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btrfs: tree-checker: Don't check max block group size as current max chunk size limit is unreliable

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[BUG]
A completely valid btrfs will refuse to mount, with error message like:
  BTRFS critical (device sdb2): corrupt leaf: root=2 block=239681536 slot=172 \
    bg_start=12018974720 bg_len=10888413184, invalid block group size, \
    have 10888413184 expect (0, 10737418240]

This has been reported several times as the 4.19 kernel is now being
used. The filesystem refuses to mount, but is otherwise ok and booting
4.18 is a workaround.

Btrfs check returns no error, and all kernels used on this fs is later
than 2011, which should all have the 10G size limit commit.

[CAUSE]
For a 12 devices btrfs, we could allocate a chunk larger than 10G due to
stripe stripe bump up.

__btrfs_alloc_chunk()
|- max_stripe_size = 1G
|- max_chunk_size = 10G
|- data_stripe = 11
|- if (1G * 11 > 10G) {
       stripe_size = 976128930;
       stripe_size = round_up(976128930, SZ_16M) = 989855744

However the final stripe_size (989855744) * 11 = 10888413184, which is
still larger than 10G.

[FIX]
For the comprehensive check, we need to do the full check at chunk read
time, and rely on bg <-> chunk mapping to do the check.

We could just skip the length check for now.

Fixes: fce466eab7 ("btrfs: tree-checker: Verify block_group_item")
Cc: stable@vger.kernel.org # v4.19+
Reported-by: Wang Yugui <wangyugui@e16-tech.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2018-11-23 09:06:36 +08:00 committed by David Sterba
parent 42a657f576
commit 10950929e9
1 changed files with 3 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/btrfs/tree-checker.c
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@ -389,13 +389,11 @@ static int check_block_group_item(struct btrfs_fs_info *fs_info,
/*
* Here we don't really care about alignment since extent allocator can
* handle it. We care more about the size, as if one block group is
* larger than maximum size, it's must be some obvious corruption.
* handle it. We care more about the size.
*/
if (key->offset > BTRFS_MAX_DATA_CHUNK_SIZE || key->offset == 0) {
if (key->offset == 0) {
block_group_err(fs_info, leaf, slot,
"invalid block group size, have %llu expect (0, %llu]",
key->offset, BTRFS_MAX_DATA_CHUNK_SIZE);
"invalid block group size 0");
return -EUCLEAN;
}