);
4473				if (ret < 0)
4474					goto out;
4475			}
4476		}
4477		ret = dup_ref(cur, &check_dirs);
4478		if (ret < 0)
4479			goto out;
4480	}
4481
4482	if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_deleted) {
4483		/*
4484		 * Check if we can already rmdir the directory. If not,
4485		 * orphanize it. For every dir item inside that gets deleted
4486		 * later, we do this check again and rmdir it then if possible.
4487		 * See the use of check_dirs for more details.
4488		 */
4489		ret = can_rmdir(sctx, sctx->cur_ino, sctx->cur_inode_gen);
4490		if (ret < 0)
4491			goto out;
4492		if (ret) {
4493			ret = send_rmdir(sctx, valid_path);
4494			if (ret < 0)
4495				goto out;
4496		} else if (!is_orphan) {
4497			ret = orphanize_inode(sctx, sctx->cur_ino,
4498					sctx->cur_inode_gen, valid_path);
4499			if (ret < 0)
4500				goto out;
4501			is_orphan = 1;
4502		}
4503
4504		list_for_each_entry(cur, &sctx->deleted_refs, list) {
4505			ret = dup_ref(cur, &check_dirs);
4506			if (ret < 0)
4507				goto out;
4508		}
4509	} else if (S_ISDIR(sctx->cur_inode_mode) &&
4510		   !list_empty(&sctx->deleted_refs)) {
4511		/*
4512		 * We have a moved dir. Add the old parent to check_dirs
4513		 */
4514		cur = list_entry(sctx->deleted_refs.next, struct recorded_ref,
4515				list);
4516		ret = dup_ref(cur, &check_dirs);
4517		if (ret < 0)
4518			goto out;
4519	} else if (!S_ISDIR(sctx->cur_inode_mode)) {
4520		/*
4521		 * We have a non dir inode. Go through all deleted refs and
4522		 * unlink them if they were not already overwritten by other
4523		 * inodes.
4524		 */
4525		list_for_each_entry(cur, &sctx->deleted_refs, list) {
4526			ret = did_overwrite_ref(sctx, cur->dir, cur->dir_gen,
4527					sctx->cur_ino, sctx->cur_inode_gen,
4528					cur->name, cur->name_len);
4529			if (ret < 0)
4530				goto out;
4531			if (!ret) {
4532				/*
4533				 * If we orphanized any ancestor before, we need
4534				 * to recompute the full path for deleted names,
4535				 * since any such path was computed before we
4536				 * processed any references and orphanized any
4537				 * ancestor inode.
4538				 */
4539				if (orphanized_ancestor) {
4540					ret = update_ref_path(sctx, cur);
4541					if (ret < 0)
4542						goto out;
4543				}
4544				ret = send_unlink(sctx, cur->full_path);
4545				if (ret < 0)
4546					goto out;
4547			}
4548			ret = dup_ref(cur, &check_dirs);
4549			if (ret < 0)
4550				goto out;
4551		}
4552		/*
4553		 * If the inode is still orphan, unlink the orphan. This may
4554		 * happen when a previous inode did overwrite the first ref
4555		 * of this inode and no new refs were added for the current
4556		 * inode. Unlinking does not mean that the inode is deleted in
4557		 * all cases. There may still be links to this inode in other
4558		 * places.
4559		 */
4560		if (is_orphan) {
4561			ret = send_unlink(sctx, valid_path);
4562			if (ret < 0)
4563				goto out;
4564		}
4565	}
4566
4567	/*
4568	 * We did collect all parent dirs where cur_inode was once located. We
4569	 * now go through all these dirs and check if they are pending for
4570	 * deletion and if it's finally possible to perform the rmdir now.
4571	 * We also update the inode stats of the parent dirs here.
4572	 */
4573	list_for_each_entry(cur, &check_dirs, list) {
4574		/*
4575		 * In case we had refs into dirs that were not processed yet,
4576		 * we don't need to do the utime and rmdir logic for these dirs.
4577		 * The dir will be processed later.
4578		 */
4579		if (cur->dir > sctx->cur_ino)
4580			continue;
4581
4582		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen, NULL, NULL);
4583		if (ret < 0)
4584			goto out;
4585
4586		if (ret == inode_state_did_create ||
4587		    ret == inode_state_no_change) {
4588			ret = cache_dir_utimes(sctx, cur->dir, cur->dir_gen);
4589			if (ret < 0)
4590				goto out;
4591		} else if (ret == inode_state_did_delete &&
4592			   cur->dir != last_dir_ino_rm) {
4593			ret = can_rmdir(sctx, cur->dir, cur->dir_gen);
4594			if (ret < 0)
4595				goto out;
4596			if (ret) {
4597				ret = get_cur_path(sctx, cur->dir,
4598						   cur->dir_gen, valid_path);
4599				if (ret < 0)
4600					goto out;
4601				ret = send_rmdir(sctx, valid_path);
4602				if (ret < 0)
4603					goto out;
4604				last_dir_ino_rm = cur->dir;
4605			}
4606		}
4607	}
4608
4609	ret = 0;
4610
4611out:
4612	__free_recorded_refs(&check_dirs);
4613	free_recorded_refs(sctx);
4614	fs_path_free(valid_path);
4615	return ret;
4616}
4617
4618static int rbtree_ref_comp(const void *k, const struct rb_node *node)
4619{
4620	const struct recorded_ref *data = k;
4621	const struct recorded_ref *ref = rb_entry(node, struct recorded_ref, node);
4622	int result;
4623
4624	if (data->dir > ref->dir)
4625		return 1;
4626	if (data->dir < ref->dir)
4627		return -1;
4628	if (data->dir_gen > ref->dir_gen)
4629		return 1;
4630	if (data->dir_gen < ref->dir_gen)
4631		return -1;
4632	if (data->name_len > ref->name_len)
4633		return 1;
4634	if (data->name_len < ref->name_len)
4635		return -1;
4636	result = strcmp(data->name, ref->name);
4637	if (result > 0)
4638		return 1;
4639	if (result < 0)
4640		return -1;
4641	return 0;
4642}
4643
4644static bool rbtree_ref_less(struct rb_node *node, const struct rb_node *parent)
4645{
4646	const struct recorded_ref *entry = rb_entry(node, struct recorded_ref, node);
4647
4648	return rbtree_ref_comp(entry, parent) < 0;
4649}
4650
4651static int record_ref_in_tree(struct rb_root *root, struct list_head *refs,
4652			      struct fs_path *name, u64 dir, u64 dir_gen,
4653			      struct send_ctx *sctx)
4654{
4655	int ret = 0;
4656	struct fs_path *path = NULL;
4657	struct recorded_ref *ref = NULL;
4658
4659	path = fs_path_alloc();
4660	if (!path) {
4661		ret = -ENOMEM;
4662		goto out;
4663	}
4664
4665	ref = recorded_ref_alloc();
4666	if (!ref) {
4667		ret = -ENOMEM;
4668		goto out;
4669	}
4670
4671	ret = get_cur_path(sctx, dir, dir_gen, path);
4672	if (ret < 0)
4673		goto out;
4674	ret = fs_path_add_path(path, name);
4675	if (ret < 0)
4676		goto out;
4677
4678	ref->dir = dir;
4679	ref->dir_gen = dir_gen;
4680	set_ref_path(ref, path);
4681	list_add_tail(&ref->list, refs);
4682	rb_add(&ref->node, root, rbtree_ref_less);
4683	ref->root = root;
4684out:
4685	if (ret) {
4686		if (path && (!ref || !ref->full_path))
4687			fs_path_free(path);
4688		recorded_ref_free(ref);
4689	}
4690	return ret;
4691}
4692
4693static int record_new_ref_if_needed(int num, u64 dir, int index,
4694				    struct fs_path *name, void *ctx)
4695{
4696	int ret = 0;
4697	struct send_ctx *sctx = ctx;
4698	struct rb_node *node = NULL;
4699	struct recorded_ref data;
4700	struct recorded_ref *ref;
4701	u64 dir_gen;
4702
4703	ret = get_inode_gen(sctx->send_root, dir, &dir_gen);
4704	if (ret < 0)
4705		goto out;
4706
4707	data.dir = dir;
4708	data.dir_gen = dir_gen;
4709	set_ref_path(&data, name);
4710	node = rb_find(&data, &sctx->rbtree_deleted_refs, rbtree_ref_comp);
4711	if (node) {
4712		ref = rb_entry(node, struct recorded_ref, node);
4713		recorded_ref_free(ref);
4714	} else {
4715		ret = record_ref_in_tree(&sctx->rbtree_new_refs,
4716					 &sctx->new_refs, name, dir, dir_gen,
4717					 sctx);
4718	}
4719out:
4720	return ret;
4721}
4722
4723static int record_deleted_ref_if_needed(int num, u64 dir, int index,
4724					struct fs_path *name, void *ctx)
4725{
4726	int ret = 0;
4727	struct send_ctx *sctx = ctx;
4728	struct rb_node *node = NULL;
4729	struct recorded_ref data;
4730	struct recorded_ref *ref;
4731	u64 dir_gen;
4732
4733	ret = get_inode_gen(sctx->parent_root, dir, &dir_gen);
4734	if (ret < 0)
4735		goto out;
4736
4737	data.dir = dir;
4738	data.dir_gen = dir_gen;
4739	set_ref_path(&data, name);
4740	node = rb_find(&data, &sctx->rbtree_new_refs, rbtree_ref_comp);
4741	if (node) {
4742		ref = rb_entry(node, struct recorded_ref, node);
4743		recorded_ref_free(ref);
4744	} else {
4745		ret = record_ref_in_tree(&sctx->rbtree_deleted_refs,
4746					 &sctx->deleted_refs, name, dir,
4747					 dir_gen, sctx);
4748	}
4749out:
4750	return ret;
4751}
4752
4753static int record_new_ref(struct send_ctx *sctx)
4754{
4755	int ret;
4756
4757	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4758				sctx->cmp_key, 0, record_new_ref_if_needed, sctx);
4759	if (ret < 0)
4760		goto out;
4761	ret = 0;
4762
4763out:
4764	return ret;
4765}
4766
4767static int record_deleted_ref(struct send_ctx *sctx)
4768{
4769	int ret;
4770
4771	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4772				sctx->cmp_key, 0, record_deleted_ref_if_needed,
4773				sctx);
4774	if (ret < 0)
4775		goto out;
4776	ret = 0;
4777
4778out:
4779	return ret;
4780}
4781
4782static int record_changed_ref(struct send_ctx *sctx)
4783{
4784	int ret = 0;
4785
4786	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4787			sctx->cmp_key, 0, record_new_ref_if_needed, sctx);
4788	if (ret < 0)
4789		goto out;
4790	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4791			sctx->cmp_key, 0, record_deleted_ref_if_needed, sctx);
4792	if (ret < 0)
4793		goto out;
4794	ret = 0;
4795
4796out:
4797	return ret;
4798}
4799
4800/*
4801 * Record and process all refs at once. Needed when an inode changes the
4802 * generation number, which means that it was deleted and recreated.
4803 */
4804static int process_all_refs(struct send_ctx *sctx,
4805			    enum btrfs_compare_tree_result cmd)
4806{
4807	int ret = 0;
4808	int iter_ret = 0;
4809	struct btrfs_root *root;
4810	struct btrfs_path *path;
4811	struct btrfs_key key;
4812	struct btrfs_key found_key;
4813	iterate_inode_ref_t cb;
4814	int pending_move = 0;
4815
4816	path = alloc_path_for_send();
4817	if (!path)
4818		return -ENOMEM;
4819
4820	if (cmd == BTRFS_COMPARE_TREE_NEW) {
4821		root = sctx->send_root;
4822		cb = record_new_ref_if_needed;
4823	} else if (cmd == BTRFS_COMPARE_TREE_DELETED) {
4824		root = sctx->parent_root;
4825		cb = record_deleted_ref_if_needed;
4826	} else {
4827		btrfs_err(sctx->send_root->fs_info,
4828				"Wrong command %d in process_all_refs", cmd);
4829		ret = -EINVAL;
4830		goto out;
4831	}
4832
4833	key.objectid = sctx->cmp_key->objectid;
4834	key.type = BTRFS_INODE_REF_KEY;
4835	key.offset = 0;
4836	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
4837		if (found_key.objectid != key.objectid ||
4838		    (found_key.type != BTRFS_INODE_REF_KEY &&
4839		     found_key.type != BTRFS_INODE_EXTREF_KEY))
4840			break;
4841
4842		ret = iterate_inode_ref(root, path, &found_key, 0, cb, sctx);
4843		if (ret < 0)
4844			goto out;
4845	}
4846	/* Catch error found during iteration */
4847	if (iter_ret < 0) {
4848		ret = iter_ret;
4849		goto out;
4850	}
4851	btrfs_release_path(path);
4852
4853	/*
4854	 * We don't actually care about pending_move as we are simply
4855	 * re-creating this inode and will be rename'ing it into place once we
4856	 * rename the parent directory.
4857	 */
4858	ret = process_recorded_refs(sctx, &pending_move);
4859out:
4860	btrfs_free_path(path);
4861	return ret;
4862}
4863
4864static int send_set_xattr(struct send_ctx *sctx,
4865			  struct fs_path *path,
4866			  const char *name, int name_len,
4867			  const char *data, int data_len)
4868{
4869	int ret = 0;
4870
4871	ret = begin_cmd(sctx, BTRFS_SEND_C_SET_XATTR);
4872	if (ret < 0)
4873		goto out;
4874
4875	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4876	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4877	TLV_PUT(sctx, BTRFS_SEND_A_XATTR_DATA, data, data_len);
4878
4879	ret = send_cmd(sctx);
4880
4881tlv_put_failure:
4882out:
4883	return ret;
4884}
4885
4886static int send_remove_xattr(struct send_ctx *sctx,
4887			  struct fs_path *path,
4888			  const char *name, int name_len)
4889{
4890	int ret = 0;
4891
4892	ret = begin_cmd(sctx, BTRFS_SEND_C_REMOVE_XATTR);
4893	if (ret < 0)
4894		goto out;
4895
4896	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4897	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4898
4899	ret = send_cmd(sctx);
4900
4901tlv_put_failure:
4902out:
4903	return ret;
4904}
4905
4906static int __process_new_xattr(int num, struct btrfs_key *di_key,
4907			       const char *name, int name_len, const char *data,
4908			       int data_len, void *ctx)
4909{
4910	int ret;
4911	struct send_ctx *sctx = ctx;
4912	struct fs_path *p;
4913	struct posix_acl_xattr_header dummy_acl;
4914
4915	/* Capabilities are emitted by finish_inode_if_needed */
4916	if (!strncmp(name, XATTR_NAME_CAPS, name_len))
4917		return 0;
4918
4919	p = fs_path_alloc();
4920	if (!p)
4921		return -ENOMEM;
4922
4923	/*
4924	 * This hack is needed because empty acls are stored as zero byte
4925	 * data in xattrs. Problem with that is, that receiving these zero byte
4926	 * acls will fail later. To fix this, we send a dummy acl list that
4927	 * only contains the version number and no entries.
4928	 */
4929	if (!strncmp(name, XATTR_NAME_POSIX_ACL_ACCESS, name_len) ||
4930	    !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT, name_len)) {
4931		if (data_len == 0) {
4932			dummy_acl.a_version =
4933					cpu_to_le32(POSIX_ACL_XATTR_VERSION);
4934			data = (char *)&dummy_acl;
4935			data_len = sizeof(dummy_acl);
4936		}
4937	}
4938
4939	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4940	if (ret < 0)
4941		goto out;
4942
4943	ret = send_set_xattr(sctx, p, name, name_len, data, data_len);
4944
4945out:
4946	fs_path_free(p);
4947	return ret;
4948}
4949
4950static int __process_deleted_xattr(int num, struct btrfs_key *di_key,
4951				   const char *name, int name_len,
4952				   const char *data, int data_len, void *ctx)
4953{
4954	int ret;
4955	struct send_ctx *sctx = ctx;
4956	struct fs_path *p;
4957
4958	p = fs_path_alloc();
4959	if (!p)
4960		return -ENOMEM;
4961
4962	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4963	if (ret < 0)
4964		goto out;
4965
4966	ret = send_remove_xattr(sctx, p, name, name_len);
4967
4968out:
4969	fs_path_free(p);
4970	return ret;
4971}
4972
4973static int process_new_xattr(struct send_ctx *sctx)
4974{
4975	int ret = 0;
4976
4977	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
4978			       __process_new_xattr, sctx);
4979
4980	return ret;
4981}
4982
4983static int process_deleted_xattr(struct send_ctx *sctx)
4984{
4985	return iterate_dir_item(sctx->parent_root, sctx->right_path,
4986				__process_deleted_xattr, sctx);
4987}
4988
4989struct find_xattr_ctx {
4990	const char *name;
4991	int name_len;
4992	int found_idx;
4993	char *found_data;
4994	int found_data_len;
4995};
4996
4997static int __find_xattr(int num, struct btrfs_key *di_key, const char *name,
4998			int name_len, const char *data, int data_len, void *vctx)
4999{
5000	struct find_xattr_ctx *ctx = vctx;
5001
5002	if (name_len == ctx->name_len &&
5003	    strncmp(name, ctx->name, name_len) == 0) {
5004		ctx->found_idx = num;
5005		ctx->found_data_len = data_len;
5006		ctx->found_data = kmemdup(data, data_len, GFP_KERNEL);
5007		if (!ctx->found_data)
5008			return -ENOMEM;
5009		return 1;
5010	}
5011	return 0;
5012}
5013
5014static int find_xattr(struct btrfs_root *root,
5015		      struct btrfs_path *path,
5016		      struct btrfs_key *key,
5017		      const char *name, int name_len,
5018		      char **data, int *data_len)
5019{
5020	int ret;
5021	struct find_xattr_ctx ctx;
5022
5023	ctx.name = name;
5024	ctx.name_len = name_len;
5025	ctx.found_idx = -1;
5026	ctx.found_data = NULL;
5027	ctx.found_data_len = 0;
5028
5029	ret = iterate_dir_item(root, path, __find_xattr, &ctx);
5030	if (ret < 0)
5031		return ret;
5032
5033	if (ctx.found_idx == -1)
5034		return -ENOENT;
5035	if (data) {
5036		*data = ctx.found_data;
5037		*data_len = ctx.found_data_len;
5038	} else {
5039		kfree(ctx.found_data);
5040	}
5041	return ctx.found_idx;
5042}
5043
5044
5045static int __process_changed_new_xattr(int num, struct btrfs_key *di_key,
5046				       const char *name, int name_len,
5047				       const char *data, int data_len,
5048				       void *ctx)
5049{
5050	int ret;
5051	struct send_ctx *sctx = ctx;
5052	char *found_data = NULL;
5053	int found_data_len  = 0;
5054
5055	ret = find_xattr(sctx->parent_root, sctx->right_path,
5056			 sctx->cmp_key, name, name_len, &found_data,
5057			 &found_data_len);
5058	if (ret == -ENOENT) {
5059		ret = __process_new_xattr(num, di_key, name, name_len, data,
5060					  data_len, ctx);
5061	} else if (ret >= 0) {
5062		if (data_len != found_data_len ||
5063		    memcmp(data, found_data, data_len)) {
5064			ret = __process_new_xattr(num, di_key, name, name_len,
5065						  data, data_len, ctx);
5066		} else {
5067			ret = 0;
5068		}
5069	}
5070
5071	kfree(found_data);
5072	return ret;
5073}
5074
5075static int __process_changed_deleted_xattr(int num, struct btrfs_key *di_key,
5076					   const char *name, int name_len,
5077					   const char *data, int data_len,
5078					   void *ctx)
5079{
5080	int ret;
5081	struct send_ctx *sctx = ctx;
5082
5083	ret = find_xattr(sctx->send_root, sctx->left_path, sctx->cmp_key,
5084			 name, name_len, NULL, NULL);
5085	if (ret == -ENOENT)
5086		ret = __process_deleted_xattr(num, di_key, name, name_len, data,
5087					      data_len, ctx);
5088	else if (ret >= 0)
5089		ret = 0;
5090
5091	return ret;
5092}
5093
5094static int process_changed_xattr(struct send_ctx *sctx)
5095{
5096	int ret = 0;
5097
5098	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
5099			__process_changed_new_xattr, sctx);
5100	if (ret < 0)
5101		goto out;
5102	ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
5103			__process_changed_deleted_xattr, sctx);
5104
5105out:
5106	return ret;
5107}
5108
5109static int process_all_new_xattrs(struct send_ctx *sctx)
5110{
5111	int ret = 0;
5112	int iter_ret = 0;
5113	struct btrfs_root *root;
5114	struct btrfs_path *path;
5115	struct btrfs_key key;
5116	struct btrfs_key found_key;
5117
5118	path = alloc_path_for_send();
5119	if (!path)
5120		return -ENOMEM;
5121
5122	root = sctx->send_root;
5123
5124	key.objectid = sctx->cmp_key->objectid;
5125	key.type = BTRFS_XATTR_ITEM_KEY;
5126	key.offset = 0;
5127	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
5128		if (found_key.objectid != key.objectid ||
5129		    found_key.type != key.type) {
5130			ret = 0;
5131			break;
5132		}
5133
5134		ret = iterate_dir_item(root, path, __process_new_xattr, sctx);
5135		if (ret < 0)
5136			break;
5137	}
5138	/* Catch error found during iteration */
5139	if (iter_ret < 0)
5140		ret = iter_ret;
5141
5142	btrfs_free_path(path);
5143	return ret;
5144}
5145
5146static int send_verity(struct send_ctx *sctx, struct fs_path *path,
5147		       struct fsverity_descriptor *desc)
5148{
5149	int ret;
5150
5151	ret = begin_cmd(sctx, BTRFS_SEND_C_ENABLE_VERITY);
5152	if (ret < 0)
5153		goto out;
5154
5155	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
5156	TLV_PUT_U8(sctx, BTRFS_SEND_A_VERITY_ALGORITHM,
5157			le8_to_cpu(desc->hash_algorithm));
5158	TLV_PUT_U32(sctx, BTRFS_SEND_A_VERITY_BLOCK_SIZE,
5159			1U << le8_to_cpu(desc->log_blocksize));
5160	TLV_PUT(sctx, BTRFS_SEND_A_VERITY_SALT_DATA, desc->salt,
5161			le8_to_cpu(desc->salt_size));
5162	TLV_PUT(sctx, BTRFS_SEND_A_VERITY_SIG_DATA, desc->signature,
5163			le32_to_cpu(desc->sig_size));
5164
5165	ret = send_cmd(sctx);
5166
5167tlv_put_failure:
5168out:
5169	return ret;
5170}
5171
5172static int process_verity(struct send_ctx *sctx)
5173{
5174	int ret = 0;
5175	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
5176	struct inode *inode;
5177	struct fs_path *p;
5178
5179	inode = btrfs_iget(fs_info->sb, sctx->cur_ino, sctx->send_root);
5180	if (IS_ERR(inode))
5181		return PTR_ERR(inode);
5182
5183	ret = btrfs_get_verity_descriptor(inode, NULL, 0);
5184	if (ret < 0)
5185		goto iput;
5186
5187	if (ret > FS_VERITY_MAX_DESCRIPTOR_SIZE) {
5188		ret = -EMSGSIZE;
5189		goto iput;
5190	}
5191	if (!sctx->verity_descriptor) {
5192		sctx->verity_descriptor = kvmalloc(FS_VERITY_MAX_DESCRIPTOR_SIZE,
5193						   GFP_KERNEL);
5194		if (!sctx->verity_descriptor) {
5195			ret = -ENOMEM;
5196			goto iput;
5197		}
5198	}
5199
5200	ret = btrfs_get_verity_descriptor(inode, sctx->verity_descriptor, ret);
5201	if (ret < 0)
5202		goto iput;
5203
5204	p = fs_path_alloc();
5205	if (!p) {
5206		ret = -ENOMEM;
5207		goto iput;
5208	}
5209	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5210	if (ret < 0)
5211		goto free_path;
5212
5213	ret = send_verity(sctx, p, sctx->verity_descriptor);
5214	if (ret < 0)
5215		goto free_path;
5216
5217free_path:
5218	fs_path_free(p);
5219iput:
5220	iput(inode);
5221	return ret;
5222}
5223
5224static inline u64 max_send_read_size(const struct send_ctx *sctx)
5225{
5226	return sctx->send_max_size - SZ_16K;
5227}
5228
5229static int put_data_header(struct send_ctx *sctx, u32 len)
5230{
5231	if (WARN_ON_ONCE(sctx->put_data))
5232		return -EINVAL;
5233	sctx->put_data = true;
5234	if (sctx->proto >= 2) {
5235		/*
5236		 * Since v2, the data attribute header doesn't include a length,
5237		 * it is implicitly to the end of the command.
5238		 */
5239		if (sctx->send_max_size - sctx->send_size < sizeof(__le16) + len)
5240			return -EOVERFLOW;
5241		put_unaligned_le16(BTRFS_SEND_A_DATA, sctx->send_buf + sctx->send_size);
5242		sctx->send_size += sizeof(__le16);
5243	} else {
5244		struct btrfs_tlv_header *hdr;
5245
5246		if (sctx->send_max_size - sctx->send_size < sizeof(*hdr) + len)
5247			return -EOVERFLOW;
5248		hdr = (struct btrfs_tlv_header *)(sctx->send_buf + sctx->send_size);
5249		put_unaligned_le16(BTRFS_SEND_A_DATA, &hdr->tlv_type);
5250		put_unaligned_le16(len, &hdr->tlv_len);
5251		sctx->send_size += sizeof(*hdr);
5252	}
5253	return 0;
5254}
5255
5256static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
5257{
5258	struct btrfs_root *root = sctx->send_root;
5259	struct btrfs_fs_info *fs_info = root->fs_info;
5260	struct page *page;
5261	pgoff_t index = offset >> PAGE_SHIFT;
5262	pgoff_t last_index;
5263	unsigned pg_offset = offset_in_page(offset);
 
