On Thu, Mar 15, 2018 at 02:35:36PM +0200, Nikolay Borisov wrote: > On 14.03.2018 22:11, fdman...@kernel.org wrote: > > From: Filipe Manana <fdman...@suse.com> > > > > Under some cases the filesystem checker reports an error when it finds > > checksum items for an extent that is referenced by an inode as a prealloc > > extent. Such cases are not an error when the extent is actually shared > > (was cloned/reflinked) with other inodes and was written through one of > > those other inodes. > > > > Example: > > > > $ mkfs.btrfs -f /dev/sdb > > $ mount /dev/sdb /mnt > > > > $ touch /mnt/foo > > $ xfs_io -c "falloc 0 256K" /mnt/foo > > $ sync > > > > $ xfs_io -c "pwrite -S 0xab 0 256K" /mnt/foo > > $ touch /mnt/bar > > $ xfs_io -c "reflink /mnt/foo 0 0 256K" /mnt/bar > > $ xfs_io -c "fsync" /mnt/bar > > > > <power fail> > > $ mount /dev/sdb /mnt > > $ umount /mnt > > > > $ btrfs check /dev/sdc > > Checking filesystem on /dev/sdb > > UUID: 52d3006e-ee3b-40eb-aa21-e56253a03d39 > > checking extents > > checking free space cache > > checking fs roots > > root 5 inode 257 errors 800, odd csum item > > ERROR: errors found in fs roots > > found 688128 bytes used, error(s) found > > total csum bytes: 256 > > total tree bytes: 163840 > > total fs tree bytes: 65536 > > total extent tree bytes: 16384 > > btree space waste bytes: 138819 > > file data blocks allocated: 10747904 > > referenced 10747904 > > $ echo $? > > 1 > > > > So teach check to not report such cases as errors by checking if the > > extent is shared with other inodes and if so, consider it an error the > > existence of checksum items only if all those other inodes are referencing > > the extent as a prealloc extent. > > This case can be hit often when running the generic/475 testcase from > > fstests. > > > > A test case will follow in a separate patch. > > > > Signed-off-by: Filipe Manana <fdman...@suse.com> > > Reviewed-by: Nikolay Borisov <nbori...@suse.com>
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