Re: [PATCH 1/7] btrfs: scrub: fix incorrectly reported logical/physical address

[David Sterba <dsterba@suse.cz>]

On Fri, Mar 15, 2024 at 06:45:04AM +1030, Qu Wenruo wrote:
> 
> 
> 在 2024/3/14 22:54, Anand Jain 写道:
> > On 3/14/24 15:20, Qu Wenruo wrote:
> >> [BUG]
> >> Scrub is not reporting the correct logical/physical address, it can be
> >> verified by the following script:
> >>
> >>   # mkfs.btrfs -f $dev1
> >>   # mount $dev1 $mnt
> >>   # xfs_io -f -c "pwrite -S 0xaa 0 128k" $mnt/file1
> >>   # umount $mnt
> >>   # xfs_io -f -c "pwrite -S 0xff 13647872 4k" $dev1
> >>   # mount $dev1 $mnt
> >>   # btrfs scrub start -fB $mnt
> >>   # umount $mnt
> >>
> >> Note above 13647872 is the physical address for logical 13631488 + 4K.
> >>
> >> Scrub would report the following error:
> >>
> >>   BTRFS error (device dm-2): unable to fixup (regular) error at 
> >> logical 13631488 on dev /dev/mapper/test-scratch1 physical 13631488
> >>   BTRFS warning (device dm-2): checksum error at logical 13631488 on 
> >> dev /dev/mapper/test-scratch1, physical 13631488, root 5, inode 257, 
> >> offset 0, length 4096, links 1 (path: file1)
> >>
> >> On the other hand, "btrfs check --check-data-csum" is reporting the
> >> correct logical/physical address:
> >>
> >>   Checking filesystem on /dev/test/scratch1
> >>   UUID: db2eb621-b09d-4f24-8199-da17dc7b3201
> >>   [5/7] checking csums against data
> >>   mirror 1 bytenr 13647872 csum 0x13fec125 expected csum 0x656bd64e
> >>   ERROR: errors found in csum tree
> >>
> >> [CAUSE]
> >> In the function scrub_stripe_report_errors(), we always use the
> >> stripe->logical and its physical address to print the error message, not
> >> taking the sector number into consideration at all.
> >>
> >> [FIX]
> >> Fix the error reporting function by calculating logical/physical with
> >> the sector number.
> >>
> >> Now the scrub report is correct:
> >>
> >>   BTRFS error (device dm-2): unable to fixup (regular) error at 
> >> logical 13647872 on dev /dev/mapper/test-scratch1 physical 13647872
> >>   BTRFS warning (device dm-2): checksum error at logical 13647872 on 
> >> dev /dev/mapper/test-scratch1, physical 13647872, root 5, inode 257, 
> >> offset 16384, length 4096, links 1 (path: file1)
> >>
> >> Fixes: 0096580713ff ("btrfs: scrub: introduce error reporting 
> >> functionality for scrub_stripe")
> >> Signed-off-by: Qu Wenruo <wqu@suse.com>
> > 
> > 
> > To help accurate debug on stable kernel, we could also add
> > CC: stable@vger.kernel.org #6.4+
> 
> IIRC Fixes: tag is more accurate than just CC stable, as stable has the 
> correct bots catching the fixes line.

Fixes: + CC: is the most reliable way to get patches to stable, CC: is
next but just Fixes: is not guaranteed as it depends on manual
processing.