5264	int ret;
5265
5266	ret = put_data_header(sctx, len);
5267	if (ret)
5268		return ret;
5269
5270	last_index = (offset + len - 1) >> PAGE_SHIFT;
5271
5272	while (index <= last_index) {
5273		unsigned cur_len = min_t(unsigned, len,
5274					 PAGE_SIZE - pg_offset);
5275
5276		page = find_lock_page(sctx->cur_inode->i_mapping, index);
5277		if (!page) {
5278			page_cache_sync_readahead(sctx->cur_inode->i_mapping,
 
5279						  &sctx->ra, NULL, index,
5280						  last_index + 1 - index);
5281
5282			page = find_or_create_page(sctx->cur_inode->i_mapping,
5283						   index, GFP_KERNEL);
5284			if (!page) {
5285				ret = -ENOMEM;
5286				break;
5287			}
5288		}
5289
5290		if (PageReadahead(page))
5291			page_cache_async_readahead(sctx->cur_inode->i_mapping,
5292						   &sctx->ra, NULL, page_folio(page),
5293						   index, last_index + 1 - index);
5294
5295		if (!PageUptodate(page)) {
5296			btrfs_read_folio(NULL, page_folio(page));
5297			lock_page(page);
5298			if (!PageUptodate(page)) {
5299				unlock_page(page);
 
5300				btrfs_err(fs_info,
5301			"send: IO error at offset %llu for inode %llu root %llu",
5302					page_offset(page), sctx->cur_ino,
5303					sctx->send_root->root_key.objectid);
5304				put_page(page);
5305				ret = -EIO;
5306				break;
5307			}
 
 
 
 
 
5308		}
5309
5310		memcpy_from_page(sctx->send_buf + sctx->send_size, page,
5311				 pg_offset, cur_len);
5312		unlock_page(page);
5313		put_page(page);
5314		index++;
5315		pg_offset = 0;
5316		len -= cur_len;
5317		sctx->send_size += cur_len;
5318	}
5319
5320	return ret;
5321}
5322
5323/*
5324 * Read some bytes from the current inode/file and send a write command to
5325 * user space.
5326 */
5327static int send_write(struct send_ctx *sctx, u64 offset, u32 len)
5328{
5329	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
5330	int ret = 0;
5331	struct fs_path *p;
5332
5333	p = fs_path_alloc();
5334	if (!p)
5335		return -ENOMEM;
5336
5337	btrfs_debug(fs_info, "send_write offset=%llu, len=%d", offset, len);
5338
5339	ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
5340	if (ret < 0)
5341		goto out;
5342
5343	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5344	if (ret < 0)
5345		goto out;
5346
5347	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5348	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5349	ret = put_file_data(sctx, offset, len);
5350	if (ret < 0)
5351		goto out;
5352
5353	ret = send_cmd(sctx);
5354
5355tlv_put_failure:
5356out:
5357	fs_path_free(p);
5358	return ret;
5359}
5360
5361/*
5362 * Send a clone command to user space.
5363 */
5364static int send_clone(struct send_ctx *sctx,
5365		      u64 offset, u32 len,
5366		      struct clone_root *clone_root)
5367{
5368	int ret = 0;
5369	struct fs_path *p;
5370	u64 gen;
5371
5372	btrfs_debug(sctx->send_root->fs_info,
5373		    "send_clone offset=%llu, len=%d, clone_root=%llu, clone_inode=%llu, clone_offset=%llu",
5374		    offset, len, clone_root->root->root_key.objectid,
5375		    clone_root->ino, clone_root->offset);
5376
5377	p = fs_path_alloc();
5378	if (!p)
5379		return -ENOMEM;
5380
5381	ret = begin_cmd(sctx, BTRFS_SEND_C_CLONE);
5382	if (ret < 0)
5383		goto out;
5384
5385	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5386	if (ret < 0)
5387		goto out;
5388
5389	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5390	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_LEN, len);
5391	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5392
5393	if (clone_root->root == sctx->send_root) {
5394		ret = get_inode_gen(sctx->send_root, clone_root->ino, &gen);
5395		if (ret < 0)
5396			goto out;
5397		ret = get_cur_path(sctx, clone_root->ino, gen, p);
5398	} else {
5399		ret = get_inode_path(clone_root->root, clone_root->ino, p);
5400	}
5401	if (ret < 0)
5402		goto out;
5403
5404	/*
5405	 * If the parent we're using has a received_uuid set then use that as
5406	 * our clone source as that is what we will look for when doing a
5407	 * receive.
5408	 *
5409	 * This covers the case that we create a snapshot off of a received
5410	 * subvolume and then use that as the parent and try to receive on a
5411	 * different host.
5412	 */
5413	if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
5414		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
5415			     clone_root->root->root_item.received_uuid);
5416	else
5417		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
5418			     clone_root->root->root_item.uuid);
5419	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
5420		    btrfs_root_ctransid(&clone_root->root->root_item));
5421	TLV_PUT_PATH(sctx, BTRFS_SEND_A_CLONE_PATH, p);
5422	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_OFFSET,
5423			clone_root->offset);
5424
5425	ret = send_cmd(sctx);
5426
5427tlv_put_failure:
5428out:
5429	fs_path_free(p);
5430	return ret;
5431}
5432
5433/*
5434 * Send an update extent command to user space.
5435 */
5436static int send_update_extent(struct send_ctx *sctx,
5437			      u64 offset, u32 len)
5438{
5439	int ret = 0;
5440	struct fs_path *p;
5441
5442	p = fs_path_alloc();
5443	if (!p)
5444		return -ENOMEM;
5445
5446	ret = begin_cmd(sctx, BTRFS_SEND_C_UPDATE_EXTENT);
5447	if (ret < 0)
5448		goto out;
5449
5450	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5451	if (ret < 0)
5452		goto out;
5453
5454	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5455	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5456	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
5457
5458	ret = send_cmd(sctx);
5459
5460tlv_put_failure:
5461out:
5462	fs_path_free(p);
5463	return ret;
5464}
5465
5466static int send_hole(struct send_ctx *sctx, u64 end)
5467{
5468	struct fs_path *p = NULL;
5469	u64 read_size = max_send_read_size(sctx);
5470	u64 offset = sctx->cur_inode_last_extent;
5471	int ret = 0;
5472
5473	/*
5474	 * A hole that starts at EOF or beyond it. Since we do not yet support
5475	 * fallocate (for extent preallocation and hole punching), sending a
5476	 * write of zeroes starting at EOF or beyond would later require issuing
5477	 * a truncate operation which would undo the write and achieve nothing.
5478	 */
5479	if (offset >= sctx->cur_inode_size)
5480		return 0;
5481
5482	/*
5483	 * Don't go beyond the inode's i_size due to prealloc extents that start
5484	 * after the i_size.
5485	 */
5486	end = min_t(u64, end, sctx->cur_inode_size);
5487
5488	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
5489		return send_update_extent(sctx, offset, end - offset);
5490
5491	p = fs_path_alloc();
5492	if (!p)
5493		return -ENOMEM;
5494	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5495	if (ret < 0)
5496		goto tlv_put_failure;
5497	while (offset < end) {
5498		u64 len = min(end - offset, read_size);
5499
5500		ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
5501		if (ret < 0)
5502			break;
5503		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5504		TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5505		ret = put_data_header(sctx, len);
5506		if (ret < 0)
5507			break;
5508		memset(sctx->send_buf + sctx->send_size, 0, len);
5509		sctx->send_size += len;
5510		ret = send_cmd(sctx);
5511		if (ret < 0)
5512			break;
5513		offset += len;
5514	}
5515	sctx->cur_inode_next_write_offset = offset;
5516tlv_put_failure:
5517	fs_path_free(p);
5518	return ret;
5519}
5520
5521static int send_encoded_inline_extent(struct send_ctx *sctx,
5522				      struct btrfs_path *path, u64 offset,
5523				      u64 len)
5524{
5525	struct btrfs_root *root = sctx->send_root;
5526	struct btrfs_fs_info *fs_info = root->fs_info;
5527	struct inode *inode;
5528	struct fs_path *fspath;
5529	struct extent_buffer *leaf = path->nodes[0];
5530	struct btrfs_key key;
5531	struct btrfs_file_extent_item *ei;
5532	u64 ram_bytes;
5533	size_t inline_size;
5534	int ret;
5535
5536	inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root);
5537	if (IS_ERR(inode))
5538		return PTR_ERR(inode);
5539
5540	fspath = fs_path_alloc();
5541	if (!fspath) {
5542		ret = -ENOMEM;
5543		goto out;
5544	}
5545
5546	ret = begin_cmd(sctx, BTRFS_SEND_C_ENCODED_WRITE);
5547	if (ret < 0)
5548		goto out;
5549
5550	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
5551	if (ret < 0)
5552		goto out;
5553
5554	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
5555	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
5556	ram_bytes = btrfs_file_extent_ram_bytes(leaf, ei);
5557	inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
5558
5559	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, fspath);
5560	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5561	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_FILE_LEN,
5562		    min(key.offset + ram_bytes - offset, len));
5563	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_LEN, ram_bytes);
5564	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_OFFSET, offset - key.offset);
5565	ret = btrfs_encoded_io_compression_from_extent(fs_info,
5566				btrfs_file_extent_compression(leaf, ei));
5567	if (ret < 0)
5568		goto out;
5569	TLV_PUT_U32(sctx, BTRFS_SEND_A_COMPRESSION, ret);
5570
5571	ret = put_data_header(sctx, inline_size);
5572	if (ret < 0)
5573		goto out;
5574	read_extent_buffer(leaf, sctx->send_buf + sctx->send_size,
5575			   btrfs_file_extent_inline_start(ei), inline_size);
5576	sctx->send_size += inline_size;
5577
5578	ret = send_cmd(sctx);
5579
5580tlv_put_failure:
5581out:
5582	fs_path_free(fspath);
5583	iput(inode);
5584	return ret;
5585}
5586
5587static int send_encoded_extent(struct send_ctx *sctx, struct btrfs_path *path,
5588			       u64 offset, u64 len)
5589{
5590	struct btrfs_root *root = sctx->send_root;
5591	struct btrfs_fs_info *fs_info = root->fs_info;
5592	struct inode *inode;
5593	struct fs_path *fspath;
5594	struct extent_buffer *leaf = path->nodes[0];
5595	struct btrfs_key key;
5596	struct btrfs_file_extent_item *ei;
5597	u64 disk_bytenr, disk_num_bytes;
5598	u32 data_offset;
5599	struct btrfs_cmd_header *hdr;
5600	u32 crc;
5601	int ret;
5602
5603	inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root);
5604	if (IS_ERR(inode))
5605		return PTR_ERR(inode);
5606
5607	fspath = fs_path_alloc();
5608	if (!fspath) {
5609		ret = -ENOMEM;
5610		goto out;
5611	}
5612
5613	ret = begin_cmd(sctx, BTRFS_SEND_C_ENCODED_WRITE);
5614	if (ret < 0)
5615		goto out;
5616
5617	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
5618	if (ret < 0)
5619		goto out;
5620
5621	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
5622	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
5623	disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
5624	disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, ei);
5625
5626	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, fspath);
5627	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5628	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_FILE_LEN,
5629		    min(key.offset + btrfs_file_extent_num_bytes(leaf, ei) - offset,
5630			len));
5631	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_LEN,
5632		    btrfs_file_extent_ram_bytes(leaf, ei));
5633	TLV_PUT_U64(sctx, BTRFS_SEND_A_UNENCODED_OFFSET,
5634		    offset - key.offset + btrfs_file_extent_offset(leaf, ei));
5635	ret = btrfs_encoded_io_compression_from_extent(fs_info,
5636				btrfs_file_extent_compression(leaf, ei));
5637	if (ret < 0)
5638		goto out;
5639	TLV_PUT_U32(sctx, BTRFS_SEND_A_COMPRESSION, ret);
5640	TLV_PUT_U32(sctx, BTRFS_SEND_A_ENCRYPTION, 0);
5641
5642	ret = put_data_header(sctx, disk_num_bytes);
5643	if (ret < 0)
5644		goto out;
5645
5646	/*
5647	 * We want to do I/O directly into the send buffer, so get the next page
5648	 * boundary in the send buffer. This means that there may be a gap
5649	 * between the beginning of the command and the file data.
5650	 */
5651	data_offset = PAGE_ALIGN(sctx->send_size);
5652	if (data_offset > sctx->send_max_size ||
5653	    sctx->send_max_size - data_offset < disk_num_bytes) {
5654		ret = -EOVERFLOW;
5655		goto out;
5656	}
5657
5658	/*
5659	 * Note that send_buf is a mapping of send_buf_pages, so this is really
5660	 * reading into send_buf.
5661	 */
5662	ret = btrfs_encoded_read_regular_fill_pages(BTRFS_I(inode), offset,
5663						    disk_bytenr, disk_num_bytes,
5664						    sctx->send_buf_pages +
5665						    (data_offset >> PAGE_SHIFT));
 
