1// SPDX-License-Identifier: GPL-2.0
   2
   3#include <linux/bitops.h>
   4#include <linux/slab.h>
   5#include <linux/bio.h>
   6#include <linux/mm.h>
   7#include <linux/pagemap.h>
   8#include <linux/page-flags.h>
   9#include <linux/sched/mm.h>
  10#include <linux/spinlock.h>
  11#include <linux/blkdev.h>
  12#include <linux/swap.h>
  13#include <linux/writeback.h>
  14#include <linux/pagevec.h>
  15#include <linux/prefetch.h>
  16#include <linux/fsverity.h>
  17#include "misc.h"
  18#include "extent_io.h"
  19#include "extent-io-tree.h"
  20#include "extent_map.h"
 
  21#include "ctree.h"
  22#include "btrfs_inode.h"
  23#include "bio.h"
 
  24#include "locking.h"
  25#include "rcu-string.h"
  26#include "backref.h"
  27#include "disk-io.h"
  28#include "subpage.h"
  29#include "zoned.h"
  30#include "block-group.h"
  31#include "compression.h"
  32#include "fs.h"
  33#include "accessors.h"
  34#include "file-item.h"
  35#include "file.h"
  36#include "dev-replace.h"
  37#include "super.h"
  38#include "transaction.h"
  39
 
  40static struct kmem_cache *extent_buffer_cache;
  41
  42#ifdef CONFIG_BTRFS_DEBUG
  43static inline void btrfs_leak_debug_add_eb(struct extent_buffer *eb)
  44{
  45	struct btrfs_fs_info *fs_info = eb->fs_info;
  46	unsigned long flags;
 
 
  47
  48	spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
  49	list_add(&eb->leak_list, &fs_info->allocated_ebs);
  50	spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  51}
  52
  53static inline void btrfs_leak_debug_del_eb(struct extent_buffer *eb)
  54{
  55	struct btrfs_fs_info *fs_info = eb->fs_info;
  56	unsigned long flags;
 
 
 
  57
  58	spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
  59	list_del(&eb->leak_list);
  60	spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
 
 
 
 
 
 
 
  61}
  62
  63void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info)
  64{
 
  65	struct extent_buffer *eb;
  66	unsigned long flags;
  67
  68	/*
  69	 * If we didn't get into open_ctree our allocated_ebs will not be
  70	 * initialized, so just skip this.
  71	 */
  72	if (!fs_info->allocated_ebs.next)
  73		return;
 
 
 
 
 
  74
  75	WARN_ON(!list_empty(&fs_info->allocated_ebs));
  76	spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
  77	while (!list_empty(&fs_info->allocated_ebs)) {
  78		eb = list_first_entry(&fs_info->allocated_ebs,
  79				      struct extent_buffer, leak_list);
  80		pr_err(
  81	"BTRFS: buffer leak start %llu len %lu refs %d bflags %lu owner %llu\n",
  82		       eb->start, eb->len, atomic_read(&eb->refs), eb->bflags,
  83		       btrfs_header_owner(eb));
  84		list_del(&eb->leak_list);
  85		kmem_cache_free(extent_buffer_cache, eb);
  86	}
  87	spin_unlock_irqrestore(&fs_info->eb_leak_lock, flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  88}
  89#else
  90#define btrfs_leak_debug_add_eb(eb)			do {} while (0)
  91#define btrfs_leak_debug_del_eb(eb)			do {} while (0)
 
 
 
 
 
 
 
 
 
 
 
  92#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  93
  94/*
  95 * Structure to record info about the bio being assembled, and other info like
  96 * how many bytes are there before stripe/ordered extent boundary.
 
 
 
 
 
  97 */
  98struct btrfs_bio_ctrl {
  99	struct btrfs_bio *bbio;
 100	enum btrfs_compression_type compress_type;
 101	u32 len_to_oe_boundary;
 102	blk_opf_t opf;
 103	btrfs_bio_end_io_t end_io_func;
 104	struct writeback_control *wbc;
 105};
 106
 107static void submit_one_bio(struct btrfs_bio_ctrl *bio_ctrl)
 108{
 109	struct btrfs_bio *bbio = bio_ctrl->bbio;
 
 110
 111	if (!bbio)
 112		return;
 113
 114	/* Caller should ensure the bio has at least some range added */
 115	ASSERT(bbio->bio.bi_iter.bi_size);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 116
 117	if (btrfs_op(&bbio->bio) == BTRFS_MAP_READ &&
 118	    bio_ctrl->compress_type != BTRFS_COMPRESS_NONE)
 119		btrfs_submit_compressed_read(bbio);
 120	else
 121		btrfs_submit_bio(bbio, 0);
 
 122
 123	/* The bbio is owned by the end_io handler now */
 124	bio_ctrl->bbio = NULL;
 
 
 
 125}
 126
 
 
 
 127/*
 128 * Submit or fail the current bio in the bio_ctrl structure.
 
 
 
 
 
 
 
 129 */
 130static void submit_write_bio(struct btrfs_bio_ctrl *bio_ctrl, int ret)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 131{
 132	struct btrfs_bio *bbio = bio_ctrl->bbio;
 
 
 133
 134	if (!bbio)
 135		return;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 136
 137	if (ret) {
 138		ASSERT(ret < 0);
 139		btrfs_bio_end_io(bbio, errno_to_blk_status(ret));
 140		/* The bio is owned by the end_io handler now */
 141		bio_ctrl->bbio = NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 142	} else {
 143		submit_one_bio(bio_ctrl);
 
 144	}
 
 145}
 146
 147int __init extent_buffer_init_cachep(void)
 
 148{
 149	extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 150			sizeof(struct extent_buffer), 0,
 151			SLAB_MEM_SPREAD, NULL);
 152	if (!extent_buffer_cache)
 153		return -ENOMEM;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 154
 155	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 156}
 157
 158void __cold extent_buffer_free_cachep(void)
 
 
 159{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 160	/*
 161	 * Make sure all delayed rcu free are flushed before we
 162	 * destroy caches.
 163	 */
 164	rcu_barrier();
 165	kmem_cache_destroy(extent_buffer_cache);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 166}
 167
 168void extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end)
 
 
 169{
 170	unsigned long index = start >> PAGE_SHIFT;
 171	unsigned long end_index = end >> PAGE_SHIFT;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 172	struct page *page;
 173
 174	while (index <= end_index) {
 175		page = find_get_page(inode->i_mapping, index);
 176		BUG_ON(!page); /* Pages should be in the extent_io_tree */
 177		clear_page_dirty_for_io(page);
 178		put_page(page);
 179		index++;
 180	}
 
 181}
 182
 183static void process_one_page(struct btrfs_fs_info *fs_info,
 184			     struct page *page, struct page *locked_page,
 185			     unsigned long page_ops, u64 start, u64 end)
 186{
 187	struct folio *folio = page_folio(page);
 188	u32 len;
 189
 190	ASSERT(end + 1 - start != 0 && end + 1 - start < U32_MAX);
 191	len = end + 1 - start;
 192
 193	if (page_ops & PAGE_SET_ORDERED)
 194		btrfs_folio_clamp_set_ordered(fs_info, folio, start, len);
 195	if (page_ops & PAGE_START_WRITEBACK) {
 196		btrfs_folio_clamp_clear_dirty(fs_info, folio, start, len);
 197		btrfs_folio_clamp_set_writeback(fs_info, folio, start, len);
 198	}
 199	if (page_ops & PAGE_END_WRITEBACK)
 200		btrfs_folio_clamp_clear_writeback(fs_info, folio, start, len);
 201
 202	if (page != locked_page && (page_ops & PAGE_UNLOCK))
 203		btrfs_folio_end_writer_lock(fs_info, folio, start, len);
 204}
 205
 206static void __process_pages_contig(struct address_space *mapping,
 207				   struct page *locked_page, u64 start, u64 end,
 208				   unsigned long page_ops)
 209{
 210	struct btrfs_fs_info *fs_info = btrfs_sb(mapping->host->i_sb);
 211	pgoff_t start_index = start >> PAGE_SHIFT;
 212	pgoff_t end_index = end >> PAGE_SHIFT;
 213	pgoff_t index = start_index;
 214	struct folio_batch fbatch;
 215	int i;
 216
 217	folio_batch_init(&fbatch);
 218	while (index <= end_index) {
 219		int found_folios;
 
 
 
 
 
 
 
 
 
 220
 221		found_folios = filemap_get_folios_contig(mapping, &index,
 222				end_index, &fbatch);
 223		for (i = 0; i < found_folios; i++) {
 224			struct folio *folio = fbatch.folios[i];
 
 
 
 225
 226			process_one_page(fs_info, &folio->page, locked_page,
 227					 page_ops, start, end);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 228		}
 229		folio_batch_release(&fbatch);
 230		cond_resched();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 231	}
 
 
 
 232}
 233
 234static noinline void __unlock_for_delalloc(struct inode *inode,
 235					   struct page *locked_page,
 236					   u64 start, u64 end)
 237{
 238	unsigned long index = start >> PAGE_SHIFT;
 239	unsigned long end_index = end >> PAGE_SHIFT;
 
 
 
 
 240
 241	ASSERT(locked_page);
 242	if (index == locked_page->index && end_index == index)
 243		return;
 244
 245	__process_pages_contig(inode->i_mapping, locked_page, start, end,
 246			       PAGE_UNLOCK);
 
 
 
 
 
 
 
 
 
 
 
 247}
 248
 249static noinline int lock_delalloc_pages(struct inode *inode,
 250					struct page *locked_page,
 251					u64 start,
 252					u64 end)
 253{
 254	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 255	struct address_space *mapping = inode->i_mapping;
 256	pgoff_t start_index = start >> PAGE_SHIFT;
 257	pgoff_t end_index = end >> PAGE_SHIFT;
 258	pgoff_t index = start_index;
 259	u64 processed_end = start;
 260	struct folio_batch fbatch;
 
 261
 
 262	if (index == locked_page->index && index == end_index)
 263		return 0;
 264
 265	folio_batch_init(&fbatch);
 266	while (index <= end_index) {
 267		unsigned int found_folios, i;
 268
 269		found_folios = filemap_get_folios_contig(mapping, &index,
 270				end_index, &fbatch);
 271		if (found_folios == 0)
 272			goto out;
 273
 274		for (i = 0; i < found_folios; i++) {
 275			struct folio *folio = fbatch.folios[i];
 276			struct page *page = folio_page(folio, 0);
 277			u32 len = end + 1 - start;
 278
 279			if (page == locked_page)
 280				continue;
 281
 282			if (btrfs_folio_start_writer_lock(fs_info, folio, start,
 283							  len))
 284				goto out;
 285
 286			if (!PageDirty(page) || page->mapping != mapping) {
 287				btrfs_folio_end_writer_lock(fs_info, folio, start,
 288							    len);
 289				goto out;
 290			}
 291
 292			processed_end = page_offset(page) + PAGE_SIZE - 1;
 293		}
 294		folio_batch_release(&fbatch);
 
 295		cond_resched();
 296	}
 297
 298	return 0;
 299out:
 300	folio_batch_release(&fbatch);
 301	if (processed_end > start)
 302		__unlock_for_delalloc(inode, locked_page, start, processed_end);
 303	return -EAGAIN;
 
 
 304}
 305
 306/*
 307 * Find and lock a contiguous range of bytes in the file marked as delalloc, no
 308 * more than @max_bytes.
 309 *
 310 * @start:	The original start bytenr to search.
 311 *		Will store the extent range start bytenr.
 312 * @end:	The original end bytenr of the search range
 313 *		Will store the extent range end bytenr.
 314 *
 315 * Return true if we find a delalloc range which starts inside the original
 316 * range, and @start/@end will store the delalloc range start/end.
 317 *
 318 * Return false if we can't find any delalloc range which starts inside the
 319 * original range, and @start/@end will be the non-delalloc range start/end.
 320 */
 321EXPORT_FOR_TESTS
 322noinline_for_stack bool find_lock_delalloc_range(struct inode *inode,
 323				    struct page *locked_page, u64 *start,
 324				    u64 *end)
 
 325{
 326	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 327	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
 328	const u64 orig_start = *start;
 329	const u64 orig_end = *end;
 330	/* The sanity tests may not set a valid fs_info. */
 331	u64 max_bytes = fs_info ? fs_info->max_extent_size : BTRFS_MAX_EXTENT_SIZE;
 332	u64 delalloc_start;
 333	u64 delalloc_end;
 334	bool found;
 335	struct extent_state *cached_state = NULL;
 336	int ret;
 337	int loops = 0;
 338
 339	/* Caller should pass a valid @end to indicate the search range end */
 340	ASSERT(orig_end > orig_start);
 341
 342	/* The range should at least cover part of the page */
 343	ASSERT(!(orig_start >= page_offset(locked_page) + PAGE_SIZE ||
 344		 orig_end <= page_offset(locked_page)));
 345again:
 346	/* step one, find a bunch of delalloc bytes starting at start */
 347	delalloc_start = *start;
 348	delalloc_end = 0;
 349	found = btrfs_find_delalloc_range(tree, &delalloc_start, &delalloc_end,
 350					  max_bytes, &cached_state);
 351	if (!found || delalloc_end <= *start || delalloc_start > orig_end) {
 352		*start = delalloc_start;
 353
 354		/* @delalloc_end can be -1, never go beyond @orig_end */
 355		*end = min(delalloc_end, orig_end);
 356		free_extent_state(cached_state);
 357		return false;
 358	}
 359
 360	/*
 361	 * start comes from the offset of locked_page.  We have to lock
 362	 * pages in order, so we can't process delalloc bytes before
 363	 * locked_page
 364	 */
 365	if (delalloc_start < *start)
 366		delalloc_start = *start;
 367
 368	/*
 369	 * make sure to limit the number of pages we try to lock down
 
 370	 */
 371	if (delalloc_end + 1 - delalloc_start > max_bytes)
 372		delalloc_end = delalloc_start + max_bytes - 1;
 373
 374	/* step two, lock all the pages after the page that has start */
 375	ret = lock_delalloc_pages(inode, locked_page,
 376				  delalloc_start, delalloc_end);
 377	ASSERT(!ret || ret == -EAGAIN);
 378	if (ret == -EAGAIN) {
 379		/* some of the pages are gone, lets avoid looping by
 380		 * shortening the size of the delalloc range we're searching
 381		 */
 382		free_extent_state(cached_state);
 383		cached_state = NULL;
 384		if (!loops) {
 385			max_bytes = PAGE_SIZE;
 
 386			loops = 1;
 387			goto again;
 388		} else {
 389			found = false;
 390			goto out_failed;
 391		}
 392	}
 
 393
 394	/* step three, lock the state bits for the whole range */
 395	lock_extent(tree, delalloc_start, delalloc_end, &cached_state);
 396
 397	/* then test to make sure it is all still delalloc */
 398	ret = test_range_bit(tree, delalloc_start, delalloc_end,
 399			     EXTENT_DELALLOC, cached_state);
 400	if (!ret) {
 401		unlock_extent(tree, delalloc_start, delalloc_end,
 402			      &cached_state);
 403		__unlock_for_delalloc(inode, locked_page,
 404			      delalloc_start, delalloc_end);
 405		cond_resched();
 406		goto again;
 407	}
 408	free_extent_state(cached_state);
 409	*start = delalloc_start;
 410	*end = delalloc_end;
 411out_failed:
 412	return found;
 413}
 414
 415void extent_clear_unlock_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
 416				  struct page *locked_page,
 417				  u32 clear_bits, unsigned long page_ops)
 
 418{
 419	clear_extent_bit(&inode->io_tree, start, end, clear_bits, NULL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 420
 421	__process_pages_contig(inode->vfs_inode.i_mapping, locked_page,
 422			       start, end, page_ops);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 423}
 424
 425static bool btrfs_verify_page(struct page *page, u64 start)
 
 
 
 
 426{
 427	if (!fsverity_active(page->mapping->host) ||
 428	    PageUptodate(page) ||
 429	    start >= i_size_read(page->mapping->host))
 430		return true;
 431	return fsverity_verify_page(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 432}
 433
 434static void end_page_read(struct page *page, bool uptodate, u64 start, u32 len)
 435{
 436	struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
 437	struct folio *folio = page_folio(page);
 
 438
 439	ASSERT(page_offset(page) <= start &&
 440	       start + len <= page_offset(page) + PAGE_SIZE);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 441
 442	if (uptodate && btrfs_verify_page(page, start))
 443		btrfs_folio_set_uptodate(fs_info, folio, start, len);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 444	else
 445		btrfs_folio_clear_uptodate(fs_info, folio, start, len);
 
 
 446
 447	if (!btrfs_is_subpage(fs_info, page->mapping))
 448		unlock_page(page);
 449	else
 450		btrfs_subpage_end_reader(fs_info, folio, start, len);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 451}
 452
 453/*
 454 * After a write IO is done, we need to:
 455 *
 456 * - clear the uptodate bits on error
 457 * - clear the writeback bits in the extent tree for the range
 458 * - filio_end_writeback()  if there is no more pending io for the folio
 459 *
 460 * Scheduling is not allowed, so the extent state tree is expected
 461 * to have one and only one object corresponding to this IO.
 462 */
 463static void end_bbio_data_write(struct btrfs_bio *bbio)
 464{
 465	struct bio *bio = &bbio->bio;
 466	int error = blk_status_to_errno(bio->bi_status);
 467	struct folio_iter fi;
 468
 469	ASSERT(!bio_flagged(bio, BIO_CLONED));
 470	bio_for_each_folio_all(fi, bio) {
 471		struct folio *folio = fi.folio;
 472		struct inode *inode = folio->mapping->host;
 473		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 474		const u32 sectorsize = fs_info->sectorsize;
 475		u64 start = folio_pos(folio) + fi.offset;
 476		u32 len = fi.length;
 477
 478		/* Only order 0 (single page) folios are allowed for data. */
 479		ASSERT(folio_order(folio) == 0);
 480
 481		/* Our read/write should always be sector aligned. */
 482		if (!IS_ALIGNED(fi.offset, sectorsize))
 483			btrfs_err(fs_info,
 484		"partial page write in btrfs with offset %zu and length %zu",
 485				  fi.offset, fi.length);
 486		else if (!IS_ALIGNED(fi.length, sectorsize))
 487			btrfs_info(fs_info,
 488		"incomplete page write with offset %zu and length %zu",
 489				   fi.offset, fi.length);
 490
 491		btrfs_finish_ordered_extent(bbio->ordered,
 492				folio_page(folio, 0), start, len, !error);
 493		if (error)
 494			mapping_set_error(folio->mapping, error);
 495		btrfs_folio_clear_writeback(fs_info, folio, start, len);
 496	}
 497
 498	bio_put(bio);
 
 
 
 
 
 
 
 
 
 499}
 500
 501/*
 502 * Record previously processed extent range
 503 *
 504 * For endio_readpage_release_extent() to handle a full extent range, reducing
 505 * the extent io operations.
 506 */
 507struct processed_extent {
 508	struct btrfs_inode *inode;
 509	/* Start of the range in @inode */
 510	u64 start;
 511	/* End of the range in @inode */
 512	u64 end;
 513	bool uptodate;
 514};
 515
 516/*
 517 * Try to release processed extent range
 518 *
 519 * May not release the extent range right now if the current range is
 520 * contiguous to processed extent.
 521 *
 522 * Will release processed extent when any of @inode, @uptodate, the range is
 523 * no longer contiguous to the processed range.
 524 *
 525 * Passing @inode == NULL will force processed extent to be released.
 526 */
 527static void endio_readpage_release_extent(struct processed_extent *processed,
 528			      struct btrfs_inode *inode, u64 start, u64 end,
 529			      bool uptodate)
 
 
 
 
 
 
 
 
 
 
 530{
 531	struct extent_state *cached = NULL;
 532	struct extent_io_tree *tree;
 
 533
 534	/* The first extent, initialize @processed */
 535	if (!processed->inode)
 536		goto update;
 
 
 
 537
 538	/*
 539	 * Contiguous to processed extent, just uptodate the end.
 540	 *
 541	 * Several things to notice:
 542	 *
 543	 * - bio can be merged as long as on-disk bytenr is contiguous
 544	 *   This means we can have page belonging to other inodes, thus need to
 545	 *   check if the inode still matches.
 546	 * - bvec can contain range beyond current page for multi-page bvec
 547	 *   Thus we need to do processed->end + 1 >= start check
 548	 */
 549	if (processed->inode == inode && processed->uptodate == uptodate &&
 550	    processed->end + 1 >= start && end >= processed->end) {
 551		processed->end = end;
 552		return;
 553	}
 554
 555	tree = &processed->inode->io_tree;
 556	/*
 557	 * Now we don't have range contiguous to the processed range, release
 558	 * the processed range now.
 559	 */
 560	unlock_extent(tree, processed->start, processed->end, &cached);
 561
 562update:
 563	/* Update processed to current range */
 564	processed->inode = inode;
 565	processed->start = start;
 566	processed->end = end;
 567	processed->uptodate = uptodate;
 568}
 569
 570static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page)
 571{
 572	struct folio *folio = page_folio(page);
 573
 574	ASSERT(folio_test_locked(folio));
 575	if (!btrfs_is_subpage(fs_info, folio->mapping))
 576		return;
 577
 578	ASSERT(folio_test_private(folio));
 579	btrfs_subpage_start_reader(fs_info, folio, page_offset(page), PAGE_SIZE);
 580}
 581
 582/*
 583 * After a data read IO is done, we need to:
 584 *
 585 * - clear the uptodate bits on error
 586 * - set the uptodate bits if things worked
 587 * - set the folio up to date if all extents in the tree are uptodate
 588 * - clear the lock bit in the extent tree
 589 * - unlock the folio if there are no other extents locked for it
 590 *
 591 * Scheduling is not allowed, so the extent state tree is expected
 592 * to have one and only one object corresponding to this IO.
 593 */
 594static void end_bbio_data_read(struct btrfs_bio *bbio)
 595{
 596	struct bio *bio = &bbio->bio;
 597	struct processed_extent processed = { 0 };
 598	struct folio_iter fi;
 599	/*
 600	 * The offset to the beginning of a bio, since one bio can never be
 601	 * larger than UINT_MAX, u32 here is enough.
 602	 */
 603	u32 bio_offset = 0;
 
 604
 605	ASSERT(!bio_flagged(bio, BIO_CLONED));
 606	bio_for_each_folio_all(fi, &bbio->bio) {
 607		bool uptodate = !bio->bi_status;
 608		struct folio *folio = fi.folio;
 609		struct inode *inode = folio->mapping->host;
 610		struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 611		const u32 sectorsize = fs_info->sectorsize;
 612		u64 start;
 613		u64 end;
 614		u32 len;
 615
 616		/* For now only order 0 folios are supported for data. */
 617		ASSERT(folio_order(folio) == 0);
 618		btrfs_debug(fs_info,
 619			"%s: bi_sector=%llu, err=%d, mirror=%u",
 620			__func__, bio->bi_iter.bi_sector, bio->bi_status,
 621			bbio->mirror_num);
 622
 623		/*
 624		 * We always issue full-sector reads, but if some block in a
 625		 * folio fails to read, blk_update_request() will advance
 626		 * bv_offset and adjust bv_len to compensate.  Print a warning
 627		 * for unaligned offsets, and an error if they don't add up to
 628		 * a full sector.
 629		 */
 630		if (!IS_ALIGNED(fi.offset, sectorsize))
 631			btrfs_err(fs_info,
 632		"partial page read in btrfs with offset %zu and length %zu",
 633				  fi.offset, fi.length);
 634		else if (!IS_ALIGNED(fi.offset + fi.length, sectorsize))
 635			btrfs_info(fs_info,
 636		"incomplete page read with offset %zu and length %zu",
 637				   fi.offset, fi.length);
 638
 639		start = folio_pos(folio) + fi.offset;
 640		end = start + fi.length - 1;
 641		len = fi.length;
 642
 643		if (likely(uptodate)) {
 644			loff_t i_size = i_size_read(inode);
 645			pgoff_t end_index = i_size >> folio_shift(folio);
 646
 647			/*
 648			 * Zero out the remaining part if this range straddles
 649			 * i_size.
 650			 *
 651			 * Here we should only zero the range inside the folio,
 652			 * not touch anything else.
 653			 *
 654			 * NOTE: i_size is exclusive while end is inclusive.
 655			 */
 656			if (folio_index(folio) == end_index && i_size <= end) {
 657				u32 zero_start = max(offset_in_folio(folio, i_size),
 658						     offset_in_folio(folio, start));
 659				u32 zero_len = offset_in_folio(folio, end) + 1 -
 660					       zero_start;
 
