1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2007 Oracle.  All rights reserved.
   4 */
   5
   6#include <linux/bio.h>
   7#include <linux/slab.h>
   8#include <linux/pagemap.h>
   9#include <linux/highmem.h>
  10#include <linux/sched/mm.h>
  11#include <crypto/hash.h>
  12#include "messages.h"
  13#include "misc.h"
  14#include "ctree.h"
  15#include "disk-io.h"
  16#include "transaction.h"
  17#include "bio.h"
  18#include "print-tree.h"
  19#include "compression.h"
  20#include "fs.h"
  21#include "accessors.h"
  22#include "file-item.h"
  23#include "super.h"
  24
  25#define __MAX_CSUM_ITEMS(r, size) ((unsigned long)(((BTRFS_LEAF_DATA_SIZE(r) - \
  26				   sizeof(struct btrfs_item) * 2) / \
  27				  size) - 1))
  28
  29#define MAX_CSUM_ITEMS(r, size) (min_t(u32, __MAX_CSUM_ITEMS(r, size), \
  30				       PAGE_SIZE))
  31
  32/*
  33 * Set inode's size according to filesystem options.
  34 *
  35 * @inode:      inode we want to update the disk_i_size for
  36 * @new_i_size: i_size we want to set to, 0 if we use i_size
  37 *
  38 * With NO_HOLES set this simply sets the disk_is_size to whatever i_size_read()
  39 * returns as it is perfectly fine with a file that has holes without hole file
  40 * extent items.
  41 *
  42 * However without NO_HOLES we need to only return the area that is contiguous
  43 * from the 0 offset of the file.  Otherwise we could end up adjust i_size up
  44 * to an extent that has a gap in between.
  45 *
  46 * Finally new_i_size should only be set in the case of truncate where we're not
  47 * ready to use i_size_read() as the limiter yet.
  48 */
  49void btrfs_inode_safe_disk_i_size_write(struct btrfs_inode *inode, u64 new_i_size)
  50{
  51	struct btrfs_fs_info *fs_info = inode->root->fs_info;
  52	u64 start, end, i_size;
  53	int ret;
  54
 
  55	i_size = new_i_size ?: i_size_read(&inode->vfs_inode);
  56	if (btrfs_fs_incompat(fs_info, NO_HOLES)) {
  57		inode->disk_i_size = i_size;
  58		return;
  59	}
  60
  61	spin_lock(&inode->lock);
  62	ret = find_contiguous_extent_bit(&inode->file_extent_tree, 0, &start,
  63					 &end, EXTENT_DIRTY);
  64	if (!ret && start == 0)
  65		i_size = min(i_size, end + 1);
  66	else
  67		i_size = 0;
  68	inode->disk_i_size = i_size;
 
  69	spin_unlock(&inode->lock);
  70}
  71
  72/*
  73 * Mark range within a file as having a new extent inserted.
  74 *
  75 * @inode: inode being modified
  76 * @start: start file offset of the file extent we've inserted
  77 * @len:   logical length of the file extent item
  78 *
  79 * Call when we are inserting a new file extent where there was none before.
  80 * Does not need to call this in the case where we're replacing an existing file
  81 * extent, however if not sure it's fine to call this multiple times.
  82 *
  83 * The start and len must match the file extent item, so thus must be sectorsize
  84 * aligned.
  85 */
  86int btrfs_inode_set_file_extent_range(struct btrfs_inode *inode, u64 start,
  87				      u64 len)
  88{
  89	if (len == 0)
  90		return 0;
  91
  92	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize));
  93
  94	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
  95		return 0;
  96	return set_extent_bits(&inode->file_extent_tree, start, start + len - 1,
  97			       EXTENT_DIRTY);
  98}
  99
 100/*
 101 * Mark an inode range as not having a backing extent.
 102 *
 103 * @inode: inode being modified
 104 * @start: start file offset of the file extent we've inserted
 105 * @len:   logical length of the file extent item
 106 *
 107 * Called when we drop a file extent, for example when we truncate.  Doesn't
 108 * need to be called for cases where we're replacing a file extent, like when
 109 * we've COWed a file extent.
 110 *
 111 * The start and len must match the file extent item, so thus must be sectorsize
 112 * aligned.
 113 */
 114int btrfs_inode_clear_file_extent_range(struct btrfs_inode *inode, u64 start,
 115					u64 len)
 116{
 117	if (len == 0)
 118		return 0;
 119
 120	ASSERT(IS_ALIGNED(start + len, inode->root->fs_info->sectorsize) ||
 121	       len == (u64)-1);
 122
 123	if (btrfs_fs_incompat(inode->root->fs_info, NO_HOLES))
 124		return 0;
 125	return clear_extent_bit(&inode->file_extent_tree, start,
 126				start + len - 1, EXTENT_DIRTY, NULL);
 127}
 128
 129static size_t bytes_to_csum_size(const struct btrfs_fs_info *fs_info, u32 bytes)
 130{
 131	ASSERT(IS_ALIGNED(bytes, fs_info->sectorsize));
 132
 133	return (bytes >> fs_info->sectorsize_bits) * fs_info->csum_size;
 134}
 135
 136static size_t csum_size_to_bytes(const struct btrfs_fs_info *fs_info, u32 csum_size)
 137{
 138	ASSERT(IS_ALIGNED(csum_size, fs_info->csum_size));
 139
 140	return (csum_size / fs_info->csum_size) << fs_info->sectorsize_bits;
 141}
 142
 143static inline u32 max_ordered_sum_bytes(const struct btrfs_fs_info *fs_info)
 144{
 145	u32 max_csum_size = round_down(PAGE_SIZE - sizeof(struct btrfs_ordered_sum),
 146				       fs_info->csum_size);
 147
 148	return csum_size_to_bytes(fs_info, max_csum_size);
 149}
 150
 151/*
 152 * Calculate the total size needed to allocate for an ordered sum structure
 153 * spanning @bytes in the file.