5666	if (ret)
5667		goto out;
5668
5669	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
5670	hdr->len = cpu_to_le32(sctx->send_size + disk_num_bytes - sizeof(*hdr));
5671	hdr->crc = 0;
5672	crc = crc32c(0, sctx->send_buf, sctx->send_size);
5673	crc = crc32c(crc, sctx->send_buf + data_offset, disk_num_bytes);
5674	hdr->crc = cpu_to_le32(crc);
5675
5676	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
5677			&sctx->send_off);
5678	if (!ret) {
5679		ret = write_buf(sctx->send_filp, sctx->send_buf + data_offset,
5680				disk_num_bytes, &sctx->send_off);
5681	}
5682	sctx->send_size = 0;
5683	sctx->put_data = false;
5684
5685tlv_put_failure:
5686out:
5687	fs_path_free(fspath);
5688	iput(inode);
5689	return ret;
5690}
5691
5692static int send_extent_data(struct send_ctx *sctx, struct btrfs_path *path,
5693			    const u64 offset, const u64 len)
5694{
5695	const u64 end = offset + len;
5696	struct extent_buffer *leaf = path->nodes[0];
5697	struct btrfs_file_extent_item *ei;
5698	u64 read_size = max_send_read_size(sctx);
5699	u64 sent = 0;
5700
5701	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
5702		return send_update_extent(sctx, offset, len);
5703
5704	ei = btrfs_item_ptr(leaf, path->slots[0],
5705			    struct btrfs_file_extent_item);
5706	if ((sctx->flags & BTRFS_SEND_FLAG_COMPRESSED) &&
5707	    btrfs_file_extent_compression(leaf, ei) != BTRFS_COMPRESS_NONE) {
5708		bool is_inline = (btrfs_file_extent_type(leaf, ei) ==
5709				  BTRFS_FILE_EXTENT_INLINE);
5710
5711		/*
5712		 * Send the compressed extent unless the compressed data is
5713		 * larger than the decompressed data. This can happen if we're
5714		 * not sending the entire extent, either because it has been
5715		 * partially overwritten/truncated or because this is a part of
5716		 * the extent that we couldn't clone in clone_range().
5717		 */
5718		if (is_inline &&
5719		    btrfs_file_extent_inline_item_len(leaf,
5720						      path->slots[0]) <= len) {
5721			return send_encoded_inline_extent(sctx, path, offset,
5722							  len);
5723		} else if (!is_inline &&
5724			   btrfs_file_extent_disk_num_bytes(leaf, ei) <= len) {
5725			return send_encoded_extent(sctx, path, offset, len);
5726		}
5727	}
5728
5729	if (sctx->cur_inode == NULL) {
5730		struct btrfs_root *root = sctx->send_root;
5731
5732		sctx->cur_inode = btrfs_iget(root->fs_info->sb, sctx->cur_ino, root);
5733		if (IS_ERR(sctx->cur_inode)) {
5734			int err = PTR_ERR(sctx->cur_inode);
5735
5736			sctx->cur_inode = NULL;
5737			return err;
5738		}
5739		memset(&sctx->ra, 0, sizeof(struct file_ra_state));
5740		file_ra_state_init(&sctx->ra, sctx->cur_inode->i_mapping);
5741
5742		/*
5743		 * It's very likely there are no pages from this inode in the page
5744		 * cache, so after reading extents and sending their data, we clean
5745		 * the page cache to avoid trashing the page cache (adding pressure
5746		 * to the page cache and forcing eviction of other data more useful
5747		 * for applications).
5748		 *
5749		 * We decide if we should clean the page cache simply by checking
5750		 * if the inode's mapping nrpages is 0 when we first open it, and
5751		 * not by using something like filemap_range_has_page() before
5752		 * reading an extent because when we ask the readahead code to
5753		 * read a given file range, it may (and almost always does) read
5754		 * pages from beyond that range (see the documentation for
5755		 * page_cache_sync_readahead()), so it would not be reliable,
5756		 * because after reading the first extent future calls to
5757		 * filemap_range_has_page() would return true because the readahead
5758		 * on the previous extent resulted in reading pages of the current
5759		 * extent as well.
5760		 */
5761		sctx->clean_page_cache = (sctx->cur_inode->i_mapping->nrpages == 0);
5762		sctx->page_cache_clear_start = round_down(offset, PAGE_SIZE);
5763	}
5764
5765	while (sent < len) {
5766		u64 size = min(len - sent, read_size);
5767		int ret;
5768
5769		ret = send_write(sctx, offset + sent, size);
5770		if (ret < 0)
5771			return ret;
5772		sent += size;
5773	}
5774
5775	if (sctx->clean_page_cache && PAGE_ALIGNED(end)) {
5776		/*
5777		 * Always operate only on ranges that are a multiple of the page
5778		 * size. This is not only to prevent zeroing parts of a page in
5779		 * the case of subpage sector size, but also to guarantee we evict
5780		 * pages, as passing a range that is smaller than page size does
5781		 * not evict the respective page (only zeroes part of its content).
5782		 *
5783		 * Always start from the end offset of the last range cleared.
5784		 * This is because the readahead code may (and very often does)
5785		 * reads pages beyond the range we request for readahead. So if
5786		 * we have an extent layout like this:
5787		 *
5788		 *            [ extent A ] [ extent B ] [ extent C ]
5789		 *
5790		 * When we ask page_cache_sync_readahead() to read extent A, it
5791		 * may also trigger reads for pages of extent B. If we are doing
5792		 * an incremental send and extent B has not changed between the
5793		 * parent and send snapshots, some or all of its pages may end
5794		 * up being read and placed in the page cache. So when truncating
5795		 * the page cache we always start from the end offset of the
5796		 * previously processed extent up to the end of the current
5797		 * extent.
5798		 */
5799		truncate_inode_pages_range(&sctx->cur_inode->i_data,
5800					   sctx->page_cache_clear_start,
5801					   end - 1);
5802		sctx->page_cache_clear_start = end;
5803	}
5804
5805	return 0;
5806}
5807
5808/*
5809 * Search for a capability xattr related to sctx->cur_ino. If the capability is
5810 * found, call send_set_xattr function to emit it.
5811 *
5812 * Return 0 if there isn't a capability, or when the capability was emitted
5813 * successfully, or < 0 if an error occurred.
5814 */
5815static int send_capabilities(struct send_ctx *sctx)
5816{
5817	struct fs_path *fspath = NULL;
5818	struct btrfs_path *path;
5819	struct btrfs_dir_item *di;
5820	struct extent_buffer *leaf;
5821	unsigned long data_ptr;
5822	char *buf = NULL;
5823	int buf_len;
5824	int ret = 0;
5825
5826	path = alloc_path_for_send();
5827	if (!path)
5828		return -ENOMEM;
5829
5830	di = btrfs_lookup_xattr(NULL, sctx->send_root, path, sctx->cur_ino,
5831				XATTR_NAME_CAPS, strlen(XATTR_NAME_CAPS), 0);
5832	if (!di) {
5833		/* There is no xattr for this inode */
5834		goto out;
5835	} else if (IS_ERR(di)) {
5836		ret = PTR_ERR(di);
5837		goto out;
5838	}
5839
5840	leaf = path->nodes[0];
5841	buf_len = btrfs_dir_data_len(leaf, di);
5842
5843	fspath = fs_path_alloc();
5844	buf = kmalloc(buf_len, GFP_KERNEL);
5845	if (!fspath || !buf) {
5846		ret = -ENOMEM;
5847		goto out;
5848	}
5849
5850	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
5851	if (ret < 0)
5852		goto out;
5853
5854	data_ptr = (unsigned long)(di + 1) + btrfs_dir_name_len(leaf, di);
5855	read_extent_buffer(leaf, buf, data_ptr, buf_len);
5856
5857	ret = send_set_xattr(sctx, fspath, XATTR_NAME_CAPS,
5858			strlen(XATTR_NAME_CAPS), buf, buf_len);
5859out:
5860	kfree(buf);
5861	fs_path_free(fspath);
5862	btrfs_free_path(path);
5863	return ret;
5864}
5865
5866static int clone_range(struct send_ctx *sctx, struct btrfs_path *dst_path,
5867		       struct clone_root *clone_root, const u64 disk_byte,
5868		       u64 data_offset, u64 offset, u64 len)
5869{
5870	struct btrfs_path *path;
5871	struct btrfs_key key;
5872	int ret;
5873	struct btrfs_inode_info info;
5874	u64 clone_src_i_size = 0;
5875
5876	/*
5877	 * Prevent cloning from a zero offset with a length matching the sector
5878	 * size because in some scenarios this will make the receiver fail.
5879	 *
5880	 * For example, if in the source filesystem the extent at offset 0
5881	 * has a length of sectorsize and it was written using direct IO, then
5882	 * it can never be an inline extent (even if compression is enabled).
5883	 * Then this extent can be cloned in the original filesystem to a non
5884	 * zero file offset, but it may not be possible to clone in the
5885	 * destination filesystem because it can be inlined due to compression
5886	 * on the destination filesystem (as the receiver's write operations are
5887	 * always done using buffered IO). The same happens when the original
5888	 * filesystem does not have compression enabled but the destination
5889	 * filesystem has.
5890	 */
5891	if (clone_root->offset == 0 &&
5892	    len == sctx->send_root->fs_info->sectorsize)
5893		return send_extent_data(sctx, dst_path, offset, len);
5894
5895	path = alloc_path_for_send();
5896	if (!path)
5897		return -ENOMEM;
5898
5899	/*
5900	 * There are inodes that have extents that lie behind its i_size. Don't
5901	 * accept clones from these extents.
5902	 */
5903	ret = get_inode_info(clone_root->root, clone_root->ino, &info);
5904	btrfs_release_path(path);
5905	if (ret < 0)
5906		goto out;
5907	clone_src_i_size = info.size;
5908
5909	/*
5910	 * We can't send a clone operation for the entire range if we find
5911	 * extent items in the respective range in the source file that
5912	 * refer to different extents or if we find holes.
5913	 * So check for that and do a mix of clone and regular write/copy
5914	 * operations if needed.
5915	 *
5916	 * Example:
5917	 *
5918	 * mkfs.btrfs -f /dev/sda
5919	 * mount /dev/sda /mnt
5920	 * xfs_io -f -c "pwrite -S 0xaa 0K 100K" /mnt/foo
5921	 * cp --reflink=always /mnt/foo /mnt/bar
5922	 * xfs_io -c "pwrite -S 0xbb 50K 50K" /mnt/foo
5923	 * btrfs subvolume snapshot -r /mnt /mnt/snap
5924	 *
5925	 * If when we send the snapshot and we are processing file bar (which
5926	 * has a higher inode number than foo) we blindly send a clone operation
5927	 * for the [0, 100K[ range from foo to bar, the receiver ends up getting
5928	 * a file bar that matches the content of file foo - iow, doesn't match
5929	 * the content from bar in the original filesystem.
5930	 */
5931	key.objectid = clone_root->ino;
5932	key.type = BTRFS_EXTENT_DATA_KEY;
5933	key.offset = clone_root->offset;
5934	ret = btrfs_search_slot(NULL, clone_root->root, &key, path, 0, 0);
5935	if (ret < 0)
5936		goto out;
5937	if (ret > 0 && path->slots[0] > 0) {
5938		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
5939		if (key.objectid == clone_root->ino &&
5940		    key.type == BTRFS_EXTENT_DATA_KEY)
5941			path->slots[0]--;
5942	}
5943
5944	while (true) {
5945		struct extent_buffer *leaf = path->nodes[0];
5946		int slot = path->slots[0];
5947		struct btrfs_file_extent_item *ei;
5948		u8 type;
5949		u64 ext_len;
5950		u64 clone_len;
5951		u64 clone_data_offset;
5952		bool crossed_src_i_size = false;
5953
5954		if (slot >= btrfs_header_nritems(leaf)) {
5955			ret = btrfs_next_leaf(clone_root->root, path);
5956			if (ret < 0)
5957				goto out;
5958			else if (ret > 0)
5959				break;
5960			continue;
5961		}
5962
5963		btrfs_item_key_to_cpu(leaf, &key, slot);
5964
5965		/*
5966		 * We might have an implicit trailing hole (NO_HOLES feature
5967		 * enabled). We deal with it after leaving this loop.
5968		 */
5969		if (key.objectid != clone_root->ino ||
5970		    key.type != BTRFS_EXTENT_DATA_KEY)
5971			break;
5972
5973		ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
5974		type = btrfs_file_extent_type(leaf, ei);
5975		if (type == BTRFS_FILE_EXTENT_INLINE) {
5976			ext_len = btrfs_file_extent_ram_bytes(leaf, ei);
5977			ext_len = PAGE_ALIGN(ext_len);
5978		} else {
5979			ext_len = btrfs_file_extent_num_bytes(leaf, ei);
5980		}
5981
5982		if (key.offset + ext_len <= clone_root->offset)
5983			goto next;
5984
5985		if (key.offset > clone_root->offset) {
5986			/* Implicit hole, NO_HOLES feature enabled. */
5987			u64 hole_len = key.offset - clone_root->offset;
5988
5989			if (hole_len > len)
5990				hole_len = len;
5991			ret = send_extent_data(sctx, dst_path, offset,
5992					       hole_len);
5993			if (ret < 0)
5994				goto out;
5995
5996			len -= hole_len;
5997			if (len == 0)
5998				break;
5999			offset += hole_len;
6000			clone_root->offset += hole_len;
6001			data_offset += hole_len;
6002		}
6003
6004		if (key.offset >= clone_root->offset + len)
6005			break;
6006
6007		if (key.offset >= clone_src_i_size)
6008			break;
6009
6010		if (key.offset + ext_len > clone_src_i_size) {
6011			ext_len = clone_src_i_size - key.offset;
6012			crossed_src_i_size = true;
6013		}
6014
6015		clone_data_offset = btrfs_file_extent_offset(leaf, ei);
6016		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte) {
6017			clone_root->offset = key.offset;
6018			if (clone_data_offset < data_offset &&
6019				clone_data_offset + ext_len > data_offset) {
6020				u64 extent_offset;
6021
6022				extent_offset = data_offset - clone_data_offset;
6023				ext_len -= extent_offset;
6024				clone_data_offset += extent_offset;
6025				clone_root->offset += extent_offset;
6026			}
6027		}
6028
6029		clone_len = min_t(u64, ext_len, len);
6030
6031		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte &&
6032		    clone_data_offset == data_offset) {
6033			const u64 src_end = clone_root->offset + clone_len;
6034			const u64 sectorsize = SZ_64K;
6035
6036			/*
6037			 * We can't clone the last block, when its size is not
6038			 * sector size aligned, into the middle of a file. If we
6039			 * do so, the receiver will get a failure (-EINVAL) when
6040			 * trying to clone or will silently corrupt the data in
6041			 * the destination file if it's on a kernel without the
6042			 * fix introduced by commit ac765f83f1397646
6043			 * ("Btrfs: fix data corruption due to cloning of eof
6044			 * block).
6045			 *
6046			 * So issue a clone of the aligned down range plus a
6047			 * regular write for the eof block, if we hit that case.
6048			 *
6049			 * Also, we use the maximum possible sector size, 64K,
6050			 * because we don't know what's the sector size of the
6051			 * filesystem that receives the stream, so we have to
6052			 * assume the largest possible sector size.
6053			 */
6054			if (src_end == clone_src_i_size &&
6055			    !IS_ALIGNED(src_end, sectorsize) &&
6056			    offset + clone_len < sctx->cur_inode_size) {
6057				u64 slen;
6058
6059				slen = ALIGN_DOWN(src_end - clone_root->offset,
6060						  sectorsize);
6061				if (slen > 0) {
6062					ret = send_clone(sctx, offset, slen,
6063							 clone_root);
6064					if (ret < 0)
6065						goto out;
6066				}
6067				ret = send_extent_data(sctx, dst_path,
6068						       offset + slen,
6069						       clone_len - slen);
6070			} else {
6071				ret = send_clone(sctx, offset, clone_len,
6072						 clone_root);
6073			}
6074		} else if (crossed_src_i_size && clone_len < len) {
6075			/*
6076			 * If we are at i_size of the clone source inode and we
6077			 * can not clone from it, terminate the loop. This is
6078			 * to avoid sending two write operations, one with a
6079			 * length matching clone_len and the final one after
6080			 * this loop with a length of len - clone_len.
6081			 *
6082			 * When using encoded writes (BTRFS_SEND_FLAG_COMPRESSED
6083			 * was passed to the send ioctl), this helps avoid
6084			 * sending an encoded write for an offset that is not
6085			 * sector size aligned, in case the i_size of the source
6086			 * inode is not sector size aligned. That will make the
6087			 * receiver fallback to decompression of the data and
6088			 * writing it using regular buffered IO, therefore while
6089			 * not incorrect, it's not optimal due decompression and
6090			 * possible re-compression at the receiver.
6091			 */
6092			break;
6093		} else {
6094			ret = send_extent_data(sctx, dst_path, offset,
6095					       clone_len);
6096		}
6097
6098		if (ret < 0)
6099			goto out;
6100
6101		len -= clone_len;
6102		if (len == 0)
6103			break;
6104		offset += clone_len;
6105		clone_root->offset += clone_len;
6106
6107		/*
6108		 * If we are cloning from the file we are currently processing,
6109		 * and using the send root as the clone root, we must stop once
6110		 * the current clone offset reaches the current eof of the file
6111		 * at the receiver, otherwise we would issue an invalid clone
6112		 * operation (source range going beyond eof) and cause the
6113		 * receiver to fail. So if we reach the current eof, bail out
6114		 * and fallback to a regular write.
6115		 */
6116		if (clone_root->root == sctx->send_root &&
6117		    clone_root->ino == sctx->cur_ino &&
6118		    clone_root->offset >= sctx->cur_inode_next_write_offset)
6119			break;
6120
6121		data_offset += clone_len;
6122next:
6123		path->slots[0]++;
6124	}
6125
6126	if (len > 0)
6127		ret = send_extent_data(sctx, dst_path, offset, len);
6128	else
6129		ret = 0;
6130out:
6131	btrfs_free_path(path);
6132	return ret;
6133}
6134
6135static int send_write_or_clone(struct send_ctx *sctx,
6136			       struct btrfs_path *path,
6137			       struct btrfs_key *key,
6138			       struct clone_root *clone_root)
6139{
6140	int ret = 0;
6141	u64 offset = key->offset;
6142	u64 end;
6143	u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
 
