btrfs: tree-checker: do not error out if extent ref hash doesn't match
The tree checker checks the extent ref hash at read and write time to make sure we do not corrupt the file system. Generally extent references go inline, but if we have enough of them we need to make an item, which looks like key.objectid = <bytenr> key.type = <BTRFS_EXTENT_DATA_REF_KEY|BTRFS_TREE_BLOCK_REF_KEY> key.offset = hash(tree, owner, offset) However if key.offset collide with an unrelated extent reference we'll simply key.offset++ until we get something that doesn't collide. Obviously this doesn't match at tree checker time, and thus we error while writing out the transaction. This is relatively easy to reproduce, simply do something like the following xfs_io -f -c "pwrite 0 1M" file offset=2 for i in {0..10000} do xfs_io -c "reflink file 0 ${offset}M 1M" file offset=$(( offset + 2 )) done xfs_io -c "reflink file 0 17999258914816 1M" file xfs_io -c "reflink file 0 35998517829632 1M" file xfs_io -c "reflink file 0 53752752058368 1M" file btrfs filesystem sync And the sync will error out because we'll abort the transaction. The magic values above are used because they generate hash collisions with the first file in the main subvol. The fix for this is to remove the hash value check from tree checker, as we have no idea which offset ours should belong to. Reported-by:Tuomas Lähdekorpi <tuomas.lahdekorpi@gmail.com> Fixes: 0785a9aa ("btrfs: tree-checker: Add EXTENT_DATA_REF check") CC: stable@vger.kernel.org # 5.4+ Reviewed-by:
Filipe Manana <fdmanana@suse.com> Signed-off-by:
Josef Bacik <josef@toxicpanda.com> Reviewed-by:
David Sterba <dsterba@suse.com> [ add comment] Signed-off-by:
David Sterba <dsterba@suse.com>
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