 154 */
 155static int btrfs_ordered_sum_size(struct btrfs_fs_info *fs_info, unsigned long bytes)
 156{
 157	return sizeof(struct btrfs_ordered_sum) + bytes_to_csum_size(fs_info, bytes);
 158}
 159
 160int btrfs_insert_hole_extent(struct btrfs_trans_handle *trans,
 161			     struct btrfs_root *root,
 162			     u64 objectid, u64 pos, u64 num_bytes)
 163{
 164	int ret = 0;
 165	struct btrfs_file_extent_item *item;
 166	struct btrfs_key file_key;
 167	struct btrfs_path *path;
 168	struct extent_buffer *leaf;
 169
 170	path = btrfs_alloc_path();
 171	if (!path)
 172		return -ENOMEM;
 173	file_key.objectid = objectid;
 174	file_key.offset = pos;
 175	file_key.type = BTRFS_EXTENT_DATA_KEY;
 176
 177	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
 178				      sizeof(*item));
 179	if (ret < 0)
 180		goto out;
 181	BUG_ON(ret); /* Can't happen */
 182	leaf = path->nodes[0];
 183	item = btrfs_item_ptr(leaf, path->slots[0],
 184			      struct btrfs_file_extent_item);
 185	btrfs_set_file_extent_disk_bytenr(leaf, item, 0);
 186	btrfs_set_file_extent_disk_num_bytes(leaf, item, 0);
 187	btrfs_set_file_extent_offset(leaf, item, 0);
 188	btrfs_set_file_extent_num_bytes(leaf, item, num_bytes);
 189	btrfs_set_file_extent_ram_bytes(leaf, item, num_bytes);
 190	btrfs_set_file_extent_generation(leaf, item, trans->transid);
 191	btrfs_set_file_extent_type(leaf, item, BTRFS_FILE_EXTENT_REG);
 192	btrfs_set_file_extent_compression(leaf, item, 0);
 193	btrfs_set_file_extent_encryption(leaf, item, 0);
 194	btrfs_set_file_extent_other_encoding(leaf, item, 0);
 195
 196	btrfs_mark_buffer_dirty(leaf);
 197out:
 198	btrfs_free_path(path);
 199	return ret;
 200}
 201
 202static struct btrfs_csum_item *
 203btrfs_lookup_csum(struct btrfs_trans_handle *trans,
 204		  struct btrfs_root *root,
 205		  struct btrfs_path *path,
 206		  u64 bytenr, int cow)
 207{
 208	struct btrfs_fs_info *fs_info = root->fs_info;
 209	int ret;
 210	struct btrfs_key file_key;
 211	struct btrfs_key found_key;
 212	struct btrfs_csum_item *item;
 213	struct extent_buffer *leaf;
 214	u64 csum_offset = 0;
 215	const u32 csum_size = fs_info->csum_size;
 216	int csums_in_item;
 217
 218	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 219	file_key.offset = bytenr;
 220	file_key.type = BTRFS_EXTENT_CSUM_KEY;
 221	ret = btrfs_search_slot(trans, root, &file_key, path, 0, cow);
 222	if (ret < 0)
 223		goto fail;
 224	leaf = path->nodes[0];
 225	if (ret > 0) {
 226		ret = 1;
 227		if (path->slots[0] == 0)
 228			goto fail;
 229		path->slots[0]--;
 230		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 231		if (found_key.type != BTRFS_EXTENT_CSUM_KEY)
 232			goto fail;
 233
 234		csum_offset = (bytenr - found_key.offset) >>
 235				fs_info->sectorsize_bits;
 236		csums_in_item = btrfs_item_size(leaf, path->slots[0]);
 237		csums_in_item /= csum_size;
 238
 239		if (csum_offset == csums_in_item) {
 240			ret = -EFBIG;
 241			goto fail;
 242		} else if (csum_offset > csums_in_item) {
 243			goto fail;
 244		}
 245	}
 246	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
 247	item = (struct btrfs_csum_item *)((unsigned char *)item +
 248					  csum_offset * csum_size);
 249	return item;
 250fail:
 251	if (ret > 0)
 252		ret = -ENOENT;
 253	return ERR_PTR(ret);
 254}
 255
 256int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
 257			     struct btrfs_root *root,
 258			     struct btrfs_path *path, u64 objectid,
 259			     u64 offset, int mod)
 260{
 261	struct btrfs_key file_key;
 262	int ins_len = mod < 0 ? -1 : 0;
 263	int cow = mod != 0;
 264
 265	file_key.objectid = objectid;
 266	file_key.offset = offset;
 267	file_key.type = BTRFS_EXTENT_DATA_KEY;
 268
 269	return btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
 270}
 271
 272/*
 273 * Find checksums for logical bytenr range [disk_bytenr, disk_bytenr + len) and
 274 * store the result to @dst.
 275 *
 276 * Return >0 for the number of sectors we found.
 277 * Return 0 for the range [disk_bytenr, disk_bytenr + sectorsize) has no csum
 278 * for it. Caller may want to try next sector until one range is hit.
 279 * Return <0 for fatal error.
 280 */
 281static int search_csum_tree(struct btrfs_fs_info *fs_info,
 282			    struct btrfs_path *path, u64 disk_bytenr,
 283			    u64 len, u8 *dst)
 284{
 285	struct btrfs_root *csum_root;
 286	struct btrfs_csum_item *item = NULL;
 287	struct btrfs_key key;
 288	const u32 sectorsize = fs_info->sectorsize;
 289	const u32 csum_size = fs_info->csum_size;
 290	u32 itemsize;
 291	int ret;
 292	u64 csum_start;
 293	u64 csum_len;
 294
 295	ASSERT(IS_ALIGNED(disk_bytenr, sectorsize) &&
 296	       IS_ALIGNED(len, sectorsize));
 297
 298	/* Check if the current csum item covers disk_bytenr */
 299	if (path->nodes[0]) {
 300		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 301				      struct btrfs_csum_item);
 302		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 303		itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
 304
 305		csum_start = key.offset;
 306		csum_len = (itemsize / csum_size) * sectorsize;
 307
 308		if (in_range(disk_bytenr, csum_start, csum_len))
 309			goto found;
 310	}
 311
 312	/* Current item doesn't contain the desired range, search again */
 313	btrfs_release_path(path);
 314	csum_root = btrfs_csum_root(fs_info, disk_bytenr);
 315	item = btrfs_lookup_csum(NULL, csum_root, path, disk_bytenr, 0);
 316	if (IS_ERR(item)) {
 317		ret = PTR_ERR(item);
 318		goto out;
 319	}
 320	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
 321	itemsize = btrfs_item_size(path->nodes[0], path->slots[0]);
 322
 323	csum_start = key.offset;
 324	csum_len = (itemsize / csum_size) * sectorsize;
 325	ASSERT(in_range(disk_bytenr, csum_start, csum_len));
 326
 327found:
 328	ret = (min(csum_start + csum_len, disk_bytenr + len) -
 329		   disk_bytenr) >> fs_info->sectorsize_bits;
 330	read_extent_buffer(path->nodes[0], dst, (unsigned long)item,
 331			ret * csum_size);
 332out:
 333	if (ret == -ENOENT || ret == -EFBIG)
 334		ret = 0;
 335	return ret;
 336}
 337
 338/*
 339 * Locate the file_offset of @cur_disk_bytenr of a @bio.
 340 *
 341 * Bio of btrfs represents read range of
 342 * [bi_sector << 9, bi_sector << 9 + bi_size).
 343 * Knowing this, we can iterate through each bvec to locate the page belong to
 344 * @cur_disk_bytenr and get the file offset.
 345 *
 346 * @inode is used to determine if the bvec page really belongs to @inode.