 
 
 
 
6144
6145	end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size);
6146	if (offset >= end)
6147		return 0;
6148
6149	if (clone_root && IS_ALIGNED(end, bs)) {
6150		struct btrfs_file_extent_item *ei;
6151		u64 disk_byte;
6152		u64 data_offset;
6153
6154		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
6155				    struct btrfs_file_extent_item);
6156		disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
6157		data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
6158		ret = clone_range(sctx, path, clone_root, disk_byte,
6159				  data_offset, offset, end - offset);
6160	} else {
6161		ret = send_extent_data(sctx, path, offset, end - offset);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
6162	}
 
 
 
 
 
 
 
 
 
 
 
 
 
6163	sctx->cur_inode_next_write_offset = end;
6164	return ret;
6165}
6166
6167static int is_extent_unchanged(struct send_ctx *sctx,
6168			       struct btrfs_path *left_path,
6169			       struct btrfs_key *ekey)
6170{
6171	int ret = 0;
6172	struct btrfs_key key;
6173	struct btrfs_path *path = NULL;
6174	struct extent_buffer *eb;
6175	int slot;
6176	struct btrfs_key found_key;
6177	struct btrfs_file_extent_item *ei;
6178	u64 left_disknr;
6179	u64 right_disknr;
6180	u64 left_offset;
6181	u64 right_offset;
6182	u64 left_offset_fixed;
6183	u64 left_len;
6184	u64 right_len;
6185	u64 left_gen;
6186	u64 right_gen;
6187	u8 left_type;
6188	u8 right_type;
6189
6190	path = alloc_path_for_send();
6191	if (!path)
6192		return -ENOMEM;
6193
6194	eb = left_path->nodes[0];
6195	slot = left_path->slots[0];
6196	ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
6197	left_type = btrfs_file_extent_type(eb, ei);
6198
6199	if (left_type != BTRFS_FILE_EXTENT_REG) {
6200		ret = 0;
6201		goto out;
6202	}
6203	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
6204	left_len = btrfs_file_extent_num_bytes(eb, ei);
6205	left_offset = btrfs_file_extent_offset(eb, ei);
6206	left_gen = btrfs_file_extent_generation(eb, ei);
6207
6208	/*
6209	 * Following comments will refer to these graphics. L is the left
6210	 * extents which we are checking at the moment. 1-8 are the right
6211	 * extents that we iterate.
6212	 *
6213	 *       |-----L-----|
6214	 * |-1-|-2a-|-3-|-4-|-5-|-6-|
6215	 *
6216	 *       |-----L-----|
6217	 * |--1--|-2b-|...(same as above)
6218	 *
6219	 * Alternative situation. Happens on files where extents got split.
6220	 *       |-----L-----|
6221	 * |-----------7-----------|-6-|
6222	 *
6223	 * Alternative situation. Happens on files which got larger.
6224	 *       |-----L-----|
6225	 * |-8-|
6226	 * Nothing follows after 8.
6227	 */
6228
6229	key.objectid = ekey->objectid;
6230	key.type = BTRFS_EXTENT_DATA_KEY;
6231	key.offset = ekey->offset;
6232	ret = btrfs_search_slot_for_read(sctx->parent_root, &key, path, 0, 0);
6233	if (ret < 0)
6234		goto out;
6235	if (ret) {
6236		ret = 0;
6237		goto out;
6238	}
6239
6240	/*
6241	 * Handle special case where the right side has no extents at all.
6242	 */
6243	eb = path->nodes[0];
6244	slot = path->slots[0];
6245	btrfs_item_key_to_cpu(eb, &found_key, slot);
6246	if (found_key.objectid != key.objectid ||
6247	    found_key.type != key.type) {
6248		/* If we're a hole then just pretend nothing changed */
6249		ret = (left_disknr) ? 0 : 1;
6250		goto out;
6251	}
6252
6253	/*
6254	 * We're now on 2a, 2b or 7.
6255	 */
6256	key = found_key;
6257	while (key.offset < ekey->offset + left_len) {
6258		ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
6259		right_type = btrfs_file_extent_type(eb, ei);
6260		if (right_type != BTRFS_FILE_EXTENT_REG &&
6261		    right_type != BTRFS_FILE_EXTENT_INLINE) {
6262			ret = 0;
6263			goto out;
6264		}
6265
6266		if (right_type == BTRFS_FILE_EXTENT_INLINE) {
6267			right_len = btrfs_file_extent_ram_bytes(eb, ei);
6268			right_len = PAGE_ALIGN(right_len);
6269		} else {
6270			right_len = btrfs_file_extent_num_bytes(eb, ei);
6271		}
6272
6273		/*
6274		 * Are we at extent 8? If yes, we know the extent is changed.
6275		 * This may only happen on the first iteration.
6276		 */
6277		if (found_key.offset + right_len <= ekey->offset) {
6278			/* If we're a hole just pretend nothing changed */
6279			ret = (left_disknr) ? 0 : 1;
6280			goto out;
6281		}
6282
6283		/*
6284		 * We just wanted to see if when we have an inline extent, what
6285		 * follows it is a regular extent (wanted to check the above
6286		 * condition for inline extents too). This should normally not
6287		 * happen but it's possible for example when we have an inline
6288		 * compressed extent representing data with a size matching
6289		 * the page size (currently the same as sector size).
6290		 */
6291		if (right_type == BTRFS_FILE_EXTENT_INLINE) {
6292			ret = 0;
6293			goto out;
6294		}
6295
6296		right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
6297		right_offset = btrfs_file_extent_offset(eb, ei);
6298		right_gen = btrfs_file_extent_generation(eb, ei);
6299
6300		left_offset_fixed = left_offset;
6301		if (key.offset < ekey->offset) {
6302			/* Fix the right offset for 2a and 7. */
6303			right_offset += ekey->offset - key.offset;
6304		} else {
6305			/* Fix the left offset for all behind 2a and 2b */
6306			left_offset_fixed += key.offset - ekey->offset;
6307		}
6308
6309		/*
6310		 * Check if we have the same extent.
6311		 */
6312		if (left_disknr != right_disknr ||
6313		    left_offset_fixed != right_offset ||
6314		    left_gen != right_gen) {
6315			ret = 0;
6316			goto out;
6317		}
6318
6319		/*
6320		 * Go to the next extent.
6321		 */
6322		ret = btrfs_next_item(sctx->parent_root, path);
6323		if (ret < 0)
6324			goto out;
6325		if (!ret) {
6326			eb = path->nodes[0];
6327			slot = path->slots[0];
6328			btrfs_item_key_to_cpu(eb, &found_key, slot);
6329		}
6330		if (ret || found_key.objectid != key.objectid ||
6331		    found_key.type != key.type) {
6332			key.offset += right_len;
6333			break;
6334		}
6335		if (found_key.offset != key.offset + right_len) {
6336			ret = 0;
6337			goto out;
6338		}
6339		key = found_key;
6340	}
6341
6342	/*
6343	 * We're now behind the left extent (treat as unchanged) or at the end
6344	 * of the right side (treat as changed).
6345	 */
6346	if (key.offset >= ekey->offset + left_len)
6347		ret = 1;
6348	else
6349		ret = 0;
6350
6351
6352out:
6353	btrfs_free_path(path);
6354	return ret;
6355}
6356
6357static int get_last_extent(struct send_ctx *sctx, u64 offset)
6358{
6359	struct btrfs_path *path;
6360	struct btrfs_root *root = sctx->send_root;
6361	struct btrfs_key key;
6362	int ret;
6363
6364	path = alloc_path_for_send();
6365	if (!path)
6366		return -ENOMEM;
6367
6368	sctx->cur_inode_last_extent = 0;
6369
6370	key.objectid = sctx->cur_ino;
6371	key.type = BTRFS_EXTENT_DATA_KEY;
6372	key.offset = offset;
6373	ret = btrfs_search_slot_for_read(root, &key, path, 0, 1);
6374	if (ret < 0)
6375		goto out;
6376	ret = 0;
6377	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
6378	if (key.objectid != sctx->cur_ino || key.type != BTRFS_EXTENT_DATA_KEY)
6379		goto out;
6380
6381	sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
6382out:
6383	btrfs_free_path(path);
6384	return ret;
6385}
6386
6387static int range_is_hole_in_parent(struct send_ctx *sctx,
6388				   const u64 start,
6389				   const u64 end)
6390{
6391	struct btrfs_path *path;
6392	struct btrfs_key key;
6393	struct btrfs_root *root = sctx->parent_root;
6394	u64 search_start = start;
6395	int ret;
6396
6397	path = alloc_path_for_send();
6398	if (!path)
6399		return -ENOMEM;
6400
6401	key.objectid = sctx->cur_ino;
6402	key.type = BTRFS_EXTENT_DATA_KEY;
6403	key.offset = search_start;
6404	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
6405	if (ret < 0)
6406		goto out;
6407	if (ret > 0 && path->slots[0] > 0)
6408		path->slots[0]--;
6409
6410	while (search_start < end) {
6411		struct extent_buffer *leaf = path->nodes[0];
6412		int slot = path->slots[0];
6413		struct btrfs_file_extent_item *fi;
6414		u64 extent_end;
6415
6416		if (slot >= btrfs_header_nritems(leaf)) {
6417			ret = btrfs_next_leaf(root, path);
6418			if (ret < 0)
6419				goto out;
6420			else if (ret > 0)
6421				break;
6422			continue;
6423		}
6424
6425		btrfs_item_key_to_cpu(leaf, &key, slot);
6426		if (key.objectid < sctx->cur_ino ||
6427		    key.type < BTRFS_EXTENT_DATA_KEY)
6428			goto next;
6429		if (key.objectid > sctx->cur_ino ||
6430		    key.type > BTRFS_EXTENT_DATA_KEY ||
6431		    key.offset >= end)
6432			break;
6433
6434		fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
6435		extent_end = btrfs_file_extent_end(path);
6436		if (extent_end <= start)
6437			goto next;
6438		if (btrfs_file_extent_disk_bytenr(leaf, fi) == 0) {
6439			search_start = extent_end;
6440			goto next;
6441		}
6442		ret = 0;
6443		goto out;
6444next:
6445		path->slots[0]++;
6446	}
6447	ret = 1;
6448out:
6449	btrfs_free_path(path);
6450	return ret;
6451}
6452
6453static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
6454			   struct btrfs_key *key)
6455{
6456	int ret = 0;
6457
6458	if (sctx->cur_ino != key->objectid || !need_send_hole(sctx))
6459		return 0;
6460
6461	if (sctx->cur_inode_last_extent == (u64)-1) {
6462		ret = get_last_extent(sctx, key->offset - 1);
6463		if (ret)
6464			return ret;
6465	}
6466
6467	if (path->slots[0] == 0 &&
6468	    sctx->cur_inode_last_extent < key->offset) {
6469		/*
6470		 * We might have skipped entire leafs that contained only
6471		 * file extent items for our current inode. These leafs have
6472		 * a generation number smaller (older) than the one in the
6473		 * current leaf and the leaf our last extent came from, and
6474		 * are located between these 2 leafs.
6475		 */
6476		ret = get_last_extent(sctx, key->offset - 1);
6477		if (ret)
6478			return ret;
6479	}
6480
6481	if (sctx->cur_inode_last_extent < key->offset) {
6482		ret = range_is_hole_in_parent(sctx,
6483					      sctx->cur_inode_last_extent,
6484					      key->offset);
6485		if (ret < 0)
6486			return ret;
6487		else if (ret == 0)
6488			ret = send_hole(sctx, key->offset);
6489		else
6490			ret = 0;
6491	}
6492	sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
6493	return ret;
6494}
6495
6496static int process_extent(struct send_ctx *sctx,
6497			  struct btrfs_path *path,
6498			  struct btrfs_key *key)
6499{
6500	struct clone_root *found_clone = NULL;
6501	int ret = 0;
6502
6503	if (S_ISLNK(sctx->cur_inode_mode))
6504		return 0;
6505
6506	if (sctx->parent_root && !sctx->cur_inode_new) {
6507		ret = is_extent_unchanged(sctx, path, key);
6508		if (ret < 0)
6509			goto out;
6510		if (ret) {
6511			ret = 0;
6512			goto out_hole;
6513		}
6514	} else {
6515		struct btrfs_file_extent_item *ei;
6516		u8 type;
6517
6518		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
6519				    struct btrfs_file_extent_item);
6520		type = btrfs_file_extent_type(path->nodes[0], ei);
6521		if (type == BTRFS_FILE_EXTENT_PREALLOC ||
6522		    type == BTRFS_FILE_EXTENT_REG) {
6523			/*
6524			 * The send spec does not have a prealloc command yet,
6525			 * so just leave a hole for prealloc'ed extents until
6526			 * we have enough commands queued up to justify rev'ing
6527			 * the send spec.
6528			 */
6529			if (type == BTRFS_FILE_EXTENT_PREALLOC) {
6530				ret = 0;
6531				goto out;
6532			}
6533
6534			/* Have a hole, just skip it. */
6535			if (btrfs_file_extent_disk_bytenr(path->nodes[0], ei) == 0) {
6536				ret = 0;
6537				goto out;
6538			}
6539		}
6540	}
6541
6542	ret = find_extent_clone(sctx, path, key->objectid, key->offset,
6543			sctx->cur_inode_size, &found_clone);
6544	if (ret != -ENOENT && ret < 0)
6545		goto out;
6546
6547	ret = send_write_or_clone(sctx, path, key, found_clone);
6548	if (ret)
6549		goto out;
6550out_hole:
6551	ret = maybe_send_hole(sctx, path, key);
6552out:
6553	return ret;
6554}
6555
6556static int process_all_extents(struct send_ctx *sctx)
6557{
6558	int ret = 0;
6559	int iter_ret = 0;
6560	struct btrfs_root *root;
6561	struct btrfs_path *path;
6562	struct btrfs_key key;
6563	struct btrfs_key found_key;
6564
6565	root = sctx->send_root;
6566	path = alloc_path_for_send();
6567	if (!path)
6568		return -ENOMEM;
6569
6570	key.objectid = sctx->cmp_key->objectid;
6571	key.type = BTRFS_EXTENT_DATA_KEY;
6572	key.offset = 0;
6573	btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) {
6574		if (found_key.objectid != key.objectid ||
6575		    found_key.type != key.type) {
6576			ret = 0;
6577			break;
6578		}
6579
6580		ret = process_extent(sctx, path, &found_key);
6581		if (ret < 0)
6582			break;
6583	}
6584	/* Catch error found during iteration */
6585	if (iter_ret < 0)
6586		ret = iter_ret;
6587
6588	btrfs_free_path(path);
6589	return ret;
6590}
6591
6592static int process_recorded_refs_if_needed(struct send_ctx *sctx, int at_end,
6593					   int *pending_move,
6594					   int *refs_processed)
6595{
6596	int ret = 0;
6597
6598	if (sctx->cur_ino == 0)
6599		goto out;
6600	if (!at_end && sctx->cur_ino == sctx->cmp_key->objectid &&
6601	    sctx->cmp_key->type <= BTRFS_INODE_EXTREF_KEY)
6602		goto out;
6603	if (list_empty(&sctx->new_refs) && list_empty(&sctx->deleted_refs))
6604		goto out;
6605
6606	ret = process_recorded_refs(sctx, pending_move);
6607	if (ret < 0)
6608		goto out;
6609
6610	*refs_processed = 1;
6611out:
6612	return ret;
6613}
6614
6615static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
6616{
6617	int ret = 0;
6618	struct btrfs_inode_info info;
6619	u64 left_mode;
6620	u64 left_uid;
6621	u64 left_gid;
6622	u64 left_fileattr;
6623	u64 right_mode;
6624	u64 right_uid;
6625	u64 right_gid;
6626	u64 right_fileattr;
6627	int need_chmod = 0;
6628	int need_chown = 0;
6629	bool need_fileattr = false;
6630	int need_truncate = 1;
6631	int pending_move = 0;
6632	int refs_processed = 0;
6633
6634	if (sctx->ignore_cur_inode)
6635		return 0;
6636
6637	ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move,
6638					      &refs_processed);
6639	if (ret < 0)
6640		goto out;
6641
6642	/*
6643	 * We have processed the refs and thus need to advance send_progress.
6644	 * Now, calls to get_cur_xxx will take the updated refs of the current
6645	 * inode into account.
6646	 *
6647	 * On the other hand, if our current inode is a directory and couldn't
6648	 * be moved/renamed because its parent was renamed/moved too and it has
6649	 * a higher inode number, we can only move/rename our current inode
6650	 * after we moved/renamed its parent. Therefore in this case operate on
6651	 * the old path (pre move/rename) of our current inode, and the
6652	 * move/rename will be performed later.
6653	 */
6654	if (refs_processed && !pending_move)
6655		sctx->send_progress = sctx->cur_ino + 1;
6656
6657	if (sctx->cur_ino == 0 || sctx->cur_inode_deleted)
6658		goto out;
6659	if (!at_end && sctx->cmp_key->objectid == sctx->cur_ino)
6660		goto out;
6661	ret = get_inode_info(sctx->send_root, sctx->cur_ino, &info);
6662	if (ret < 0)
6663		goto out;
6664	left_mode = info.mode;
6665	left_uid = info.uid;
6666	left_gid = info.gid;
6667	left_fileattr = info.fileattr;
6668
6669	if (!sctx->parent_root || sctx->cur_inode_new) {
6670		need_chown = 1;
6671		if (!S_ISLNK(sctx->cur_inode_mode))
6672			need_chmod = 1;
6673		if (sctx->cur_inode_next_write_offset == sctx->cur_inode_size)
6674			need_truncate = 0;
6675	} else {
6676		u64 old_size;
6677
6678		ret = get_inode_info(sctx->parent_root, sctx->cur_ino, &info);
6679		if (ret < 0)
6680			goto out;
6681		old_size = info.size;
6682		right_mode = info.mode;
6683		right_uid = info.uid;
6684		right_gid = info.gid;
6685		right_fileattr = info.fileattr;
6686
6687		if (left_uid != right_uid || left_gid != right_gid)
6688			need_chown = 1;
6689		if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
6690			need_chmod = 1;
6691		if (!S_ISLNK(sctx->cur_inode_mode) && left_fileattr != right_fileattr)
6692			need_fileattr = true;
6693		if ((old_size == sctx->cur_inode_size) ||
6694		    (sctx->cur_inode_size > old_size &&
6695		     sctx->cur_inode_next_write_offset == sctx->cur_inode_size))
6696			need_truncate = 0;
6697	}
6698
6699	if (S_ISREG(sctx->cur_inode_mode)) {
6700		if (need_send_hole(sctx)) {
6701			if (sctx->cur_inode_last_extent == (u64)-1 ||
6702			    sctx->cur_inode_last_extent <
6703			    sctx->cur_inode_size) {
6704				ret = get_last_extent(sctx, (u64)-1);
6705				if (ret)
6706					goto out;
6707			}
6708			if (sctx->cur_inode_last_extent < sctx->cur_inode_size) {
6709				ret = range_is_hole_in_parent(sctx,
6710						      sctx->cur_inode_last_extent,
6711						      sctx->cur_inode_size);
6712				if (ret < 0) {
6713					goto out;
6714				} else if (ret == 0) {
6715					ret = send_hole(sctx, sctx->cur_inode_size);
6716					if (ret < 0)
6717						goto out;
6718				} else {
6719					/* Range is already a hole, skip. */
6720					ret = 0;
6721				}
6722			}
6723		}
6724		if (need_truncate) {
6725			ret = send_truncate(sctx, sctx->cur_ino,
6726					    sctx->cur_inode_gen,
6727					    sctx->cur_inode_size);
6728			if (ret < 0)
6729				goto out;
6730		}
6731	}
6732
6733	if (need_chown) {
6734		ret = send_chown(sctx, sctx->cur_ino, sctx->cur_inode_gen,
6735				left_uid, left_gid);
6736		if (ret < 0)
6737			goto out;
6738	}
6739	if (need_chmod) {
6740		ret = send_chmod(sctx, sctx->cur_ino, sctx->cur_inode_gen,
6741				left_mode);
6742		if (ret < 0)
6743			goto out;
6744	}
6745	if (need_fileattr) {
6746		ret = send_fileattr(sctx, sctx->cur_ino, sctx->cur_inode_gen,
6747				    left_fileattr);
6748		if (ret < 0)
6749			goto out;
6750	}
6751
6752	if (proto_cmd_ok(sctx, BTRFS_SEND_C_ENABLE_VERITY)
6753	    && sctx->cur_inode_needs_verity) {
6754		ret = process_verity(sctx);
6755		if (ret < 0)
6756			goto out;
6757	}
6758
6759	ret = send_capabilities(sctx);
6760	if (ret < 0)
6761		goto out;
6762
6763	/*
6764	 * If other directory inodes depended on our current directory
6765	 * inode's move/rename, now do their move/rename operations.
6766	 */
6767	if (!is_waiting_for_move(sctx, sctx->cur_ino)) {
6768		ret = apply_children_dir_moves(sctx);
6769		if (ret)
6770			goto out;
6771		/*
6772		 * Need to send that every time, no matter if it actually
6773		 * changed between the two trees as we have done changes to
6774		 * the inode before. If our inode is a directory and it's
6775		 * waiting to be moved/renamed, we will send its utimes when
6776		 * it's moved/renamed, therefore we don't need to do it here.
6777		 */
6778		sctx->send_progress = sctx->cur_ino + 1;
6779
6780		/*
6781		 * If the current inode is a non-empty directory, delay issuing
6782		 * the utimes command for it, as it's very likely we have inodes
6783		 * with an higher number inside it. We want to issue the utimes
6784		 * command only after adding all dentries to it.
6785		 */
6786		if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_size > 0)
6787			ret = cache_dir_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
6788		else
6789			ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
6790
6791		if (ret < 0)
6792			goto out;
6793	}
6794
6795out:
6796	if (!ret)
6797		ret = trim_dir_utimes_cache(sctx);
6798
6799	return ret;
6800}
6801
6802static void close_current_inode(struct send_ctx *sctx)
6803{
6804	u64 i_size;
6805
6806	if (sctx->cur_inode == NULL)
6807		return;
6808
6809	i_size = i_size_read(sctx->cur_inode);
6810
6811	/*
6812	 * If we are doing an incremental send, we may have extents between the
6813	 * last processed extent and the i_size that have not been processed
6814	 * because they haven't changed but we may have read some of their pages
6815	 * through readahead, see the comments at send_extent_data().
6816	 */
6817	if (sctx->clean_page_cache && sctx->page_cache_clear_start < i_size)
6818		truncate_inode_pages_range(&sctx->cur_inode->i_data,
6819					   sctx->page_cache_clear_start,
6820					   round_up(i_size, PAGE_SIZE) - 1);
6821
6822	iput(sctx->cur_inode);
6823	sctx->cur_inode = NULL;
6824}
6825
6826static int changed_inode(struct send_ctx *sctx,
6827			 enum btrfs_compare_tree_result result)
6828{
6829	int ret = 0;
6830	struct btrfs_key *key = sctx->cmp_key;
6831	struct btrfs_inode_item *left_ii = NULL;
6832	struct btrfs_inode_item *right_ii = NULL;
6833	u64 left_gen = 0;
6834	u64 right_gen = 0;
6835
6836	close_current_inode(sctx);
6837
6838	sctx->cur_ino = key->objectid;
6839	sctx->cur_inode_new_gen = false;
6840	sctx->cur_inode_last_extent = (u64)-1;
6841	sctx->cur_inode_next_write_offset = 0;
6842	sctx->ignore_cur_inode = false;
6843
6844	/*
6845	 * Set send_progress to current inode. This will tell all get_cur_xxx
6846	 * functions that the current inode's refs are not updated yet. Later,