 
 
 
 
 
 
 
 
 
 
 
 661
 662				folio_zero_range(folio, zero_start, zero_len);
 663			}
 664		}
 665
 666		/* Update page status and unlock. */
 667		end_page_read(folio_page(folio, 0), uptodate, start, len);
 668		endio_readpage_release_extent(&processed, BTRFS_I(inode),
 669					      start, end, uptodate);
 670
 671		ASSERT(bio_offset + len > bio_offset);
 672		bio_offset += len;
 
 
 
 
 
 673
 
 
 
 
 
 
 
 674	}
 675	/* Release the last extent */
 676	endio_readpage_release_extent(&processed, NULL, 0, 0, false);
 677	bio_put(bio);
 678}
 679
 680/*
 681 * Populate every free slot in a provided array with pages.
 682 *
 683 * @nr_pages:   number of pages to allocate
 684 * @page_array: the array to fill with pages; any existing non-null entries in
 685 * 		the array will be skipped
 686 * @extra_gfp:	the extra GFP flags for the allocation.
 687 *
 688 * Return: 0        if all pages were able to be allocated;
 689 *         -ENOMEM  otherwise, the partially allocated pages would be freed and
 690 *                  the array slots zeroed
 691 */
 692int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array,
 693			   gfp_t extra_gfp)
 694{
 695	unsigned int allocated;
 
 
 
 
 
 
 
 
 696
 697	for (allocated = 0; allocated < nr_pages;) {
 698		unsigned int last = allocated;
 
 
 
 699
 700		allocated = alloc_pages_bulk_array(GFP_NOFS | extra_gfp,
 701						   nr_pages, page_array);
 
 
 702
 703		if (allocated == nr_pages)
 704			return 0;
 705
 706		/*
 707		 * During this iteration, no page could be allocated, even
 708		 * though alloc_pages_bulk_array() falls back to alloc_page()
 709		 * if  it could not bulk-allocate. So we must be out of memory.
 710		 */
 711		if (allocated == last) {
 712			for (int i = 0; i < allocated; i++) {
 713				__free_page(page_array[i]);
 714				page_array[i] = NULL;
 715			}
 716			return -ENOMEM;
 717		}
 718
 719		memalloc_retry_wait(GFP_NOFS);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 720	}
 721	return 0;
 
 
 
 
 
 722}
 723
 724/*
 725 * Populate needed folios for the extent buffer.
 726 *
 727 * For now, the folios populated are always in order 0 (aka, single page).
 
 
 728 */
 729static int alloc_eb_folio_array(struct extent_buffer *eb, gfp_t extra_gfp)
 
 
 
 730{
 731	struct page *page_array[INLINE_EXTENT_BUFFER_PAGES] = { 0 };
 732	int num_pages = num_extent_pages(eb);
 
 
 
 
 
 
 
 733	int ret;
 
 
 734
 735	ret = btrfs_alloc_page_array(num_pages, page_array, extra_gfp);
 736	if (ret < 0)
 737		return ret;
 738
 739	for (int i = 0; i < num_pages; i++)
 740		eb->folios[i] = page_folio(page_array[i]);
 741	return 0;
 742}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 743
 744static bool btrfs_bio_is_contig(struct btrfs_bio_ctrl *bio_ctrl,
 745				struct page *page, u64 disk_bytenr,
 746				unsigned int pg_offset)
 747{
 748	struct bio *bio = &bio_ctrl->bbio->bio;
 749	struct bio_vec *bvec = bio_last_bvec_all(bio);
 750	const sector_t sector = disk_bytenr >> SECTOR_SHIFT;
 751
 752	if (bio_ctrl->compress_type != BTRFS_COMPRESS_NONE) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 753		/*
 754		 * For compression, all IO should have its logical bytenr set
 755		 * to the starting bytenr of the compressed extent.
 
 756		 */
 757		return bio->bi_iter.bi_sector == sector;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 758	}
 759
 760	/*
 761	 * The contig check requires the following conditions to be met:
 762	 *
 763	 * 1) The pages are belonging to the same inode
 764	 *    This is implied by the call chain.
 765	 *
 766	 * 2) The range has adjacent logical bytenr
 767	 *
 768	 * 3) The range has adjacent file offset
 769	 *    This is required for the usage of btrfs_bio->file_offset.
 770	 */
 771	return bio_end_sector(bio) == sector &&
 772		page_offset(bvec->bv_page) + bvec->bv_offset + bvec->bv_len ==
 773		page_offset(page) + pg_offset;
 774}
 775
 776static void alloc_new_bio(struct btrfs_inode *inode,
 777			  struct btrfs_bio_ctrl *bio_ctrl,
 778			  u64 disk_bytenr, u64 file_offset)
 779{
 780	struct btrfs_fs_info *fs_info = inode->root->fs_info;
 781	struct btrfs_bio *bbio;
 782
 783	bbio = btrfs_bio_alloc(BIO_MAX_VECS, bio_ctrl->opf, fs_info,
 784			       bio_ctrl->end_io_func, NULL);
 785	bbio->bio.bi_iter.bi_sector = disk_bytenr >> SECTOR_SHIFT;
 786	bbio->inode = inode;
 787	bbio->file_offset = file_offset;
 788	bio_ctrl->bbio = bbio;
 789	bio_ctrl->len_to_oe_boundary = U32_MAX;
 790
 791	/* Limit data write bios to the ordered boundary. */
 792	if (bio_ctrl->wbc) {
 793		struct btrfs_ordered_extent *ordered;
 794
 795		ordered = btrfs_lookup_ordered_extent(inode, file_offset);
 796		if (ordered) {
 797			bio_ctrl->len_to_oe_boundary = min_t(u32, U32_MAX,
 798					ordered->file_offset +
 799					ordered->disk_num_bytes - file_offset);
 800			bbio->ordered = ordered;
 801		}
 802
 803		/*
 804		 * Pick the last added device to support cgroup writeback.  For
 805		 * multi-device file systems this means blk-cgroup policies have
 806		 * to always be set on the last added/replaced device.
 807		 * This is a bit odd but has been like that for a long time.
 808		 */
 809		bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
 810		wbc_init_bio(bio_ctrl->wbc, &bbio->bio);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 811	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 812}
 813
 814/*
 815 * @disk_bytenr: logical bytenr where the write will be
 816 * @page:	page to add to the bio
 817 * @size:	portion of page that we want to write to
 818 * @pg_offset:	offset of the new bio or to check whether we are adding
 819 *              a contiguous page to the previous one
 820 *
 821 * The will either add the page into the existing @bio_ctrl->bbio, or allocate a
 822 * new one in @bio_ctrl->bbio.
 823 * The mirror number for this IO should already be initizlied in
 824 * @bio_ctrl->mirror_num.
 825 */
 826static void submit_extent_page(struct btrfs_bio_ctrl *bio_ctrl,
 827			       u64 disk_bytenr, struct page *page,
 828			       size_t size, unsigned long pg_offset)
 829{
 830	struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
 831
 832	ASSERT(pg_offset + size <= PAGE_SIZE);
 833	ASSERT(bio_ctrl->end_io_func);
 834
 835	if (bio_ctrl->bbio &&
 836	    !btrfs_bio_is_contig(bio_ctrl, page, disk_bytenr, pg_offset))
 837		submit_one_bio(bio_ctrl);
 838
 839	do {
 840		u32 len = size;
 
 841
 842		/* Allocate new bio if needed */
 843		if (!bio_ctrl->bbio) {
 844			alloc_new_bio(inode, bio_ctrl, disk_bytenr,
 845				      page_offset(page) + pg_offset);
 846		}
 847
 848		/* Cap to the current ordered extent boundary if there is one. */
 849		if (len > bio_ctrl->len_to_oe_boundary) {
 850			ASSERT(bio_ctrl->compress_type == BTRFS_COMPRESS_NONE);
 851			ASSERT(is_data_inode(&inode->vfs_inode));
 852			len = bio_ctrl->len_to_oe_boundary;
 853		}
 
 854
 855		if (bio_add_page(&bio_ctrl->bbio->bio, page, len, pg_offset) != len) {
 856			/* bio full: move on to a new one */
 857			submit_one_bio(bio_ctrl);
 858			continue;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 859		}
 
 860
 861		if (bio_ctrl->wbc)
 862			wbc_account_cgroup_owner(bio_ctrl->wbc, page, len);
 
 
 
 
 
 
 
 863
 864		size -= len;
 865		pg_offset += len;
 866		disk_bytenr += len;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 867
 868		/*
 869		 * len_to_oe_boundary defaults to U32_MAX, which isn't page or
 870		 * sector aligned.  alloc_new_bio() then sets it to the end of
 871		 * our ordered extent for writes into zoned devices.
 872		 *
 873		 * When len_to_oe_boundary is tracking an ordered extent, we
 874		 * trust the ordered extent code to align things properly, and
 875		 * the check above to cap our write to the ordered extent
 876		 * boundary is correct.
 877		 *
 878		 * When len_to_oe_boundary is U32_MAX, the cap above would
 879		 * result in a 4095 byte IO for the last page right before
 880		 * we hit the bio limit of UINT_MAX.  bio_add_page() has all
 881		 * the checks required to make sure we don't overflow the bio,
 882		 * and we should just ignore len_to_oe_boundary completely
 883		 * unless we're using it to track an ordered extent.
 884		 *
 885		 * It's pretty hard to make a bio sized U32_MAX, but it can
 886		 * happen when the page cache is able to feed us contiguous
 887		 * pages for large extents.
 888		 */
 889		if (bio_ctrl->len_to_oe_boundary != U32_MAX)
 890			bio_ctrl->len_to_oe_boundary -= len;
 
 891
 892		/* Ordered extent boundary: move on to a new bio. */
 893		if (bio_ctrl->len_to_oe_boundary == 0)
 894			submit_one_bio(bio_ctrl);
 895	} while (size);
 896}
 897
 898static int attach_extent_buffer_folio(struct extent_buffer *eb,
 899				      struct folio *folio,
 900				      struct btrfs_subpage *prealloc)
 901{
 902	struct btrfs_fs_info *fs_info = eb->fs_info;
 903	int ret = 0;
 904
 905	/*
 906	 * If the page is mapped to btree inode, we should hold the private
 907	 * lock to prevent race.
 908	 * For cloned or dummy extent buffers, their pages are not mapped and
 909	 * will not race with any other ebs.
 910	 */
 911	if (folio->mapping)
 912		lockdep_assert_held(&folio->mapping->i_private_lock);
 913
 914	if (fs_info->nodesize >= PAGE_SIZE) {
 915		if (!folio_test_private(folio))
 916			folio_attach_private(folio, eb);
 917		else
 918			WARN_ON(folio_get_private(folio) != eb);
 919		return 0;
 920	}
 921
 922	/* Already mapped, just free prealloc */
 923	if (folio_test_private(folio)) {
 924		btrfs_free_subpage(prealloc);
 925		return 0;
 926	}
 927
 928	if (prealloc)
 929		/* Has preallocated memory for subpage */
 930		folio_attach_private(folio, prealloc);
 931	else
 932		/* Do new allocation to attach subpage */
 933		ret = btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_METADATA);
 934	return ret;
 935}
 936
 937int set_page_extent_mapped(struct page *page)
 
 
 
 
 
 938{
 939	struct folio *folio = page_folio(page);
 940	struct btrfs_fs_info *fs_info;
 
 
 
 941
 942	ASSERT(page->mapping);
 943
 944	if (folio_test_private(folio))
 945		return 0;
 946
 947	fs_info = btrfs_sb(page->mapping->host->i_sb);
 948
 949	if (btrfs_is_subpage(fs_info, page->mapping))
 950		return btrfs_attach_subpage(fs_info, folio, BTRFS_SUBPAGE_DATA);
 
 
 
 951
 952	folio_attach_private(folio, (void *)EXTENT_FOLIO_PRIVATE);
 953	return 0;
 
 
 954}
 955
 956void clear_page_extent_mapped(struct page *page)
 
 
 957{
 958	struct folio *folio = page_folio(page);
 959	struct btrfs_fs_info *fs_info;
 960
 961	ASSERT(page->mapping);
 962
 963	if (!folio_test_private(folio))
 964		return;
 965
 966	fs_info = btrfs_sb(page->mapping->host->i_sb);
 967	if (btrfs_is_subpage(fs_info, page->mapping))
 968		return btrfs_detach_subpage(fs_info, folio);
 969
 970	folio_detach_private(folio);
 971}
 972
 973static struct extent_map *
 974__get_extent_map(struct inode *inode, struct page *page, size_t pg_offset,
 975		 u64 start, u64 len, struct extent_map **em_cached)
 
 
 
 
 
 
 
 976{
 977	struct extent_map *em;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 978
 979	if (em_cached && *em_cached) {
 980		em = *em_cached;
 981		if (extent_map_in_tree(em) && start >= em->start &&
 982		    start < extent_map_end(em)) {
 983			refcount_inc(&em->refs);
 984			return em;
 
 
 
 
 985		}
 
 
 
 
 
 986
 987		free_extent_map(em);
 988		*em_cached = NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 989	}
 
 990
 991	em = btrfs_get_extent(BTRFS_I(inode), page, pg_offset, start, len);
 992	if (em_cached && !IS_ERR(em)) {
 993		BUG_ON(*em_cached);
 994		refcount_inc(&em->refs);
 995		*em_cached = em;
 
 996	}
 997	return em;
 998}
 
 999/*
1000 * basic readpage implementation.  Locked extent state structs are inserted
1001 * into the tree that are removed when the IO is done (by the end_io
1002 * handlers)
1003 * XXX JDM: This needs looking at to ensure proper page locking
1004 * return 0 on success, otherwise return error
1005 */
1006static int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
1007		      struct btrfs_bio_ctrl *bio_ctrl, u64 *prev_em_start)
 
 
 
1008{
1009	struct inode *inode = page->mapping->host;
1010	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
1011	u64 start = page_offset(page);
1012	const u64 end = start + PAGE_SIZE - 1;
1013	u64 cur = start;
1014	u64 extent_offset;
1015	u64 last_byte = i_size_read(inode);
1016	u64 block_start;
 
 
1017	struct extent_map *em;
1018	int ret = 0;
 
 
 
1019	size_t pg_offset = 0;
1020	size_t iosize;
 
1021	size_t blocksize = inode->i_sb->s_blocksize;
1022	struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
1023
1024	ret = set_page_extent_mapped(page);
1025	if (ret < 0) {
1026		unlock_extent(tree, start, end, NULL);
1027		unlock_page(page);
1028		return ret;
 
 
1029	}
1030
1031	if (page->index == last_byte >> PAGE_SHIFT) {
1032		size_t zero_offset = offset_in_page(last_byte);
 
 
 
 
 
 
 
 
 
 
 
 
1033
1034		if (zero_offset) {
1035			iosize = PAGE_SIZE - zero_offset;
1036			memzero_page(page, zero_offset, iosize);
 
 
 
1037		}
1038	}
1039	bio_ctrl->end_io_func = end_bbio_data_read;
1040	begin_page_read(fs_info, page);
1041	while (cur <= end) {
1042		enum btrfs_compression_type compress_type = BTRFS_COMPRESS_NONE;
1043		bool force_bio_submit = false;
1044		u64 disk_bytenr;
1045
1046		ASSERT(IS_ALIGNED(cur, fs_info->sectorsize));
1047		if (cur >= last_byte) {
1048			iosize = PAGE_SIZE - pg_offset;
1049			memzero_page(page, pg_offset, iosize);
1050			unlock_extent(tree, cur, cur + iosize - 1, NULL);
1051			end_page_read(page, true, cur, iosize);
 
 
 
 
 
 
 
 
1052			break;
1053		}
1054		em = __get_extent_map(inode, page, pg_offset, cur,
1055				      end - cur + 1, em_cached);
1056		if (IS_ERR(em)) {
1057			unlock_extent(tree, cur, end, NULL);
1058			end_page_read(page, false, cur, end + 1 - cur);
1059			return PTR_ERR(em);
1060		}
1061		extent_offset = cur - em->start;
1062		BUG_ON(extent_map_end(em) <= cur);
1063		BUG_ON(end < cur);
1064
1065		compress_type = extent_map_compression(em);
 
 
 
 
1066
1067		iosize = min(extent_map_end(em) - cur, end - cur + 1);
1068		iosize = ALIGN(iosize, blocksize);
1069		if (compress_type != BTRFS_COMPRESS_NONE)
1070			disk_bytenr = em->block_start;
1071		else
1072			disk_bytenr = em->block_start + extent_offset;
 
 
 
 
 
1073		block_start = em->block_start;
1074		if (em->flags & EXTENT_FLAG_PREALLOC)
1075			block_start = EXTENT_MAP_HOLE;
1076
1077		/*
1078		 * If we have a file range that points to a compressed extent
1079		 * and it's followed by a consecutive file range that points
1080		 * to the same compressed extent (possibly with a different
1081		 * offset and/or length, so it either points to the whole extent
1082		 * or only part of it), we must make sure we do not submit a
1083		 * single bio to populate the pages for the 2 ranges because
1084		 * this makes the compressed extent read zero out the pages
1085		 * belonging to the 2nd range. Imagine the following scenario:
1086		 *
1087		 *  File layout
1088		 *  [0 - 8K]                     [8K - 24K]
1089		 *    |                               |
1090		 *    |                               |
1091		 * points to extent X,         points to extent X,
1092		 * offset 4K, length of 8K     offset 0, length 16K
1093		 *
1094		 * [extent X, compressed length = 4K uncompressed length = 16K]
1095		 *
1096		 * If the bio to read the compressed extent covers both ranges,
1097		 * it will decompress extent X into the pages belonging to the
1098		 * first range and then it will stop, zeroing out the remaining
1099		 * pages that belong to the other range that points to extent X.
1100		 * So here we make sure we submit 2 bios, one for the first
1101		 * range and another one for the third range. Both will target
1102		 * the same physical extent from disk, but we can't currently
1103		 * make the compressed bio endio callback populate the pages
1104		 * for both ranges because each compressed bio is tightly
1105		 * coupled with a single extent map, and each range can have
1106		 * an extent map with a different offset value relative to the
1107		 * uncompressed data of our extent and different lengths. This
1108		 * is a corner case so we prioritize correctness over
1109		 * non-optimal behavior (submitting 2 bios for the same extent).
1110		 */
1111		if (compress_type != BTRFS_COMPRESS_NONE &&
1112		    prev_em_start && *prev_em_start != (u64)-1 &&
1113		    *prev_em_start != em->start)
1114			force_bio_submit = true;
1115
1116		if (prev_em_start)
1117			*prev_em_start = em->start;
1118
1119		free_extent_map(em);
1120		em = NULL;
1121
1122		/* we've found a hole, just zero and go on */
1123		if (block_start == EXTENT_MAP_HOLE) {
1124			memzero_page(page, pg_offset, iosize);
 
1125
1126			unlock_extent(tree, cur, cur + iosize - 1, NULL);
1127			end_page_read(page, true, cur, iosize);
 
 
 
 
 
 
 
1128			cur = cur + iosize;
1129			pg_offset += iosize;
1130			continue;
1131		}
1132		/* the get_extent function already copied into the page */
 
 
 
 
 
 
 
 
 
 
 
1133		if (block_start == EXTENT_MAP_INLINE) {
1134			unlock_extent(tree, cur, cur + iosize - 1, NULL);
1135			end_page_read(page, true, cur, iosize);
1136			cur = cur + iosize;
1137			pg_offset += iosize;
1138			continue;
1139		}
1140
1141		if (bio_ctrl->compress_type != compress_type) {
1142			submit_one_bio(bio_ctrl);
1143			bio_ctrl->compress_type = compress_type;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1144		}
1145
1146		if (force_bio_submit)
1147			submit_one_bio(bio_ctrl);
1148		submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
1149				   pg_offset);
1150		cur = cur + iosize;
1151		pg_offset += iosize;
1152	}
1153
 
 
 
 
 
1154	return 0;
1155}
1156
1157int btrfs_read_folio(struct file *file, struct folio *folio)
 
1158{
1159	struct page *page = &folio->page;
1160	struct btrfs_inode *inode = BTRFS_I(page->mapping->host);
1161	u64 start = page_offset(page);
1162	u64 end = start + PAGE_SIZE - 1;
1163	struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ };
1164	int ret;
1165
1166	btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
1167
1168	ret = btrfs_do_readpage(page, NULL, &bio_ctrl, NULL);
1169	/*
1170	 * If btrfs_do_readpage() failed we will want to submit the assembled
1171	 * bio to do the cleanup.
1172	 */
1173	submit_one_bio(&bio_ctrl);
1174	return ret;
1175}
1176
1177static inline void contiguous_readpages(struct page *pages[], int nr_pages,
1178					u64 start, u64 end,
1179					struct extent_map **em_cached,
1180					struct btrfs_bio_ctrl *bio_ctrl,
1181					u64 *prev_em_start)
1182{
1183	struct btrfs_inode *inode = BTRFS_I(pages[0]->mapping->host);
1184	int index;
1185
1186	btrfs_lock_and_flush_ordered_range(inode, start, end, NULL);
1187
1188	for (index = 0; index < nr_pages; index++) {
1189		btrfs_do_readpage(pages[index], em_cached, bio_ctrl,
1190				  prev_em_start);
1191		put_page(pages[index]);
1192	}
1193}
1194
1195/*
1196 * helper for __extent_writepage, doing all of the delayed allocation setup.
1197 *
1198 * This returns 1 if btrfs_run_delalloc_range function did all the work required
1199 * to write the page (copy into inline extent).  In this case the IO has
1200 * been started and the page is already unlocked.
1201 *
1202 * This returns 0 if all went well (page still locked)
1203 * This returns < 0 if there were errors (page still locked)
1204 */
1205static noinline_for_stack int writepage_delalloc(struct btrfs_inode *inode,
1206		struct page *page, struct writeback_control *wbc)
1207{
1208	const u64 page_start = page_offset(page);
1209	const u64 page_end = page_start + PAGE_SIZE - 1;
1210	u64 delalloc_start = page_start;
1211	u64 delalloc_end = page_end;
1212	u64 delalloc_to_write = 0;
1213	int ret = 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1214
1215	while (delalloc_start < page_end) {
1216		delalloc_end = page_end;
1217		if (!find_lock_delalloc_range(&inode->vfs_inode, page,
1218					      &delalloc_start, &delalloc_end)) {
1219			delalloc_start = delalloc_end + 1;
1220			continue;
1221		}
1222
1223		ret = btrfs_run_delalloc_range(inode, page, delalloc_start,
1224					       delalloc_end, wbc);
1225		if (ret < 0)
1226			return ret;
1227
1228		delalloc_start = delalloc_end + 1;
1229	}
1230
1231	/*
1232	 * delalloc_end is already one less than the total length, so
1233	 * we don't subtract one from PAGE_SIZE
1234	 */
1235	delalloc_to_write +=
1236		DIV_ROUND_UP(delalloc_end + 1 - page_start, PAGE_SIZE);
1237
1238	/*
1239	 * If btrfs_run_dealloc_range() already started I/O and unlocked
1240	 * the pages, we just need to account for them here.
1241	 */
1242	if (ret == 1) {
1243		wbc->nr_to_write -= delalloc_to_write;
1244		return 1;
1245	}
1246
1247	if (wbc->nr_to_write < delalloc_to_write) {
1248		int thresh = 8192;
1249
1250		if (delalloc_to_write < thresh * 2)
1251			thresh = delalloc_to_write;
1252		wbc->nr_to_write = min_t(u64, delalloc_to_write,
1253					 thresh);
 