 347 *
 348 * Return 0 if we can't find the file offset
 349 * Return >0 if we find the file offset and restore it to @file_offset_ret
 350 */
 351static int search_file_offset_in_bio(struct bio *bio, struct inode *inode,
 352				     u64 disk_bytenr, u64 *file_offset_ret)
 353{
 354	struct bvec_iter iter;
 355	struct bio_vec bvec;
 356	u64 cur = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 357	int ret = 0;
 358
 359	bio_for_each_segment(bvec, bio, iter) {
 360		struct page *page = bvec.bv_page;
 361
 362		if (cur > disk_bytenr)
 363			break;
 364		if (cur + bvec.bv_len <= disk_bytenr) {
 365			cur += bvec.bv_len;
 366			continue;
 367		}
 368		ASSERT(in_range(disk_bytenr, cur, bvec.bv_len));
 369		if (page->mapping && page->mapping->host &&
 370		    page->mapping->host == inode) {
 371			ret = 1;
 372			*file_offset_ret = page_offset(page) + bvec.bv_offset +
 373					   disk_bytenr - cur;
 374			break;
 375		}
 376	}
 377	return ret;
 378}
 379
 380/*
 381 * Lookup the checksum for the read bio in csum tree.
 382 *
 383 * @inode:  inode that the bio is for.
 384 * @bio:    bio to look up.
 385 * @dst:    Buffer of size nblocks * btrfs_super_csum_size() used to return
 386 *          checksum (nblocks = bio->bi_iter.bi_size / fs_info->sectorsize). If
 387 *          NULL, the checksum buffer is allocated and returned in
 388 *          btrfs_bio(bio)->csum instead.
 389 *
 390 * Return: BLK_STS_RESOURCE if allocating memory fails, BLK_STS_OK otherwise.
 391 */
 392blk_status_t btrfs_lookup_bio_sums(struct inode *inode, struct bio *bio, u8 *dst)
 393{
 394	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 395	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 396	struct btrfs_bio *bbio = NULL;
 397	struct btrfs_path *path;
 398	const u32 sectorsize = fs_info->sectorsize;
 399	const u32 csum_size = fs_info->csum_size;
 400	u32 orig_len = bio->bi_iter.bi_size;
 401	u64 orig_disk_bytenr = bio->bi_iter.bi_sector << SECTOR_SHIFT;
 402	u64 cur_disk_bytenr;
 403	u8 *csum;
 404	const unsigned int nblocks = orig_len >> fs_info->sectorsize_bits;
 405	int count = 0;
 406	blk_status_t ret = BLK_STS_OK;
 
 407
 408	if ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM) ||
 409	    test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state))
 410		return BLK_STS_OK;
 411
 412	/*
 413	 * This function is only called for read bio.
 414	 *
 415	 * This means two things:
 416	 * - All our csums should only be in csum tree
 417	 *   No ordered extents csums, as ordered extents are only for write
 418	 *   path.
 419	 * - No need to bother any other info from bvec
 420	 *   Since we're looking up csums, the only important info is the
 421	 *   disk_bytenr and the length, which can be extracted from bi_iter
 422	 *   directly.
 423	 */
 424	ASSERT(bio_op(bio) == REQ_OP_READ);
 425	path = btrfs_alloc_path();
 426	if (!path)
 427		return BLK_STS_RESOURCE;
 428
 429	if (!dst) {
 430		bbio = btrfs_bio(bio);
 431
 432		if (nblocks * csum_size > BTRFS_BIO_INLINE_CSUM_SIZE) {
 433			bbio->csum = kmalloc_array(nblocks, csum_size, GFP_NOFS);
 434			if (!bbio->csum) {
 435				btrfs_free_path(path);
 436				return BLK_STS_RESOURCE;
 437			}
 438		} else {
 439			bbio->csum = bbio->csum_inline;
 440		}
 441		csum = bbio->csum;
 442	} else {
 443		csum = dst;
 444	}
 445
 446	/*
 447	 * If requested number of sectors is larger than one leaf can contain,
 448	 * kick the readahead for csum tree.
 449	 */
 450	if (nblocks > fs_info->csums_per_leaf)
 451		path->reada = READA_FORWARD;
 452
 453	/*
 454	 * the free space stuff is only read when it hasn't been
 455	 * updated in the current transaction.  So, we can safely
 456	 * read from the commit root and sidestep a nasty deadlock
 457	 * between reading the free space cache and updating the csum tree.
 458	 */
 459	if (btrfs_is_free_space_inode(BTRFS_I(inode))) {
 460		path->search_commit_root = 1;
 461		path->skip_locking = 1;
 462	}
 463
 464	for (cur_disk_bytenr = orig_disk_bytenr;
 465	     cur_disk_bytenr < orig_disk_bytenr + orig_len;
 466	     cur_disk_bytenr += (count * sectorsize)) {
 467		u64 search_len = orig_disk_bytenr + orig_len - cur_disk_bytenr;
 468		unsigned int sector_offset;
 469		u8 *csum_dst;
 470
 471		/*
 472		 * Although both cur_disk_bytenr and orig_disk_bytenr is u64,
 473		 * we're calculating the offset to the bio start.
 474		 *
 475		 * Bio size is limited to UINT_MAX, thus unsigned int is large
 476		 * enough to contain the raw result, not to mention the right
 477		 * shifted result.
 478		 */
 479		ASSERT(cur_disk_bytenr - orig_disk_bytenr < UINT_MAX);
 480		sector_offset = (cur_disk_bytenr - orig_disk_bytenr) >>
 481				fs_info->sectorsize_bits;
 482		csum_dst = csum + sector_offset * csum_size;
 483
 484		count = search_csum_tree(fs_info, path, cur_disk_bytenr,
 485					 search_len, csum_dst);
 486		if (count < 0) {
 487			ret = errno_to_blk_status(count);
 488			if (bbio)
 489				btrfs_bio_free_csum(bbio);
 
 490			break;
 491		}
 492
 493		/*
 494		 * We didn't find a csum for this range.  We need to make sure
 495		 * we complain loudly about this, because we are not NODATASUM.
 496		 *
 497		 * However for the DATA_RELOC inode we could potentially be
 498		 * relocating data extents for a NODATASUM inode, so the inode
 499		 * itself won't be marked with NODATASUM, but the extent we're
 500		 * copying is in fact NODATASUM.  If we don't find a csum we
 501		 * assume this is the case.
