[BUG]
There is a bug report that, one btrfs got its underlying device shrunk
accidentally.
Fortunately the user has no data at the truncated range. However kernel
will reject such filesystem, while btrfs-check reports nothing wrong
with it.
This can be easily reproduced by:
# truncate -s 1G test.img
# mkfs.btrfs test.img
# truncate -s 996M test.img
# btrfs check test.img
Opening filesystem to check...
Checking filesystem on test.img
UUID: dbf0a16d-f158-4383-9025-29d7f4c43f17
[1/7] checking root items
[2/7] checking extents
[3/7] checking free space tree
[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 16527360 bytes used, no error found
^^^^^^^^^^^^^^
total csum bytes: 13836
total tree bytes: 2359296
total fs tree bytes: 2162688
total extent tree bytes: 65536
btree space waste bytes: 503569
file data blocks allocated: 14168064
referenced 14168064
[CAUSE]
Btrfs check really only checks the metadata cross references, not really
bothering if the underlying device has correct size. Thus we completely
ignored such size mismatch.
[FIX]
For both regular and lowmem mode, add extra check against the underlying
block device size.
If the block device size is smaller than its total_bytes, gives a error
message and error out.
Now the check looks like this for both modes:
...
[2/7] checking extents
ERROR: block device size is smaller than total_bytes in device item, has 1046478848 expect >= 1073741824
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space tree
...
found 16527360 bytes used, error(s) found
Issue: #504
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
0a348d3c81