1254	}
 
1255
1256	return 0;
1257}
1258
1259/*
1260 * Find the first byte we need to write.
1261 *
1262 * For subpage, one page can contain several sectors, and
1263 * __extent_writepage_io() will just grab all extent maps in the page
1264 * range and try to submit all non-inline/non-compressed extents.
1265 *
1266 * This is a big problem for subpage, we shouldn't re-submit already written
1267 * data at all.
1268 * This function will lookup subpage dirty bit to find which range we really
1269 * need to submit.
1270 *
1271 * Return the next dirty range in [@start, @end).
1272 * If no dirty range is found, @start will be page_offset(page) + PAGE_SIZE.
1273 */
1274static void find_next_dirty_byte(struct btrfs_fs_info *fs_info,
1275				 struct page *page, u64 *start, u64 *end)
1276{
1277	struct folio *folio = page_folio(page);
1278	struct btrfs_subpage *subpage = folio_get_private(folio);
1279	struct btrfs_subpage_info *spi = fs_info->subpage_info;
1280	u64 orig_start = *start;
1281	/* Declare as unsigned long so we can use bitmap ops */
1282	unsigned long flags;
1283	int range_start_bit;
1284	int range_end_bit;
1285
1286	/*
1287	 * For regular sector size == page size case, since one page only
1288	 * contains one sector, we return the page offset directly.
1289	 */
1290	if (!btrfs_is_subpage(fs_info, page->mapping)) {
1291		*start = page_offset(page);
1292		*end = page_offset(page) + PAGE_SIZE;
1293		return;
1294	}
1295
1296	range_start_bit = spi->dirty_offset +
1297			  (offset_in_page(orig_start) >> fs_info->sectorsize_bits);
 
 
 
 
 
 
 
 
1298
1299	/* We should have the page locked, but just in case */
1300	spin_lock_irqsave(&subpage->lock, flags);
1301	bitmap_next_set_region(subpage->bitmaps, &range_start_bit, &range_end_bit,
1302			       spi->dirty_offset + spi->bitmap_nr_bits);
1303	spin_unlock_irqrestore(&subpage->lock, flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1304
1305	range_start_bit -= spi->dirty_offset;
1306	range_end_bit -= spi->dirty_offset;
 
 
 
1307
1308	*start = page_offset(page) + range_start_bit * fs_info->sectorsize;
1309	*end = page_offset(page) + range_end_bit * fs_info->sectorsize;
1310}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1311
1312/*
1313 * helper for __extent_writepage.  This calls the writepage start hooks,
1314 * and does the loop to map the page into extents and bios.
1315 *
1316 * We return 1 if the IO is started and the page is unlocked,
1317 * 0 if all went well (page still locked)
1318 * < 0 if there were errors (page still locked)
1319 */
1320static noinline_for_stack int __extent_writepage_io(struct btrfs_inode *inode,
1321				 struct page *page,
1322				 struct btrfs_bio_ctrl *bio_ctrl,
1323				 loff_t i_size,
1324				 int *nr_ret)
1325{
1326	struct btrfs_fs_info *fs_info = inode->root->fs_info;
1327	u64 cur = page_offset(page);
1328	u64 end = cur + PAGE_SIZE - 1;
1329	u64 extent_offset;
1330	u64 block_start;
1331	struct extent_map *em;
1332	int ret = 0;
1333	int nr = 0;
1334
1335	ret = btrfs_writepage_cow_fixup(page);
1336	if (ret) {
1337		/* Fixup worker will requeue */
1338		redirty_page_for_writepage(bio_ctrl->wbc, page);
1339		unlock_page(page);
1340		return 1;
1341	}
1342
1343	bio_ctrl->end_io_func = end_bbio_data_write;
 
1344	while (cur <= end) {
1345		u32 len = end - cur + 1;
1346		u64 disk_bytenr;
1347		u64 em_end;
1348		u64 dirty_range_start = cur;
1349		u64 dirty_range_end;
1350		u32 iosize;
1351
1352		if (cur >= i_size) {
1353			btrfs_mark_ordered_io_finished(inode, page, cur, len,
1354						       true);
1355			/*
1356			 * This range is beyond i_size, thus we don't need to
1357			 * bother writing back.
1358			 * But we still need to clear the dirty subpage bit, or
1359			 * the next time the page gets dirtied, we will try to
1360			 * writeback the sectors with subpage dirty bits,
1361			 * causing writeback without ordered extent.
1362			 */
1363			btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, len);
1364			break;
1365		}
1366
1367		find_next_dirty_byte(fs_info, page, &dirty_range_start,
1368				     &dirty_range_end);
1369		if (cur < dirty_range_start) {
1370			cur = dirty_range_start;
1371			continue;
1372		}
1373
1374		em = btrfs_get_extent(inode, NULL, 0, cur, len);
1375		if (IS_ERR(em)) {
1376			ret = PTR_ERR_OR_ZERO(em);
1377			goto out_error;
1378		}
1379
1380		extent_offset = cur - em->start;
1381		em_end = extent_map_end(em);
1382		ASSERT(cur <= em_end);
1383		ASSERT(cur < end);
1384		ASSERT(IS_ALIGNED(em->start, fs_info->sectorsize));
1385		ASSERT(IS_ALIGNED(em->len, fs_info->sectorsize));
1386
1387		block_start = em->block_start;
1388		disk_bytenr = em->block_start + extent_offset;
1389
1390		ASSERT(!extent_map_is_compressed(em));
1391		ASSERT(block_start != EXTENT_MAP_HOLE);
1392		ASSERT(block_start != EXTENT_MAP_INLINE);
1393
1394		/*
1395		 * Note that em_end from extent_map_end() and dirty_range_end from
1396		 * find_next_dirty_byte() are all exclusive
1397		 */
1398		iosize = min(min(em_end, end + 1), dirty_range_end) - cur;
1399		free_extent_map(em);
1400		em = NULL;
1401
1402		btrfs_set_range_writeback(inode, cur, cur + iosize - 1);
1403		if (!PageWriteback(page)) {
1404			btrfs_err(inode->root->fs_info,
1405				   "page %lu not writeback, cur %llu end %llu",
1406			       page->index, cur, end);
1407		}
1408
1409		/*
1410		 * Although the PageDirty bit is cleared before entering this
1411		 * function, subpage dirty bit is not cleared.
1412		 * So clear subpage dirty bit here so next time we won't submit
1413		 * page for range already written to disk.
1414		 */
1415		btrfs_folio_clear_dirty(fs_info, page_folio(page), cur, iosize);
1416
1417		submit_extent_page(bio_ctrl, disk_bytenr, page, iosize,
1418				   cur - page_offset(page));
1419		cur += iosize;
1420		nr++;
1421	}
1422
1423	btrfs_folio_assert_not_dirty(fs_info, page_folio(page));
1424	*nr_ret = nr;
1425	return 0;
1426
1427out_error:
1428	/*
1429	 * If we finish without problem, we should not only clear page dirty,
1430	 * but also empty subpage dirty bits
1431	 */
1432	*nr_ret = nr;
1433	return ret;
1434}
1435
1436/*
1437 * the writepage semantics are similar to regular writepage.  extent
1438 * records are inserted to lock ranges in the tree, and as dirty areas
1439 * are found, they are marked writeback.  Then the lock bits are removed
1440 * and the end_io handler clears the writeback ranges
1441 *
1442 * Return 0 if everything goes well.
1443 * Return <0 for error.
1444 */
1445static int __extent_writepage(struct page *page, struct btrfs_bio_ctrl *bio_ctrl)
1446{
1447	struct folio *folio = page_folio(page);
1448	struct inode *inode = page->mapping->host;
1449	const u64 page_start = page_offset(page);
1450	int ret;
1451	int nr = 0;
1452	size_t pg_offset;
1453	loff_t i_size = i_size_read(inode);
1454	unsigned long end_index = i_size >> PAGE_SHIFT;
1455
1456	trace___extent_writepage(page, inode, bio_ctrl->wbc);
 
 
 
 
 
 
 
 
 
1457
1458	WARN_ON(!PageLocked(page));
 
 
 
 
 
 
1459
1460	pg_offset = offset_in_page(i_size);
1461	if (page->index > end_index ||
1462	   (page->index == end_index && !pg_offset)) {
1463		folio_invalidate(folio, 0, folio_size(folio));
1464		folio_unlock(folio);
1465		return 0;
 
 
 
 
 
1466	}
1467
1468	if (page->index == end_index)
1469		memzero_page(page, pg_offset, PAGE_SIZE - pg_offset);
1470
1471	ret = set_page_extent_mapped(page);
1472	if (ret < 0)
1473		goto done;
1474
1475	ret = writepage_delalloc(BTRFS_I(inode), page, bio_ctrl->wbc);
1476	if (ret == 1)
1477		return 0;
1478	if (ret)
1479		goto done;
1480
1481	ret = __extent_writepage_io(BTRFS_I(inode), page, bio_ctrl, i_size, &nr);
1482	if (ret == 1)
1483		return 0;
1484
1485	bio_ctrl->wbc->nr_to_write--;
1486
1487done:
1488	if (nr == 0) {
1489		/* make sure the mapping tag for page dirty gets cleared */
1490		set_page_writeback(page);
1491		end_page_writeback(page);
1492	}
1493	if (ret) {
1494		btrfs_mark_ordered_io_finished(BTRFS_I(inode), page, page_start,
1495					       PAGE_SIZE, !ret);
1496		mapping_set_error(page->mapping, ret);
1497	}
1498	unlock_page(page);
1499	ASSERT(ret <= 0);
1500	return ret;
 
 
 
 
1501}
1502
1503void wait_on_extent_buffer_writeback(struct extent_buffer *eb)
1504{
1505	wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_WRITEBACK,
1506		       TASK_UNINTERRUPTIBLE);
1507}
1508
1509/*
1510 * Lock extent buffer status and pages for writeback.
1511 *
1512 * Return %false if the extent buffer doesn't need to be submitted (e.g. the
1513 * extent buffer is not dirty)
1514 * Return %true is the extent buffer is submitted to bio.
1515 */
1516static noinline_for_stack bool lock_extent_buffer_for_io(struct extent_buffer *eb,
1517			  struct writeback_control *wbc)
1518{
1519	struct btrfs_fs_info *fs_info = eb->fs_info;
1520	bool ret = false;
 
1521
1522	btrfs_tree_lock(eb);
1523	while (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags)) {
1524		btrfs_tree_unlock(eb);
1525		if (wbc->sync_mode != WB_SYNC_ALL)
1526			return false;
1527		wait_on_extent_buffer_writeback(eb);
 
 
 
 
 
1528		btrfs_tree_lock(eb);
1529	}
1530
1531	/*
1532	 * We need to do this to prevent races in people who check if the eb is
1533	 * under IO since we can end up having no IO bits set for a short period
1534	 * of time.
1535	 */
1536	spin_lock(&eb->refs_lock);
 
 
 
 
 
 
 
 
 
 
 
1537	if (test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
1538		set_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
1539		spin_unlock(&eb->refs_lock);
1540		btrfs_set_header_flag(eb, BTRFS_HEADER_FLAG_WRITTEN);
1541		percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
1542					 -eb->len,
1543					 fs_info->dirty_metadata_batch);
1544		ret = true;
1545	} else {
1546		spin_unlock(&eb->refs_lock);
 
1547	}
1548	btrfs_tree_unlock(eb);
1549	return ret;
1550}
1551
1552static void set_btree_ioerr(struct extent_buffer *eb)
1553{
1554	struct btrfs_fs_info *fs_info = eb->fs_info;
1555
1556	set_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
1557
1558	/*
1559	 * A read may stumble upon this buffer later, make sure that it gets an
1560	 * error and knows there was an error.
1561	 */
1562	clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
1563
1564	/*
1565	 * We need to set the mapping with the io error as well because a write
1566	 * error will flip the file system readonly, and then syncfs() will
1567	 * return a 0 because we are readonly if we don't modify the err seq for
1568	 * the superblock.
1569	 */
1570	mapping_set_error(eb->fs_info->btree_inode->i_mapping, -EIO);
1571
1572	/*
1573	 * If writeback for a btree extent that doesn't belong to a log tree
1574	 * failed, increment the counter transaction->eb_write_errors.
1575	 * We do this because while the transaction is running and before it's
1576	 * committing (when we call filemap_fdata[write|wait]_range against
1577	 * the btree inode), we might have
1578	 * btree_inode->i_mapping->a_ops->writepages() called by the VM - if it
1579	 * returns an error or an error happens during writeback, when we're
1580	 * committing the transaction we wouldn't know about it, since the pages
1581	 * can be no longer dirty nor marked anymore for writeback (if a
1582	 * subsequent modification to the extent buffer didn't happen before the
1583	 * transaction commit), which makes filemap_fdata[write|wait]_range not
1584	 * able to find the pages tagged with SetPageError at transaction
1585	 * commit time. So if this happens we must abort the transaction,
1586	 * otherwise we commit a super block with btree roots that point to
1587	 * btree nodes/leafs whose content on disk is invalid - either garbage
1588	 * or the content of some node/leaf from a past generation that got
1589	 * cowed or deleted and is no longer valid.
1590	 *
1591	 * Note: setting AS_EIO/AS_ENOSPC in the btree inode's i_mapping would
1592	 * not be enough - we need to distinguish between log tree extents vs
1593	 * non-log tree extents, and the next filemap_fdatawait_range() call
1594	 * will catch and clear such errors in the mapping - and that call might
1595	 * be from a log sync and not from a transaction commit. Also, checking
1596	 * for the eb flag EXTENT_BUFFER_WRITE_ERR at transaction commit time is
1597	 * not done and would not be reliable - the eb might have been released
1598	 * from memory and reading it back again means that flag would not be
1599	 * set (since it's a runtime flag, not persisted on disk).
1600	 *
1601	 * Using the flags below in the btree inode also makes us achieve the
1602	 * goal of AS_EIO/AS_ENOSPC when writepages() returns success, started
1603	 * writeback for all dirty pages and before filemap_fdatawait_range()
1604	 * is called, the writeback for all dirty pages had already finished
1605	 * with errors - because we were not using AS_EIO/AS_ENOSPC,
1606	 * filemap_fdatawait_range() would return success, as it could not know
1607	 * that writeback errors happened (the pages were no longer tagged for
1608	 * writeback).
1609	 */
1610	switch (eb->log_index) {
1611	case -1:
1612		set_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags);
1613		break;
1614	case 0:
1615		set_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
1616		break;
1617	case 1:
1618		set_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
1619		break;
1620	default:
1621		BUG(); /* unexpected, logic error */
1622	}
1623}
1624
1625/*
1626 * The endio specific version which won't touch any unsafe spinlock in endio
1627 * context.
1628 */
1629static struct extent_buffer *find_extent_buffer_nolock(
1630		struct btrfs_fs_info *fs_info, u64 start)
1631{
1632	struct extent_buffer *eb;
1633
1634	rcu_read_lock();
1635	eb = radix_tree_lookup(&fs_info->buffer_radix,
1636			       start >> fs_info->sectorsize_bits);
1637	if (eb && atomic_inc_not_zero(&eb->refs)) {
1638		rcu_read_unlock();
1639		return eb;
1640	}
1641	rcu_read_unlock();
1642	return NULL;
1643}
1644
1645static void end_bbio_meta_write(struct btrfs_bio *bbio)
1646{
1647	struct extent_buffer *eb = bbio->private;
1648	struct btrfs_fs_info *fs_info = eb->fs_info;
1649	bool uptodate = !bbio->bio.bi_status;
1650	struct folio_iter fi;
1651	u32 bio_offset = 0;
1652
1653	if (!uptodate)
1654		set_btree_ioerr(eb);
1655
1656	bio_for_each_folio_all(fi, &bbio->bio) {
1657		u64 start = eb->start + bio_offset;
1658		struct folio *folio = fi.folio;
1659		u32 len = fi.length;
1660
1661		btrfs_folio_clear_writeback(fs_info, folio, start, len);
1662		bio_offset += len;
1663	}
1664
1665	clear_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags);
1666	smp_mb__after_atomic();
1667	wake_up_bit(&eb->bflags, EXTENT_BUFFER_WRITEBACK);
1668
1669	bio_put(&bbio->bio);
1670}
1671
1672static void prepare_eb_write(struct extent_buffer *eb)
1673{
1674	u32 nritems;
1675	unsigned long start;
1676	unsigned long end;
1677
1678	clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
1679
1680	/* Set btree blocks beyond nritems with 0 to avoid stale content */
1681	nritems = btrfs_header_nritems(eb);
1682	if (btrfs_header_level(eb) > 0) {
1683		end = btrfs_node_key_ptr_offset(eb, nritems);
1684		memzero_extent_buffer(eb, end, eb->len - end);
1685	} else {
1686		/*
1687		 * Leaf:
1688		 * header 0 1 2 .. N ... data_N .. data_2 data_1 data_0
1689		 */
1690		start = btrfs_item_nr_offset(eb, nritems);
1691		end = btrfs_item_nr_offset(eb, 0);
1692		if (nritems == 0)
1693			end += BTRFS_LEAF_DATA_SIZE(eb->fs_info);
1694		else
1695			end += btrfs_item_offset(eb, nritems - 1);
1696		memzero_extent_buffer(eb, start, end - start);
1697	}
1698}
1699
1700static noinline_for_stack void write_one_eb(struct extent_buffer *eb,
1701					    struct writeback_control *wbc)
1702{
1703	struct btrfs_fs_info *fs_info = eb->fs_info;
1704	struct btrfs_bio *bbio;
1705
1706	prepare_eb_write(eb);
1707
1708	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
1709			       REQ_OP_WRITE | REQ_META | wbc_to_write_flags(wbc),
1710			       eb->fs_info, end_bbio_meta_write, eb);
1711	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
1712	bio_set_dev(&bbio->bio, fs_info->fs_devices->latest_dev->bdev);
1713	wbc_init_bio(wbc, &bbio->bio);
1714	bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
1715	bbio->file_offset = eb->start;
1716	if (fs_info->nodesize < PAGE_SIZE) {
1717		struct folio *folio = eb->folios[0];
1718		bool ret;
1719
1720		folio_lock(folio);
1721		btrfs_subpage_set_writeback(fs_info, folio, eb->start, eb->len);
1722		if (btrfs_subpage_clear_and_test_dirty(fs_info, folio, eb->start,
1723						       eb->len)) {
1724			folio_clear_dirty_for_io(folio);
1725			wbc->nr_to_write--;
1726		}
1727		ret = bio_add_folio(&bbio->bio, folio, eb->len,
1728				    eb->start - folio_pos(folio));
1729		ASSERT(ret);
1730		wbc_account_cgroup_owner(wbc, folio_page(folio, 0), eb->len);
1731		folio_unlock(folio);
1732	} else {
1733		int num_folios = num_extent_folios(eb);
1734
1735		for (int i = 0; i < num_folios; i++) {
1736			struct folio *folio = eb->folios[i];
1737			bool ret;
1738
1739			folio_lock(folio);
1740			folio_clear_dirty_for_io(folio);
1741			folio_start_writeback(folio);
1742			ret = bio_add_folio(&bbio->bio, folio, folio_size(folio), 0);
1743			ASSERT(ret);
1744			wbc_account_cgroup_owner(wbc, folio_page(folio, 0),
1745						 folio_size(folio));
1746			wbc->nr_to_write -= folio_nr_pages(folio);
1747			folio_unlock(folio);
1748		}
1749	}
1750	btrfs_submit_bio(bbio, 0);
1751}
1752
1753/*
1754 * Submit one subpage btree page.
1755 *
1756 * The main difference to submit_eb_page() is:
1757 * - Page locking
1758 *   For subpage, we don't rely on page locking at all.
1759 *
1760 * - Flush write bio
1761 *   We only flush bio if we may be unable to fit current extent buffers into
1762 *   current bio.
1763 *
1764 * Return >=0 for the number of submitted extent buffers.
1765 * Return <0 for fatal error.
1766 */
1767static int submit_eb_subpage(struct page *page, struct writeback_control *wbc)
1768{
1769	struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
1770	struct folio *folio = page_folio(page);
1771	int submitted = 0;
1772	u64 page_start = page_offset(page);
1773	int bit_start = 0;
1774	int sectors_per_node = fs_info->nodesize >> fs_info->sectorsize_bits;
1775
1776	/* Lock and write each dirty extent buffers in the range */
1777	while (bit_start < fs_info->subpage_info->bitmap_nr_bits) {
1778		struct btrfs_subpage *subpage = folio_get_private(folio);
1779		struct extent_buffer *eb;
1780		unsigned long flags;
1781		u64 start;
1782
1783		/*
1784		 * Take private lock to ensure the subpage won't be detached
1785		 * in the meantime.
1786		 */
1787		spin_lock(&page->mapping->i_private_lock);
1788		if (!folio_test_private(folio)) {
1789			spin_unlock(&page->mapping->i_private_lock);
1790			break;
1791		}
1792		spin_lock_irqsave(&subpage->lock, flags);
1793		if (!test_bit(bit_start + fs_info->subpage_info->dirty_offset,
1794			      subpage->bitmaps)) {
1795			spin_unlock_irqrestore(&subpage->lock, flags);
1796			spin_unlock(&page->mapping->i_private_lock);
1797			bit_start++;
1798			continue;
1799		}
1800
1801		start = page_start + bit_start * fs_info->sectorsize;
1802		bit_start += sectors_per_node;
1803
1804		/*
1805		 * Here we just want to grab the eb without touching extra
1806		 * spin locks, so call find_extent_buffer_nolock().
1807		 */
1808		eb = find_extent_buffer_nolock(fs_info, start);
1809		spin_unlock_irqrestore(&subpage->lock, flags);
1810		spin_unlock(&page->mapping->i_private_lock);
1811
1812		/*
1813		 * The eb has already reached 0 refs thus find_extent_buffer()
1814		 * doesn't return it. We don't need to write back such eb
1815		 * anyway.
1816		 */
1817		if (!eb)
1818			continue;
1819
1820		if (lock_extent_buffer_for_io(eb, wbc)) {
1821			write_one_eb(eb, wbc);
1822			submitted++;
1823		}
1824		free_extent_buffer(eb);
1825	}
1826	return submitted;
1827}
1828
1829/*
1830 * Submit all page(s) of one extent buffer.
1831 *
1832 * @page:	the page of one extent buffer
1833 * @eb_context:	to determine if we need to submit this page, if current page
1834 *		belongs to this eb, we don't need to submit
1835 *
1836 * The caller should pass each page in their bytenr order, and here we use
1837 * @eb_context to determine if we have submitted pages of one extent buffer.
1838 *
1839 * If we have, we just skip until we hit a new page that doesn't belong to
1840 * current @eb_context.
1841 *
1842 * If not, we submit all the page(s) of the extent buffer.
1843 *
1844 * Return >0 if we have submitted the extent buffer successfully.
1845 * Return 0 if we don't need to submit the page, as it's already submitted by
1846 * previous call.
1847 * Return <0 for fatal error.
1848 */
1849static int submit_eb_page(struct page *page, struct btrfs_eb_write_context *ctx)
1850{
1851	struct writeback_control *wbc = ctx->wbc;
1852	struct address_space *mapping = page->mapping;
1853	struct folio *folio = page_folio(page);
1854	struct extent_buffer *eb;
1855	int ret;
1856
1857	if (!folio_test_private(folio))
1858		return 0;
1859
1860	if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE)
1861		return submit_eb_subpage(page, wbc);
1862
1863	spin_lock(&mapping->i_private_lock);
1864	if (!folio_test_private(folio)) {
1865		spin_unlock(&mapping->i_private_lock);
1866		return 0;
1867	}
1868
1869	eb = folio_get_private(folio);
1870
1871	/*
1872	 * Shouldn't happen and normally this would be a BUG_ON but no point
1873	 * crashing the machine for something we can survive anyway.
1874	 */
1875	if (WARN_ON(!eb)) {
1876		spin_unlock(&mapping->i_private_lock);
1877		return 0;
1878	}
1879
1880	if (eb == ctx->eb) {
1881		spin_unlock(&mapping->i_private_lock);
1882		return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1883	}
1884	ret = atomic_inc_not_zero(&eb->refs);
1885	spin_unlock(&mapping->i_private_lock);
1886	if (!ret)
1887		return 0;
1888
1889	ctx->eb = eb;
1890
1891	ret = btrfs_check_meta_write_pointer(eb->fs_info, ctx);
1892	if (ret) {
1893		if (ret == -EBUSY)
1894			ret = 0;
1895		free_extent_buffer(eb);
1896		return ret;
1897	}
1898
1899	if (!lock_extent_buffer_for_io(eb, wbc)) {
1900		free_extent_buffer(eb);
1901		return 0;
1902	}
1903	/* Implies write in zoned mode. */
1904	if (ctx->zoned_bg) {
1905		/* Mark the last eb in the block group. */
1906		btrfs_schedule_zone_finish_bg(ctx->zoned_bg, eb);
1907		ctx->zoned_bg->meta_write_pointer += eb->len;
1908	}
1909	write_one_eb(eb, wbc);
1910	free_extent_buffer(eb);
1911	return 1;
1912}
1913
1914int btree_write_cache_pages(struct address_space *mapping,
1915				   struct writeback_control *wbc)
1916{
1917	struct btrfs_eb_write_context ctx = { .wbc = wbc };
1918	struct btrfs_fs_info *fs_info = BTRFS_I(mapping->host)->root->fs_info;
 