 502		 */
 503		if (count == 0) {
 504			memset(csum_dst, 0, csum_size);
 505			count = 1;
 506
 507			if (BTRFS_I(inode)->root->root_key.objectid ==
 508			    BTRFS_DATA_RELOC_TREE_OBJECTID) {
 509				u64 file_offset;
 510				int ret;
 511
 512				ret = search_file_offset_in_bio(bio, inode,
 513						cur_disk_bytenr, &file_offset);
 514				if (ret)
 515					set_extent_bits(io_tree, file_offset,
 516						file_offset + sectorsize - 1,
 517						EXTENT_NODATASUM);
 518			} else {
 519				btrfs_warn_rl(fs_info,
 520			"csum hole found for disk bytenr range [%llu, %llu)",
 521				cur_disk_bytenr, cur_disk_bytenr + sectorsize);
 522			}
 523		}
 
 524	}
 525
 526	btrfs_free_path(path);
 527	return ret;
 528}
 529
 530int btrfs_lookup_csums_list(struct btrfs_root *root, u64 start, u64 end,
 531			    struct list_head *list, int search_commit,
 532			    bool nowait)
 533{
 534	struct btrfs_fs_info *fs_info = root->fs_info;
 535	struct btrfs_key key;
 536	struct btrfs_path *path;
 537	struct extent_buffer *leaf;
 538	struct btrfs_ordered_sum *sums;
 539	struct btrfs_csum_item *item;
 540	LIST_HEAD(tmplist);
 541	int ret;
 542
 543	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 544	       IS_ALIGNED(end + 1, fs_info->sectorsize));
 545
 546	path = btrfs_alloc_path();
 547	if (!path)
 548		return -ENOMEM;
 549
 550	path->nowait = nowait;
 551	if (search_commit) {
 552		path->skip_locking = 1;
 553		path->reada = READA_FORWARD;
 554		path->search_commit_root = 1;
 555	}
 556
 557	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 558	key.offset = start;
 559	key.type = BTRFS_EXTENT_CSUM_KEY;
 560
 561	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 562	if (ret < 0)
 563		goto fail;
 564	if (ret > 0 && path->slots[0] > 0) {
 565		leaf = path->nodes[0];
 566		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 567
 568		/*
 569		 * There are two cases we can hit here for the previous csum
 570		 * item:
 571		 *
 572		 *		|<- search range ->|
 573		 *	|<- csum item ->|
 574		 *
 575		 * Or
 576		 *				|<- search range ->|
 577		 *	|<- csum item ->|
 578		 *
 579		 * Check if the previous csum item covers the leading part of
 580		 * the search range.  If so we have to start from previous csum
 581		 * item.
 582		 */
 583		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 584		    key.type == BTRFS_EXTENT_CSUM_KEY) {
 585			if (bytes_to_csum_size(fs_info, start - key.offset) <
 586			    btrfs_item_size(leaf, path->slots[0] - 1))
 587				path->slots[0]--;
 588		}
 589	}
 590
 591	while (start <= end) {
 592		u64 csum_end;
 593
 594		leaf = path->nodes[0];
 595		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 596			ret = btrfs_next_leaf(root, path);
 597			if (ret < 0)
 598				goto fail;
 599			if (ret > 0)
 600				break;
 601			leaf = path->nodes[0];
 602		}
 603
 604		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 605		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 606		    key.type != BTRFS_EXTENT_CSUM_KEY ||
 607		    key.offset > end)
 608			break;
 609
 610		if (key.offset > start)
 611			start = key.offset;
 612
 613		csum_end = key.offset + csum_size_to_bytes(fs_info,
 614					btrfs_item_size(leaf, path->slots[0]));
 615		if (csum_end <= start) {
 616			path->slots[0]++;
 617			continue;
 618		}
 619
 620		csum_end = min(csum_end, end + 1);
 621		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 622				      struct btrfs_csum_item);
 623		while (start < csum_end) {
 624			unsigned long offset;
 625			size_t size;
 626
 627			size = min_t(size_t, csum_end - start,
 628				     max_ordered_sum_bytes(fs_info));
 629			sums = kzalloc(btrfs_ordered_sum_size(fs_info, size),
 630				       GFP_NOFS);
 631			if (!sums) {
 632				ret = -ENOMEM;
 633				goto fail;
 634			}
 635
 636			sums->bytenr = start;
 637			sums->len = (int)size;
 638
 639			offset = bytes_to_csum_size(fs_info, start - key.offset);
 640
 641			read_extent_buffer(path->nodes[0],
 642					   sums->sums,
 643					   ((unsigned long)item) + offset,
 644					   bytes_to_csum_size(fs_info, size));
 645
 646			start += size;
 647			list_add_tail(&sums->list, &tmplist);
 648		}
 649		path->slots[0]++;
 650	}
 651	ret = 0;
 652fail:
 653	while (ret < 0 && !list_empty(&tmplist)) {
 654		sums = list_entry(tmplist.next, struct btrfs_ordered_sum, list);
 655		list_del(&sums->list);
 656		kfree(sums);
 657	}
 658	list_splice_tail(&tmplist, list);
 659
 660	btrfs_free_path(path);
 661	return ret;
 662}
 663
 664/*
 665 * Do the same work as btrfs_lookup_csums_list(), the difference is in how
 666 * we return the result.
 667 *
 668 * This version will set the corresponding bits in @csum_bitmap to represent
 669 * that there is a csum found.
 670 * Each bit represents a sector. Thus caller should ensure @csum_buf passed
 671 * in is large enough to contain all csums.
 672 */
 673int btrfs_lookup_csums_bitmap(struct btrfs_root *root, u64 start, u64 end,
 674			      u8 *csum_buf, unsigned long *csum_bitmap)
 
 675{
 676	struct btrfs_fs_info *fs_info = root->fs_info;
 677	struct btrfs_key key;
 678	struct btrfs_path *path;
 679	struct extent_buffer *leaf;
 680	struct btrfs_csum_item *item;
 681	const u64 orig_start = start;
 
 682	int ret;
 683
 684	ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
 685	       IS_ALIGNED(end + 1, fs_info->sectorsize));
 686
 687	path = btrfs_alloc_path();
 688	if (!path)
 689		return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 690
 691	key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 692	key.type = BTRFS_EXTENT_CSUM_KEY;
 693	key.offset = start;
 694
 695	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 696	if (ret < 0)
 697		goto fail;
 698	if (ret > 0 && path->slots[0] > 0) {
 699		leaf = path->nodes[0];
 700		btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
 701
 702		/*
 703		 * There are two cases we can hit here for the previous csum
 704		 * item:
 705		 *
 706		 *		|<- search range ->|
 707		 *	|<- csum item ->|
 708		 *
 709		 * Or
 710		 *				|<- search range ->|
 711		 *	|<- csum item ->|
 712		 *
 713		 * Check if the previous csum item covers the leading part of
 714		 * the search range.  If so we have to start from previous csum
 715		 * item.
