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6a06115861
[BUG]
For a fuzzed image, `btrfs check` will segfault at open_ctree() stage:
$ btrfs check --mode=lowmem issue_207.raw
Opening filesystem to check...
extent_io.c:665: free_extent_buffer_internal: BUG_ON `eb->refs < 0` triggered, value 1
btrfs(+0x6bf67)[0x56431d278f67]
btrfs(+0x6c16e)[0x56431d27916e]
btrfs(alloc_extent_buffer+0x45)[0x56431d279db5]
btrfs(read_tree_block+0x59)[0x56431d2848f9]
btrfs(btrfs_setup_all_roots+0x29c)[0x56431d28535c]
btrfs(+0x78903)[0x56431d285903]
btrfs(open_ctree_fs_info+0x90)[0x56431d285b60]
btrfs(+0x45a01)[0x56431d252a01]
btrfs(main+0x94)[0x56431d2220c4]
/usr/lib/libc.so.6(__libc_start_main+0xf3)[0x7f6e28519153]
btrfs(_start+0x2e)[0x56431d22235e]
[CAUSE]
The fuzzed image has a strange log root bytenr:
log_root 61440
log_root_transid 0
In fact, the log_root seems to be fuzzed, as its transid is 0, which is
invalid.
Note that range [61440, 77824) covers the physical offset of the primary
super block.
The bug is caused by the following sequence:
1. cache for tree block [64K, 68K) is created by open_ctree()
__open_ctree_fd()
|- btrfs_setup_chunk_tree_and_device_map()
|- btrfs_read_sys_array()
|- sb = btrfs_find_create_tree_block()
|- free_extent_buffer(sb)
This created an extent buffer [64K, 68K) in fs_info->extent_cache, then
reduce the refcount of that eb back to 0, but not freed yet.
2. Try to read that corrupted log root
__open_ctree_fd()
|- btrfs_setup_chunk_tree_and_device_map()
|- btrfs_setup_all_roots()
|- find_and_setup_log_root()
|- read_tree_block()
|- btrfs_find_create_tree_block()
|- alloc_extent_buffer()
The final alloc_extent_buffer() will try to free that cached eb
[64K, 68K), since it doesn't match with current search.
And since that cached eb is already released (refcount == 0), the
extra free_extent_buffer() will cause above BUG_ON().
[FIX]
Here we fix it through a more comprehensive method, instead of simply
verifying log_root_transid, here we just don't pollute eb cache when
reading sys chunk array.
So that we won't have an eb cache [64K, 68K), and will error out at
logical mapping phase.
Issue: #207
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
186 lines
6.4 KiB
C
186 lines
6.4 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_EXTENT_IO_H__
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#define __BTRFS_EXTENT_IO_H__
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#if BTRFS_FLAT_INCLUDES
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#include "kerncompat.h"
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#include "extent-cache.h"
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#include "kernel-lib/list.h"
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#else
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#include <btrfs/kerncompat.h>
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#include <btrfs/extent-cache.h>
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#include <btrfs/list.h>
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#endif /* BTRFS_FLAT_INCLUDES */
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#define EXTENT_DIRTY (1U << 0)
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#define EXTENT_WRITEBACK (1U << 1)
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#define EXTENT_UPTODATE (1U << 2)
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#define EXTENT_LOCKED (1U << 3)
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#define EXTENT_NEW (1U << 4)
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#define EXTENT_DELALLOC (1U << 5)
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#define EXTENT_DEFRAG (1U << 6)
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#define EXTENT_DEFRAG_DONE (1U << 7)
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#define EXTENT_BUFFER_FILLED (1U << 8)
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#define EXTENT_CSUM (1U << 9)
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#define EXTENT_BAD_TRANSID (1U << 10)
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#define EXTENT_BUFFER_DUMMY (1U << 11)
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#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
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#define BLOCK_GROUP_DATA (1U << 1)
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#define BLOCK_GROUP_METADATA (1U << 2)
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#define BLOCK_GROUP_SYSTEM (1U << 4)
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#define BLOCK_GROUP_DIRTY (1U)
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/*
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* The extent buffer bitmap operations are done with byte granularity instead of
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* word granularity for two reasons:
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* 1. The bitmaps must be little-endian on disk.
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* 2. Bitmap items are not guaranteed to be aligned to a word and therefore a
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* single word in a bitmap may straddle two pages in the extent buffer.
