xfs: don't commit sunit/swidth updates to disk if that would cause repair failures
Alex Lyakas reported[1] that mounting an xfs filesystem with new sunit
and swidth values could cause xfs_repair to fail loudly. The problem
here is that repair calculates the where mkfs should have allocated the
root inode, based on the superblock geometry. The allocation decisions
depend on sunit, which means that we really can't go updating sunit if
it would lead to a subsequent repair failure on an otherwise correct
filesystem.
Port the computation code from xfs_repair and teach mount to avoid the
ondisk update if it would cause problems for repair. We allow the mount
to proceed (and new allocations will reflect this new geometry) because
we've never screened this kind of thing before.
[1] https://lore.kernel.org/linux-xfs/20191125130744.GA44777@bfoster/T/#m00f9594b511e076e2fcdd489d78bc30216d72a7d
Reported-by: Alex Lyakas <alex@zadara.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
2 files changed