 
 
 
 
 
 
1919	int ret = 0;
1920	int done = 0;
1921	int nr_to_write_done = 0;
1922	struct folio_batch fbatch;
1923	unsigned int nr_folios;
1924	pgoff_t index;
1925	pgoff_t end;		/* Inclusive */
1926	int scanned = 0;
1927	xa_mark_t tag;
1928
1929	folio_batch_init(&fbatch);
1930	if (wbc->range_cyclic) {
1931		index = mapping->writeback_index; /* Start from prev offset */
1932		end = -1;
1933		/*
1934		 * Start from the beginning does not need to cycle over the
1935		 * range, mark it as scanned.
1936		 */
1937		scanned = (index == 0);
1938	} else {
1939		index = wbc->range_start >> PAGE_SHIFT;
1940		end = wbc->range_end >> PAGE_SHIFT;
1941		scanned = 1;
1942	}
1943	if (wbc->sync_mode == WB_SYNC_ALL)
1944		tag = PAGECACHE_TAG_TOWRITE;
1945	else
1946		tag = PAGECACHE_TAG_DIRTY;
1947	btrfs_zoned_meta_io_lock(fs_info);
1948retry:
1949	if (wbc->sync_mode == WB_SYNC_ALL)
1950		tag_pages_for_writeback(mapping, index, end);
1951	while (!done && !nr_to_write_done && (index <= end) &&
1952	       (nr_folios = filemap_get_folios_tag(mapping, &index, end,
1953					    tag, &fbatch))) {
1954		unsigned i;
1955
1956		for (i = 0; i < nr_folios; i++) {
1957			struct folio *folio = fbatch.folios[i];
 
 
 
 
 
 
 
 
 
1958
1959			ret = submit_eb_page(&folio->page, &ctx);
1960			if (ret == 0)
 
1961				continue;
1962			if (ret < 0) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1963				done = 1;
 
1964				break;
1965			}
 
1966
1967			/*
1968			 * the filesystem may choose to bump up nr_to_write.
1969			 * We have to make sure to honor the new nr_to_write
1970			 * at any time
1971			 */
1972			nr_to_write_done = wbc->nr_to_write <= 0;
1973		}
1974		folio_batch_release(&fbatch);
1975		cond_resched();
1976	}
1977	if (!scanned && !done) {
1978		/*
1979		 * We hit the last page and there is more work to be done: wrap
1980		 * back to the start of the file
1981		 */
1982		scanned = 1;
1983		index = 0;
1984		goto retry;
1985	}
1986	/*
1987	 * If something went wrong, don't allow any metadata write bio to be
1988	 * submitted.
1989	 *
1990	 * This would prevent use-after-free if we had dirty pages not
1991	 * cleaned up, which can still happen by fuzzed images.
1992	 *
1993	 * - Bad extent tree
1994	 *   Allowing existing tree block to be allocated for other trees.
1995	 *
1996	 * - Log tree operations
1997	 *   Exiting tree blocks get allocated to log tree, bumps its
1998	 *   generation, then get cleaned in tree re-balance.
1999	 *   Such tree block will not be written back, since it's clean,
2000	 *   thus no WRITTEN flag set.
2001	 *   And after log writes back, this tree block is not traced by
2002	 *   any dirty extent_io_tree.
2003	 *
2004	 * - Offending tree block gets re-dirtied from its original owner
2005	 *   Since it has bumped generation, no WRITTEN flag, it can be
2006	 *   reused without COWing. This tree block will not be traced
2007	 *   by btrfs_transaction::dirty_pages.
2008	 *
2009	 *   Now such dirty tree block will not be cleaned by any dirty
2010	 *   extent io tree. Thus we don't want to submit such wild eb
2011	 *   if the fs already has error.
2012	 *
2013	 * We can get ret > 0 from submit_extent_page() indicating how many ebs
2014	 * were submitted. Reset it to 0 to avoid false alerts for the caller.
2015	 */
2016	if (ret > 0)
2017		ret = 0;
2018	if (!ret && BTRFS_FS_ERROR(fs_info))
2019		ret = -EROFS;
2020
2021	if (ctx.zoned_bg)
2022		btrfs_put_block_group(ctx.zoned_bg);
2023	btrfs_zoned_meta_io_unlock(fs_info);
2024	return ret;
2025}
2026
2027/*
2028 * Walk the list of dirty pages of the given address space and write all of them.
2029 *
2030 * @mapping:   address space structure to write
2031 * @wbc:       subtract the number of written pages from *@wbc->nr_to_write
2032 * @bio_ctrl:  holds context for the write, namely the bio
2033 *
2034 * If a page is already under I/O, write_cache_pages() skips it, even
2035 * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
2036 * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
2037 * and msync() need to guarantee that all the data which was dirty at the time
2038 * the call was made get new I/O started against them.  If wbc->sync_mode is
2039 * WB_SYNC_ALL then we were called for data integrity and we must wait for
2040 * existing IO to complete.
2041 */
2042static int extent_write_cache_pages(struct address_space *mapping,
2043			     struct btrfs_bio_ctrl *bio_ctrl)
 
 
 
2044{
2045	struct writeback_control *wbc = bio_ctrl->wbc;
2046	struct inode *inode = mapping->host;
2047	int ret = 0;
2048	int done = 0;
2049	int nr_to_write_done = 0;
2050	struct folio_batch fbatch;
2051	unsigned int nr_folios;
2052	pgoff_t index;
2053	pgoff_t end;		/* Inclusive */
2054	pgoff_t done_index;
2055	int range_whole = 0;
2056	int scanned = 0;
2057	xa_mark_t tag;
2058
2059	/*
2060	 * We have to hold onto the inode so that ordered extents can do their
2061	 * work when the IO finishes.  The alternative to this is failing to add
2062	 * an ordered extent if the igrab() fails there and that is a huge pain
2063	 * to deal with, so instead just hold onto the inode throughout the
2064	 * writepages operation.  If it fails here we are freeing up the inode
2065	 * anyway and we'd rather not waste our time writing out stuff that is
2066	 * going to be truncated anyway.
2067	 */
2068	if (!igrab(inode))
2069		return 0;
2070
2071	folio_batch_init(&fbatch);
2072	if (wbc->range_cyclic) {
2073		index = mapping->writeback_index; /* Start from prev offset */
2074		end = -1;
2075		/*
2076		 * Start from the beginning does not need to cycle over the
2077		 * range, mark it as scanned.
2078		 */
2079		scanned = (index == 0);
2080	} else {
2081		index = wbc->range_start >> PAGE_SHIFT;
2082		end = wbc->range_end >> PAGE_SHIFT;
2083		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2084			range_whole = 1;
2085		scanned = 1;
2086	}
2087
2088	/*
2089	 * We do the tagged writepage as long as the snapshot flush bit is set
2090	 * and we are the first one who do the filemap_flush() on this inode.
2091	 *
2092	 * The nr_to_write == LONG_MAX is needed to make sure other flushers do
2093	 * not race in and drop the bit.
2094	 */
2095	if (range_whole && wbc->nr_to_write == LONG_MAX &&
2096	    test_and_clear_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
2097			       &BTRFS_I(inode)->runtime_flags))
2098		wbc->tagged_writepages = 1;
2099
2100	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2101		tag = PAGECACHE_TAG_TOWRITE;
2102	else
2103		tag = PAGECACHE_TAG_DIRTY;
2104retry:
2105	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2106		tag_pages_for_writeback(mapping, index, end);
2107	done_index = index;
2108	while (!done && !nr_to_write_done && (index <= end) &&
2109			(nr_folios = filemap_get_folios_tag(mapping, &index,
2110							end, tag, &fbatch))) {
2111		unsigned i;
2112
2113		for (i = 0; i < nr_folios; i++) {
2114			struct folio *folio = fbatch.folios[i];
 
2115
2116			done_index = folio_next_index(folio);
2117			/*
2118			 * At this point we hold neither the i_pages lock nor
2119			 * the page lock: the page may be truncated or
2120			 * invalidated (changing page->mapping to NULL),
2121			 * or even swizzled back from swapper_space to
2122			 * tmpfs file mapping
2123			 */
2124			if (!folio_trylock(folio)) {
2125				submit_write_bio(bio_ctrl, 0);
2126				folio_lock(folio);
 
 
 
 
 
 
2127			}
2128
2129			if (unlikely(folio->mapping != mapping)) {
2130				folio_unlock(folio);
2131				continue;
2132			}
2133
2134			if (!folio_test_dirty(folio)) {
2135				/* Someone wrote it for us. */
2136				folio_unlock(folio);
2137				continue;
2138			}
2139
2140			if (wbc->sync_mode != WB_SYNC_NONE) {
2141				if (folio_test_writeback(folio))
2142					submit_write_bio(bio_ctrl, 0);
2143				folio_wait_writeback(folio);
2144			}
2145
2146			if (folio_test_writeback(folio) ||
2147			    !folio_clear_dirty_for_io(folio)) {
2148				folio_unlock(folio);
2149				continue;
2150			}
2151
2152			ret = __extent_writepage(&folio->page, bio_ctrl);
2153			if (ret < 0) {
2154				done = 1;
2155				break;
 
2156			}
 
 
2157
2158			/*
2159			 * The filesystem may choose to bump up nr_to_write.
2160			 * We have to make sure to honor the new nr_to_write
2161			 * at any time.
2162			 */
2163			nr_to_write_done = (wbc->sync_mode == WB_SYNC_NONE &&
2164					    wbc->nr_to_write <= 0);
2165		}
2166		folio_batch_release(&fbatch);
2167		cond_resched();
2168	}
2169	if (!scanned && !done) {
2170		/*
2171		 * We hit the last page and there is more work to be done: wrap
2172		 * back to the start of the file
2173		 */
2174		scanned = 1;
2175		index = 0;
2176
2177		/*
2178		 * If we're looping we could run into a page that is locked by a
2179		 * writer and that writer could be waiting on writeback for a
2180		 * page in our current bio, and thus deadlock, so flush the
2181		 * write bio here.
2182		 */
2183		submit_write_bio(bio_ctrl, 0);
2184		goto retry;
2185	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2186
2187	if (wbc->range_cyclic || (wbc->nr_to_write > 0 && range_whole))
2188		mapping->writeback_index = done_index;
 
 
 
2189
2190	btrfs_add_delayed_iput(BTRFS_I(inode));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2191	return ret;
2192}
2193
2194/*
2195 * Submit the pages in the range to bio for call sites which delalloc range has
2196 * already been ran (aka, ordered extent inserted) and all pages are still
2197 * locked.
2198 */
2199void extent_write_locked_range(struct inode *inode, struct page *locked_page,
2200			       u64 start, u64 end, struct writeback_control *wbc,
2201			       bool pages_dirty)
2202{
2203	bool found_error = false;
2204	int ret = 0;
2205	struct address_space *mapping = inode->i_mapping;
2206	struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
2207	const u32 sectorsize = fs_info->sectorsize;
2208	loff_t i_size = i_size_read(inode);
2209	u64 cur = start;
2210	struct btrfs_bio_ctrl bio_ctrl = {
2211		.wbc = wbc,
2212		.opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
2213	};
2214
2215	if (wbc->no_cgroup_owner)
2216		bio_ctrl.opf |= REQ_BTRFS_CGROUP_PUNT;
2217
2218	ASSERT(IS_ALIGNED(start, sectorsize) && IS_ALIGNED(end + 1, sectorsize));
 
 
 
 
 
 
 
 
 
 
 
 
2219
2220	while (cur <= end) {
2221		u64 cur_end = min(round_down(cur, PAGE_SIZE) + PAGE_SIZE - 1, end);
2222		u32 cur_len = cur_end + 1 - cur;
2223		struct page *page;
2224		int nr = 0;
2225
2226		page = find_get_page(mapping, cur >> PAGE_SHIFT);
2227		ASSERT(PageLocked(page));
2228		if (pages_dirty && page != locked_page) {
2229			ASSERT(PageDirty(page));
2230			clear_page_dirty_for_io(page);
2231		}
2232
2233		ret = __extent_writepage_io(BTRFS_I(inode), page, &bio_ctrl,
2234					    i_size, &nr);
2235		if (ret == 1)
2236			goto next_page;
2237
2238		/* Make sure the mapping tag for page dirty gets cleared. */
2239		if (nr == 0) {
2240			set_page_writeback(page);
2241			end_page_writeback(page);
2242		}
2243		if (ret) {
2244			btrfs_mark_ordered_io_finished(BTRFS_I(inode), page,
2245						       cur, cur_len, !ret);
2246			mapping_set_error(page->mapping, ret);
2247		}
2248		btrfs_folio_unlock_writer(fs_info, page_folio(page), cur, cur_len);
2249		if (ret < 0)
2250			found_error = true;
2251next_page:
2252		put_page(page);
2253		cur = cur_end + 1;
2254	}
2255
2256	submit_write_bio(&bio_ctrl, found_error ? ret : 0);
 
2257}
2258
2259int extent_writepages(struct address_space *mapping,
 
 
2260		      struct writeback_control *wbc)
2261{
2262	struct inode *inode = mapping->host;
2263	int ret = 0;
2264	struct btrfs_bio_ctrl bio_ctrl = {
2265		.wbc = wbc,
2266		.opf = REQ_OP_WRITE | wbc_to_write_flags(wbc),
 
 
 
2267	};
2268
2269	/*
2270	 * Allow only a single thread to do the reloc work in zoned mode to
2271	 * protect the write pointer updates.
2272	 */
2273	btrfs_zoned_data_reloc_lock(BTRFS_I(inode));
2274	ret = extent_write_cache_pages(mapping, &bio_ctrl);
2275	submit_write_bio(&bio_ctrl, ret);
2276	btrfs_zoned_data_reloc_unlock(BTRFS_I(inode));
2277	return ret;
2278}
2279
2280void extent_readahead(struct readahead_control *rac)
2281{
2282	struct btrfs_bio_ctrl bio_ctrl = { .opf = REQ_OP_READ | REQ_RAHEAD };
2283	struct page *pagepool[16];
2284	struct extent_map *em_cached = NULL;
2285	u64 prev_em_start = (u64)-1;
2286	int nr;
2287
2288	while ((nr = readahead_page_batch(rac, pagepool))) {
2289		u64 contig_start = readahead_pos(rac);
2290		u64 contig_end = contig_start + readahead_batch_length(rac) - 1;
2291
2292		contiguous_readpages(pagepool, nr, contig_start, contig_end,
2293				&em_cached, &bio_ctrl, &prev_em_start);
2294	}
2295
2296	if (em_cached)
2297		free_extent_map(em_cached);
2298	submit_one_bio(&bio_ctrl);
 
 
 
 
 
 
2299}
2300
2301/*
2302 * basic invalidate_folio code, this waits on any locked or writeback
2303 * ranges corresponding to the folio, and then deletes any extent state
2304 * records from the tree
2305 */
2306int extent_invalidate_folio(struct extent_io_tree *tree,
2307			  struct folio *folio, size_t offset)
2308{
2309	struct extent_state *cached_state = NULL;
2310	u64 start = folio_pos(folio);
2311	u64 end = start + folio_size(folio) - 1;
2312	size_t blocksize = folio->mapping->host->i_sb->s_blocksize;
2313
2314	/* This function is only called for the btree inode */
2315	ASSERT(tree->owner == IO_TREE_BTREE_INODE_IO);
2316
2317	start += ALIGN(offset, blocksize);
2318	if (start > end)
2319		return 0;
2320
2321	lock_extent(tree, start, end, &cached_state);
2322	folio_wait_writeback(folio);
2323
2324	/*
2325	 * Currently for btree io tree, only EXTENT_LOCKED is utilized,
2326	 * so here we only need to unlock the extent range to free any
2327	 * existing extent state.
2328	 */
2329	unlock_extent(tree, start, end, &cached_state);
2330	return 0;
2331}
2332
2333/*
2334 * a helper for release_folio, this tests for areas of the page that
2335 * are locked or under IO and drops the related state bits if it is safe
2336 * to drop the page.
2337 */
2338static int try_release_extent_state(struct extent_io_tree *tree,
2339				    struct page *page, gfp_t mask)
 
2340{
2341	u64 start = page_offset(page);
2342	u64 end = start + PAGE_SIZE - 1;
2343	int ret = 1;
2344
2345	if (test_range_bit_exists(tree, start, end, EXTENT_LOCKED)) {
 
2346		ret = 0;
2347	} else {
2348		u32 clear_bits = ~(EXTENT_LOCKED | EXTENT_NODATASUM |
2349				   EXTENT_DELALLOC_NEW | EXTENT_CTLBITS |
2350				   EXTENT_QGROUP_RESERVED);
2351
2352		/*
2353		 * At this point we can safely clear everything except the
2354		 * locked bit, the nodatasum bit and the delalloc new bit.
2355		 * The delalloc new bit will be cleared by ordered extent
2356		 * completion.
2357		 */
2358		ret = __clear_extent_bit(tree, start, end, clear_bits, NULL, NULL);
 
 
2359
2360		/* if clear_extent_bit failed for enomem reasons,
2361		 * we can't allow the release to continue.
2362		 */
2363		if (ret < 0)
2364			ret = 0;
2365		else
2366			ret = 1;
2367	}
2368	return ret;
2369}
2370
2371/*
2372 * a helper for release_folio.  As long as there are no locked extents
2373 * in the range corresponding to the page, both state records and extent
2374 * map records are removed
2375 */
2376int try_release_extent_mapping(struct page *page, gfp_t mask)
 