 716		 */
 717		if (key.objectid == BTRFS_EXTENT_CSUM_OBJECTID &&
 718		    key.type == BTRFS_EXTENT_CSUM_KEY) {
 719			if (bytes_to_csum_size(fs_info, start - key.offset) <
 720			    btrfs_item_size(leaf, path->slots[0] - 1))
 721				path->slots[0]--;
 722		}
 723	}
 724
 
 725	while (start <= end) {
 726		u64 csum_end;
 727
 728		leaf = path->nodes[0];
 729		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 730			ret = btrfs_next_leaf(root, path);
 731			if (ret < 0)
 732				goto fail;
 733			if (ret > 0)
 734				break;
 735			leaf = path->nodes[0];
 736		}
 737
 738		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 739		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
 740		    key.type != BTRFS_EXTENT_CSUM_KEY ||
 741		    key.offset > end)
 742			break;
 743
 744		if (key.offset > start)
 745			start = key.offset;
 746
 747		csum_end = key.offset + csum_size_to_bytes(fs_info,
 748					btrfs_item_size(leaf, path->slots[0]));
 749		if (csum_end <= start) {
 750			path->slots[0]++;
 751			continue;
 752		}
 753
 754		csum_end = min(csum_end, end + 1);
 755		item = btrfs_item_ptr(path->nodes[0], path->slots[0],
 756				      struct btrfs_csum_item);
 757		while (start < csum_end) {
 758			unsigned long offset;
 759			size_t size;
 760			u8 *csum_dest = csum_buf + bytes_to_csum_size(fs_info,
 761						start - orig_start);
 762
 763			size = min_t(size_t, csum_end - start, end + 1 - start);
 764
 765			offset = bytes_to_csum_size(fs_info, start - key.offset);
 766
 767			read_extent_buffer(path->nodes[0], csum_dest,
 768					   ((unsigned long)item) + offset,
 769					   bytes_to_csum_size(fs_info, size));
 770
 771			bitmap_set(csum_bitmap,
 772				(start - orig_start) >> fs_info->sectorsize_bits,
 773				size >> fs_info->sectorsize_bits);
 774
 775			start += size;
 776		}
 777		path->slots[0]++;
 778	}
 779	ret = 0;
 780fail:
 781	btrfs_free_path(path);
 
 782	return ret;
 783}
 784
 785/*
 786 * Calculate checksums of the data contained inside a bio.
 787 *
 788 * @inode:	 Owner of the data inside the bio
 789 * @bio:	 Contains the data to be checksummed
 790 * @offset:      If (u64)-1, @bio may contain discontiguous bio vecs, so the
 791 *               file offsets are determined from the page offsets in the bio.
 792 *               Otherwise, this is the starting file offset of the bio vecs in
 793 *               @bio, which must be contiguous.
 794 * @one_ordered: If true, @bio only refers to one ordered extent.
 795 */
 796blk_status_t btrfs_csum_one_bio(struct btrfs_inode *inode, struct bio *bio,
 797				u64 offset, bool one_ordered)
 798{
 
 
 799	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 800	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
 
 801	struct btrfs_ordered_sum *sums;
 802	struct btrfs_ordered_extent *ordered = NULL;
 803	const bool use_page_offsets = (offset == (u64)-1);
 804	char *data;
 805	struct bvec_iter iter;
 806	struct bio_vec bvec;
 807	int index;
 808	unsigned int blockcount;
 809	unsigned long total_bytes = 0;
 810	unsigned long this_sum_bytes = 0;
 811	int i;
 812	unsigned nofs_flag;
 813
 814	nofs_flag = memalloc_nofs_save();
 815	sums = kvzalloc(btrfs_ordered_sum_size(fs_info, bio->bi_iter.bi_size),
 816		       GFP_KERNEL);
 817	memalloc_nofs_restore(nofs_flag);
 818
 819	if (!sums)
 820		return BLK_STS_RESOURCE;
 821
 822	sums->len = bio->bi_iter.bi_size;
 823	INIT_LIST_HEAD(&sums->list);
 824
 825	sums->bytenr = bio->bi_iter.bi_sector << 9;
 826	index = 0;
 827
 828	shash->tfm = fs_info->csum_shash;
 829
 830	bio_for_each_segment(bvec, bio, iter) {
 831		if (use_page_offsets)
 832			offset = page_offset(bvec.bv_page) + bvec.bv_offset;
 833
 834		if (!ordered) {
 835			ordered = btrfs_lookup_ordered_extent(inode, offset);
 836			/*
 837			 * The bio range is not covered by any ordered extent,
 838			 * must be a code logic error.
 839			 */
 840			if (unlikely(!ordered)) {
 841				WARN(1, KERN_WARNING
 842			"no ordered extent for root %llu ino %llu offset %llu\n",
 843				     inode->root->root_key.objectid,
 844				     btrfs_ino(inode), offset);
 845				kvfree(sums);
 846				return BLK_STS_IOERR;
 847			}
 848		}
 849
 850		blockcount = BTRFS_BYTES_TO_BLKS(fs_info,
 851						 bvec.bv_len + fs_info->sectorsize
 852						 - 1);
 853
 854		for (i = 0; i < blockcount; i++) {
 855			if (!one_ordered &&
 856			    !in_range(offset, ordered->file_offset,
 857				      ordered->num_bytes)) {
 858				unsigned long bytes_left;
 859
 860				sums->len = this_sum_bytes;
 861				this_sum_bytes = 0;
 862				btrfs_add_ordered_sum(ordered, sums);
 863				btrfs_put_ordered_extent(ordered);
 864
 865				bytes_left = bio->bi_iter.bi_size - total_bytes;
 866
 867				nofs_flag = memalloc_nofs_save();
 868				sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
 869						      bytes_left), GFP_KERNEL);
 870				memalloc_nofs_restore(nofs_flag);
 871				BUG_ON(!sums); /* -ENOMEM */
 872				sums->len = bytes_left;
 873				ordered = btrfs_lookup_ordered_extent(inode,
 874								offset);
 875				ASSERT(ordered); /* Logic error */
 876				sums->bytenr = (bio->bi_iter.bi_sector << 9)
 877					+ total_bytes;
 878				index = 0;
 879			}
 880
 881			data = bvec_kmap_local(&bvec);
 882			crypto_shash_digest(shash,
 883					    data + (i * fs_info->sectorsize),
 884					    fs_info->sectorsize,
 885					    sums->sums + index);
 886			kunmap_local(data);
 887			index += fs_info->csum_size;
 888			offset += fs_info->sectorsize;
 889			this_sum_bytes += fs_info->sectorsize;
 890			total_bytes += fs_info->sectorsize;
 891		}
 892
 893	}
 894	this_sum_bytes = 0;
 
 895	btrfs_add_ordered_sum(ordered, sums);
 896	btrfs_put_ordered_extent(ordered);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 897	return 0;
 898}
 899
 900/*
 901 * Remove one checksum overlapping a range.
 902 *
 903 * This expects the key to describe the csum pointed to by the path, and it
 904 * expects the csum to overlap the range [bytenr, len]
 905 *
 906 * The csum should not be entirely contained in the range and the range should
 907 * not be entirely contained in the csum.