6847	 * when process_recorded_refs is finished, it is set to cur_ino + 1.
6848	 */
6849	sctx->send_progress = sctx->cur_ino;
6850
6851	if (result == BTRFS_COMPARE_TREE_NEW ||
6852	    result == BTRFS_COMPARE_TREE_CHANGED) {
6853		left_ii = btrfs_item_ptr(sctx->left_path->nodes[0],
6854				sctx->left_path->slots[0],
6855				struct btrfs_inode_item);
6856		left_gen = btrfs_inode_generation(sctx->left_path->nodes[0],
6857				left_ii);
6858	} else {
6859		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
6860				sctx->right_path->slots[0],
6861				struct btrfs_inode_item);
6862		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
6863				right_ii);
6864	}
6865	if (result == BTRFS_COMPARE_TREE_CHANGED) {
6866		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
6867				sctx->right_path->slots[0],
6868				struct btrfs_inode_item);
6869
6870		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
6871				right_ii);
6872
6873		/*
6874		 * The cur_ino = root dir case is special here. We can't treat
6875		 * the inode as deleted+reused because it would generate a
6876		 * stream that tries to delete/mkdir the root dir.
6877		 */
6878		if (left_gen != right_gen &&
6879		    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
6880			sctx->cur_inode_new_gen = true;
6881	}
6882
6883	/*
6884	 * Normally we do not find inodes with a link count of zero (orphans)
6885	 * because the most common case is to create a snapshot and use it
6886	 * for a send operation. However other less common use cases involve
6887	 * using a subvolume and send it after turning it to RO mode just
6888	 * after deleting all hard links of a file while holding an open
6889	 * file descriptor against it or turning a RO snapshot into RW mode,
6890	 * keep an open file descriptor against a file, delete it and then
6891	 * turn the snapshot back to RO mode before using it for a send
6892	 * operation. The former is what the receiver operation does.
6893	 * Therefore, if we want to send these snapshots soon after they're
6894	 * received, we need to handle orphan inodes as well. Moreover, orphans
6895	 * can appear not only in the send snapshot but also in the parent
6896	 * snapshot. Here are several cases:
6897	 *
6898	 * Case 1: BTRFS_COMPARE_TREE_NEW
6899	 *       |  send snapshot  | action
6900	 * --------------------------------
6901	 * nlink |        0        | ignore
6902	 *
6903	 * Case 2: BTRFS_COMPARE_TREE_DELETED
6904	 *       | parent snapshot | action
6905	 * ----------------------------------
6906	 * nlink |        0        | as usual
6907	 * Note: No unlinks will be sent because there're no paths for it.
6908	 *
6909	 * Case 3: BTRFS_COMPARE_TREE_CHANGED
6910	 *           |       | parent snapshot | send snapshot | action
6911	 * -----------------------------------------------------------------------
6912	 * subcase 1 | nlink |        0        |       0       | ignore
6913	 * subcase 2 | nlink |       >0        |       0       | new_gen(deletion)
6914	 * subcase 3 | nlink |        0        |      >0       | new_gen(creation)
6915	 *
6916	 */
6917	if (result == BTRFS_COMPARE_TREE_NEW) {
6918		if (btrfs_inode_nlink(sctx->left_path->nodes[0], left_ii) == 0) {
6919			sctx->ignore_cur_inode = true;
6920			goto out;
6921		}
6922		sctx->cur_inode_gen = left_gen;
6923		sctx->cur_inode_new = true;
6924		sctx->cur_inode_deleted = false;
6925		sctx->cur_inode_size = btrfs_inode_size(
6926				sctx->left_path->nodes[0], left_ii);
6927		sctx->cur_inode_mode = btrfs_inode_mode(
6928				sctx->left_path->nodes[0], left_ii);
6929		sctx->cur_inode_rdev = btrfs_inode_rdev(
6930				sctx->left_path->nodes[0], left_ii);
6931		if (sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
6932			ret = send_create_inode_if_needed(sctx);
6933	} else if (result == BTRFS_COMPARE_TREE_DELETED) {
6934		sctx->cur_inode_gen = right_gen;
6935		sctx->cur_inode_new = false;
6936		sctx->cur_inode_deleted = true;
6937		sctx->cur_inode_size = btrfs_inode_size(
6938				sctx->right_path->nodes[0], right_ii);
6939		sctx->cur_inode_mode = btrfs_inode_mode(
6940				sctx->right_path->nodes[0], right_ii);
6941	} else if (result == BTRFS_COMPARE_TREE_CHANGED) {
6942		u32 new_nlinks, old_nlinks;
6943
6944		new_nlinks = btrfs_inode_nlink(sctx->left_path->nodes[0], left_ii);
6945		old_nlinks = btrfs_inode_nlink(sctx->right_path->nodes[0], right_ii);
6946		if (new_nlinks == 0 && old_nlinks == 0) {
6947			sctx->ignore_cur_inode = true;
6948			goto out;
6949		} else if (new_nlinks == 0 || old_nlinks == 0) {
6950			sctx->cur_inode_new_gen = 1;
6951		}
6952		/*
6953		 * We need to do some special handling in case the inode was
6954		 * reported as changed with a changed generation number. This
6955		 * means that the original inode was deleted and new inode
6956		 * reused the same inum. So we have to treat the old inode as
6957		 * deleted and the new one as new.
6958		 */
6959		if (sctx->cur_inode_new_gen) {
6960			/*
6961			 * First, process the inode as if it was deleted.
6962			 */
6963			if (old_nlinks > 0) {
6964				sctx->cur_inode_gen = right_gen;
6965				sctx->cur_inode_new = false;
6966				sctx->cur_inode_deleted = true;
6967				sctx->cur_inode_size = btrfs_inode_size(
6968						sctx->right_path->nodes[0], right_ii);
6969				sctx->cur_inode_mode = btrfs_inode_mode(
6970						sctx->right_path->nodes[0], right_ii);
6971				ret = process_all_refs(sctx,
6972						BTRFS_COMPARE_TREE_DELETED);
6973				if (ret < 0)
6974					goto out;
6975			}
6976
6977			/*
6978			 * Now process the inode as if it was new.
6979			 */
6980			if (new_nlinks > 0) {
6981				sctx->cur_inode_gen = left_gen;
6982				sctx->cur_inode_new = true;
6983				sctx->cur_inode_deleted = false;
6984				sctx->cur_inode_size = btrfs_inode_size(
6985						sctx->left_path->nodes[0],
6986						left_ii);
6987				sctx->cur_inode_mode = btrfs_inode_mode(
6988						sctx->left_path->nodes[0],
6989						left_ii);
6990				sctx->cur_inode_rdev = btrfs_inode_rdev(
6991						sctx->left_path->nodes[0],
6992						left_ii);
6993				ret = send_create_inode_if_needed(sctx);
6994				if (ret < 0)
6995					goto out;
6996
6997				ret = process_all_refs(sctx, BTRFS_COMPARE_TREE_NEW);
6998				if (ret < 0)
6999					goto out;
7000				/*
7001				 * Advance send_progress now as we did not get
7002				 * into process_recorded_refs_if_needed in the
7003				 * new_gen case.
7004				 */
7005				sctx->send_progress = sctx->cur_ino + 1;
7006
7007				/*
7008				 * Now process all extents and xattrs of the
7009				 * inode as if they were all new.
7010				 */
7011				ret = process_all_extents(sctx);
7012				if (ret < 0)
7013					goto out;
7014				ret = process_all_new_xattrs(sctx);
7015				if (ret < 0)
7016					goto out;
7017			}
7018		} else {
7019			sctx->cur_inode_gen = left_gen;
7020			sctx->cur_inode_new = false;
7021			sctx->cur_inode_new_gen = false;
7022			sctx->cur_inode_deleted = false;
7023			sctx->cur_inode_size = btrfs_inode_size(
7024					sctx->left_path->nodes[0], left_ii);
7025			sctx->cur_inode_mode = btrfs_inode_mode(
7026					sctx->left_path->nodes[0], left_ii);
7027		}
7028	}
7029
7030out:
7031	return ret;
7032}
7033
7034/*
7035 * We have to process new refs before deleted refs, but compare_trees gives us
7036 * the new and deleted refs mixed. To fix this, we record the new/deleted refs
7037 * first and later process them in process_recorded_refs.
7038 * For the cur_inode_new_gen case, we skip recording completely because
7039 * changed_inode did already initiate processing of refs. The reason for this is
7040 * that in this case, compare_tree actually compares the refs of 2 different
7041 * inodes. To fix this, process_all_refs is used in changed_inode to handle all
7042 * refs of the right tree as deleted and all refs of the left tree as new.
7043 */
7044static int changed_ref(struct send_ctx *sctx,
7045		       enum btrfs_compare_tree_result result)
7046{
7047	int ret = 0;
7048
7049	if (sctx->cur_ino != sctx->cmp_key->objectid) {
7050		inconsistent_snapshot_error(sctx, result, "reference");
7051		return -EIO;
7052	}
7053
7054	if (!sctx->cur_inode_new_gen &&
7055	    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID) {
7056		if (result == BTRFS_COMPARE_TREE_NEW)
7057			ret = record_new_ref(sctx);
7058		else if (result == BTRFS_COMPARE_TREE_DELETED)
7059			ret = record_deleted_ref(sctx);
7060		else if (result == BTRFS_COMPARE_TREE_CHANGED)
7061			ret = record_changed_ref(sctx);
7062	}
7063
7064	return ret;
7065}
7066
7067/*
7068 * Process new/deleted/changed xattrs. We skip processing in the
7069 * cur_inode_new_gen case because changed_inode did already initiate processing
7070 * of xattrs. The reason is the same as in changed_ref
7071 */
7072static int changed_xattr(struct send_ctx *sctx,
7073			 enum btrfs_compare_tree_result result)
7074{
7075	int ret = 0;
7076
7077	if (sctx->cur_ino != sctx->cmp_key->objectid) {
7078		inconsistent_snapshot_error(sctx, result, "xattr");
7079		return -EIO;
7080	}
7081
7082	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
7083		if (result == BTRFS_COMPARE_TREE_NEW)
7084			ret = process_new_xattr(sctx);
7085		else if (result == BTRFS_COMPARE_TREE_DELETED)
7086			ret = process_deleted_xattr(sctx);
7087		else if (result == BTRFS_COMPARE_TREE_CHANGED)
7088			ret = process_changed_xattr(sctx);
7089	}
7090
7091	return ret;
7092}
7093
7094/*
7095 * Process new/deleted/changed extents. We skip processing in the
7096 * cur_inode_new_gen case because changed_inode did already initiate processing
7097 * of extents. The reason is the same as in changed_ref
7098 */
7099static int changed_extent(struct send_ctx *sctx,
7100			  enum btrfs_compare_tree_result result)
7101{
7102	int ret = 0;
7103
7104	/*
7105	 * We have found an extent item that changed without the inode item
7106	 * having changed. This can happen either after relocation (where the
7107	 * disk_bytenr of an extent item is replaced at
7108	 * relocation.c:replace_file_extents()) or after deduplication into a
7109	 * file in both the parent and send snapshots (where an extent item can
7110	 * get modified or replaced with a new one). Note that deduplication
7111	 * updates the inode item, but it only changes the iversion (sequence
7112	 * field in the inode item) of the inode, so if a file is deduplicated
7113	 * the same amount of times in both the parent and send snapshots, its
7114	 * iversion becomes the same in both snapshots, whence the inode item is
7115	 * the same on both snapshots.
7116	 */
7117	if (sctx->cur_ino != sctx->cmp_key->objectid)
7118		return 0;
7119
7120	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
7121		if (result != BTRFS_COMPARE_TREE_DELETED)
7122			ret = process_extent(sctx, sctx->left_path,
7123					sctx->cmp_key);
7124	}
7125
7126	return ret;
7127}
7128
7129static int changed_verity(struct send_ctx *sctx, enum btrfs_compare_tree_result result)
7130{
7131	int ret = 0;
7132
7133	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
7134		if (result == BTRFS_COMPARE_TREE_NEW)
7135			sctx->cur_inode_needs_verity = true;
7136	}
7137	return ret;
7138}
7139
7140static int dir_changed(struct send_ctx *sctx, u64 dir)
7141{
7142	u64 orig_gen, new_gen;
7143	int ret;
7144
7145	ret = get_inode_gen(sctx->send_root, dir, &new_gen);
7146	if (ret)
7147		return ret;
7148
7149	ret = get_inode_gen(sctx->parent_root, dir, &orig_gen);
7150	if (ret)
7151		return ret;
7152
7153	return (orig_gen != new_gen) ? 1 : 0;
7154}
7155
7156static int compare_refs(struct send_ctx *sctx, struct btrfs_path *path,
7157			struct btrfs_key *key)
7158{
7159	struct btrfs_inode_extref *extref;
7160	struct extent_buffer *leaf;
7161	u64 dirid = 0, last_dirid = 0;
7162	unsigned long ptr;
7163	u32 item_size;
7164	u32 cur_offset = 0;
7165	int ref_name_len;
7166	int ret = 0;
7167
7168	/* Easy case, just check this one dirid */
7169	if (key->type == BTRFS_INODE_REF_KEY) {
7170		dirid = key->offset;
7171
7172		ret = dir_changed(sctx, dirid);
7173		goto out;
7174	}
7175
7176	leaf = path->nodes[0];
7177	item_size = btrfs_item_size(leaf, path->slots[0]);
7178	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
7179	while (cur_offset < item_size) {
7180		extref = (struct btrfs_inode_extref *)(ptr +
7181						       cur_offset);
7182		dirid = btrfs_inode_extref_parent(leaf, extref);
7183		ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
7184		cur_offset += ref_name_len + sizeof(*extref);
7185		if (dirid == last_dirid)
7186			continue;
7187		ret = dir_changed(sctx, dirid);
7188		if (ret)
7189			break;
7190		last_dirid = dirid;
7191	}
7192out:
7193	return ret;
7194}
7195
7196/*
7197 * Updates compare related fields in sctx and simply forwards to the actual
7198 * changed_xxx functions.
7199 */
7200static int changed_cb(struct btrfs_path *left_path,
7201		      struct btrfs_path *right_path,
7202		      struct btrfs_key *key,
7203		      enum btrfs_compare_tree_result result,
7204		      struct send_ctx *sctx)
7205{
7206	int ret = 0;
7207
7208	/*
7209	 * We can not hold the commit root semaphore here. This is because in
7210	 * the case of sending and receiving to the same filesystem, using a
7211	 * pipe, could result in a deadlock:
7212	 *
7213	 * 1) The task running send blocks on the pipe because it's full;
7214	 *
7215	 * 2) The task running receive, which is the only consumer of the pipe,
7216	 *    is waiting for a transaction commit (for example due to a space
7217	 *    reservation when doing a write or triggering a transaction commit
7218	 *    when creating a subvolume);
7219	 *
7220	 * 3) The transaction is waiting to write lock the commit root semaphore,
7221	 *    but can not acquire it since it's being held at 1).
7222	 *
7223	 * Down this call chain we write to the pipe through kernel_write().
7224	 * The same type of problem can also happen when sending to a file that
7225	 * is stored in the same filesystem - when reserving space for a write
7226	 * into the file, we can trigger a transaction commit.
7227	 *
7228	 * Our caller has supplied us with clones of leaves from the send and
7229	 * parent roots, so we're safe here from a concurrent relocation and
7230	 * further reallocation of metadata extents while we are here. Below we
7231	 * also assert that the leaves are clones.
7232	 */
7233	lockdep_assert_not_held(&sctx->send_root->fs_info->commit_root_sem);
7234
7235	/*
7236	 * We always have a send root, so left_path is never NULL. We will not
7237	 * have a leaf when we have reached the end of the send root but have
7238	 * not yet reached the end of the parent root.
7239	 */
7240	if (left_path->nodes[0])
7241		ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
7242				&left_path->nodes[0]->bflags));
7243	/*
7244	 * When doing a full send we don't have a parent root, so right_path is
7245	 * NULL. When doing an incremental send, we may have reached the end of
7246	 * the parent root already, so we don't have a leaf at right_path.
7247	 */
7248	if (right_path && right_path->nodes[0])
7249		ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
7250				&right_path->nodes[0]->bflags));
7251
7252	if (result == BTRFS_COMPARE_TREE_SAME) {
7253		if (key->type == BTRFS_INODE_REF_KEY ||
7254		    key->type == BTRFS_INODE_EXTREF_KEY) {
7255			ret = compare_refs(sctx, left_path, key);
7256			if (!ret)
7257				return 0;
7258			if (ret < 0)
7259				return ret;
7260		} else if (key->type == BTRFS_EXTENT_DATA_KEY) {
7261			return maybe_send_hole(sctx, left_path, key);
7262		} else {
7263			return 0;
7264		}
7265		result = BTRFS_COMPARE_TREE_CHANGED;
7266		ret = 0;
7267	}
7268
7269	sctx->left_path = left_path;
7270	sctx->right_path = right_path;
7271	sctx->cmp_key = key;
7272
7273	ret = finish_inode_if_needed(sctx, 0);
7274	if (ret < 0)
7275		goto out;
7276
7277	/* Ignore non-FS objects */
7278	if (key->objectid == BTRFS_FREE_INO_OBJECTID ||
7279	    key->objectid == BTRFS_FREE_SPACE_OBJECTID)
7280		goto out;
7281
7282	if (key->type == BTRFS_INODE_ITEM_KEY) {
7283		ret = changed_inode(sctx, result);
7284	} else if (!sctx->ignore_cur_inode) {
7285		if (key->type == BTRFS_INODE_REF_KEY ||
7286		    key->type == BTRFS_INODE_EXTREF_KEY)
7287			ret = changed_ref(sctx, result);
7288		else if (key->type == BTRFS_XATTR_ITEM_KEY)
7289			ret = changed_xattr(sctx, result);
7290		else if (key->type == BTRFS_EXTENT_DATA_KEY)
7291			ret = changed_extent(sctx, result);
7292		else if (key->type == BTRFS_VERITY_DESC_ITEM_KEY &&
7293			 key->offset == 0)
7294			ret = changed_verity(sctx, result);
7295	}
7296
7297out:
7298	return ret;
7299}
7300
7301static int search_key_again(const struct send_ctx *sctx,
7302			    struct btrfs_root *root,
7303			    struct btrfs_path *path,
7304			    const struct btrfs_key *key)
7305{
7306	int ret;
7307
7308	if (!path->need_commit_sem)
7309		lockdep_assert_held_read(&root->fs_info->commit_root_sem);
7310
7311	/*
7312	 * Roots used for send operations are readonly and no one can add,
7313	 * update or remove keys from them, so we should be able to find our
7314	 * key again. The only exception is deduplication, which can operate on
7315	 * readonly roots and add, update or remove keys to/from them - but at
7316	 * the moment we don't allow it to run in parallel with send.
7317	 */
7318	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
7319	ASSERT(ret <= 0);
7320	if (ret > 0) {
7321		btrfs_print_tree(path->nodes[path->lowest_level], false);
7322		btrfs_err(root->fs_info,
7323"send: key (%llu %u %llu) not found in %s root %llu, lowest_level %d, slot %d",
7324			  key->objectid, key->type, key->offset,
7325			  (root == sctx->parent_root ? "parent" : "send"),
7326			  root->root_key.objectid, path->lowest_level,
7327			  path->slots[path->lowest_level]);
7328		return -EUCLEAN;
7329	}
7330
7331	return ret;
7332}
7333
7334static int full_send_tree(struct send_ctx *sctx)
7335{
7336	int ret;
7337	struct btrfs_root *send_root = sctx->send_root;
7338	struct btrfs_key key;
7339	struct btrfs_fs_info *fs_info = send_root->fs_info;
7340	struct btrfs_path *path;
7341
7342	path = alloc_path_for_send();
7343	if (!path)
7344		return -ENOMEM;
7345	path->reada = READA_FORWARD_ALWAYS;
7346
7347	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
7348	key.type = BTRFS_INODE_ITEM_KEY;
7349	key.offset = 0;
7350
7351	down_read(&fs_info->commit_root_sem);
7352	sctx->last_reloc_trans = fs_info->last_reloc_trans;
7353	up_read(&fs_info->commit_root_sem);
7354
7355	ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
7356	if (ret < 0)
7357		goto out;
7358	if (ret)
7359		goto out_finish;
7360
7361	while (1) {
7362		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
7363
7364		ret = changed_cb(path, NULL, &key,
7365				 BTRFS_COMPARE_TREE_NEW, sctx);
7366		if (ret < 0)
7367			goto out;
7368
7369		down_read(&fs_info->commit_root_sem);
7370		if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
7371			sctx->last_reloc_trans = fs_info->last_reloc_trans;
7372			up_read(&fs_info->commit_root_sem);
7373			/*
7374			 * A transaction used for relocating a block group was
7375			 * committed or is about to finish its commit. Release
7376			 * our path (leaf) and restart the search, so that we
7377			 * avoid operating on any file extent items that are
7378			 * stale, with a disk_bytenr that reflects a pre
7379			 * relocation value. This way we avoid as much as
7380			 * possible to fallback to regular writes when checking
7381			 * if we can clone file ranges.
7382			 */
7383			btrfs_release_path(path);
7384			ret = search_key_again(sctx, send_root, path, &key);
7385			if (ret < 0)
7386				goto out;
7387		} else {
7388			up_read(&fs_info->commit_root_sem);
7389		}
7390
7391		ret = btrfs_next_item(send_root, path);
7392		if (ret < 0)
7393			goto out;
7394		if (ret) {
7395			ret  = 0;
7396			break;
7397		}
7398	}
7399
7400out_finish:
7401	ret = finish_inode_if_needed(sctx, 1);
7402
7403out:
7404	btrfs_free_path(path);
7405	return ret;
7406}
7407
7408static int replace_node_with_clone(struct btrfs_path *path, int level)
7409{
7410	struct extent_buffer *clone;
7411
7412	clone = btrfs_clone_extent_buffer(path->nodes[level]);
7413	if (!clone)
7414		return -ENOMEM;
7415
7416	free_extent_buffer(path->nodes[level]);
7417	path->nodes[level] = clone;
7418
7419	return 0;
7420}
7421
7422static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen)
7423{
7424	struct extent_buffer *eb;
7425	struct extent_buffer *parent = path->nodes[*level];
7426	int slot = path->slots[*level];
7427	const int nritems = btrfs_header_nritems(parent);
7428	u64 reada_max;
7429	u64 reada_done = 0;
7430
7431	lockdep_assert_held_read(&parent->fs_info->commit_root_sem);
 