 
2377{
2378	struct extent_map *em;
2379	u64 start = page_offset(page);
2380	u64 end = start + PAGE_SIZE - 1;
2381	struct btrfs_inode *btrfs_inode = BTRFS_I(page->mapping->host);
2382	struct extent_io_tree *tree = &btrfs_inode->io_tree;
2383	struct extent_map_tree *map = &btrfs_inode->extent_tree;
2384
2385	if (gfpflags_allow_blocking(mask) &&
2386	    page->mapping->host->i_size > SZ_16M) {
2387		u64 len;
2388		while (start <= end) {
2389			struct btrfs_fs_info *fs_info;
2390			u64 cur_gen;
2391
2392			len = end - start + 1;
2393			write_lock(&map->lock);
2394			em = lookup_extent_mapping(map, start, len);
2395			if (!em) {
2396				write_unlock(&map->lock);
2397				break;
2398			}
2399			if ((em->flags & EXTENT_FLAG_PINNED) ||
2400			    em->start != start) {
2401				write_unlock(&map->lock);
2402				free_extent_map(em);
2403				break;
2404			}
2405			if (test_range_bit_exists(tree, em->start,
2406						  extent_map_end(em) - 1,
2407						  EXTENT_LOCKED))
2408				goto next;
2409			/*
2410			 * If it's not in the list of modified extents, used
2411			 * by a fast fsync, we can remove it. If it's being
2412			 * logged we can safely remove it since fsync took an
2413			 * extra reference on the em.
2414			 */
2415			if (list_empty(&em->list) ||
2416			    (em->flags & EXTENT_FLAG_LOGGING))
2417				goto remove_em;
2418			/*
2419			 * If it's in the list of modified extents, remove it
2420			 * only if its generation is older then the current one,
2421			 * in which case we don't need it for a fast fsync.
2422			 * Otherwise don't remove it, we could be racing with an
2423			 * ongoing fast fsync that could miss the new extent.
2424			 */
2425			fs_info = btrfs_inode->root->fs_info;
2426			spin_lock(&fs_info->trans_lock);
2427			cur_gen = fs_info->generation;
2428			spin_unlock(&fs_info->trans_lock);
2429			if (em->generation >= cur_gen)
2430				goto next;
2431remove_em:
2432			/*
2433			 * We only remove extent maps that are not in the list of
2434			 * modified extents or that are in the list but with a
2435			 * generation lower then the current generation, so there
2436			 * is no need to set the full fsync flag on the inode (it
2437			 * hurts the fsync performance for workloads with a data
2438			 * size that exceeds or is close to the system's memory).
2439			 */
2440			remove_extent_mapping(map, em);
2441			/* once for the rb tree */
2442			free_extent_map(em);
2443next:
2444			start = extent_map_end(em);
2445			write_unlock(&map->lock);
2446
2447			/* once for us */
2448			free_extent_map(em);
2449
2450			cond_resched(); /* Allow large-extent preemption. */
2451		}
2452	}
2453	return try_release_extent_state(tree, page, mask);
2454}
2455
2456/*
2457 * To cache previous fiemap extent
2458 *
2459 * Will be used for merging fiemap extent
2460 */
2461struct fiemap_cache {
2462	u64 offset;
2463	u64 phys;
2464	u64 len;
2465	u32 flags;
2466	bool cached;
2467};
2468
2469/*
2470 * Helper to submit fiemap extent.
2471 *
2472 * Will try to merge current fiemap extent specified by @offset, @phys,
2473 * @len and @flags with cached one.
2474 * And only when we fails to merge, cached one will be submitted as
2475 * fiemap extent.
2476 *
2477 * Return value is the same as fiemap_fill_next_extent().
2478 */
2479static int emit_fiemap_extent(struct fiemap_extent_info *fieinfo,
2480				struct fiemap_cache *cache,
2481				u64 offset, u64 phys, u64 len, u32 flags)
2482{
2483	u64 cache_end;
2484	int ret = 0;
2485
2486	/* Set at the end of extent_fiemap(). */
2487	ASSERT((flags & FIEMAP_EXTENT_LAST) == 0);
2488
2489	if (!cache->cached)
2490		goto assign;
2491
2492	/*
2493	 * When iterating the extents of the inode, at extent_fiemap(), we may
2494	 * find an extent that starts at an offset behind the end offset of the
2495	 * previous extent we processed. This happens if fiemap is called
2496	 * without FIEMAP_FLAG_SYNC and there are ordered extents completing
2497	 * while we call btrfs_next_leaf() (through fiemap_next_leaf_item()).
2498	 *
2499	 * For example we are in leaf X processing its last item, which is the
2500	 * file extent item for file range [512K, 1M[, and after
2501	 * btrfs_next_leaf() releases the path, there's an ordered extent that
2502	 * completes for the file range [768K, 2M[, and that results in trimming
2503	 * the file extent item so that it now corresponds to the file range
2504	 * [512K, 768K[ and a new file extent item is inserted for the file
2505	 * range [768K, 2M[, which may end up as the last item of leaf X or as
2506	 * the first item of the next leaf - in either case btrfs_next_leaf()
2507	 * will leave us with a path pointing to the new extent item, for the
2508	 * file range [768K, 2M[, since that's the first key that follows the
2509	 * last one we processed. So in order not to report overlapping extents
2510	 * to user space, we trim the length of the previously cached extent and
2511	 * emit it.
2512	 *
2513	 * Upon calling btrfs_next_leaf() we may also find an extent with an
2514	 * offset smaller than or equals to cache->offset, and this happens
2515	 * when we had a hole or prealloc extent with several delalloc ranges in
2516	 * it, but after btrfs_next_leaf() released the path, delalloc was
2517	 * flushed and the resulting ordered extents were completed, so we can
2518	 * now have found a file extent item for an offset that is smaller than
2519	 * or equals to what we have in cache->offset. We deal with this as
2520	 * described below.
2521	 */
2522	cache_end = cache->offset + cache->len;
2523	if (cache_end > offset) {
2524		if (offset == cache->offset) {
2525			/*
2526			 * We cached a dealloc range (found in the io tree) for
2527			 * a hole or prealloc extent and we have now found a
2528			 * file extent item for the same offset. What we have
2529			 * now is more recent and up to date, so discard what
2530			 * we had in the cache and use what we have just found.
2531			 */
2532			goto assign;
2533		} else if (offset > cache->offset) {
2534			/*
2535			 * The extent range we previously found ends after the
2536			 * offset of the file extent item we found and that
2537			 * offset falls somewhere in the middle of that previous
2538			 * extent range. So adjust the range we previously found
2539			 * to end at the offset of the file extent item we have
2540			 * just found, since this extent is more up to date.
2541			 * Emit that adjusted range and cache the file extent
2542			 * item we have just found. This corresponds to the case
2543			 * where a previously found file extent item was split
2544			 * due to an ordered extent completing.
2545			 */
2546			cache->len = offset - cache->offset;
2547			goto emit;
2548		} else {
2549			const u64 range_end = offset + len;
2550
2551			/*
2552			 * The offset of the file extent item we have just found
2553			 * is behind the cached offset. This means we were
2554			 * processing a hole or prealloc extent for which we
2555			 * have found delalloc ranges (in the io tree), so what
2556			 * we have in the cache is the last delalloc range we
2557			 * found while the file extent item we found can be
2558			 * either for a whole delalloc range we previously
2559			 * emmitted or only a part of that range.
2560			 *
2561			 * We have two cases here:
2562			 *
2563			 * 1) The file extent item's range ends at or behind the
2564			 *    cached extent's end. In this case just ignore the
2565			 *    current file extent item because we don't want to
2566			 *    overlap with previous ranges that may have been
2567			 *    emmitted already;
2568			 *
2569			 * 2) The file extent item starts behind the currently
2570			 *    cached extent but its end offset goes beyond the
2571			 *    end offset of the cached extent. We don't want to
2572			 *    overlap with a previous range that may have been
2573			 *    emmitted already, so we emit the currently cached
2574			 *    extent and then partially store the current file
2575			 *    extent item's range in the cache, for the subrange
2576			 *    going the cached extent's end to the end of the
2577			 *    file extent item.
2578			 */
2579			if (range_end <= cache_end)
2580				return 0;
2581
2582			if (!(flags & (FIEMAP_EXTENT_ENCODED | FIEMAP_EXTENT_DELALLOC)))
2583				phys += cache_end - offset;
 
 
 
 
 
 
2584
2585			offset = cache_end;
2586			len = range_end - cache_end;
2587			goto emit;
 
2588		}
2589	}
2590
2591	/*
2592	 * Only merges fiemap extents if
2593	 * 1) Their logical addresses are continuous
2594	 *
2595	 * 2) Their physical addresses are continuous
2596	 *    So truly compressed (physical size smaller than logical size)
2597	 *    extents won't get merged with each other
2598	 *
2599	 * 3) Share same flags
2600	 */
2601	if (cache->offset + cache->len  == offset &&
2602	    cache->phys + cache->len == phys  &&
2603	    cache->flags == flags) {
2604		cache->len += len;
2605		return 0;
2606	}
2607
2608emit:
2609	/* Not mergeable, need to submit cached one */
2610	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
2611				      cache->len, cache->flags);
2612	cache->cached = false;
2613	if (ret)
2614		return ret;
2615assign:
2616	cache->cached = true;
2617	cache->offset = offset;
2618	cache->phys = phys;
2619	cache->len = len;
2620	cache->flags = flags;
2621
2622	return 0;
2623}
2624
2625/*
2626 * Emit last fiemap cache
2627 *
2628 * The last fiemap cache may still be cached in the following case:
2629 * 0		      4k		    8k
2630 * |<- Fiemap range ->|
2631 * |<------------  First extent ----------->|
2632 *
2633 * In this case, the first extent range will be cached but not emitted.
2634 * So we must emit it before ending extent_fiemap().
2635 */
2636static int emit_last_fiemap_cache(struct fiemap_extent_info *fieinfo,
2637				  struct fiemap_cache *cache)
2638{
2639	int ret;
2640
2641	if (!cache->cached)
2642		return 0;
2643
2644	ret = fiemap_fill_next_extent(fieinfo, cache->offset, cache->phys,
2645				      cache->len, cache->flags);
2646	cache->cached = false;
2647	if (ret > 0)
2648		ret = 0;
2649	return ret;
2650}
 
 
 
 
 
 
 
2651
2652static int fiemap_next_leaf_item(struct btrfs_inode *inode, struct btrfs_path *path)
2653{
2654	struct extent_buffer *clone;
2655	struct btrfs_key key;
2656	int slot;
2657	int ret;
2658
2659	path->slots[0]++;
2660	if (path->slots[0] < btrfs_header_nritems(path->nodes[0]))
2661		return 0;
 
2662
2663	ret = btrfs_next_leaf(inode->root, path);
2664	if (ret != 0)
2665		return ret;
2666
2667	/*
2668	 * Don't bother with cloning if there are no more file extent items for
2669	 * our inode.
2670	 */
2671	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2672	if (key.objectid != btrfs_ino(inode) || key.type != BTRFS_EXTENT_DATA_KEY)
2673		return 1;
2674
2675	/* See the comment at fiemap_search_slot() about why we clone. */
2676	clone = btrfs_clone_extent_buffer(path->nodes[0]);
2677	if (!clone)
2678		return -ENOMEM;
2679
2680	slot = path->slots[0];
2681	btrfs_release_path(path);
2682	path->nodes[0] = clone;
2683	path->slots[0] = slot;
2684
2685	return 0;
2686}
2687
2688/*
2689 * Search for the first file extent item that starts at a given file offset or
2690 * the one that starts immediately before that offset.
2691 * Returns: 0 on success, < 0 on error, 1 if not found.
2692 */
2693static int fiemap_search_slot(struct btrfs_inode *inode, struct btrfs_path *path,
2694			      u64 file_offset)
2695{
2696	const u64 ino = btrfs_ino(inode);
2697	struct btrfs_root *root = inode->root;
2698	struct extent_buffer *clone;
2699	struct btrfs_key key;
2700	int slot;
2701	int ret;
2702
2703	key.objectid = ino;
2704	key.type = BTRFS_EXTENT_DATA_KEY;
2705	key.offset = file_offset;
2706
2707	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2708	if (ret < 0)
2709		return ret;
2710
2711	if (ret > 0 && path->slots[0] > 0) {
2712		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
2713		if (key.objectid == ino && key.type == BTRFS_EXTENT_DATA_KEY)
2714			path->slots[0]--;
2715	}
2716
2717	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2718		ret = btrfs_next_leaf(root, path);
2719		if (ret != 0)
2720			return ret;
2721
2722		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
2723		if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY)
2724			return 1;
2725	}
2726
2727	/*
2728	 * We clone the leaf and use it during fiemap. This is because while
2729	 * using the leaf we do expensive things like checking if an extent is
2730	 * shared, which can take a long time. In order to prevent blocking
2731	 * other tasks for too long, we use a clone of the leaf. We have locked
2732	 * the file range in the inode's io tree, so we know none of our file
2733	 * extent items can change. This way we avoid blocking other tasks that
2734	 * want to insert items for other inodes in the same leaf or b+tree
2735	 * rebalance operations (triggered for example when someone is trying
2736	 * to push items into this leaf when trying to insert an item in a
2737	 * neighbour leaf).
2738	 * We also need the private clone because holding a read lock on an
2739	 * extent buffer of the subvolume's b+tree will make lockdep unhappy
2740	 * when we call fiemap_fill_next_extent(), because that may cause a page
2741	 * fault when filling the user space buffer with fiemap data.
2742	 */
2743	clone = btrfs_clone_extent_buffer(path->nodes[0]);
2744	if (!clone)
2745		return -ENOMEM;
2746
2747	slot = path->slots[0];
2748	btrfs_release_path(path);
2749	path->nodes[0] = clone;
2750	path->slots[0] = slot;
2751
2752	return 0;
2753}
2754
2755/*
2756 * Process a range which is a hole or a prealloc extent in the inode's subvolume
2757 * btree. If @disk_bytenr is 0, we are dealing with a hole, otherwise a prealloc
2758 * extent. The end offset (@end) is inclusive.
2759 */
2760static int fiemap_process_hole(struct btrfs_inode *inode,
2761			       struct fiemap_extent_info *fieinfo,
2762			       struct fiemap_cache *cache,
2763			       struct extent_state **delalloc_cached_state,
2764			       struct btrfs_backref_share_check_ctx *backref_ctx,
2765			       u64 disk_bytenr, u64 extent_offset,
2766			       u64 extent_gen,
2767			       u64 start, u64 end)
2768{
2769	const u64 i_size = i_size_read(&inode->vfs_inode);
2770	u64 cur_offset = start;
2771	u64 last_delalloc_end = 0;
2772	u32 prealloc_flags = FIEMAP_EXTENT_UNWRITTEN;
2773	bool checked_extent_shared = false;
2774	int ret;
2775
2776	/*
2777	 * There can be no delalloc past i_size, so don't waste time looking for
2778	 * it beyond i_size.
2779	 */
2780	while (cur_offset < end && cur_offset < i_size) {
2781		struct extent_state *cached_state = NULL;
2782		u64 delalloc_start;
2783		u64 delalloc_end;
2784		u64 prealloc_start;
2785		u64 lockstart;
2786		u64 lockend;
2787		u64 prealloc_len = 0;
2788		bool delalloc;
2789
2790		lockstart = round_down(cur_offset, inode->root->fs_info->sectorsize);
2791		lockend = round_up(end, inode->root->fs_info->sectorsize);
2792
2793		/*
2794		 * We are only locking for the delalloc range because that's the
2795		 * only thing that can change here.  With fiemap we have a lock
2796		 * on the inode, so no buffered or direct writes can happen.
2797		 *
2798		 * However mmaps and normal page writeback will cause this to
2799		 * change arbitrarily.  We have to lock the extent lock here to
2800		 * make sure that nobody messes with the tree while we're doing
2801		 * btrfs_find_delalloc_in_range.
2802		 */
2803		lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
2804		delalloc = btrfs_find_delalloc_in_range(inode, cur_offset, end,
2805							delalloc_cached_state,
2806							&delalloc_start,
2807							&delalloc_end);
2808		unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
2809		if (!delalloc)
2810			break;
2811
2812		/*
2813		 * If this is a prealloc extent we have to report every section
2814		 * of it that has no delalloc.
 
2815		 */
2816		if (disk_bytenr != 0) {
2817			if (last_delalloc_end == 0) {
2818				prealloc_start = start;
2819				prealloc_len = delalloc_start - start;
2820			} else {
2821				prealloc_start = last_delalloc_end + 1;
2822				prealloc_len = delalloc_start - prealloc_start;
2823			}
2824		}
2825
2826		if (prealloc_len > 0) {
2827			if (!checked_extent_shared && fieinfo->fi_extents_max) {
2828				ret = btrfs_is_data_extent_shared(inode,
2829								  disk_bytenr,
2830								  extent_gen,
2831								  backref_ctx);
2832				if (ret < 0)
2833					return ret;
2834				else if (ret > 0)
2835					prealloc_flags |= FIEMAP_EXTENT_SHARED;
2836
2837				checked_extent_shared = true;
2838			}
2839			ret = emit_fiemap_extent(fieinfo, cache, prealloc_start,
2840						 disk_bytenr + extent_offset,
2841						 prealloc_len, prealloc_flags);
2842			if (ret)
2843				return ret;
2844			extent_offset += prealloc_len;
2845		}
2846
2847		ret = emit_fiemap_extent(fieinfo, cache, delalloc_start, 0,
2848					 delalloc_end + 1 - delalloc_start,
2849					 FIEMAP_EXTENT_DELALLOC |
2850					 FIEMAP_EXTENT_UNKNOWN);
2851		if (ret)
2852			return ret;
2853
2854		last_delalloc_end = delalloc_end;
2855		cur_offset = delalloc_end + 1;
2856		extent_offset += cur_offset - delalloc_start;
2857		cond_resched();
2858	}
2859
2860	/*
2861	 * Either we found no delalloc for the whole prealloc extent or we have
2862	 * a prealloc extent that spans i_size or starts at or after i_size.
2863	 */
2864	if (disk_bytenr != 0 && last_delalloc_end < end) {
2865		u64 prealloc_start;
2866		u64 prealloc_len;
2867
2868		if (last_delalloc_end == 0) {
2869			prealloc_start = start;
2870			prealloc_len = end + 1 - start;
2871		} else {
2872			prealloc_start = last_delalloc_end + 1;
2873			prealloc_len = end + 1 - prealloc_start;
2874		}
2875
2876		if (!checked_extent_shared && fieinfo->fi_extents_max) {
2877			ret = btrfs_is_data_extent_shared(inode,
2878							  disk_bytenr,
2879							  extent_gen,
2880							  backref_ctx);
2881			if (ret < 0)
2882				return ret;
2883			else if (ret > 0)
2884				prealloc_flags |= FIEMAP_EXTENT_SHARED;
2885		}
2886		ret = emit_fiemap_extent(fieinfo, cache, prealloc_start,
2887					 disk_bytenr + extent_offset,
2888					 prealloc_len, prealloc_flags);
2889		if (ret)
2890			return ret;
2891	}
2892
2893	return 0;
2894}
2895
2896static int fiemap_find_last_extent_offset(struct btrfs_inode *inode,
2897					  struct btrfs_path *path,
2898					  u64 *last_extent_end_ret)
2899{
2900	const u64 ino = btrfs_ino(inode);
2901	struct btrfs_root *root = inode->root;
2902	struct extent_buffer *leaf;
2903	struct btrfs_file_extent_item *ei;
2904	struct btrfs_key key;
2905	u64 disk_bytenr;
2906	int ret;
2907
2908	/*
2909	 * Lookup the last file extent. We're not using i_size here because
2910	 * there might be preallocation past i_size.
2911	 */
2912	ret = btrfs_lookup_file_extent(NULL, root, path, ino, (u64)-1, 0);
2913	/* There can't be a file extent item at offset (u64)-1 */
2914	ASSERT(ret != 0);
2915	if (ret < 0)
2916		return ret;
2917
2918	/*
2919	 * For a non-existing key, btrfs_search_slot() always leaves us at a
2920	 * slot > 0, except if the btree is empty, which is impossible because
2921	 * at least it has the inode item for this inode and all the items for
2922	 * the root inode 256.
2923	 */
2924	ASSERT(path->slots[0] > 0);
2925	path->slots[0]--;
2926	leaf = path->nodes[0];
2927	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2928	if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY) {
2929		/* No file extent items in the subvolume tree. */
2930		*last_extent_end_ret = 0;
2931		return 0;
2932	}
2933
2934	/*
2935	 * For an inline extent, the disk_bytenr is where inline data starts at,
2936	 * so first check if we have an inline extent item before checking if we
2937	 * have an implicit hole (disk_bytenr == 0).
2938	 */
2939	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
2940	if (btrfs_file_extent_type(leaf, ei) == BTRFS_FILE_EXTENT_INLINE) {
2941		*last_extent_end_ret = btrfs_file_extent_end(path);
2942		return 0;
2943	}
 
2944
2945	/*
2946	 * Find the last file extent item that is not a hole (when NO_HOLES is
2947	 * not enabled). This should take at most 2 iterations in the worst
2948	 * case: we have one hole file extent item at slot 0 of a leaf and
2949	 * another hole file extent item as the last item in the previous leaf.
2950	 * This is because we merge file extent items that represent holes.
2951	 */
2952	disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
2953	while (disk_bytenr == 0) {
2954		ret = btrfs_previous_item(root, path, ino, BTRFS_EXTENT_DATA_KEY);
2955		if (ret < 0) {
2956			return ret;
2957		} else if (ret > 0) {
2958			/* No file extent items that are not holes. */
2959			*last_extent_end_ret = 0;
2960			return 0;
2961		}
2962		leaf = path->nodes[0];
2963		ei = btrfs_item_ptr(leaf, path->slots[0],
2964				    struct btrfs_file_extent_item);
2965		disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
2966	}
2967
2968	*last_extent_end_ret = btrfs_file_extent_end(path);
2969	return 0;
2970}
2971
2972int extent_fiemap(struct btrfs_inode *inode, struct fiemap_extent_info *fieinfo,
2973		  u64 start, u64 len)
2974{
2975	const u64 ino = btrfs_ino(inode);
2976	struct extent_state *delalloc_cached_state = NULL;
2977	struct btrfs_path *path;
2978	struct fiemap_cache cache = { 0 };
2979	struct btrfs_backref_share_check_ctx *backref_ctx;
2980	u64 last_extent_end;
2981	u64 prev_extent_end;
2982	u64 range_start;
2983	u64 range_end;
2984	const u64 sectorsize = inode->root->fs_info->sectorsize;
2985	bool stopped = false;
2986	int ret;
2987
2988	backref_ctx = btrfs_alloc_backref_share_check_ctx();
2989	path = btrfs_alloc_path();
2990	if (!backref_ctx || !path) {
2991		ret = -ENOMEM;
2992		goto out;
2993	}
2994
2995	range_start = round_down(start, sectorsize);
2996	range_end = round_up(start + len, sectorsize);
2997	prev_extent_end = range_start;
2998
2999	ret = fiemap_find_last_extent_offset(inode, path, &last_extent_end);
3000	if (ret < 0)
 
3001		goto out;
3002	btrfs_release_path(path);
3003
3004	path->reada = READA_FORWARD;
3005	ret = fiemap_search_slot(inode, path, range_start);
3006	if (ret < 0) {
3007		goto out;
3008	} else if (ret > 0) {
3009		/*
3010		 * No file extent item found, but we may have delalloc between
3011		 * the current offset and i_size. So check for that.
3012		 */
3013		ret = 0;
3014		goto check_eof_delalloc;
3015	}
3016
3017	while (prev_extent_end < range_end) {
3018		struct extent_buffer *leaf = path->nodes[0];
3019		struct btrfs_file_extent_item *ei;
3020		struct btrfs_key key;
3021		u64 extent_end;
3022		u64 extent_len;
3023		u64 extent_offset = 0;
3024		u64 extent_gen;
3025		u64 disk_bytenr = 0;
3026		u64 flags = 0;
3027		int extent_type;
3028		u8 compression;
3029
3030		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3031		if (key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY)
3032			break;
3033
3034		extent_end = btrfs_file_extent_end(path);
3035
3036		/*
3037		 * The first iteration can leave us at an extent item that ends
3038		 * before our range's start. Move to the next item.
 