 908 *
 909 * This calls btrfs_truncate_item with the correct args based on the overlap,
 910 * and fixes up the key as required.
 911 */
 912static noinline void truncate_one_csum(struct btrfs_fs_info *fs_info,
 913				       struct btrfs_path *path,
 914				       struct btrfs_key *key,
 915				       u64 bytenr, u64 len)
 916{
 
 917	struct extent_buffer *leaf;
 918	const u32 csum_size = fs_info->csum_size;
 919	u64 csum_end;
 920	u64 end_byte = bytenr + len;
 921	u32 blocksize_bits = fs_info->sectorsize_bits;
 922
 923	leaf = path->nodes[0];
 924	csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
 925	csum_end <<= blocksize_bits;
 926	csum_end += key->offset;
 927
 928	if (key->offset < bytenr && csum_end <= end_byte) {
 929		/*
 930		 *         [ bytenr - len ]
 931		 *         [   ]
 932		 *   [csum     ]
 933		 *   A simple truncate off the end of the item
 934		 */
 935		u32 new_size = (bytenr - key->offset) >> blocksize_bits;
 936		new_size *= csum_size;
 937		btrfs_truncate_item(path, new_size, 1);
 938	} else if (key->offset >= bytenr && csum_end > end_byte &&
 939		   end_byte > key->offset) {
 940		/*
 941		 *         [ bytenr - len ]
 942		 *                 [ ]
 943		 *                 [csum     ]
 944		 * we need to truncate from the beginning of the csum
 945		 */
 946		u32 new_size = (csum_end - end_byte) >> blocksize_bits;
 947		new_size *= csum_size;
 948
 949		btrfs_truncate_item(path, new_size, 0);
 950
 951		key->offset = end_byte;
 952		btrfs_set_item_key_safe(fs_info, path, key);
 953	} else {
 954		BUG();
 955	}
 956}
 957
 958/*
 959 * Delete the csum items from the csum tree for a given range of bytes.
 960 */
 961int btrfs_del_csums(struct btrfs_trans_handle *trans,
 962		    struct btrfs_root *root, u64 bytenr, u64 len)
 963{
 964	struct btrfs_fs_info *fs_info = trans->fs_info;
 965	struct btrfs_path *path;
 966	struct btrfs_key key;
 967	u64 end_byte = bytenr + len;
 968	u64 csum_end;
 969	struct extent_buffer *leaf;
 970	int ret = 0;
 971	const u32 csum_size = fs_info->csum_size;
 972	u32 blocksize_bits = fs_info->sectorsize_bits;
 973
 974	ASSERT(root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID ||
 975	       root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
 976
 977	path = btrfs_alloc_path();
 978	if (!path)
 979		return -ENOMEM;
 980
 981	while (1) {
 982		key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
 983		key.offset = end_byte - 1;
 984		key.type = BTRFS_EXTENT_CSUM_KEY;
 985
 986		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 987		if (ret > 0) {
 988			ret = 0;
 989			if (path->slots[0] == 0)
 990				break;
 991			path->slots[0]--;
 992		} else if (ret < 0) {
 993			break;
 994		}
 995
 996		leaf = path->nodes[0];
 997		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 998
 999		if (key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1000		    key.type != BTRFS_EXTENT_CSUM_KEY) {
1001			break;
1002		}
1003
1004		if (key.offset >= end_byte)
1005			break;
1006
1007		csum_end = btrfs_item_size(leaf, path->slots[0]) / csum_size;
1008		csum_end <<= blocksize_bits;
1009		csum_end += key.offset;
1010
1011		/* this csum ends before we start, we're done */
1012		if (csum_end <= bytenr)
1013			break;
1014
1015		/* delete the entire item, it is inside our range */
1016		if (key.offset >= bytenr && csum_end <= end_byte) {
1017			int del_nr = 1;
1018
1019			/*
1020			 * Check how many csum items preceding this one in this
1021			 * leaf correspond to our range and then delete them all
1022			 * at once.
1023			 */
1024			if (key.offset > bytenr && path->slots[0] > 0) {
1025				int slot = path->slots[0] - 1;
1026
1027				while (slot >= 0) {
1028					struct btrfs_key pk;
1029
1030					btrfs_item_key_to_cpu(leaf, &pk, slot);
1031					if (pk.offset < bytenr ||
1032					    pk.type != BTRFS_EXTENT_CSUM_KEY ||
1033					    pk.objectid !=
1034					    BTRFS_EXTENT_CSUM_OBJECTID)
1035						break;
1036					path->slots[0] = slot;
1037					del_nr++;
1038					key.offset = pk.offset;
1039					slot--;
1040				}
1041			}
1042			ret = btrfs_del_items(trans, root, path,
1043					      path->slots[0], del_nr);
1044			if (ret)
1045				break;
1046			if (key.offset == bytenr)
1047				break;
1048		} else if (key.offset < bytenr && csum_end > end_byte) {
1049			unsigned long offset;
1050			unsigned long shift_len;
1051			unsigned long item_offset;
1052			/*
1053			 *        [ bytenr - len ]
1054			 *     [csum                ]
1055			 *
1056			 * Our bytes are in the middle of the csum,
1057			 * we need to split this item and insert a new one.
1058			 *
1059			 * But we can't drop the path because the
1060			 * csum could change, get removed, extended etc.
1061			 *
1062			 * The trick here is the max size of a csum item leaves
1063			 * enough room in the tree block for a single
1064			 * item header.  So, we split the item in place,
1065			 * adding a new header pointing to the existing
1066			 * bytes.  Then we loop around again and we have
1067			 * a nicely formed csum item that we can neatly
1068			 * truncate.