7432
7433	BUG_ON(*level == 0);
7434	eb = btrfs_read_node_slot(parent, slot);
7435	if (IS_ERR(eb))
7436		return PTR_ERR(eb);
7437
7438	/*
7439	 * Trigger readahead for the next leaves we will process, so that it is
7440	 * very likely that when we need them they are already in memory and we
7441	 * will not block on disk IO. For nodes we only do readahead for one,
7442	 * since the time window between processing nodes is typically larger.
7443	 */
7444	reada_max = (*level == 1 ? SZ_128K : eb->fs_info->nodesize);
7445
7446	for (slot++; slot < nritems && reada_done < reada_max; slot++) {
7447		if (btrfs_node_ptr_generation(parent, slot) > reada_min_gen) {
7448			btrfs_readahead_node_child(parent, slot);
7449			reada_done += eb->fs_info->nodesize;
7450		}
7451	}
7452
7453	path->nodes[*level - 1] = eb;
7454	path->slots[*level - 1] = 0;
7455	(*level)--;
7456
7457	if (*level == 0)
7458		return replace_node_with_clone(path, 0);
7459
7460	return 0;
7461}
7462
7463static int tree_move_next_or_upnext(struct btrfs_path *path,
7464				    int *level, int root_level)
7465{
7466	int ret = 0;
7467	int nritems;
7468	nritems = btrfs_header_nritems(path->nodes[*level]);
7469
7470	path->slots[*level]++;
7471
7472	while (path->slots[*level] >= nritems) {
7473		if (*level == root_level) {
7474			path->slots[*level] = nritems - 1;
7475			return -1;
7476		}
7477
7478		/* move upnext */
7479		path->slots[*level] = 0;
7480		free_extent_buffer(path->nodes[*level]);
7481		path->nodes[*level] = NULL;
7482		(*level)++;
7483		path->slots[*level]++;
7484
7485		nritems = btrfs_header_nritems(path->nodes[*level]);
7486		ret = 1;
7487	}
7488	return ret;
7489}
7490
7491/*
7492 * Returns 1 if it had to move up and next. 0 is returned if it moved only next
7493 * or down.
7494 */
7495static int tree_advance(struct btrfs_path *path,
7496			int *level, int root_level,
7497			int allow_down,
7498			struct btrfs_key *key,
7499			u64 reada_min_gen)
7500{
7501	int ret;
7502
7503	if (*level == 0 || !allow_down) {
7504		ret = tree_move_next_or_upnext(path, level, root_level);
7505	} else {
7506		ret = tree_move_down(path, level, reada_min_gen);
7507	}
7508
7509	/*
7510	 * Even if we have reached the end of a tree, ret is -1, update the key
7511	 * anyway, so that in case we need to restart due to a block group
7512	 * relocation, we can assert that the last key of the root node still
7513	 * exists in the tree.
7514	 */
7515	if (*level == 0)
7516		btrfs_item_key_to_cpu(path->nodes[*level], key,
7517				      path->slots[*level]);
7518	else
7519		btrfs_node_key_to_cpu(path->nodes[*level], key,
7520				      path->slots[*level]);
7521
7522	return ret;
7523}
7524
7525static int tree_compare_item(struct btrfs_path *left_path,
7526			     struct btrfs_path *right_path,
7527			     char *tmp_buf)
7528{
7529	int cmp;
7530	int len1, len2;
7531	unsigned long off1, off2;
7532
7533	len1 = btrfs_item_size(left_path->nodes[0], left_path->slots[0]);
7534	len2 = btrfs_item_size(right_path->nodes[0], right_path->slots[0]);
7535	if (len1 != len2)
7536		return 1;
7537
7538	off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
7539	off2 = btrfs_item_ptr_offset(right_path->nodes[0],
7540				right_path->slots[0]);
7541
7542	read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
7543
7544	cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
7545	if (cmp)
7546		return 1;
7547	return 0;
7548}
7549
7550/*
7551 * A transaction used for relocating a block group was committed or is about to
7552 * finish its commit. Release our paths and restart the search, so that we are
7553 * not using stale extent buffers:
7554 *
7555 * 1) For levels > 0, we are only holding references of extent buffers, without
7556 *    any locks on them, which does not prevent them from having been relocated
7557 *    and reallocated after the last time we released the commit root semaphore.
7558 *    The exception are the root nodes, for which we always have a clone, see
7559 *    the comment at btrfs_compare_trees();
7560 *
7561 * 2) For leaves, level 0, we are holding copies (clones) of extent buffers, so
7562 *    we are safe from the concurrent relocation and reallocation. However they
7563 *    can have file extent items with a pre relocation disk_bytenr value, so we
7564 *    restart the start from the current commit roots and clone the new leaves so
7565 *    that we get the post relocation disk_bytenr values. Not doing so, could
7566 *    make us clone the wrong data in case there are new extents using the old
7567 *    disk_bytenr that happen to be shared.
7568 */
7569static int restart_after_relocation(struct btrfs_path *left_path,
7570				    struct btrfs_path *right_path,
7571				    const struct btrfs_key *left_key,
7572				    const struct btrfs_key *right_key,
7573				    int left_level,
7574				    int right_level,
7575				    const struct send_ctx *sctx)
7576{
7577	int root_level;
7578	int ret;
7579
7580	lockdep_assert_held_read(&sctx->send_root->fs_info->commit_root_sem);
7581
7582	btrfs_release_path(left_path);
7583	btrfs_release_path(right_path);
7584
7585	/*
7586	 * Since keys can not be added or removed to/from our roots because they
7587	 * are readonly and we do not allow deduplication to run in parallel
7588	 * (which can add, remove or change keys), the layout of the trees should
7589	 * not change.
7590	 */
7591	left_path->lowest_level = left_level;
7592	ret = search_key_again(sctx, sctx->send_root, left_path, left_key);
7593	if (ret < 0)
7594		return ret;
7595
7596	right_path->lowest_level = right_level;
7597	ret = search_key_again(sctx, sctx->parent_root, right_path, right_key);
7598	if (ret < 0)
7599		return ret;
7600
7601	/*
7602	 * If the lowest level nodes are leaves, clone them so that they can be
7603	 * safely used by changed_cb() while not under the protection of the
7604	 * commit root semaphore, even if relocation and reallocation happens in
7605	 * parallel.
7606	 */
7607	if (left_level == 0) {
7608		ret = replace_node_with_clone(left_path, 0);
7609		if (ret < 0)
7610			return ret;
7611	}
7612
7613	if (right_level == 0) {
7614		ret = replace_node_with_clone(right_path, 0);
7615		if (ret < 0)
7616			return ret;
7617	}
7618
7619	/*
7620	 * Now clone the root nodes (unless they happen to be the leaves we have
7621	 * already cloned). This is to protect against concurrent snapshotting of
7622	 * the send and parent roots (see the comment at btrfs_compare_trees()).
7623	 */
7624	root_level = btrfs_header_level(sctx->send_root->commit_root);
7625	if (root_level > 0) {
7626		ret = replace_node_with_clone(left_path, root_level);
7627		if (ret < 0)
7628			return ret;
7629	}
7630
7631	root_level = btrfs_header_level(sctx->parent_root->commit_root);
7632	if (root_level > 0) {
7633		ret = replace_node_with_clone(right_path, root_level);
7634		if (ret < 0)
7635			return ret;
7636	}
7637
7638	return 0;
7639}
7640
7641/*
7642 * This function compares two trees and calls the provided callback for
7643 * every changed/new/deleted item it finds.
7644 * If shared tree blocks are encountered, whole subtrees are skipped, making
7645 * the compare pretty fast on snapshotted subvolumes.
7646 *
7647 * This currently works on commit roots only. As commit roots are read only,
7648 * we don't do any locking. The commit roots are protected with transactions.
7649 * Transactions are ended and rejoined when a commit is tried in between.
7650 *
7651 * This function checks for modifications done to the trees while comparing.
7652 * If it detects a change, it aborts immediately.
7653 */
7654static int btrfs_compare_trees(struct btrfs_root *left_root,
7655			struct btrfs_root *right_root, struct send_ctx *sctx)
7656{
7657	struct btrfs_fs_info *fs_info = left_root->fs_info;
7658	int ret;
7659	int cmp;
7660	struct btrfs_path *left_path = NULL;
7661	struct btrfs_path *right_path = NULL;
7662	struct btrfs_key left_key;
7663	struct btrfs_key right_key;
7664	char *tmp_buf = NULL;
7665	int left_root_level;
7666	int right_root_level;
7667	int left_level;
7668	int right_level;
7669	int left_end_reached = 0;
7670	int right_end_reached = 0;
7671	int advance_left = 0;
7672	int advance_right = 0;
7673	u64 left_blockptr;
7674	u64 right_blockptr;
7675	u64 left_gen;
7676	u64 right_gen;
7677	u64 reada_min_gen;
7678
7679	left_path = btrfs_alloc_path();
7680	if (!left_path) {
7681		ret = -ENOMEM;
7682		goto out;
7683	}
7684	right_path = btrfs_alloc_path();
7685	if (!right_path) {
7686		ret = -ENOMEM;
7687		goto out;
7688	}
7689
7690	tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
7691	if (!tmp_buf) {
7692		ret = -ENOMEM;
7693		goto out;
7694	}
7695
7696	left_path->search_commit_root = 1;
7697	left_path->skip_locking = 1;
7698	right_path->search_commit_root = 1;
7699	right_path->skip_locking = 1;
7700
7701	/*
7702	 * Strategy: Go to the first items of both trees. Then do
7703	 *
7704	 * If both trees are at level 0
7705	 *   Compare keys of current items
7706	 *     If left < right treat left item as new, advance left tree
7707	 *       and repeat
7708	 *     If left > right treat right item as deleted, advance right tree
7709	 *       and repeat
7710	 *     If left == right do deep compare of items, treat as changed if
7711	 *       needed, advance both trees and repeat
7712	 * If both trees are at the same level but not at level 0
7713	 *   Compare keys of current nodes/leafs
7714	 *     If left < right advance left tree and repeat
7715	 *     If left > right advance right tree and repeat
7716	 *     If left == right compare blockptrs of the next nodes/leafs
7717	 *       If they match advance both trees but stay at the same level
7718	 *         and repeat
7719	 *       If they don't match advance both trees while allowing to go
7720	 *         deeper and repeat
7721	 * If tree levels are different
7722	 *   Advance the tree that needs it and repeat
7723	 *
7724	 * Advancing a tree means:
7725	 *   If we are at level 0, try to go to the next slot. If that's not
7726	 *   possible, go one level up and repeat. Stop when we found a level
7727	 *   where we could go to the next slot. We may at this point be on a
7728	 *   node or a leaf.
7729	 *
7730	 *   If we are not at level 0 and not on shared tree blocks, go one
7731	 *   level deeper.
7732	 *
7733	 *   If we are not at level 0 and on shared tree blocks, go one slot to
7734	 *   the right if possible or go up and right.
7735	 */
7736
7737	down_read(&fs_info->commit_root_sem);
7738	left_level = btrfs_header_level(left_root->commit_root);
7739	left_root_level = left_level;
7740	/*
7741	 * We clone the root node of the send and parent roots to prevent races
7742	 * with snapshot creation of these roots. Snapshot creation COWs the
7743	 * root node of a tree, so after the transaction is committed the old
7744	 * extent can be reallocated while this send operation is still ongoing.
7745	 * So we clone them, under the commit root semaphore, to be race free.
7746	 */
7747	left_path->nodes[left_level] =
7748			btrfs_clone_extent_buffer(left_root->commit_root);
7749	if (!left_path->nodes[left_level]) {
7750		ret = -ENOMEM;
7751		goto out_unlock;
7752	}
7753
7754	right_level = btrfs_header_level(right_root->commit_root);
7755	right_root_level = right_level;
7756	right_path->nodes[right_level] =
7757			btrfs_clone_extent_buffer(right_root->commit_root);
7758	if (!right_path->nodes[right_level]) {
7759		ret = -ENOMEM;
7760		goto out_unlock;
7761	}
7762	/*
7763	 * Our right root is the parent root, while the left root is the "send"
7764	 * root. We know that all new nodes/leaves in the left root must have
7765	 * a generation greater than the right root's generation, so we trigger
7766	 * readahead for those nodes and leaves of the left root, as we know we
7767	 * will need to read them at some point.
7768	 */
7769	reada_min_gen = btrfs_header_generation(right_root->commit_root);
7770
7771	if (left_level == 0)
7772		btrfs_item_key_to_cpu(left_path->nodes[left_level],
7773				&left_key, left_path->slots[left_level]);
7774	else
7775		btrfs_node_key_to_cpu(left_path->nodes[left_level],
7776				&left_key, left_path->slots[left_level]);
7777	if (right_level == 0)
7778		btrfs_item_key_to_cpu(right_path->nodes[right_level],
7779				&right_key, right_path->slots[right_level]);
7780	else
7781		btrfs_node_key_to_cpu(right_path->nodes[right_level],
7782				&right_key, right_path->slots[right_level]);
7783
7784	sctx->last_reloc_trans = fs_info->last_reloc_trans;
7785
7786	while (1) {
7787		if (need_resched() ||
7788		    rwsem_is_contended(&fs_info->commit_root_sem)) {
7789			up_read(&fs_info->commit_root_sem);
7790			cond_resched();
7791			down_read(&fs_info->commit_root_sem);
7792		}
7793
7794		if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
7795			ret = restart_after_relocation(left_path, right_path,
7796						       &left_key, &right_key,
7797						       left_level, right_level,
7798						       sctx);
7799			if (ret < 0)
7800				goto out_unlock;
7801			sctx->last_reloc_trans = fs_info->last_reloc_trans;
7802		}
7803
7804		if (advance_left && !left_end_reached) {
7805			ret = tree_advance(left_path, &left_level,
7806					left_root_level,
7807					advance_left != ADVANCE_ONLY_NEXT,
7808					&left_key, reada_min_gen);
7809			if (ret == -1)
7810				left_end_reached = ADVANCE;
7811			else if (ret < 0)
7812				goto out_unlock;
7813			advance_left = 0;
7814		}
7815		if (advance_right && !right_end_reached) {
7816			ret = tree_advance(right_path, &right_level,
7817					right_root_level,
7818					advance_right != ADVANCE_ONLY_NEXT,
7819					&right_key, reada_min_gen);
7820			if (ret == -1)
7821				right_end_reached = ADVANCE;
7822			else if (ret < 0)
7823				goto out_unlock;
7824			advance_right = 0;
7825		}
7826
7827		if (left_end_reached && right_end_reached) {
7828			ret = 0;
7829			goto out_unlock;
7830		} else if (left_end_reached) {
7831			if (right_level == 0) {
7832				up_read(&fs_info->commit_root_sem);
7833				ret = changed_cb(left_path, right_path,
7834						&right_key,
7835						BTRFS_COMPARE_TREE_DELETED,
7836						sctx);
7837				if (ret < 0)
7838					goto out;
7839				down_read(&fs_info->commit_root_sem);
7840			}
7841			advance_right = ADVANCE;
7842			continue;
7843		} else if (right_end_reached) {
7844			if (left_level == 0) {
7845				up_read(&fs_info->commit_root_sem);
7846				ret = changed_cb(left_path, right_path,
7847						&left_key,
7848						BTRFS_COMPARE_TREE_NEW,
7849						sctx);
7850				if (ret < 0)
7851					goto out;
7852				down_read(&fs_info->commit_root_sem);
7853			}
7854			advance_left = ADVANCE;
7855			continue;
7856		}
7857
7858		if (left_level == 0 && right_level == 0) {
7859			up_read(&fs_info->commit_root_sem);
7860			cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
7861			if (cmp < 0) {
7862				ret = changed_cb(left_path, right_path,
7863						&left_key,
7864						BTRFS_COMPARE_TREE_NEW,
7865						sctx);
7866				advance_left = ADVANCE;
7867			} else if (cmp > 0) {
7868				ret = changed_cb(left_path, right_path,
7869						&right_key,
7870						BTRFS_COMPARE_TREE_DELETED,
7871						sctx);
7872				advance_right = ADVANCE;
7873			} else {
7874				enum btrfs_compare_tree_result result;
7875
7876				WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
7877				ret = tree_compare_item(left_path, right_path,
7878							tmp_buf);
7879				if (ret)
7880					result = BTRFS_COMPARE_TREE_CHANGED;
7881				else
7882					result = BTRFS_COMPARE_TREE_SAME;
7883				ret = changed_cb(left_path, right_path,
7884						 &left_key, result, sctx);
7885				advance_left = ADVANCE;
7886				advance_right = ADVANCE;
7887			}
7888
7889			if (ret < 0)
7890				goto out;
7891			down_read(&fs_info->commit_root_sem);
7892		} else if (left_level == right_level) {
7893			cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
7894			if (cmp < 0) {
7895				advance_left = ADVANCE;
7896			} else if (cmp > 0) {
7897				advance_right = ADVANCE;
7898			} else {
7899				left_blockptr = btrfs_node_blockptr(
7900						left_path->nodes[left_level],
7901						left_path->slots[left_level]);
7902				right_blockptr = btrfs_node_blockptr(
7903						right_path->nodes[right_level],
7904						right_path->slots[right_level]);
7905				left_gen = btrfs_node_ptr_generation(
7906						left_path->nodes[left_level],
7907						left_path->slots[left_level]);
7908				right_gen = btrfs_node_ptr_generation(
7909						right_path->nodes[right_level],
7910						right_path->slots[right_level]);
7911				if (left_blockptr == right_blockptr &&
7912				    left_gen == right_gen) {
7913					/*
7914					 * As we're on a shared block, don't
7915					 * allow to go deeper.
7916					 */
7917					advance_left = ADVANCE_ONLY_NEXT;
7918					advance_right = ADVANCE_ONLY_NEXT;
7919				} else {
7920					advance_left = ADVANCE;
7921					advance_right = ADVANCE;
7922				}
7923			}
7924		} else if (left_level < right_level) {
7925			advance_right = ADVANCE;
7926		} else {
7927			advance_left = ADVANCE;
7928		}
7929	}
7930
7931out_unlock:
7932	up_read(&fs_info->commit_root_sem);
7933out:
7934	btrfs_free_path(left_path);
7935	btrfs_free_path(right_path);
7936	kvfree(tmp_buf);
7937	return ret;
7938}
7939
7940static int send_subvol(struct send_ctx *sctx)
7941{
7942	int ret;
7943
7944	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_STREAM_HEADER)) {
7945		ret = send_header(sctx);
7946		if (ret < 0)
7947			goto out;
7948	}
7949
7950	ret = send_subvol_begin(sctx);
7951	if (ret < 0)
7952		goto out;
7953
7954	if (sctx->parent_root) {
7955		ret = btrfs_compare_trees(sctx->send_root, sctx->parent_root, sctx);
7956		if (ret < 0)
7957			goto out;
7958		ret = finish_inode_if_needed(sctx, 1);
7959		if (ret < 0)
7960			goto out;
7961	} else {
7962		ret = full_send_tree(sctx);
7963		if (ret < 0)
7964			goto out;
7965	}
7966
7967out:
7968	free_recorded_refs(sctx);
7969	return ret;
7970}
7971
7972/*
7973 * If orphan cleanup did remove any orphans from a root, it means the tree
7974 * was modified and therefore the commit root is not the same as the current
7975 * root anymore. This is a problem, because send uses the commit root and
7976 * therefore can see inode items that don't exist in the current root anymore,
7977 * and for example make calls to btrfs_iget, which will do tree lookups based
7978 * on the current root and not on the commit root. Those lookups will fail,
7979 * returning a -ESTALE error, and making send fail with that error. So make
7980 * sure a send does not see any orphans we have just removed, and that it will
7981 * see the same inodes regardless of whether a transaction commit happened
7982 * before it started (meaning that the commit root will be the same as the
7983 * current root) or not.
7984 */
7985static int ensure_commit_roots_uptodate(struct send_ctx *sctx)
7986{
7987	int i;
7988	struct btrfs_trans_handle *trans = NULL;
7989
7990again:
7991	if (sctx->parent_root &&
7992	    sctx->parent_root->node != sctx->parent_root->commit_root)
7993		goto commit_trans;
7994
7995	for (i = 0; i < sctx->clone_roots_cnt; i++)
7996		if (sctx->clone_roots[i].root->node !=
7997		    sctx->clone_roots[i].root->commit_root)
7998			goto commit_trans;
7999
8000	if (trans)
8001		return btrfs_end_transaction(trans);
8002
8003	return 0;
 