 
3039		 */
3040		if (extent_end <= range_start)
3041			goto next_item;
3042
3043		backref_ctx->curr_leaf_bytenr = leaf->start;
3044
3045		/* We have in implicit hole (NO_HOLES feature enabled). */
3046		if (prev_extent_end < key.offset) {
3047			const u64 hole_end = min(key.offset, range_end) - 1;
3048
3049			ret = fiemap_process_hole(inode, fieinfo, &cache,
3050						  &delalloc_cached_state,
3051						  backref_ctx, 0, 0, 0,
3052						  prev_extent_end, hole_end);
3053			if (ret < 0) {
3054				goto out;
3055			} else if (ret > 0) {
3056				/* fiemap_fill_next_extent() told us to stop. */
3057				stopped = true;
3058				break;
3059			}
3060
3061			/* We've reached the end of the fiemap range, stop. */
3062			if (key.offset >= range_end) {
3063				stopped = true;
3064				break;
3065			}
3066		}
3067
3068		extent_len = extent_end - key.offset;
3069		ei = btrfs_item_ptr(leaf, path->slots[0],
3070				    struct btrfs_file_extent_item);
3071		compression = btrfs_file_extent_compression(leaf, ei);
3072		extent_type = btrfs_file_extent_type(leaf, ei);
3073		extent_gen = btrfs_file_extent_generation(leaf, ei);
3074
3075		if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
3076			disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, ei);
3077			if (compression == BTRFS_COMPRESS_NONE)
3078				extent_offset = btrfs_file_extent_offset(leaf, ei);
3079		}
3080
3081		if (compression != BTRFS_COMPRESS_NONE)
3082			flags |= FIEMAP_EXTENT_ENCODED;
3083
3084		if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
3085			flags |= FIEMAP_EXTENT_DATA_INLINE;
3086			flags |= FIEMAP_EXTENT_NOT_ALIGNED;
3087			ret = emit_fiemap_extent(fieinfo, &cache, key.offset, 0,
3088						 extent_len, flags);
3089		} else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
3090			ret = fiemap_process_hole(inode, fieinfo, &cache,
3091						  &delalloc_cached_state,
3092						  backref_ctx,
3093						  disk_bytenr, extent_offset,
3094						  extent_gen, key.offset,
3095						  extent_end - 1);
3096		} else if (disk_bytenr == 0) {
3097			/* We have an explicit hole. */
3098			ret = fiemap_process_hole(inode, fieinfo, &cache,
3099						  &delalloc_cached_state,
3100						  backref_ctx, 0, 0, 0,
3101						  key.offset, extent_end - 1);
3102		} else {
3103			/* We have a regular extent. */
3104			if (fieinfo->fi_extents_max) {
3105				ret = btrfs_is_data_extent_shared(inode,
3106								  disk_bytenr,
3107								  extent_gen,
3108								  backref_ctx);
3109				if (ret < 0)
3110					goto out;
3111				else if (ret > 0)
3112					flags |= FIEMAP_EXTENT_SHARED;
3113			}
3114
3115			ret = emit_fiemap_extent(fieinfo, &cache, key.offset,
3116						 disk_bytenr + extent_offset,
3117						 extent_len, flags);
3118		}
 
 
3119
3120		if (ret < 0) {
3121			goto out;
3122		} else if (ret > 0) {
3123			/* fiemap_fill_next_extent() told us to stop. */
3124			stopped = true;
3125			break;
3126		}
3127
3128		prev_extent_end = extent_end;
3129next_item:
3130		if (fatal_signal_pending(current)) {
3131			ret = -EINTR;
 
3132			goto out;
3133		}
3134
3135		ret = fiemap_next_leaf_item(inode, path);
3136		if (ret < 0) {
3137			goto out;
3138		} else if (ret > 0) {
3139			/* No more file extent items for this inode. */
3140			break;
3141		}
3142		cond_resched();
3143	}
3144
3145check_eof_delalloc:
3146	/*
3147	 * Release (and free) the path before emitting any final entries to
3148	 * fiemap_fill_next_extent() to keep lockdep happy. This is because
3149	 * once we find no more file extent items exist, we may have a
3150	 * non-cloned leaf, and fiemap_fill_next_extent() can trigger page
3151	 * faults when copying data to the user space buffer.
3152	 */
3153	btrfs_free_path(path);
3154	path = NULL;
3155
3156	if (!stopped && prev_extent_end < range_end) {
3157		ret = fiemap_process_hole(inode, fieinfo, &cache,
3158					  &delalloc_cached_state, backref_ctx,
3159					  0, 0, 0, prev_extent_end, range_end - 1);
3160		if (ret < 0)
3161			goto out;
3162		prev_extent_end = range_end;
3163	}
3164
3165	if (cache.cached && cache.offset + cache.len >= last_extent_end) {
3166		const u64 i_size = i_size_read(&inode->vfs_inode);
3167
3168		if (prev_extent_end < i_size) {
3169			struct extent_state *cached_state = NULL;
3170			u64 delalloc_start;
3171			u64 delalloc_end;
3172			u64 lockstart;
3173			u64 lockend;
3174			bool delalloc;
3175
3176			lockstart = round_down(prev_extent_end, sectorsize);
3177			lockend = round_up(i_size, sectorsize);
3178
3179			/*
3180			 * See the comment in fiemap_process_hole as to why
3181			 * we're doing the locking here.
3182			 */
3183			lock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
3184			delalloc = btrfs_find_delalloc_in_range(inode,
3185								prev_extent_end,
3186								i_size - 1,
3187								&delalloc_cached_state,
3188								&delalloc_start,
3189								&delalloc_end);
3190			unlock_extent(&inode->io_tree, lockstart, lockend, &cached_state);
3191			if (!delalloc)
3192				cache.flags |= FIEMAP_EXTENT_LAST;
3193		} else {
3194			cache.flags |= FIEMAP_EXTENT_LAST;
3195		}
 
 
 
 
3196	}
3197
3198	ret = emit_last_fiemap_cache(fieinfo, &cache);
3199out:
3200	free_extent_state(delalloc_cached_state);
3201	btrfs_free_backref_share_ctx(backref_ctx);
3202	btrfs_free_path(path);
3203	return ret;
3204}
3205
3206static void __free_extent_buffer(struct extent_buffer *eb)
3207{
3208	kmem_cache_free(extent_buffer_cache, eb);
3209}
3210
3211static int extent_buffer_under_io(const struct extent_buffer *eb)
3212{
3213	return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
3214		test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
3215}
3216
3217static bool folio_range_has_eb(struct btrfs_fs_info *fs_info, struct folio *folio)
3218{
3219	struct btrfs_subpage *subpage;
3220
3221	lockdep_assert_held(&folio->mapping->i_private_lock);
3222
3223	if (folio_test_private(folio)) {
3224		subpage = folio_get_private(folio);
3225		if (atomic_read(&subpage->eb_refs))
3226			return true;
3227		/*
3228		 * Even there is no eb refs here, we may still have
3229		 * end_page_read() call relying on page::private.
3230		 */
3231		if (atomic_read(&subpage->readers))
3232			return true;
3233	}
3234	return false;
3235}
3236
3237static void detach_extent_buffer_folio(struct extent_buffer *eb, struct folio *folio)
3238{
3239	struct btrfs_fs_info *fs_info = eb->fs_info;
3240	const bool mapped = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
3241
3242	/*
3243	 * For mapped eb, we're going to change the folio private, which should
3244	 * be done under the i_private_lock.
3245	 */
3246	if (mapped)
3247		spin_lock(&folio->mapping->i_private_lock);
3248
3249	if (!folio_test_private(folio)) {
3250		if (mapped)
3251			spin_unlock(&folio->mapping->i_private_lock);
3252		return;
3253	}
3254
3255	if (fs_info->nodesize >= PAGE_SIZE) {
3256		/*
3257		 * We do this since we'll remove the pages after we've
3258		 * removed the eb from the radix tree, so we could race
3259		 * and have this page now attached to the new eb.  So
3260		 * only clear folio if it's still connected to
3261		 * this eb.
3262		 */
3263		if (folio_test_private(folio) && folio_get_private(folio) == eb) {
3264			BUG_ON(test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
3265			BUG_ON(folio_test_dirty(folio));
3266			BUG_ON(folio_test_writeback(folio));
3267			/* We need to make sure we haven't be attached to a new eb. */
3268			folio_detach_private(folio);
3269		}
3270		if (mapped)
3271			spin_unlock(&folio->mapping->i_private_lock);
3272		return;
3273	}
3274
3275	/*
3276	 * For subpage, we can have dummy eb with folio private attached.  In
3277	 * this case, we can directly detach the private as such folio is only
3278	 * attached to one dummy eb, no sharing.
3279	 */
3280	if (!mapped) {
3281		btrfs_detach_subpage(fs_info, folio);
3282		return;
3283	}
3284
3285	btrfs_folio_dec_eb_refs(fs_info, folio);
3286
3287	/*
3288	 * We can only detach the folio private if there are no other ebs in the
3289	 * page range and no unfinished IO.
3290	 */
3291	if (!folio_range_has_eb(fs_info, folio))
3292		btrfs_detach_subpage(fs_info, folio);
3293
3294	spin_unlock(&folio->mapping->i_private_lock);
3295}
3296
3297/* Release all pages attached to the extent buffer */
3298static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb)
3299{
3300	ASSERT(!extent_buffer_under_io(eb));
3301
3302	for (int i = 0; i < INLINE_EXTENT_BUFFER_PAGES; i++) {
3303		struct folio *folio = eb->folios[i];
3304
3305		if (!folio)
3306			continue;
3307
3308		detach_extent_buffer_folio(eb, folio);
3309
3310		/* One for when we allocated the folio. */
3311		folio_put(folio);
3312	}
3313}
3314
3315/*
3316 * Helper for releasing the extent buffer.
3317 */
3318static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
3319{
3320	btrfs_release_extent_buffer_pages(eb);
3321	btrfs_leak_debug_del_eb(eb);
3322	__free_extent_buffer(eb);
 
 
 
 
 
 
3323}
3324
3325static struct extent_buffer *
3326__alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
3327		      unsigned long len)
 
3328{
3329	struct extent_buffer *eb = NULL;
 
 
 
3330
3331	eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
 
 
3332	eb->start = start;
3333	eb->len = len;
3334	eb->fs_info = fs_info;
3335	init_rwsem(&eb->lock);
3336
3337	btrfs_leak_debug_add_eb(eb);
3338
 
 
 
 
 
 
 
 
 
 
 
 
 
3339	spin_lock_init(&eb->refs_lock);
3340	atomic_set(&eb->refs, 1);
 
3341
3342	ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE);
 
 
 
 
 
 
 
 
 
 
 
 
3343
3344	return eb;
3345}
3346
3347struct extent_buffer *btrfs_clone_extent_buffer(const struct extent_buffer *src)
3348{
 
 
3349	struct extent_buffer *new;
3350	int num_folios = num_extent_folios(src);
3351	int ret;
3352
3353	new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
3354	if (new == NULL)
3355		return NULL;
3356
3357	/*
3358	 * Set UNMAPPED before calling btrfs_release_extent_buffer(), as
3359	 * btrfs_release_extent_buffer() have different behavior for
3360	 * UNMAPPED subpage extent buffer.
3361	 */
3362	set_bit(EXTENT_BUFFER_UNMAPPED, &new->bflags);
3363
3364	ret = alloc_eb_folio_array(new, 0);
3365	if (ret) {
3366		btrfs_release_extent_buffer(new);
3367		return NULL;
3368	}
3369
3370	for (int i = 0; i < num_folios; i++) {
3371		struct folio *folio = new->folios[i];
3372		int ret;
3373
3374		ret = attach_extent_buffer_folio(new, folio, NULL);
3375		if (ret < 0) {
3376			btrfs_release_extent_buffer(new);
3377			return NULL;
3378		}
3379		WARN_ON(folio_test_dirty(folio));
3380	}
3381	copy_extent_buffer_full(new, src);
3382	set_extent_buffer_uptodate(new);
3383
3384	return new;
3385}
3386
3387struct extent_buffer *__alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
3388						  u64 start, unsigned long len)
3389{
3390	struct extent_buffer *eb;
3391	int num_folios = 0;
3392	int ret;
3393
3394	eb = __alloc_extent_buffer(fs_info, start, len);
3395	if (!eb)
3396		return NULL;
3397
3398	ret = alloc_eb_folio_array(eb, 0);
3399	if (ret)
3400		goto err;
3401
3402	num_folios = num_extent_folios(eb);
3403	for (int i = 0; i < num_folios; i++) {
3404		ret = attach_extent_buffer_folio(eb, eb->folios[i], NULL);
3405		if (ret < 0)
3406			goto err;
3407	}
3408
3409	set_extent_buffer_uptodate(eb);
3410	btrfs_set_header_nritems(eb, 0);
3411	set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
3412
3413	return eb;
3414err:
3415	for (int i = 0; i < num_folios; i++) {
3416		if (eb->folios[i]) {
3417			detach_extent_buffer_folio(eb, eb->folios[i]);
3418			__folio_put(eb->folios[i]);
3419		}
3420	}
3421	__free_extent_buffer(eb);
3422	return NULL;
3423}
3424
3425struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
3426						u64 start)
3427{
3428	return __alloc_dummy_extent_buffer(fs_info, start, fs_info->nodesize);
3429}
3430
3431static void check_buffer_tree_ref(struct extent_buffer *eb)
3432{
3433	int refs;
3434	/*
3435	 * The TREE_REF bit is first set when the extent_buffer is added
3436	 * to the radix tree. It is also reset, if unset, when a new reference
3437	 * is created by find_extent_buffer.
3438	 *
3439	 * It is only cleared in two cases: freeing the last non-tree
3440	 * reference to the extent_buffer when its STALE bit is set or
3441	 * calling release_folio when the tree reference is the only reference.
3442	 *
3443	 * In both cases, care is taken to ensure that the extent_buffer's
3444	 * pages are not under io. However, release_folio can be concurrently
3445	 * called with creating new references, which is prone to race
3446	 * conditions between the calls to check_buffer_tree_ref in those
3447	 * codepaths and clearing TREE_REF in try_release_extent_buffer.
3448	 *
3449	 * The actual lifetime of the extent_buffer in the radix tree is
3450	 * adequately protected by the refcount, but the TREE_REF bit and
3451	 * its corresponding reference are not. To protect against this
3452	 * class of races, we call check_buffer_tree_ref from the codepaths
3453	 * which trigger io. Note that once io is initiated, TREE_REF can no
3454	 * longer be cleared, so that is the moment at which any such race is
3455	 * best fixed.
3456	 */
3457	refs = atomic_read(&eb->refs);
3458	if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
3459		return;
3460
3461	spin_lock(&eb->refs_lock);
3462	if (!test_and_set_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
3463		atomic_inc(&eb->refs);
3464	spin_unlock(&eb->refs_lock);
3465}
3466
3467static void mark_extent_buffer_accessed(struct extent_buffer *eb)
 
 
 
 
3468{
3469	int num_folios= num_extent_folios(eb);
 
 
 
3470
3471	check_buffer_tree_ref(eb);
3472
3473	for (int i = 0; i < num_folios; i++)
3474		folio_mark_accessed(eb->folios[i]);
3475}
 
3476
3477struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info,
3478					 u64 start)
3479{
3480	struct extent_buffer *eb;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3481
3482	eb = find_extent_buffer_nolock(fs_info, start);
3483	if (!eb)
3484		return NULL;
3485	/*
3486	 * Lock our eb's refs_lock to avoid races with free_extent_buffer().
3487	 * When we get our eb it might be flagged with EXTENT_BUFFER_STALE and
3488	 * another task running free_extent_buffer() might have seen that flag
3489	 * set, eb->refs == 2, that the buffer isn't under IO (dirty and
3490	 * writeback flags not set) and it's still in the tree (flag
3491	 * EXTENT_BUFFER_TREE_REF set), therefore being in the process of
3492	 * decrementing the extent buffer's reference count twice.  So here we
3493	 * could race and increment the eb's reference count, clear its stale
3494	 * flag, mark it as dirty and drop our reference before the other task
3495	 * finishes executing free_extent_buffer, which would later result in
3496	 * an attempt to free an extent buffer that is dirty.
3497	 */
3498	if (test_bit(EXTENT_BUFFER_STALE, &eb->bflags)) {
3499		spin_lock(&eb->refs_lock);
3500		spin_unlock(&eb->refs_lock);
3501	}
3502	mark_extent_buffer_accessed(eb);
3503	return eb;
3504}
3505
3506#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
3507struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info,
3508					u64 start)
 
3509{
3510	struct extent_buffer *eb, *exists = NULL;
3511	int ret;
3512
3513	eb = find_extent_buffer(fs_info, start);
3514	if (eb)
3515		return eb;
3516	eb = alloc_dummy_extent_buffer(fs_info, start);
3517	if (!eb)
3518		return ERR_PTR(-ENOMEM);
3519	eb->fs_info = fs_info;
3520again:
3521	ret = radix_tree_preload(GFP_NOFS);
3522	if (ret) {
3523		exists = ERR_PTR(ret);
3524		goto free_eb;
3525	}
3526	spin_lock(&fs_info->buffer_lock);
3527	ret = radix_tree_insert(&fs_info->buffer_radix,
3528				start >> fs_info->sectorsize_bits, eb);
3529	spin_unlock(&fs_info->buffer_lock);
3530	radix_tree_preload_end();
3531	if (ret == -EEXIST) {
3532		exists = find_extent_buffer(fs_info, start);
3533		if (exists)
3534			goto free_eb;
3535		else
3536			goto again;
3537	}
3538	check_buffer_tree_ref(eb);
3539	set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
3540
3541	return eb;
3542free_eb:
3543	btrfs_release_extent_buffer(eb);
3544	return exists;
3545}
3546#endif
3547
3548static struct extent_buffer *grab_extent_buffer(
3549		struct btrfs_fs_info *fs_info, struct page *page)
3550{
3551	struct folio *folio = page_folio(page);
3552	struct extent_buffer *exists;
3553
3554	/*
3555	 * For subpage case, we completely rely on radix tree to ensure we
3556	 * don't try to insert two ebs for the same bytenr.  So here we always
3557	 * return NULL and just continue.
3558	 */
3559	if (fs_info->nodesize < PAGE_SIZE)
3560		return NULL;
3561
3562	/* Page not yet attached to an extent buffer */
3563	if (!folio_test_private(folio))
3564		return NULL;
3565
3566	/*
3567	 * We could have already allocated an eb for this page and attached one
3568	 * so lets see if we can get a ref on the existing eb, and if we can we
3569	 * know it's good and we can just return that one, else we know we can
3570	 * just overwrite folio private.
3571	 */
3572	exists = folio_get_private(folio);
3573	if (atomic_inc_not_zero(&exists->refs))
3574		return exists;
3575
3576	WARN_ON(PageDirty(page));
3577	folio_detach_private(folio);
3578	return NULL;
3579}
3580
3581static int check_eb_alignment(struct btrfs_fs_info *fs_info, u64 start)
3582{
3583	if (!IS_ALIGNED(start, fs_info->sectorsize)) {
3584		btrfs_err(fs_info, "bad tree block start %llu", start);
3585		return -EINVAL;
3586	}
3587
3588	if (fs_info->nodesize < PAGE_SIZE &&
3589	    offset_in_page(start) + fs_info->nodesize > PAGE_SIZE) {
3590		btrfs_err(fs_info,
3591		"tree block crosses page boundary, start %llu nodesize %u",
3592			  start, fs_info->nodesize);
3593		return -EINVAL;
3594	}
3595	if (fs_info->nodesize >= PAGE_SIZE &&
3596	    !PAGE_ALIGNED(start)) {
3597		btrfs_err(fs_info,
3598		"tree block is not page aligned, start %llu nodesize %u",
3599			  start, fs_info->nodesize);
3600		return -EINVAL;
3601	}
3602	if (!IS_ALIGNED(start, fs_info->nodesize) &&
3603	    !test_and_set_bit(BTRFS_FS_UNALIGNED_TREE_BLOCK, &fs_info->flags)) {
3604		btrfs_warn(fs_info,
3605"tree block not nodesize aligned, start %llu nodesize %u, can be resolved by a full metadata balance",
3606			      start, fs_info->nodesize);
3607	}
3608	return 0;
3609}
3610
3611
3612/*
3613 * Return 0 if eb->folios[i] is attached to btree inode successfully.
3614 * Return >0 if there is already another extent buffer for the range,
3615 * and @found_eb_ret would be updated.
3616 * Return -EAGAIN if the filemap has an existing folio but with different size
3617 * than @eb.
3618 * The caller needs to free the existing folios and retry using the same order.
3619 */
3620static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i,
3621				      struct extent_buffer **found_eb_ret)
3622{
 
3623
3624	struct btrfs_fs_info *fs_info = eb->fs_info;
3625	struct address_space *mapping = fs_info->btree_inode->i_mapping;
3626	const unsigned long index = eb->start >> PAGE_SHIFT;
3627	struct folio *existing_folio;
3628	int ret;
3629
3630	ASSERT(found_eb_ret);
3631
3632	/* Caller should ensure the folio exists. */
3633	ASSERT(eb->folios[i]);
3634
3635retry:
3636	ret = filemap_add_folio(mapping, eb->folios[i], index + i,
3637				GFP_NOFS | __GFP_NOFAIL);
3638	if (!ret)
3639		return 0;
3640
3641	existing_folio = filemap_lock_folio(mapping, index + i);
3642	/* The page cache only exists for a very short time, just retry. */
3643	if (IS_ERR(existing_folio))
3644		goto retry;
3645
3646	/* For now, we should only have single-page folios for btree inode. */
3647	ASSERT(folio_nr_pages(existing_folio) == 1);
3648
3649	if (folio_size(existing_folio) != folio_size(eb->folios[0])) {
3650		folio_unlock(existing_folio);
3651		folio_put(existing_folio);
3652		return -EAGAIN;
3653	}
3654
3655	if (fs_info->nodesize < PAGE_SIZE) {
3656		/*
3657		 * We're going to reuse the existing page, can drop our page
3658		 * and subpage structure now.
3659		 */
3660		__free_page(folio_page(eb->folios[i], 0));
3661		eb->folios[i] = existing_folio;
3662	} else {
3663		struct extent_buffer *existing_eb;
3664
3665		existing_eb = grab_extent_buffer(fs_info,
3666						 folio_page(existing_folio, 0));
3667		if (existing_eb) {
3668			/* The extent buffer still exists, we can use it directly. */
3669			*found_eb_ret = existing_eb;
3670			folio_unlock(existing_folio);
3671			folio_put(existing_folio);
3672			return 1;
3673		}
3674		/* The extent buffer no longer exists, we can reuse the folio. */
3675		__free_page(folio_page(eb->folios[i], 0));
3676		eb->folios[i] = existing_folio;
3677	}
3678	return 0;
3679}
3680
3681struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
3682					  u64 start, u64 owner_root, int level)
3683{
3684	unsigned long len = fs_info->nodesize;
3685	int num_folios;
3686	int attached = 0;
3687	struct extent_buffer *eb;
3688	struct extent_buffer *existing_eb = NULL;
3689	struct address_space *mapping = fs_info->btree_inode->i_mapping;
3690	struct btrfs_subpage *prealloc = NULL;
3691	u64 lockdep_owner = owner_root;
3692	bool page_contig = true;
3693	int uptodate = 1;
3694	int ret;
3695
3696	if (check_eb_alignment(fs_info, start))
3697		return ERR_PTR(-EINVAL);
3698
3699#if BITS_PER_LONG == 32
3700	if (start >= MAX_LFS_FILESIZE) {
3701		btrfs_err_rl(fs_info,
3702		"extent buffer %llu is beyond 32bit page cache limit", start);
3703		btrfs_err_32bit_limit(fs_info);
3704		return ERR_PTR(-EOVERFLOW);
3705	}
3706	if (start >= BTRFS_32BIT_EARLY_WARN_THRESHOLD)
3707		btrfs_warn_32bit_limit(fs_info);
3708#endif
3709
3710	eb = find_extent_buffer(fs_info, start);
3711	if (eb)
3712		return eb;
3713
3714	eb = __alloc_extent_buffer(fs_info, start, len);
3715	if (!eb)
3716		return ERR_PTR(-ENOMEM);
3717
3718	/*
3719	 * The reloc trees are just snapshots, so we need them to appear to be
3720	 * just like any other fs tree WRT lockdep.
3721	 */
3722	if (lockdep_owner == BTRFS_TREE_RELOC_OBJECTID)
3723		lockdep_owner = BTRFS_FS_TREE_OBJECTID;
3724
3725	btrfs_set_buffer_lockdep_class(lockdep_owner, eb, level);
3726
3727	/*
3728	 * Preallocate folio private for subpage case, so that we won't
3729	 * allocate memory with i_private_lock nor page lock hold.
3730	 *
3731	 * The memory will be freed by attach_extent_buffer_page() or freed
3732	 * manually if we exit earlier.
3733	 */
3734	if (fs_info->nodesize < PAGE_SIZE) {
3735		prealloc = btrfs_alloc_subpage(fs_info, BTRFS_SUBPAGE_METADATA);
3736		if (IS_ERR(prealloc)) {
3737			ret = PTR_ERR(prealloc);
3738			goto out;
3739		}
3740	}
3741
3742reallocate:
3743	/* Allocate all pages first. */
3744	ret = alloc_eb_folio_array(eb, __GFP_NOFAIL);
3745	if (ret < 0) {
3746		btrfs_free_subpage(prealloc);
3747		goto out;
3748	}
 