1069			 */
1070			offset = (bytenr - key.offset) >> blocksize_bits;
1071			offset *= csum_size;
1072
1073			shift_len = (len >> blocksize_bits) * csum_size;
1074
1075			item_offset = btrfs_item_ptr_offset(leaf,
1076							    path->slots[0]);
1077
1078			memzero_extent_buffer(leaf, item_offset + offset,
1079					     shift_len);
1080			key.offset = bytenr;
1081
1082			/*
1083			 * btrfs_split_item returns -EAGAIN when the
1084			 * item changed size or key
1085			 */
1086			ret = btrfs_split_item(trans, root, path, &key, offset);
1087			if (ret && ret != -EAGAIN) {
1088				btrfs_abort_transaction(trans, ret);
1089				break;
1090			}
1091			ret = 0;
1092
1093			key.offset = end_byte - 1;
1094		} else {
1095			truncate_one_csum(fs_info, path, &key, bytenr, len);
1096			if (key.offset < bytenr)
1097				break;
1098		}
1099		btrfs_release_path(path);
1100	}
1101	btrfs_free_path(path);
1102	return ret;
1103}
1104
1105static int find_next_csum_offset(struct btrfs_root *root,
1106				 struct btrfs_path *path,
1107				 u64 *next_offset)
1108{
1109	const u32 nritems = btrfs_header_nritems(path->nodes[0]);
1110	struct btrfs_key found_key;
1111	int slot = path->slots[0] + 1;
1112	int ret;
1113
1114	if (nritems == 0 || slot >= nritems) {
1115		ret = btrfs_next_leaf(root, path);
1116		if (ret < 0) {
1117			return ret;
1118		} else if (ret > 0) {
1119			*next_offset = (u64)-1;
1120			return 0;
1121		}
1122		slot = path->slots[0];
1123	}
1124
1125	btrfs_item_key_to_cpu(path->nodes[0], &found_key, slot);
1126
1127	if (found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1128	    found_key.type != BTRFS_EXTENT_CSUM_KEY)
1129		*next_offset = (u64)-1;
1130	else
1131		*next_offset = found_key.offset;
1132
1133	return 0;
1134}
1135
1136int btrfs_csum_file_blocks(struct btrfs_trans_handle *trans,
1137			   struct btrfs_root *root,
1138			   struct btrfs_ordered_sum *sums)
1139{
1140	struct btrfs_fs_info *fs_info = root->fs_info;
1141	struct btrfs_key file_key;
1142	struct btrfs_key found_key;
1143	struct btrfs_path *path;
1144	struct btrfs_csum_item *item;
1145	struct btrfs_csum_item *item_end;
1146	struct extent_buffer *leaf = NULL;
1147	u64 next_offset;
1148	u64 total_bytes = 0;
1149	u64 csum_offset;
1150	u64 bytenr;
1151	u32 ins_size;
1152	int index = 0;
1153	int found_next;
1154	int ret;
1155	const u32 csum_size = fs_info->csum_size;
1156
1157	path = btrfs_alloc_path();
1158	if (!path)
1159		return -ENOMEM;
1160again:
1161	next_offset = (u64)-1;
1162	found_next = 0;
1163	bytenr = sums->bytenr + total_bytes;
1164	file_key.objectid = BTRFS_EXTENT_CSUM_OBJECTID;
1165	file_key.offset = bytenr;
1166	file_key.type = BTRFS_EXTENT_CSUM_KEY;
1167
1168	item = btrfs_lookup_csum(trans, root, path, bytenr, 1);
1169	if (!IS_ERR(item)) {
1170		ret = 0;
1171		leaf = path->nodes[0];
1172		item_end = btrfs_item_ptr(leaf, path->slots[0],
1173					  struct btrfs_csum_item);
1174		item_end = (struct btrfs_csum_item *)((char *)item_end +
1175			   btrfs_item_size(leaf, path->slots[0]));
1176		goto found;
1177	}
1178	ret = PTR_ERR(item);
1179	if (ret != -EFBIG && ret != -ENOENT)
1180		goto out;
1181
1182	if (ret == -EFBIG) {
1183		u32 item_size;
1184		/* we found one, but it isn't big enough yet */
1185		leaf = path->nodes[0];
1186		item_size = btrfs_item_size(leaf, path->slots[0]);
1187		if ((item_size / csum_size) >=
1188		    MAX_CSUM_ITEMS(fs_info, csum_size)) {
1189			/* already at max size, make a new one */
1190			goto insert;
1191		}
1192	} else {
1193		/* We didn't find a csum item, insert one. */
1194		ret = find_next_csum_offset(root, path, &next_offset);
1195		if (ret < 0)
1196			goto out;
1197		found_next = 1;
1198		goto insert;
1199	}
1200
1201	/*
1202	 * At this point, we know the tree has a checksum item that ends at an
1203	 * offset matching the start of the checksum range we want to insert.
1204	 * We try to extend that item as much as possible and then add as many
1205	 * checksums to it as they fit.
1206	 *
1207	 * First check if the leaf has enough free space for at least one
1208	 * checksum. If it has go directly to the item extension code, otherwise
1209	 * release the path and do a search for insertion before the extension.
1210	 */
1211	if (btrfs_leaf_free_space(leaf) >= csum_size) {
1212		btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1213		csum_offset = (bytenr - found_key.offset) >>
1214			fs_info->sectorsize_bits;
1215		goto extend_csum;
1216	}
1217
1218	btrfs_release_path(path);
1219	path->search_for_extension = 1;
1220	ret = btrfs_search_slot(trans, root, &file_key, path,
1221				csum_size, 1);
1222	path->search_for_extension = 0;
1223	if (ret < 0)
1224		goto out;
1225
1226	if (ret > 0) {
1227		if (path->slots[0] == 0)
1228			goto insert;
1229		path->slots[0]--;
1230	}
1231
1232	leaf = path->nodes[0];
1233	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
1234	csum_offset = (bytenr - found_key.offset) >> fs_info->sectorsize_bits;
1235
1236	if (found_key.type != BTRFS_EXTENT_CSUM_KEY ||
1237	    found_key.objectid != BTRFS_EXTENT_CSUM_OBJECTID ||
1238	    csum_offset >= MAX_CSUM_ITEMS(fs_info, csum_size)) {
1239		goto insert;
1240	}
1241
1242extend_csum:
1243	if (csum_offset == btrfs_item_size(leaf, path->slots[0]) /
1244	    csum_size) {
1245		int extend_nr;
1246		u64 tmp;
1247		u32 diff;
1248
1249		tmp = sums->len - total_bytes;
1250		tmp >>= fs_info->sectorsize_bits;
1251		WARN_ON(tmp < 1);
1252		extend_nr = max_t(int, 1, tmp);
1253
1254		/*
1255		 * A log tree can already have checksum items with a subset of
1256		 * the checksums we are trying to log. This can happen after
1257		 * doing a sequence of partial writes into prealloc extents and
1258		 * fsyncs in between, with a full fsync logging a larger subrange
1259		 * of an extent for which a previous fast fsync logged a smaller
1260		 * subrange. And this happens in particular due to merging file
1261		 * extent items when we complete an ordered extent for a range
1262		 * covered by a prealloc extent - this is done at
1263		 * btrfs_mark_extent_written().
1264		 *
1265		 * So if we try to extend the previous checksum item, which has
1266		 * a range that ends at the start of the range we want to insert,
1267		 * make sure we don't extend beyond the start offset of the next
1268		 * checksum item. If we are at the last item in the leaf, then
1269		 * forget the optimization of extending and add a new checksum
1270		 * item - it is not worth the complexity of releasing the path,
1271		 * getting the first key for the next leaf, repeat the btree
1272		 * search, etc, because log trees are temporary anyway and it
1273		 * would only save a few bytes of leaf space.