8004
8005commit_trans:
8006	/* Use any root, all fs roots will get their commit roots updated. */
8007	if (!trans) {
8008		trans = btrfs_join_transaction(sctx->send_root);
8009		if (IS_ERR(trans))
8010			return PTR_ERR(trans);
8011		goto again;
8012	}
8013
8014	return btrfs_commit_transaction(trans);
8015}
8016
8017/*
8018 * Make sure any existing dellaloc is flushed for any root used by a send
8019 * operation so that we do not miss any data and we do not race with writeback
8020 * finishing and changing a tree while send is using the tree. This could
8021 * happen if a subvolume is in RW mode, has delalloc, is turned to RO mode and
8022 * a send operation then uses the subvolume.
8023 * After flushing delalloc ensure_commit_roots_uptodate() must be called.
8024 */
8025static int flush_delalloc_roots(struct send_ctx *sctx)
8026{
8027	struct btrfs_root *root = sctx->parent_root;
8028	int ret;
8029	int i;
8030
8031	if (root) {
8032		ret = btrfs_start_delalloc_snapshot(root, false);
8033		if (ret)
8034			return ret;
8035		btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
8036	}
8037
8038	for (i = 0; i < sctx->clone_roots_cnt; i++) {
8039		root = sctx->clone_roots[i].root;
8040		ret = btrfs_start_delalloc_snapshot(root, false);
8041		if (ret)
8042			return ret;
8043		btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
8044	}
8045
8046	return 0;
8047}
8048
8049static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
8050{
8051	spin_lock(&root->root_item_lock);
8052	root->send_in_progress--;
8053	/*
8054	 * Not much left to do, we don't know why it's unbalanced and
8055	 * can't blindly reset it to 0.
8056	 */
8057	if (root->send_in_progress < 0)
8058		btrfs_err(root->fs_info,
8059			  "send_in_progress unbalanced %d root %llu",
8060			  root->send_in_progress, root->root_key.objectid);
8061	spin_unlock(&root->root_item_lock);
8062}
8063
8064static void dedupe_in_progress_warn(const struct btrfs_root *root)
8065{
8066	btrfs_warn_rl(root->fs_info,
8067"cannot use root %llu for send while deduplications on it are in progress (%d in progress)",
8068		      root->root_key.objectid, root->dedupe_in_progress);
8069}
8070
8071long btrfs_ioctl_send(struct inode *inode, struct btrfs_ioctl_send_args *arg)
8072{
8073	int ret = 0;
8074	struct btrfs_root *send_root = BTRFS_I(inode)->root;
8075	struct btrfs_fs_info *fs_info = send_root->fs_info;
8076	struct btrfs_root *clone_root;
8077	struct send_ctx *sctx = NULL;
8078	u32 i;
8079	u64 *clone_sources_tmp = NULL;
8080	int clone_sources_to_rollback = 0;
8081	size_t alloc_size;
8082	int sort_clone_roots = 0;
8083	struct btrfs_lru_cache_entry *entry;
8084	struct btrfs_lru_cache_entry *tmp;
8085
8086	if (!capable(CAP_SYS_ADMIN))
8087		return -EPERM;
8088
8089	/*
8090	 * The subvolume must remain read-only during send, protect against
8091	 * making it RW. This also protects against deletion.
8092	 */
8093	spin_lock(&send_root->root_item_lock);
8094	if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) {
 