3749
3750	num_folios = num_extent_folios(eb);
3751	/* Attach all pages to the filemap. */
3752	for (int i = 0; i < num_folios; i++) {
3753		struct folio *folio;
3754
3755		ret = attach_eb_folio_to_filemap(eb, i, &existing_eb);
3756		if (ret > 0) {
3757			ASSERT(existing_eb);
3758			goto out;
3759		}
3760
3761		/*
3762		 * TODO: Special handling for a corner case where the order of
3763		 * folios mismatch between the new eb and filemap.
3764		 *
3765		 * This happens when:
3766		 *
3767		 * - the new eb is using higher order folio
3768		 *
3769		 * - the filemap is still using 0-order folios for the range
3770		 *   This can happen at the previous eb allocation, and we don't
3771		 *   have higher order folio for the call.
3772		 *
3773		 * - the existing eb has already been freed
3774		 *
3775		 * In this case, we have to free the existing folios first, and
3776		 * re-allocate using the same order.
3777		 * Thankfully this is not going to happen yet, as we're still
3778		 * using 0-order folios.
3779		 */
3780		if (unlikely(ret == -EAGAIN)) {
3781			ASSERT(0);
3782			goto reallocate;
3783		}
3784		attached++;
3785
3786		/*
3787		 * Only after attach_eb_folio_to_filemap(), eb->folios[] is
3788		 * reliable, as we may choose to reuse the existing page cache
3789		 * and free the allocated page.
3790		 */
3791		folio = eb->folios[i];
3792		spin_lock(&mapping->i_private_lock);
3793		/* Should not fail, as we have preallocated the memory */
3794		ret = attach_extent_buffer_folio(eb, folio, prealloc);
3795		ASSERT(!ret);
3796		/*
3797		 * To inform we have extra eb under allocation, so that
3798		 * detach_extent_buffer_page() won't release the folio private
3799		 * when the eb hasn't yet been inserted into radix tree.
3800		 *
3801		 * The ref will be decreased when the eb released the page, in
3802		 * detach_extent_buffer_page().
3803		 * Thus needs no special handling in error path.
3804		 */
3805		btrfs_folio_inc_eb_refs(fs_info, folio);
3806		spin_unlock(&mapping->i_private_lock);
3807
3808		WARN_ON(btrfs_folio_test_dirty(fs_info, folio, eb->start, eb->len));
3809
3810		/*
3811		 * Check if the current page is physically contiguous with previous eb
3812		 * page.
3813		 * At this stage, either we allocated a large folio, thus @i
3814		 * would only be 0, or we fall back to per-page allocation.
3815		 */
3816		if (i && folio_page(eb->folios[i - 1], 0) + 1 != folio_page(folio, 0))
3817			page_contig = false;
3818
3819		if (!btrfs_folio_test_uptodate(fs_info, folio, eb->start, eb->len))
 
 
 
 
 
 
 
 
 
 
 
 
 
3820			uptodate = 0;
3821
3822		/*
3823		 * We can't unlock the pages just yet since the extent buffer
3824		 * hasn't been properly inserted in the radix tree, this
3825		 * opens a race with btree_release_folio which can free a page
3826		 * while we are still filling in all pages for the buffer and
3827		 * we could crash.
3828		 */
3829	}
3830	if (uptodate)
3831		set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
3832	/* All pages are physically contiguous, can skip cross page handling. */
3833	if (page_contig)
3834		eb->addr = folio_address(eb->folios[0]) + offset_in_page(eb->start);
3835again:
3836	ret = radix_tree_preload(GFP_NOFS);
3837	if (ret)
3838		goto out;
3839
3840	spin_lock(&fs_info->buffer_lock);
3841	ret = radix_tree_insert(&fs_info->buffer_radix,
3842				start >> fs_info->sectorsize_bits, eb);
3843	spin_unlock(&fs_info->buffer_lock);
3844	radix_tree_preload_end();
3845	if (ret == -EEXIST) {
3846		ret = 0;
3847		existing_eb = find_extent_buffer(fs_info, start);
3848		if (existing_eb)
3849			goto out;
3850		else
 
3851			goto again;
 
 
 
 
 
3852	}
3853	/* add one reference for the tree */
 
3854	check_buffer_tree_ref(eb);
3855	set_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags);
 
 
3856
3857	/*
3858	 * Now it's safe to unlock the pages because any calls to
3859	 * btree_release_folio will correctly detect that a page belongs to a
3860	 * live buffer and won't free them prematurely.
3861	 */
3862	for (int i = 0; i < num_folios; i++)
3863		unlock_page(folio_page(eb->folios[i], 0));
 
 
 
 
 
 
 
 
 
3864	return eb;
3865
3866out:
 
 
 
 
 
3867	WARN_ON(!atomic_dec_and_test(&eb->refs));
 
 
 
3868
3869	/*
3870	 * Any attached folios need to be detached before we unlock them.  This
3871	 * is because when we're inserting our new folios into the mapping, and
3872	 * then attaching our eb to that folio.  If we fail to insert our folio
3873	 * we'll lookup the folio for that index, and grab that EB.  We do not
3874	 * want that to grab this eb, as we're getting ready to free it.  So we
3875	 * have to detach it first and then unlock it.
3876	 *
3877	 * We have to drop our reference and NULL it out here because in the
3878	 * subpage case detaching does a btrfs_folio_dec_eb_refs() for our eb.
3879	 * Below when we call btrfs_release_extent_buffer() we will call
3880	 * detach_extent_buffer_folio() on our remaining pages in the !subpage
3881	 * case.  If we left eb->folios[i] populated in the subpage case we'd
3882	 * double put our reference and be super sad.
3883	 */
3884	for (int i = 0; i < attached; i++) {
3885		ASSERT(eb->folios[i]);
3886		detach_extent_buffer_folio(eb, eb->folios[i]);
3887		unlock_page(folio_page(eb->folios[i], 0));
3888		folio_put(eb->folios[i]);
3889		eb->folios[i] = NULL;
3890	}
3891	/*
3892	 * Now all pages of that extent buffer is unmapped, set UNMAPPED flag,
3893	 * so it can be cleaned up without utlizing page->mapping.
3894	 */
3895	set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
3896
3897	btrfs_release_extent_buffer(eb);
3898	if (ret < 0)
3899		return ERR_PTR(ret);
3900	ASSERT(existing_eb);
3901	return existing_eb;
3902}
3903
3904static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head)
3905{
3906	struct extent_buffer *eb =
3907			container_of(head, struct extent_buffer, rcu_head);
3908
3909	__free_extent_buffer(eb);
3910}
3911
3912static int release_extent_buffer(struct extent_buffer *eb)
3913	__releases(&eb->refs_lock)
3914{
3915	lockdep_assert_held(&eb->refs_lock);
3916
3917	WARN_ON(atomic_read(&eb->refs) == 0);
3918	if (atomic_dec_and_test(&eb->refs)) {
3919		if (test_and_clear_bit(EXTENT_BUFFER_IN_TREE, &eb->bflags)) {
3920			struct btrfs_fs_info *fs_info = eb->fs_info;
3921
3922			spin_unlock(&eb->refs_lock);
3923
3924			spin_lock(&fs_info->buffer_lock);
3925			radix_tree_delete(&fs_info->buffer_radix,
3926					  eb->start >> fs_info->sectorsize_bits);
3927			spin_unlock(&fs_info->buffer_lock);
3928		} else {
 
 
3929			spin_unlock(&eb->refs_lock);
 
 
 
 
 
3930		}
3931
3932		btrfs_leak_debug_del_eb(eb);
3933		/* Should be safe to release our pages at this point */
3934		btrfs_release_extent_buffer_pages(eb);
3935#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
3936		if (unlikely(test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags))) {
3937			__free_extent_buffer(eb);
3938			return 1;
3939		}
3940#endif
3941		call_rcu(&eb->rcu_head, btrfs_release_extent_buffer_rcu);
3942		return 1;
3943	}
3944	spin_unlock(&eb->refs_lock);
3945
3946	return 0;
3947}
3948
3949void free_extent_buffer(struct extent_buffer *eb)
3950{
3951	int refs;
3952	if (!eb)
3953		return;
3954
3955	refs = atomic_read(&eb->refs);
3956	while (1) {
3957		if ((!test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) && refs <= 3)
3958		    || (test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags) &&
3959			refs == 1))
3960			break;
3961		if (atomic_try_cmpxchg(&eb->refs, &refs, refs - 1))
3962			return;
3963	}
3964
3965	spin_lock(&eb->refs_lock);
3966	if (atomic_read(&eb->refs) == 2 &&
 
 
 
 
3967	    test_bit(EXTENT_BUFFER_STALE, &eb->bflags) &&
3968	    !extent_buffer_under_io(eb) &&
3969	    test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
3970		atomic_dec(&eb->refs);
3971
3972	/*
3973	 * I know this is terrible, but it's temporary until we stop tracking
3974	 * the uptodate bits and such for the extent buffers.
3975	 */
3976	release_extent_buffer(eb);
3977}
3978
3979void free_extent_buffer_stale(struct extent_buffer *eb)
3980{
3981	if (!eb)
3982		return;
3983
3984	spin_lock(&eb->refs_lock);
3985	set_bit(EXTENT_BUFFER_STALE, &eb->bflags);
3986
3987	if (atomic_read(&eb->refs) == 2 && !extent_buffer_under_io(eb) &&
3988	    test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
3989		atomic_dec(&eb->refs);
3990	release_extent_buffer(eb);
3991}
3992
3993static void btree_clear_folio_dirty(struct folio *folio)
3994{
3995	ASSERT(folio_test_dirty(folio));
3996	ASSERT(folio_test_locked(folio));
3997	folio_clear_dirty_for_io(folio);
3998	xa_lock_irq(&folio->mapping->i_pages);
3999	if (!folio_test_dirty(folio))
4000		__xa_clear_mark(&folio->mapping->i_pages,
4001				folio_index(folio), PAGECACHE_TAG_DIRTY);
4002	xa_unlock_irq(&folio->mapping->i_pages);
4003}
4004
4005static void clear_subpage_extent_buffer_dirty(const struct extent_buffer *eb)
4006{
4007	struct btrfs_fs_info *fs_info = eb->fs_info;
4008	struct folio *folio = eb->folios[0];
4009	bool last;
4010
4011	/* btree_clear_folio_dirty() needs page locked. */
4012	folio_lock(folio);
4013	last = btrfs_subpage_clear_and_test_dirty(fs_info, folio, eb->start, eb->len);
4014	if (last)
4015		btree_clear_folio_dirty(folio);
4016	folio_unlock(folio);
4017	WARN_ON(atomic_read(&eb->refs) == 0);
4018}
4019
4020void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans,
4021			      struct extent_buffer *eb)
4022{
4023	struct btrfs_fs_info *fs_info = eb->fs_info;
4024	int num_folios;
4025
4026	btrfs_assert_tree_write_locked(eb);
4027
4028	if (trans && btrfs_header_generation(eb) != trans->transid)
4029		return;
4030
4031	/*
4032	 * Instead of clearing the dirty flag off of the buffer, mark it as
4033	 * EXTENT_BUFFER_ZONED_ZEROOUT. This allows us to preserve
4034	 * write-ordering in zoned mode, without the need to later re-dirty
4035	 * the extent_buffer.
4036	 *
4037	 * The actual zeroout of the buffer will happen later in
4038	 * btree_csum_one_bio.
4039	 */
4040	if (btrfs_is_zoned(fs_info)) {
4041		set_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &eb->bflags);
4042		return;
4043	}
4044
4045	if (!test_and_clear_bit(EXTENT_BUFFER_DIRTY, &eb->bflags))
4046		return;
4047
4048	percpu_counter_add_batch(&fs_info->dirty_metadata_bytes, -eb->len,
4049				 fs_info->dirty_metadata_batch);
4050
4051	if (eb->fs_info->nodesize < PAGE_SIZE)
4052		return clear_subpage_extent_buffer_dirty(eb);
 
 
4053
4054	num_folios = num_extent_folios(eb);
4055	for (int i = 0; i < num_folios; i++) {
4056		struct folio *folio = eb->folios[i];
4057
4058		if (!folio_test_dirty(folio))
4059			continue;
4060		folio_lock(folio);
4061		btree_clear_folio_dirty(folio);
4062		folio_unlock(folio);
 
 
 
 
 
4063	}
4064	WARN_ON(atomic_read(&eb->refs) == 0);
4065}
4066
4067void set_extent_buffer_dirty(struct extent_buffer *eb)
4068{
4069	int num_folios;
4070	bool was_dirty;
 
4071
4072	check_buffer_tree_ref(eb);
4073
4074	was_dirty = test_and_set_bit(EXTENT_BUFFER_DIRTY, &eb->bflags);
4075
4076	num_folios = num_extent_folios(eb);
4077	WARN_ON(atomic_read(&eb->refs) == 0);
4078	WARN_ON(!test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags));
4079
4080	if (!was_dirty) {
4081		bool subpage = eb->fs_info->nodesize < PAGE_SIZE;
 
 
4082
4083		/*
4084		 * For subpage case, we can have other extent buffers in the
4085		 * same page, and in clear_subpage_extent_buffer_dirty() we
4086		 * have to clear page dirty without subpage lock held.
4087		 * This can cause race where our page gets dirty cleared after
4088		 * we just set it.
4089		 *
4090		 * Thankfully, clear_subpage_extent_buffer_dirty() has locked
4091		 * its page for other reasons, we can use page lock to prevent
4092		 * the above race.
4093		 */
4094		if (subpage)
4095			lock_page(folio_page(eb->folios[0], 0));
4096		for (int i = 0; i < num_folios; i++)
4097			btrfs_folio_set_dirty(eb->fs_info, eb->folios[i],
4098					      eb->start, eb->len);
4099		if (subpage)
4100			unlock_page(folio_page(eb->folios[0], 0));
4101		percpu_counter_add_batch(&eb->fs_info->dirty_metadata_bytes,
4102					 eb->len,
4103					 eb->fs_info->dirty_metadata_batch);
4104	}
4105#ifdef CONFIG_BTRFS_DEBUG
4106	for (int i = 0; i < num_folios; i++)
4107		ASSERT(folio_test_dirty(eb->folios[i]));
4108#endif
4109}
4110
4111void clear_extent_buffer_uptodate(struct extent_buffer *eb)
4112{
4113	struct btrfs_fs_info *fs_info = eb->fs_info;
4114	int num_folios = num_extent_folios(eb);
 
4115
4116	clear_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4117	for (int i = 0; i < num_folios; i++) {
4118		struct folio *folio = eb->folios[i];
4119
4120		if (!folio)
4121			continue;
4122
4123		/*
4124		 * This is special handling for metadata subpage, as regular
4125		 * btrfs_is_subpage() can not handle cloned/dummy metadata.
4126		 */
4127		if (fs_info->nodesize >= PAGE_SIZE)
4128			folio_clear_uptodate(folio);
4129		else
4130			btrfs_subpage_clear_uptodate(fs_info, folio,
4131						     eb->start, eb->len);
4132	}
 
4133}
4134
4135void set_extent_buffer_uptodate(struct extent_buffer *eb)
4136{
4137	struct btrfs_fs_info *fs_info = eb->fs_info;
4138	int num_folios = num_extent_folios(eb);
 
4139
4140	set_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags);
4141	for (int i = 0; i < num_folios; i++) {
4142		struct folio *folio = eb->folios[i];
4143
4144		/*
4145		 * This is special handling for metadata subpage, as regular
4146		 * btrfs_is_subpage() can not handle cloned/dummy metadata.
4147		 */
4148		if (fs_info->nodesize >= PAGE_SIZE)
4149			folio_mark_uptodate(folio);
4150		else
4151			btrfs_subpage_set_uptodate(fs_info, folio,
4152						   eb->start, eb->len);
4153	}
 
4154}
4155
4156static void end_bbio_meta_read(struct btrfs_bio *bbio)
 
4157{
4158	struct extent_buffer *eb = bbio->private;
4159	struct btrfs_fs_info *fs_info = eb->fs_info;
4160	bool uptodate = !bbio->bio.bi_status;
4161	struct folio_iter fi;
4162	u32 bio_offset = 0;
4163
4164	eb->read_mirror = bbio->mirror_num;
4165
4166	if (uptodate &&
4167	    btrfs_validate_extent_buffer(eb, &bbio->parent_check) < 0)
4168		uptodate = false;
4169
4170	if (uptodate) {
4171		set_extent_buffer_uptodate(eb);
4172	} else {
4173		clear_extent_buffer_uptodate(eb);
4174		set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
4175	}
4176
4177	bio_for_each_folio_all(fi, &bbio->bio) {
4178		struct folio *folio = fi.folio;
4179		u64 start = eb->start + bio_offset;
4180		u32 len = fi.length;
4181
4182		if (uptodate)
4183			btrfs_folio_set_uptodate(fs_info, folio, start, len);
4184		else
4185			btrfs_folio_clear_uptodate(fs_info, folio, start, len);
4186
4187		bio_offset += len;
4188	}
 
 
4189
4190	clear_bit(EXTENT_BUFFER_READING, &eb->bflags);
4191	smp_mb__after_atomic();
4192	wake_up_bit(&eb->bflags, EXTENT_BUFFER_READING);
4193	free_extent_buffer(eb);
4194
4195	bio_put(&bbio->bio);
4196}
4197
4198int read_extent_buffer_pages(struct extent_buffer *eb, int wait, int mirror_num,
4199			     struct btrfs_tree_parent_check *check)
 
4200{
4201	struct btrfs_bio *bbio;
4202	bool ret;
 
 
 
 
 
 
 
 
 
4203
4204	if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
4205		return 0;
4206
4207	/*
4208	 * We could have had EXTENT_BUFFER_UPTODATE cleared by the write
4209	 * operation, which could potentially still be in flight.  In this case
4210	 * we simply want to return an error.
4211	 */
4212	if (unlikely(test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags)))
4213		return -EIO;
4214
4215	/* Someone else is already reading the buffer, just wait for it. */
4216	if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags))
4217		goto done;
4218
4219	clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
4220	eb->read_mirror = 0;
4221	check_buffer_tree_ref(eb);
4222	atomic_inc(&eb->refs);
4223
4224	bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
4225			       REQ_OP_READ | REQ_META, eb->fs_info,
4226			       end_bbio_meta_read, eb);
4227	bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
4228	bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
4229	bbio->file_offset = eb->start;
4230	memcpy(&bbio->parent_check, check, sizeof(*check));
4231	if (eb->fs_info->nodesize < PAGE_SIZE) {
4232		ret = bio_add_folio(&bbio->bio, eb->folios[0], eb->len,
4233				    eb->start - folio_pos(eb->folios[0]));
4234		ASSERT(ret);
4235	} else {
4236		int num_folios = num_extent_folios(eb);
4237
4238		for (int i = 0; i < num_folios; i++) {
4239			struct folio *folio = eb->folios[i];
4240
4241			ret = bio_add_folio(&bbio->bio, folio, folio_size(folio), 0);
4242			ASSERT(ret);
 
 
 
 
 
 
 
 
 
 
 
4243		}
4244	}
4245	btrfs_submit_bio(bbio, mirror_num);
4246
4247done:
4248	if (wait == WAIT_COMPLETE) {
4249		wait_on_bit_io(&eb->bflags, EXTENT_BUFFER_READING, TASK_UNINTERRUPTIBLE);
4250		if (!test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))
4251			return -EIO;
4252	}
4253
4254	return 0;
4255}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4256
4257static bool report_eb_range(const struct extent_buffer *eb, unsigned long start,
4258			    unsigned long len)
4259{
4260	btrfs_warn(eb->fs_info,
4261		"access to eb bytenr %llu len %lu out of range start %lu len %lu",
4262		eb->start, eb->len, start, len);
4263	WARN_ON(IS_ENABLED(CONFIG_BTRFS_DEBUG));
4264
4265	return true;
4266}
4267
4268/*
4269 * Check if the [start, start + len) range is valid before reading/writing
4270 * the eb.
4271 * NOTE: @start and @len are offset inside the eb, not logical address.
4272 *
4273 * Caller should not touch the dst/src memory if this function returns error.
4274 */
4275static inline int check_eb_range(const struct extent_buffer *eb,
4276				 unsigned long start, unsigned long len)
4277{
4278	unsigned long offset;
4279
4280	/* start, start + len should not go beyond eb->len nor overflow */
4281	if (unlikely(check_add_overflow(start, len, &offset) || offset > eb->len))
4282		return report_eb_range(eb, start, len);
4283
4284	return false;
 
 
 
 
 
 
 
 
4285}
4286
4287void read_extent_buffer(const struct extent_buffer *eb, void *dstv,
4288			unsigned long start, unsigned long len)
 
4289{
4290	const int unit_size = folio_size(eb->folios[0]);
4291	size_t cur;
4292	size_t offset;
 
 
4293	char *dst = (char *)dstv;
4294	unsigned long i = get_eb_folio_index(eb, start);
4295
4296	if (check_eb_range(eb, start, len)) {
4297		/*
4298		 * Invalid range hit, reset the memory, so callers won't get
4299		 * some random garbage for their uninitialized memory.
4300		 */
4301		memset(dstv, 0, len);
4302		return;
4303	}
4304
4305	if (eb->addr) {
4306		memcpy(dstv, eb->addr + start, len);
4307		return;
4308	}
4309
4310	offset = get_eb_offset_in_folio(eb, start);
4311
4312	while (len > 0) {
4313		char *kaddr;
4314
4315		cur = min(len, unit_size - offset);
4316		kaddr = folio_address(eb->folios[i]);
4317		memcpy(dst, kaddr + offset, cur);
4318
4319		dst += cur;
4320		len -= cur;
4321		offset = 0;
4322		i++;
4323	}
4324}
4325
4326int read_extent_buffer_to_user_nofault(const struct extent_buffer *eb,
4327				       void __user *dstv,
4328				       unsigned long start, unsigned long len)
 
4329{
4330	const int unit_size = folio_size(eb->folios[0]);
4331	size_t cur;
4332	size_t offset;
4333	char __user *dst = (char __user *)dstv;
4334	unsigned long i = get_eb_folio_index(eb, start);
4335	int ret = 0;
 
4336
4337	WARN_ON(start > eb->len);
4338	WARN_ON(start + len > eb->start + eb->len);
4339
4340	if (eb->addr) {
4341		if (copy_to_user_nofault(dstv, eb->addr + start, len))
4342			ret = -EFAULT;
4343		return ret;
 
 
4344	}
4345
4346	offset = get_eb_offset_in_folio(eb, start);
4347
4348	while (len > 0) {
4349		char *kaddr;
4350
4351		cur = min(len, unit_size - offset);
4352		kaddr = folio_address(eb->folios[i]);
4353		if (copy_to_user_nofault(dst, kaddr + offset, cur)) {
4354			ret = -EFAULT;
4355			break;
4356		}
4357
4358		dst += cur;
4359		len -= cur;
4360		offset = 0;
4361		i++;
4362	}
4363
4364	return ret;
 
 
 
 
4365}
4366
4367int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
4368			 unsigned long start, unsigned long len)
 
4369{
4370	const int unit_size = folio_size(eb->folios[0]);
4371	size_t cur;
4372	size_t offset;
 
