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btrfs-progs: convert: ensure the data chunks size never exceed device size

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[BUG]
The following script could lead to corrupted btrfs fs after
btrfs-convert:

  fallocate -l 1G test.img
  mkfs.ext4 test.img
  mount test.img $mnt
  fallocate -l 200m $mnt/file1
  fallocate -l 200m $mnt/file2
  fallocate -l 200m $mnt/file3
  fallocate -l 200m $mnt/file4
  fallocate -l 205m $mnt/file1
  fallocate -l 205m $mnt/file2
  fallocate -l 205m $mnt/file3
  fallocate -l 205m $mnt/file4
  umount $mnt
  btrfs-convert test.img

The result btrfs will have a device extent beyond its boundary:
  pening filesystem to check...
  Checking filesystem on test.img
  UUID: bbcd7399-fd5b-41a7-81ae-d48bc6935e43
  [1/7] checking root items
  [2/7] checking extents
  ERROR: dev extent devid 1 physical offset 993198080 len 85786624 is beyond device boundary 1073741824
  ERROR: errors found in extent allocation tree or chunk allocation
  [3/7] checking free space cache
  [4/7] checking fs roots
  [5/7] checking only csums items (without verifying data)
  [6/7] checking root refs
  [7/7] checking quota groups skipped (not enabled on this FS)
  found 913960960 bytes used, error(s) found
  total csum bytes: 891500
  total tree bytes: 1064960
  total fs tree bytes: 49152
  total extent tree bytes: 16384
  btree space waste bytes: 144885
  file data blocks allocated: 2129063936
   referenced 1772728320

[CAUSE]
Btrfs-convert first collect all used blocks in the original fs, then
slightly enlarge the used blocks range as new btrfs data chunks.

However the enlarge part has a problem, that it doesn't take the device
boundary into consideration.

Thus it caused device extents and data chunks to go beyond device
boundary.

[FIX]
Just to extra check before inserting data chunks into
btrfs_convert_context::data_chunk.

Reported-by: Jiachen YANG <farseerfc@gmail.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2020-06-24 19:55:26 +08:00 committed by David Sterba
parent 2eb48d8c81
commit 0ff7a9b521
1 changed files with 2 additions and 0 deletions
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2
convert/main.c
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@ -669,6 +669,8 @@ static int calculate_available_space(struct btrfs_convert_context *cctx)
cur_off = cache->start;
cur_len = max(cache->start + cache->size - cur_off,
min_stripe_size);
/* data chunks should never exceed device boundary */
cur_len = min(cctx->total_bytes - cur_off, cur_len);
ret = add_merge_cache_extent(data_chunks, cur_off, cur_len);
if (ret < 0)
goto out;