This backport is going to address the following possible corruption for
btrfs RAID56:
- RMW always writes the full P/Q stripe
This happens even only some vertical stripes are dirty.
If some data sectors are corrupted in the clean vertical stripes,
then such unnecessary P/Q updates will wipe the chance or recovery,
as the P/Q will be calculated using corrupted data.
This will be addressed by the first backport patch.
- Don't trust any cached sector when doing recovery
Although above patch will avoid unnecessary P/Q writes, the full P/Q
stripe will still be updated in the in-memory only RAID56 cache.
To properly recovery data stripes, we should not trust any cached
sector, and always read data from disk, which will avoid corrupted
P/Q sectors.
This will be addressed by the second backport patch.
This would make some previously always-fail test cases, like btrfs/125,
to pass, and end users have a lower chance to corrupt their RAID56 data.
Since this is a data corruption related fix, these backport patches are
needed for all stable branches.
Unfortunately due to the new cleanups in v6.0-rc, these backport patches
have quite some conflicts (even for 5.19), and have to be manually resolved.
Almost every stable branch will need their own backports.
Acked-by: David Sterba <dsterba@xxxxxxxx>
Qu Wenruo (2):
btrfs: only write the sectors in the vertical stripe which has data
stripes
btrfs: raid56: don't trust any cached sector in
__raid56_parity_recover()
fs/btrfs/raid56.c | 68 ++++++++++++++++++++++++++++++++++++++---------
1 file changed, 55 insertions(+), 13 deletions(-)
--
2.37.1