4373	char *kaddr;
4374	char *ptr = (char *)ptrv;
4375	unsigned long i = get_eb_folio_index(eb, start);
 
4376	int ret = 0;
4377
4378	if (check_eb_range(eb, start, len))
4379		return -EINVAL;
4380
4381	if (eb->addr)
4382		return memcmp(ptrv, eb->addr + start, len);
4383
4384	offset = get_eb_offset_in_folio(eb, start);
4385
4386	while (len > 0) {
4387		cur = min(len, unit_size - offset);
4388		kaddr = folio_address(eb->folios[i]);
 
 
 
4389		ret = memcmp(ptr, kaddr + offset, cur);
4390		if (ret)
4391			break;
4392
4393		ptr += cur;
4394		len -= cur;
4395		offset = 0;
4396		i++;
4397	}
4398	return ret;
4399}
4400
4401/*
4402 * Check that the extent buffer is uptodate.
4403 *
4404 * For regular sector size == PAGE_SIZE case, check if @page is uptodate.
4405 * For subpage case, check if the range covered by the eb has EXTENT_UPTODATE.
4406 */
4407static void assert_eb_folio_uptodate(const struct extent_buffer *eb, int i)
4408{
4409	struct btrfs_fs_info *fs_info = eb->fs_info;
4410	struct folio *folio = eb->folios[i];
4411
4412	ASSERT(folio);
4413
4414	/*
4415	 * If we are using the commit root we could potentially clear a page
4416	 * Uptodate while we're using the extent buffer that we've previously
4417	 * looked up.  We don't want to complain in this case, as the page was
4418	 * valid before, we just didn't write it out.  Instead we want to catch
4419	 * the case where we didn't actually read the block properly, which
4420	 * would have !PageUptodate and !EXTENT_BUFFER_WRITE_ERR.
4421	 */
4422	if (test_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags))
4423		return;
4424
4425	if (fs_info->nodesize < PAGE_SIZE) {
4426		struct folio *folio = eb->folios[0];
4427
4428		ASSERT(i == 0);
4429		if (WARN_ON(!btrfs_subpage_test_uptodate(fs_info, folio,
4430							 eb->start, eb->len)))
4431			btrfs_subpage_dump_bitmap(fs_info, folio, eb->start, eb->len);
4432	} else {
4433		WARN_ON(!folio_test_uptodate(folio));
4434	}
4435}
4436
4437static void __write_extent_buffer(const struct extent_buffer *eb,
4438				  const void *srcv, unsigned long start,
4439				  unsigned long len, bool use_memmove)
4440{
4441	const int unit_size = folio_size(eb->folios[0]);
4442	size_t cur;
4443	size_t offset;
 
4444	char *kaddr;
4445	char *src = (char *)srcv;
4446	unsigned long i = get_eb_folio_index(eb, start);
4447	/* For unmapped (dummy) ebs, no need to check their uptodate status. */
4448	const bool check_uptodate = !test_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);
4449
4450	if (check_eb_range(eb, start, len))
4451		return;
4452
4453	if (eb->addr) {
4454		if (use_memmove)
4455			memmove(eb->addr + start, srcv, len);
4456		else
4457			memcpy(eb->addr + start, srcv, len);
4458		return;
4459	}
4460
4461	offset = get_eb_offset_in_folio(eb, start);
4462
4463	while (len > 0) {
4464		if (check_uptodate)
4465			assert_eb_folio_uptodate(eb, i);
4466
4467		cur = min(len, unit_size - offset);
4468		kaddr = folio_address(eb->folios[i]);
4469		if (use_memmove)
4470			memmove(kaddr + offset, src, cur);
4471		else
4472			memcpy(kaddr + offset, src, cur);
4473
4474		src += cur;
4475		len -= cur;
4476		offset = 0;
4477		i++;
4478	}
4479}
4480
4481void write_extent_buffer(const struct extent_buffer *eb, const void *srcv,
4482			 unsigned long start, unsigned long len)
4483{
4484	return __write_extent_buffer(eb, srcv, start, len, false);
4485}
4486
4487static void memset_extent_buffer(const struct extent_buffer *eb, int c,
4488				 unsigned long start, unsigned long len)
4489{
4490	const int unit_size = folio_size(eb->folios[0]);
4491	unsigned long cur = start;
4492
4493	if (eb->addr) {
4494		memset(eb->addr + start, c, len);
4495		return;
4496	}
4497
4498	while (cur < start + len) {
4499		unsigned long index = get_eb_folio_index(eb, cur);
4500		unsigned int offset = get_eb_offset_in_folio(eb, cur);
4501		unsigned int cur_len = min(start + len - cur, unit_size - offset);
4502
4503		assert_eb_folio_uptodate(eb, index);
4504		memset(folio_address(eb->folios[index]) + offset, c, cur_len);
4505
4506		cur += cur_len;
4507	}
4508}
4509
4510void memzero_extent_buffer(const struct extent_buffer *eb, unsigned long start,
4511			   unsigned long len)
4512{
4513	if (check_eb_range(eb, start, len))
4514		return;
4515	return memset_extent_buffer(eb, 0, start, len);
4516}
4517
4518void copy_extent_buffer_full(const struct extent_buffer *dst,
4519			     const struct extent_buffer *src)
4520{
4521	const int unit_size = folio_size(src->folios[0]);
4522	unsigned long cur = 0;
4523
4524	ASSERT(dst->len == src->len);
4525
4526	while (cur < src->len) {
4527		unsigned long index = get_eb_folio_index(src, cur);
4528		unsigned long offset = get_eb_offset_in_folio(src, cur);
4529		unsigned long cur_len = min(src->len, unit_size - offset);
4530		void *addr = folio_address(src->folios[index]) + offset;
4531
4532		write_extent_buffer(dst, addr, cur, cur_len);
 
 
4533
4534		cur += cur_len;
 
 
4535	}
4536}
4537
4538void copy_extent_buffer(const struct extent_buffer *dst,
4539			const struct extent_buffer *src,
4540			unsigned long dst_offset, unsigned long src_offset,
4541			unsigned long len)
4542{
4543	const int unit_size = folio_size(dst->folios[0]);
4544	u64 dst_len = dst->len;
4545	size_t cur;
4546	size_t offset;
 
4547	char *kaddr;
4548	unsigned long i = get_eb_folio_index(dst, dst_offset);
4549
4550	if (check_eb_range(dst, dst_offset, len) ||
4551	    check_eb_range(src, src_offset, len))
4552		return;
4553
4554	WARN_ON(src->len != dst_len);
4555
4556	offset = get_eb_offset_in_folio(dst, dst_offset);
 
4557
4558	while (len > 0) {
4559		assert_eb_folio_uptodate(dst, i);
 
4560
4561		cur = min(len, (unsigned long)(unit_size - offset));
4562
4563		kaddr = folio_address(dst->folios[i]);
4564		read_extent_buffer(src, kaddr + offset, src_offset, cur);
4565
4566		src_offset += cur;
4567		len -= cur;
4568		offset = 0;
4569		i++;
4570	}
4571}
4572
4573/*
4574 * Calculate the folio and offset of the byte containing the given bit number.
4575 *
4576 * @eb:           the extent buffer
4577 * @start:        offset of the bitmap item in the extent buffer
4578 * @nr:           bit number
4579 * @folio_index:  return index of the folio in the extent buffer that contains
4580 *                the given bit number
4581 * @folio_offset: return offset into the folio given by folio_index
4582 *
4583 * This helper hides the ugliness of finding the byte in an extent buffer which
4584 * contains a given bit.
4585 */
4586static inline void eb_bitmap_offset(const struct extent_buffer *eb,
4587				    unsigned long start, unsigned long nr,
4588				    unsigned long *folio_index,
4589				    size_t *folio_offset)
4590{
4591	size_t byte_offset = BIT_BYTE(nr);
4592	size_t offset;
4593
4594	/*
4595	 * The byte we want is the offset of the extent buffer + the offset of
4596	 * the bitmap item in the extent buffer + the offset of the byte in the
4597	 * bitmap item.
4598	 */
4599	offset = start + offset_in_folio(eb->folios[0], eb->start) + byte_offset;
4600
4601	*folio_index = offset >> folio_shift(eb->folios[0]);
4602	*folio_offset = offset_in_folio(eb->folios[0], offset);
4603}
4604
4605/*
4606 * Determine whether a bit in a bitmap item is set.
4607 *
4608 * @eb:     the extent buffer
4609 * @start:  offset of the bitmap item in the extent buffer
4610 * @nr:     bit number to test
4611 */
4612int extent_buffer_test_bit(const struct extent_buffer *eb, unsigned long start,
4613			   unsigned long nr)
4614{
4615	unsigned long i;
4616	size_t offset;
4617	u8 *kaddr;
4618
4619	eb_bitmap_offset(eb, start, nr, &i, &offset);
4620	assert_eb_folio_uptodate(eb, i);
4621	kaddr = folio_address(eb->folios[i]);
4622	return 1U & (kaddr[offset] >> (nr & (BITS_PER_BYTE - 1)));
4623}
4624
4625static u8 *extent_buffer_get_byte(const struct extent_buffer *eb, unsigned long bytenr)
4626{
4627	unsigned long index = get_eb_folio_index(eb, bytenr);
4628
4629	if (check_eb_range(eb, bytenr, 1))
4630		return NULL;
4631	return folio_address(eb->folios[index]) + get_eb_offset_in_folio(eb, bytenr);
4632}
4633
4634/*
4635 * Set an area of a bitmap to 1.
4636 *
4637 * @eb:     the extent buffer
4638 * @start:  offset of the bitmap item in the extent buffer
4639 * @pos:    bit number of the first bit
4640 * @len:    number of bits to set
4641 */
4642void extent_buffer_bitmap_set(const struct extent_buffer *eb, unsigned long start,
4643			      unsigned long pos, unsigned long len)
4644{
4645	unsigned int first_byte = start + BIT_BYTE(pos);
4646	unsigned int last_byte = start + BIT_BYTE(pos + len - 1);
4647	const bool same_byte = (first_byte == last_byte);
4648	u8 mask = BITMAP_FIRST_BYTE_MASK(pos);
4649	u8 *kaddr;
4650
4651	if (same_byte)
4652		mask &= BITMAP_LAST_BYTE_MASK(pos + len);
4653
4654	/* Handle the first byte. */
4655	kaddr = extent_buffer_get_byte(eb, first_byte);
4656	*kaddr |= mask;
4657	if (same_byte)
4658		return;
4659
4660	/* Handle the byte aligned part. */
4661	ASSERT(first_byte + 1 <= last_byte);
4662	memset_extent_buffer(eb, 0xff, first_byte + 1, last_byte - first_byte - 1);
4663
4664	/* Handle the last byte. */
4665	kaddr = extent_buffer_get_byte(eb, last_byte);
4666	*kaddr |= BITMAP_LAST_BYTE_MASK(pos + len);
4667}
4668
4669
4670/*
4671 * Clear an area of a bitmap.
4672 *
4673 * @eb:     the extent buffer
4674 * @start:  offset of the bitmap item in the extent buffer
4675 * @pos:    bit number of the first bit
4676 * @len:    number of bits to clear
4677 */
4678void extent_buffer_bitmap_clear(const struct extent_buffer *eb,
4679				unsigned long start, unsigned long pos,
4680				unsigned long len)
4681{
4682	unsigned int first_byte = start + BIT_BYTE(pos);
4683	unsigned int last_byte = start + BIT_BYTE(pos + len - 1);
4684	const bool same_byte = (first_byte == last_byte);
4685	u8 mask = BITMAP_FIRST_BYTE_MASK(pos);
4686	u8 *kaddr;
4687
4688	if (same_byte)
4689		mask &= BITMAP_LAST_BYTE_MASK(pos + len);
4690
4691	/* Handle the first byte. */
4692	kaddr = extent_buffer_get_byte(eb, first_byte);
4693	*kaddr &= ~mask;
4694	if (same_byte)
4695		return;
4696
4697	/* Handle the byte aligned part. */
4698	ASSERT(first_byte + 1 <= last_byte);
4699	memset_extent_buffer(eb, 0, first_byte + 1, last_byte - first_byte - 1);
4700
4701	/* Handle the last byte. */
4702	kaddr = extent_buffer_get_byte(eb, last_byte);
4703	*kaddr &= ~BITMAP_LAST_BYTE_MASK(pos + len);
4704}
4705
4706static inline bool areas_overlap(unsigned long src, unsigned long dst, unsigned long len)
4707{
4708	unsigned long distance = (src > dst) ? src - dst : dst - src;
4709	return distance < len;
4710}
4711
4712void memcpy_extent_buffer(const struct extent_buffer *dst,
4713			  unsigned long dst_offset, unsigned long src_offset,
4714			  unsigned long len)
4715{
4716	const int unit_size = folio_size(dst->folios[0]);
4717	unsigned long cur_off = 0;
 
4718
4719	if (check_eb_range(dst, dst_offset, len) ||
4720	    check_eb_range(dst, src_offset, len))
4721		return;
 
 
 
 
4722
4723	if (dst->addr) {
4724		const bool use_memmove = areas_overlap(src_offset, dst_offset, len);
 
 
 
4725
4726		if (use_memmove)
4727			memmove(dst->addr + dst_offset, dst->addr + src_offset, len);
4728		else
4729			memcpy(dst->addr + dst_offset, dst->addr + src_offset, len);
4730		return;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4731	}
4732
4733	while (cur_off < len) {
4734		unsigned long cur_src = cur_off + src_offset;
4735		unsigned long folio_index = get_eb_folio_index(dst, cur_src);
4736		unsigned long folio_off = get_eb_offset_in_folio(dst, cur_src);
4737		unsigned long cur_len = min(src_offset + len - cur_src,
4738					    unit_size - folio_off);
4739		void *src_addr = folio_address(dst->folios[folio_index]) + folio_off;
4740		const bool use_memmove = areas_overlap(src_offset + cur_off,
4741						       dst_offset + cur_off, cur_len);
4742
4743		__write_extent_buffer(dst, src_addr, dst_offset + cur_off, cur_len,
4744				      use_memmove);
4745		cur_off += cur_len;
 
 
 
 
 
 
 
 
4746	}
4747}
4748
4749void memmove_extent_buffer(const struct extent_buffer *dst,
4750			   unsigned long dst_offset, unsigned long src_offset,
4751			   unsigned long len)
4752{
 
 
 
4753	unsigned long dst_end = dst_offset + len - 1;
4754	unsigned long src_end = src_offset + len - 1;
4755
4756	if (check_eb_range(dst, dst_offset, len) ||
4757	    check_eb_range(dst, src_offset, len))
4758		return;
4759
 
 
 
 
 
 
 
 
 
4760	if (dst_offset < src_offset) {
4761		memcpy_extent_buffer(dst, dst_offset, src_offset, len);
4762		return;
4763	}
4764
4765	if (dst->addr) {
4766		memmove(dst->addr + dst_offset, dst->addr + src_offset, len);
4767		return;
4768	}
4769
4770	while (len > 0) {
4771		unsigned long src_i;
4772		size_t cur;
4773		size_t dst_off_in_folio;
4774		size_t src_off_in_folio;
4775		void *src_addr;
4776		bool use_memmove;
4777
4778		src_i = get_eb_folio_index(dst, src_end);
4779
4780		dst_off_in_folio = get_eb_offset_in_folio(dst, dst_end);
4781		src_off_in_folio = get_eb_offset_in_folio(dst, src_end);
4782
4783		cur = min_t(unsigned long, len, src_off_in_folio + 1);
4784		cur = min(cur, dst_off_in_folio + 1);
4785
4786		src_addr = folio_address(dst->folios[src_i]) + src_off_in_folio -
4787					 cur + 1;
4788		use_memmove = areas_overlap(src_end - cur + 1, dst_end - cur + 1,
4789					    cur);
4790
4791		__write_extent_buffer(dst, src_addr, dst_end - cur + 1, cur,
4792				      use_memmove);
 
 
 
 
 
 
 
 
 
4793
4794		dst_end -= cur;
4795		src_end -= cur;
4796		len -= cur;
4797	}
4798}
4799
4800#define GANG_LOOKUP_SIZE	16
4801static struct extent_buffer *get_next_extent_buffer(
4802		struct btrfs_fs_info *fs_info, struct page *page, u64 bytenr)
4803{
4804	struct extent_buffer *gang[GANG_LOOKUP_SIZE];
4805	struct extent_buffer *found = NULL;
4806	u64 page_start = page_offset(page);
4807	u64 cur = page_start;
4808
4809	ASSERT(in_range(bytenr, page_start, PAGE_SIZE));
4810	lockdep_assert_held(&fs_info->buffer_lock);
4811
4812	while (cur < page_start + PAGE_SIZE) {
4813		int ret;
4814		int i;
4815
4816		ret = radix_tree_gang_lookup(&fs_info->buffer_radix,
4817				(void **)gang, cur >> fs_info->sectorsize_bits,
4818				min_t(unsigned int, GANG_LOOKUP_SIZE,
4819				      PAGE_SIZE / fs_info->nodesize));
4820		if (ret == 0)
4821			goto out;
4822		for (i = 0; i < ret; i++) {
4823			/* Already beyond page end */
4824			if (gang[i]->start >= page_start + PAGE_SIZE)
4825				goto out;
4826			/* Found one */
4827			if (gang[i]->start >= bytenr) {
4828				found = gang[i];
4829				goto out;
4830			}
4831		}
4832		cur = gang[ret - 1]->start + gang[ret - 1]->len;
4833	}
4834out:
4835	return found;
4836}
4837
4838static int try_release_subpage_extent_buffer(struct page *page)
4839{
4840	struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
4841	u64 cur = page_offset(page);
4842	const u64 end = page_offset(page) + PAGE_SIZE;
4843	int ret;
4844
4845	while (cur < end) {
4846		struct extent_buffer *eb = NULL;
4847
4848		/*
4849		 * Unlike try_release_extent_buffer() which uses folio private
4850		 * to grab buffer, for subpage case we rely on radix tree, thus
4851		 * we need to ensure radix tree consistency.
4852		 *
4853		 * We also want an atomic snapshot of the radix tree, thus go
4854		 * with spinlock rather than RCU.
4855		 */
4856		spin_lock(&fs_info->buffer_lock);
4857		eb = get_next_extent_buffer(fs_info, page, cur);
4858		if (!eb) {
4859			/* No more eb in the page range after or at cur */
4860			spin_unlock(&fs_info->buffer_lock);
4861			break;
4862		}
4863		cur = eb->start + eb->len;
4864
4865		/*
4866		 * The same as try_release_extent_buffer(), to ensure the eb
4867		 * won't disappear out from under us.
4868		 */
4869		spin_lock(&eb->refs_lock);
4870		if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
4871			spin_unlock(&eb->refs_lock);
4872			spin_unlock(&fs_info->buffer_lock);
4873			break;
4874		}
4875		spin_unlock(&fs_info->buffer_lock);
4876
4877		/*
4878		 * If tree ref isn't set then we know the ref on this eb is a
4879		 * real ref, so just return, this eb will likely be freed soon
4880		 * anyway.
4881		 */
4882		if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
4883			spin_unlock(&eb->refs_lock);
4884			break;
4885		}
4886
4887		/*
4888		 * Here we don't care about the return value, we will always
4889		 * check the folio private at the end.  And
4890		 * release_extent_buffer() will release the refs_lock.
4891		 */
4892		release_extent_buffer(eb);
4893	}
4894	/*
4895	 * Finally to check if we have cleared folio private, as if we have
4896	 * released all ebs in the page, the folio private should be cleared now.
4897	 */
4898	spin_lock(&page->mapping->i_private_lock);
4899	if (!folio_test_private(page_folio(page)))
4900		ret = 1;
4901	else
4902		ret = 0;
4903	spin_unlock(&page->mapping->i_private_lock);
4904	return ret;
4905
4906}
4907
4908int try_release_extent_buffer(struct page *page)
4909{
4910	struct folio *folio = page_folio(page);
4911	struct extent_buffer *eb;
4912
4913	if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE)
4914		return try_release_subpage_extent_buffer(page);
4915
4916	/*
4917	 * We need to make sure nobody is changing folio private, as we rely on
4918	 * folio private as the pointer to extent buffer.
4919	 */
4920	spin_lock(&page->mapping->i_private_lock);
4921	if (!folio_test_private(folio)) {
4922		spin_unlock(&page->mapping->i_private_lock);
4923		return 1;
4924	}
4925
4926	eb = folio_get_private(folio);
4927	BUG_ON(!eb);
4928
4929	/*
4930	 * This is a little awful but should be ok, we need to make sure that
4931	 * the eb doesn't disappear out from under us while we're looking at
4932	 * this page.
4933	 */
4934	spin_lock(&eb->refs_lock);
4935	if (atomic_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
4936		spin_unlock(&eb->refs_lock);
4937		spin_unlock(&page->mapping->i_private_lock);
4938		return 0;
4939	}
4940	spin_unlock(&page->mapping->i_private_lock);
 
 
 
4941
4942	/*
4943	 * If tree ref isn't set then we know the ref on this eb is a real ref,
4944	 * so just return, this page will likely be freed soon anyway.
4945	 */
4946	if (!test_and_clear_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags)) {
4947		spin_unlock(&eb->refs_lock);
4948		return 0;
4949	}
 
4950
4951	return release_extent_buffer(eb);
4952}
4953
4954/*
4955 * Attempt to readahead a child block.
4956 *
4957 * @fs_info:	the fs_info
4958 * @bytenr:	bytenr to read
4959 * @owner_root: objectid of the root that owns this eb
4960 * @gen:	generation for the uptodate check, can be 0
4961 * @level:	level for the eb
4962 *
4963 * Attempt to readahead a tree block at @bytenr.  If @gen is 0 then we do a
4964 * normal uptodate check of the eb, without checking the generation.  If we have
4965 * to read the block we will not block on anything.
4966 */
4967void btrfs_readahead_tree_block(struct btrfs_fs_info *fs_info,
4968				u64 bytenr, u64 owner_root, u64 gen, int level)
4969{
4970	struct btrfs_tree_parent_check check = {
4971		.has_first_key = 0,
4972		.level = level,
4973		.transid = gen
4974	};
4975	struct extent_buffer *eb;
4976	int ret;
4977
4978	eb = btrfs_find_create_tree_block(fs_info, bytenr, owner_root, level);
4979	if (IS_ERR(eb))
4980		return;
4981
4982	if (btrfs_buffer_uptodate(eb, gen, 1)) {
4983		free_extent_buffer(eb);
4984		return;
4985	}
4986
4987	ret = read_extent_buffer_pages(eb, WAIT_NONE, 0, &check);
4988	if (ret < 0)
4989		free_extent_buffer_stale(eb);
4990	else
4991		free_extent_buffer(eb);
4992}
4993
4994/*
4995 * Readahead a node's child block.
4996 *
4997 * @node:	parent node we're reading from
4998 * @slot:	slot in the parent node for the child we want to read
4999 *
5000 * A helper for btrfs_readahead_tree_block, we simply read the bytenr pointed at
5001 * the slot in the node provided.
5002 */
5003void btrfs_readahead_node_child(struct extent_buffer *node, int slot)
5004{
5005	btrfs_readahead_tree_block(node->fs_info,
5006				   btrfs_node_blockptr(node, slot),
5007				   btrfs_header_owner(node),
5008				   btrfs_node_ptr_generation(node, slot),
5009				   btrfs_header_level(node) - 1);
5010}