 
 
 
 
 
 
 
 
 
 
 
 
8095		dedupe_in_progress_warn(send_root);
8096		spin_unlock(&send_root->root_item_lock);
8097		return -EAGAIN;
8098	}
8099	send_root->send_in_progress++;
8100	spin_unlock(&send_root->root_item_lock);
8101
8102	/*
8103	 * Userspace tools do the checks and warn the user if it's
8104	 * not RO.
8105	 */
8106	if (!btrfs_root_readonly(send_root)) {
8107		ret = -EPERM;
8108		goto out;
8109	}
8110
8111	/*
8112	 * Check that we don't overflow at later allocations, we request
8113	 * clone_sources_count + 1 items, and compare to unsigned long inside
8114	 * access_ok. Also set an upper limit for allocation size so this can't
8115	 * easily exhaust memory. Max number of clone sources is about 200K.
8116	 */
8117	if (arg->clone_sources_count > SZ_8M / sizeof(struct clone_root)) {
8118		ret = -EINVAL;
8119		goto out;
8120	}
8121
8122	if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
8123		ret = -EOPNOTSUPP;
8124		goto out;
8125	}
8126
8127	sctx = kzalloc(sizeof(struct send_ctx), GFP_KERNEL);
8128	if (!sctx) {
8129		ret = -ENOMEM;
8130		goto out;
8131	}
8132
8133	INIT_LIST_HEAD(&sctx->new_refs);
8134	INIT_LIST_HEAD(&sctx->deleted_refs);
8135
8136	btrfs_lru_cache_init(&sctx->name_cache, SEND_MAX_NAME_CACHE_SIZE);
8137	btrfs_lru_cache_init(&sctx->backref_cache, SEND_MAX_BACKREF_CACHE_SIZE);
8138	btrfs_lru_cache_init(&sctx->dir_created_cache,
8139			     SEND_MAX_DIR_CREATED_CACHE_SIZE);
8140	/*
8141	 * This cache is periodically trimmed to a fixed size elsewhere, see
8142	 * cache_dir_utimes() and trim_dir_utimes_cache().
8143	 */
8144	btrfs_lru_cache_init(&sctx->dir_utimes_cache, 0);
8145
8146	sctx->pending_dir_moves = RB_ROOT;
8147	sctx->waiting_dir_moves = RB_ROOT;
8148	sctx->orphan_dirs = RB_ROOT;
8149	sctx->rbtree_new_refs = RB_ROOT;
8150	sctx->rbtree_deleted_refs = RB_ROOT;
8151
8152	sctx->flags = arg->flags;
8153
8154	if (arg->flags & BTRFS_SEND_FLAG_VERSION) {
8155		if (arg->version > BTRFS_SEND_STREAM_VERSION) {
8156			ret = -EPROTO;
8157			goto out;
8158		}
8159		/* Zero means "use the highest version" */
8160		sctx->proto = arg->version ?: BTRFS_SEND_STREAM_VERSION;
8161	} else {
8162		sctx->proto = 1;
8163	}
8164	if ((arg->flags & BTRFS_SEND_FLAG_COMPRESSED) && sctx->proto < 2) {
8165		ret = -EINVAL;
8166		goto out;
8167	}
8168
8169	sctx->send_filp = fget(arg->send_fd);
8170	if (!sctx->send_filp || !(sctx->send_filp->f_mode & FMODE_WRITE)) {
8171		ret = -EBADF;
8172		goto out;
8173	}
8174
8175	sctx->send_root = send_root;
8176	/*
8177	 * Unlikely but possible, if the subvolume is marked for deletion but
8178	 * is slow to remove the directory entry, send can still be started
8179	 */
8180	if (btrfs_root_dead(sctx->send_root)) {
8181		ret = -EPERM;
8182		goto out;
8183	}
8184
8185	sctx->clone_roots_cnt = arg->clone_sources_count;
8186
8187	if (sctx->proto >= 2) {
8188		u32 send_buf_num_pages;
8189
8190		sctx->send_max_size = BTRFS_SEND_BUF_SIZE_V2;
8191		sctx->send_buf = vmalloc(sctx->send_max_size);
8192		if (!sctx->send_buf) {
8193			ret = -ENOMEM;
8194			goto out;
8195		}
8196		send_buf_num_pages = sctx->send_max_size >> PAGE_SHIFT;
8197		sctx->send_buf_pages = kcalloc(send_buf_num_pages,
8198					       sizeof(*sctx->send_buf_pages),
8199					       GFP_KERNEL);
8200		if (!sctx->send_buf_pages) {
8201			ret = -ENOMEM;
8202			goto out;
8203		}
8204		for (i = 0; i < send_buf_num_pages; i++) {
8205			sctx->send_buf_pages[i] =
8206				vmalloc_to_page(sctx->send_buf + (i << PAGE_SHIFT));
8207		}
8208	} else {
8209		sctx->send_max_size = BTRFS_SEND_BUF_SIZE_V1;
8210		sctx->send_buf = kvmalloc(sctx->send_max_size, GFP_KERNEL);
8211	}
8212	if (!sctx->send_buf) {
8213		ret = -ENOMEM;
8214		goto out;
8215	}
8216
8217	sctx->clone_roots = kvcalloc(arg->clone_sources_count + 1,
8218				     sizeof(*sctx->clone_roots),
8219				     GFP_KERNEL);
8220	if (!sctx->clone_roots) {
8221		ret = -ENOMEM;
8222		goto out;
8223	}
8224
8225	alloc_size = array_size(sizeof(*arg->clone_sources),
8226				arg->clone_sources_count);
8227
8228	if (arg->clone_sources_count) {
8229		clone_sources_tmp = kvmalloc(alloc_size, GFP_KERNEL);
8230		if (!clone_sources_tmp) {
8231			ret = -ENOMEM;
8232			goto out;
8233		}
8234
8235		ret = copy_from_user(clone_sources_tmp, arg->clone_sources,
8236				alloc_size);
8237		if (ret) {
8238			ret = -EFAULT;
8239			goto out;
8240		}
8241
8242		for (i = 0; i < arg->clone_sources_count; i++) {
8243			clone_root = btrfs_get_fs_root(fs_info,
8244						clone_sources_tmp[i], true);
8245			if (IS_ERR(clone_root)) {
8246				ret = PTR_ERR(clone_root);
8247				goto out;
8248			}
8249			spin_lock(&clone_root->root_item_lock);
8250			if (!btrfs_root_readonly(clone_root) ||
8251			    btrfs_root_dead(clone_root)) {
8252				spin_unlock(&clone_root->root_item_lock);
8253				btrfs_put_root(clone_root);
8254				ret = -EPERM;
8255				goto out;
8256			}
8257			if (clone_root->dedupe_in_progress) {
8258				dedupe_in_progress_warn(clone_root);
8259				spin_unlock(&clone_root->root_item_lock);
8260				btrfs_put_root(clone_root);
8261				ret = -EAGAIN;
8262				goto out;
8263			}
8264			clone_root->send_in_progress++;
8265			spin_unlock(&clone_root->root_item_lock);
8266
8267			sctx->clone_roots[i].root = clone_root;
8268			clone_sources_to_rollback = i + 1;
8269		}
8270		kvfree(clone_sources_tmp);
8271		clone_sources_tmp = NULL;
8272	}
8273
8274	if (arg->parent_root) {
8275		sctx->parent_root = btrfs_get_fs_root(fs_info, arg->parent_root,
8276						      true);
8277		if (IS_ERR(sctx->parent_root)) {
8278			ret = PTR_ERR(sctx->parent_root);
8279			goto out;
8280		}
8281
8282		spin_lock(&sctx->parent_root->root_item_lock);
8283		sctx->parent_root->send_in_progress++;
8284		if (!btrfs_root_readonly(sctx->parent_root) ||
8285				btrfs_root_dead(sctx->parent_root)) {
8286			spin_unlock(&sctx->parent_root->root_item_lock);
8287			ret = -EPERM;
8288			goto out;
8289		}
8290		if (sctx->parent_root->dedupe_in_progress) {
8291			dedupe_in_progress_warn(sctx->parent_root);
8292			spin_unlock(&sctx->parent_root->root_item_lock);
8293			ret = -EAGAIN;
8294			goto out;
8295		}
8296		spin_unlock(&sctx->parent_root->root_item_lock);
8297	}
8298
8299	/*
8300	 * Clones from send_root are allowed, but only if the clone source
8301	 * is behind the current send position. This is checked while searching
8302	 * for possible clone sources.
8303	 */
8304	sctx->clone_roots[sctx->clone_roots_cnt++].root =
8305		btrfs_grab_root(sctx->send_root);
8306
8307	/* We do a bsearch later */
8308	sort(sctx->clone_roots, sctx->clone_roots_cnt,
8309			sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
8310			NULL);
8311	sort_clone_roots = 1;
8312
8313	ret = flush_delalloc_roots(sctx);
8314	if (ret)
8315		goto out;
8316
8317	ret = ensure_commit_roots_uptodate(sctx);
8318	if (ret)
8319		goto out;
8320
8321	ret = send_subvol(sctx);
8322	if (ret < 0)
8323		goto out;
8324
8325	btrfs_lru_cache_for_each_entry_safe(&sctx->dir_utimes_cache, entry, tmp) {
8326		ret = send_utimes(sctx, entry->key, entry->gen);
8327		if (ret < 0)
8328			goto out;
8329		btrfs_lru_cache_remove(&sctx->dir_utimes_cache, entry);
8330	}
8331
8332	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_END_CMD)) {
8333		ret = begin_cmd(sctx, BTRFS_SEND_C_END);
8334		if (ret < 0)
8335			goto out;
8336		ret = send_cmd(sctx);
8337		if (ret < 0)
8338			goto out;
8339	}
8340
8341out:
8342	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->pending_dir_moves));
8343	while (sctx && !RB_EMPTY_ROOT(&sctx->pending_dir_moves)) {
8344		struct rb_node *n;
8345		struct pending_dir_move *pm;
8346
8347		n = rb_first(&sctx->pending_dir_moves);
8348		pm = rb_entry(n, struct pending_dir_move, node);
8349		while (!list_empty(&pm->list)) {
8350			struct pending_dir_move *pm2;
8351
8352			pm2 = list_first_entry(&pm->list,
8353					       struct pending_dir_move, list);
8354			free_pending_move(sctx, pm2);
8355		}
8356		free_pending_move(sctx, pm);
8357	}
8358
8359	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves));
8360	while (sctx && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves)) {
8361		struct rb_node *n;
8362		struct waiting_dir_move *dm;
8363
8364		n = rb_first(&sctx->waiting_dir_moves);
8365		dm = rb_entry(n, struct waiting_dir_move, node);
8366		rb_erase(&dm->node, &sctx->waiting_dir_moves);
8367		kfree(dm);
8368	}
8369
8370	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->orphan_dirs));
8371	while (sctx && !RB_EMPTY_ROOT(&sctx->orphan_dirs)) {
8372		struct rb_node *n;
8373		struct orphan_dir_info *odi;
8374
8375		n = rb_first(&sctx->orphan_dirs);
8376		odi = rb_entry(n, struct orphan_dir_info, node);
8377		free_orphan_dir_info(sctx, odi);
8378	}
8379
8380	if (sort_clone_roots) {
8381		for (i = 0; i < sctx->clone_roots_cnt; i++) {
8382			btrfs_root_dec_send_in_progress(
8383					sctx->clone_roots[i].root);
8384			btrfs_put_root(sctx->clone_roots[i].root);
8385		}
8386	} else {
8387		for (i = 0; sctx && i < clone_sources_to_rollback; i++) {
8388			btrfs_root_dec_send_in_progress(
8389					sctx->clone_roots[i].root);
8390			btrfs_put_root(sctx->clone_roots[i].root);
8391		}
8392
8393		btrfs_root_dec_send_in_progress(send_root);
8394	}
8395	if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) {
8396		btrfs_root_dec_send_in_progress(sctx->parent_root);
8397		btrfs_put_root(sctx->parent_root);
8398	}
8399
8400	kvfree(clone_sources_tmp);
8401
8402	if (sctx) {
8403		if (sctx->send_filp)
8404			fput(sctx->send_filp);
8405
8406		kvfree(sctx->clone_roots);
8407		kfree(sctx->send_buf_pages);
8408		kvfree(sctx->send_buf);
8409		kvfree(sctx->verity_descriptor);
8410
8411		close_current_inode(sctx);
8412
8413		btrfs_lru_cache_clear(&sctx->name_cache);
8414		btrfs_lru_cache_clear(&sctx->backref_cache);
8415		btrfs_lru_cache_clear(&sctx->dir_created_cache);
8416		btrfs_lru_cache_clear(&sctx->dir_utimes_cache);
8417
8418		kfree(sctx);
8419	}
8420
8421	return ret;
8422}