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*/
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#define BIT_BYTE(nr) ((nr) / BITS_PER_BYTE)
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#define BYTE_MASK ((1 << BITS_PER_BYTE) - 1)
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#define BITMAP_FIRST_BYTE_MASK(start) \
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((BYTE_MASK << ((start) & (BITS_PER_BYTE - 1))) & BYTE_MASK)
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#define BITMAP_LAST_BYTE_MASK(nbits) \
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(BYTE_MASK >> (-(nbits) & (BITS_PER_BYTE - 1)))
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static inline int le_test_bit(int nr, const u8 *addr)
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{
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return 1U & (addr[BIT_BYTE(nr)] >> (nr & (BITS_PER_BYTE-1)));
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}
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struct btrfs_fs_info;
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struct extent_io_tree {
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struct cache_tree state;
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struct cache_tree cache;
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struct list_head lru;
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u64 cache_size;
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u64 max_cache_size;
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};
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struct extent_state {
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struct cache_extent cache_node;
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u64 start;
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u64 end;
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int refs;
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unsigned long state;
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u64 xprivate;
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};
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struct extent_buffer {
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struct cache_extent cache_node;
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u64 start;
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u64 dev_bytenr;
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struct extent_io_tree *tree;
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struct list_head lru;
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struct list_head recow;
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u32 len;
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int refs;
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u32 flags;
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int fd;
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struct btrfs_fs_info *fs_info;
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char data[] __attribute__((aligned(8)));
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};
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static inline void extent_buffer_get(struct extent_buffer *eb)
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{
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eb->refs++;
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}
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void extent_io_tree_init(struct extent_io_tree *tree);
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void extent_io_tree_init_cache_max(struct extent_io_tree *tree,
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u64 max_cache_size);
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void extent_io_tree_cleanup(struct extent_io_tree *tree);
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int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, int bits);
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int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end, int bits);
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int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
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u64 *start_ret, u64 *end_ret, int bits);
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int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
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int bits, int filled);
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int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end);
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int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end);
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static inline int set_extent_buffer_uptodate(struct extent_buffer *eb)
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{
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eb->flags |= EXTENT_UPTODATE;
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return 0;
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}
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static inline int clear_extent_buffer_uptodate(struct extent_buffer *eb)
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{
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eb->flags &= ~EXTENT_UPTODATE;
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return 0;
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}
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static inline int extent_buffer_uptodate(struct extent_buffer *eb)
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{
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if (!eb || IS_ERR(eb))
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return 0;
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if (eb->flags & EXTENT_UPTODATE)
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return 1;
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return 0;
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}
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int set_state_private(struct extent_io_tree *tree, u64 start, u64 xprivate);
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int get_state_private(struct extent_io_tree *tree, u64 start, u64 *xprivate);
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struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
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u64 bytenr, u32 blocksize);
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struct extent_buffer *find_first_extent_buffer(struct extent_io_tree *tree,
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u64 start);
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struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
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u64 bytenr, u32 blocksize);
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struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src);
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struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
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u64 bytenr, u32 blocksize);
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void free_extent_buffer(struct extent_buffer *eb);
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void free_extent_buffer_nocache(struct extent_buffer *eb);
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int read_extent_from_disk(struct extent_buffer *eb,
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unsigned long offset, unsigned long len);
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int write_extent_to_disk(struct extent_buffer *eb);
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int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
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unsigned long start, unsigned long len);
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void read_extent_buffer(const struct extent_buffer *eb, void *dst,
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unsigned long start, unsigned long len);
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void write_extent_buffer(struct extent_buffer *eb, const void *src,
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unsigned long start, unsigned long len);
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void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
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unsigned long dst_offset, unsigned long src_offset,
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unsigned long len);
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void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
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unsigned long src_offset, unsigned long len);
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void memset_extent_buffer(struct extent_buffer *eb, char c,
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unsigned long start, unsigned long len);
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int extent_buffer_test_bit(struct extent_buffer *eb, unsigned long start,
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unsigned long nr);
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int set_extent_buffer_dirty(struct extent_buffer *eb);
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int clear_extent_buffer_dirty(struct extent_buffer *eb);
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int read_data_from_disk(struct btrfs_fs_info *info, void *buf, u64 offset,
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u64 bytes, int mirror);
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int write_data_to_disk(struct btrfs_fs_info *info, void *buf, u64 offset,
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u64 bytes, int mirror);
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void extent_buffer_bitmap_clear(struct extent_buffer *eb, unsigned long start,
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unsigned long pos, unsigned long len);
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void extent_buffer_bitmap_set(struct extent_buffer *eb, unsigned long start,
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unsigned long pos, unsigned long len);
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#endif
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