xfs: disable sparse inode chunk alignment check when there is no alignment

While testing a 64k-blocksize filesystem, I noticed that xfs/709 fails
to rebuild the inode btree with a bunch of "Corruption remains"
messages.  It turns out that when the inode chunk size is smaller than a
single filesystem block, no block alignments constraints are necessary
for inode chunk allocations, and sb_spino_align is zero.  Hence we can
skip the check.

Fixes: dbfbf3bd ("xfs: repair inode btrees")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

fs/xfs/scrub/ialloc_repair.c

@@ -369,7 +369,7 @@ xrep_ibt_check_inode_ext(
 	 * On a sparse inode fs, this cluster could be part of a sparse chunk.
 	 * Sparse clusters must be aligned to sparse chunk alignment.
 	 */
-	if (xfs_has_sparseinodes(mp) &&
+	if (xfs_has_sparseinodes(mp) && mp->m_sb.sb_spino_align &&
 	    (!IS_ALIGNED(agbno, mp->m_sb.sb_spino_align) ||
 	     !IS_ALIGNED(agbno + len, mp->m_sb.sb_spino_align)))
 		return -EFSCORRUPTED;