[PATCH 0/3] xfs: miscellaneous bug fixes

[Dave Chinner <david@fromorbit.com>]

These are three bug fixes for recent issues.

The first is a repost of the original patch to prevent allocation of
sparse inode clusters at the end of an unaligned runt AG. There
was plenty of discussion over that fix here:

https://lore.kernel.org/linux-xfs/20241024025142.4082218-1-david@fromorbit.com/

And the outcome of that discussion is that we can't allow sparse
inode clusters overlapping the end of the runt AG without an on disk
format definition change. Hence this patch to ensure the check is
done correctly is the only change we need to make to the kernel to
avoid this problem in the future.

Filesystems that have this problem on disk will need to run
xfs_repair to remove the bad cluster, but no data loss is possible
from this because the kernel currently disallows inode allocation
from the bad cluster and so none of the inodes in the sparse cluster
can actually be used. Hence there is no possible data loss or other
metadata corruption possible from this situation, all we need to do
is ensure that it doesn't happen again once repair has done it's
work.

The other two patches are for issues I've recently hit when running
lots of fstests in parallel. That changes loading and hence timing
of events during tests, exposing latent race conditions in the code.
The quota fix removes racy debug code that has been there since the
quota code was first committed in 1996.

The log shutdown race fix is a much more recent issue created by
trying to ensure shutdowns operate in a sane and predictable manner.
The logic flaw is that we allow multiple log shutdowns to start and
force the log before selecting on a single log shutdown task. This
leads to a situation where shutdown log item callback processing
gets stuck waiting on a task holding a buffer lock that is waiting
on a log force that is waiting on shutdown log item callback
processing to complete...

Thoughts?