xfs_scrub: don't blow away new inodes in bulkstat_single_step

xfs_scrub: don't blow away new inodes in bulkstat_single_step

bulkstat_single_step has an ugly misfeature -- given the inumbers
record, it expects to find bulkstat data for those inodes, in the exact
order that they were specified in inumbers.  If a new inode is created
after inumbers but before bulkstat, bulkstat will return stat data for
that inode, only to have bulkstat_single_step obliterate it.  Then we
fail to scan that inode.

Instead, we should use the returned bulkstat array to compute a bitmask
of inodes that bulkstat had to have seen while it was walking the inobt.
An important detail is that any inode between the @ino parameter passed
to bulkstat and the last bulkstat record it returns was seen, even if no
bstat record was produced.

Any inode set in xi_allocmask but not set in the seen_mask is missing
and needs to be loaded.  Load bstat data for those inodes into the /end/
of the array so that we don't obliterate bstat data for a newly created
inode, then re-sort the array so we always scan in ascending inumber
order.

Cc: <linux-xfs@vger.kernel.org> # v5.18.0
Fixes: 245c72a6eeb720 ("xfs_scrub: balance inode chunk scan across CPUs")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>