1274		 */
1275		if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
1276			if (path->slots[0] + 1 >=
1277			    btrfs_header_nritems(path->nodes[0])) {
1278				ret = find_next_csum_offset(root, path, &next_offset);
1279				if (ret < 0)
1280					goto out;
1281				found_next = 1;
1282				goto insert;
1283			}
1284
1285			ret = find_next_csum_offset(root, path, &next_offset);
1286			if (ret < 0)
1287				goto out;
1288
1289			tmp = (next_offset - bytenr) >> fs_info->sectorsize_bits;
1290			if (tmp <= INT_MAX)
1291				extend_nr = min_t(int, extend_nr, tmp);
1292		}
1293
1294		diff = (csum_offset + extend_nr) * csum_size;
1295		diff = min(diff,
1296			   MAX_CSUM_ITEMS(fs_info, csum_size) * csum_size);
1297
1298		diff = diff - btrfs_item_size(leaf, path->slots[0]);
1299		diff = min_t(u32, btrfs_leaf_free_space(leaf), diff);
1300		diff /= csum_size;
1301		diff *= csum_size;
1302
1303		btrfs_extend_item(path, diff);
1304		ret = 0;
1305		goto csum;
1306	}
1307
1308insert:
1309	btrfs_release_path(path);
1310	csum_offset = 0;
1311	if (found_next) {
1312		u64 tmp;
1313
1314		tmp = sums->len - total_bytes;
1315		tmp >>= fs_info->sectorsize_bits;
1316		tmp = min(tmp, (next_offset - file_key.offset) >>
1317					 fs_info->sectorsize_bits);
1318
1319		tmp = max_t(u64, 1, tmp);
1320		tmp = min_t(u64, tmp, MAX_CSUM_ITEMS(fs_info, csum_size));
1321		ins_size = csum_size * tmp;
1322	} else {
1323		ins_size = csum_size;
1324	}
1325	ret = btrfs_insert_empty_item(trans, root, path, &file_key,
1326				      ins_size);
1327	if (ret < 0)
1328		goto out;
1329	if (WARN_ON(ret != 0))
1330		goto out;
1331	leaf = path->nodes[0];
1332csum:
1333	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_csum_item);
1334	item_end = (struct btrfs_csum_item *)((unsigned char *)item +
1335				      btrfs_item_size(leaf, path->slots[0]));
1336	item = (struct btrfs_csum_item *)((unsigned char *)item +
1337					  csum_offset * csum_size);
1338found:
1339	ins_size = (u32)(sums->len - total_bytes) >> fs_info->sectorsize_bits;
1340	ins_size *= csum_size;
1341	ins_size = min_t(u32, (unsigned long)item_end - (unsigned long)item,
1342			      ins_size);
1343	write_extent_buffer(leaf, sums->sums + index, (unsigned long)item,
1344			    ins_size);
1345
1346	index += ins_size;
1347	ins_size /= csum_size;
1348	total_bytes += ins_size * fs_info->sectorsize;
1349
1350	btrfs_mark_buffer_dirty(path->nodes[0]);
1351	if (total_bytes < sums->len) {
1352		btrfs_release_path(path);
1353		cond_resched();
1354		goto again;
1355	}
1356out:
1357	btrfs_free_path(path);
1358	return ret;
1359}
1360
1361void btrfs_extent_item_to_extent_map(struct btrfs_inode *inode,
1362				     const struct btrfs_path *path,
1363				     struct btrfs_file_extent_item *fi,
1364				     struct extent_map *em)
1365{
1366	struct btrfs_fs_info *fs_info = inode->root->fs_info;
1367	struct btrfs_root *root = inode->root;
1368	struct extent_buffer *leaf = path->nodes[0];
1369	const int slot = path->slots[0];
1370	struct btrfs_key key;
1371	u64 extent_start, extent_end;
1372	u64 bytenr;
1373	u8 type = btrfs_file_extent_type(leaf, fi);
1374	int compress_type = btrfs_file_extent_compression(leaf, fi);
1375
1376	btrfs_item_key_to_cpu(leaf, &key, slot);
1377	extent_start = key.offset;
1378	extent_end = btrfs_file_extent_end(path);
1379	em->ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
1380	em->generation = btrfs_file_extent_generation(leaf, fi);
1381	if (type == BTRFS_FILE_EXTENT_REG ||
1382	    type == BTRFS_FILE_EXTENT_PREALLOC) {
1383		em->start = extent_start;
1384		em->len = extent_end - extent_start;
1385		em->orig_start = extent_start -
1386			btrfs_file_extent_offset(leaf, fi);
1387		em->orig_block_len = btrfs_file_extent_disk_num_bytes(leaf, fi);
1388		bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1389		if (bytenr == 0) {
1390			em->block_start = EXTENT_MAP_HOLE;
1391			return;
1392		}
1393		if (compress_type != BTRFS_COMPRESS_NONE) {
1394			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1395			em->compress_type = compress_type;
1396			em->block_start = bytenr;
1397			em->block_len = em->orig_block_len;
1398		} else {
1399			bytenr += btrfs_file_extent_offset(leaf, fi);
1400			em->block_start = bytenr;
1401			em->block_len = em->len;
1402			if (type == BTRFS_FILE_EXTENT_PREALLOC)
1403				set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
1404		}
1405	} else if (type == BTRFS_FILE_EXTENT_INLINE) {
1406		em->block_start = EXTENT_MAP_INLINE;
1407		em->start = extent_start;
1408		em->len = extent_end - extent_start;
1409		/*
1410		 * Initialize orig_start and block_len with the same values
1411		 * as in inode.c:btrfs_get_extent().
1412		 */
1413		em->orig_start = EXTENT_MAP_HOLE;
1414		em->block_len = (u64)-1;
1415		em->compress_type = compress_type;
1416		if (compress_type != BTRFS_COMPRESS_NONE)
1417			set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
1418	} else {
1419		btrfs_err(fs_info,
1420			  "unknown file extent item type %d, inode %llu, offset %llu, "
1421			  "root %llu", type, btrfs_ino(inode), extent_start,
1422			  root->root_key.objectid);
1423	}
1424}
1425
1426/*
1427 * Returns the end offset (non inclusive) of the file extent item the given path
1428 * points to. If it points to an inline extent, the returned offset is rounded
1429 * up to the sector size.
1430 */
1431u64 btrfs_file_extent_end(const struct btrfs_path *path)
1432{
1433	const struct extent_buffer *leaf = path->nodes[0];
1434	const int slot = path->slots[0];
1435	struct btrfs_file_extent_item *fi;
1436	struct btrfs_key key;
1437	u64 end;
1438
1439	btrfs_item_key_to_cpu(leaf, &key, slot);
1440	ASSERT(key.type == BTRFS_EXTENT_DATA_KEY);
1441	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1442
1443	if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
1444		end = btrfs_file_extent_ram_bytes(leaf, fi);
1445		end = ALIGN(key.offset + end, leaf->fs_info->sectorsize);
1446	} else {
1447		end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1448	}
1449
1450	return end;
1451}