A cascade of MD reverts occurred late in the v5.10-rcX cycle due to MD
raid10 discard optimizations having introduced potential for
corruption. Those reverts exposed a dm-raid.c compiler warning that
wasn't ever knowingly introduced. That min_not_zero() type mismatch
warning was thought to be safely fixed simply by changing 'struct
mddev' to use 'unsigned int' rather than int for chunk_sectors members
in that struct. I proposed either using a cast local to dm-raid.c but
thought changing the type to 'unsigned int' more correct. While that
may be, not enough testing was paired with code review associated with
making that change. As such we were left exposed and the result was a
report that with v5.10 btrfs on MD RAID6 failed to mount:
https://lkml.org/lkml/2020/12/14/7
Given that report, it is justified to simply revert these offending
commits. stable@ has already taken steps to revert these for 5.10.1 -
this pull request just makes sure mainline does so too.
Revert "dm raid: fix discard limits for raid1 and raid10"
This reverts commit e0910c8e4f87bb9f767e61a778b0d9271c4dc512.
Reverting 6ffeb1c3f822 ("md: change mddev 'chunk_sectors' from int to
unsigned") exposes dm-raid.c compiler warnings detailed that commit's
header. Clearly this more conservative fix, of simply reverting
e0910c8e4f8, would've been more prudent given how late we were in the
v5.10 release. Lessons have been learned.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1 file changed
