xfs: update incore per-AG inode count

For whatever reason we never actually update pagi_count (the in-core
perag inode count) when we allocate or free inode chunks.  Online scrub
is going to use it, so we need to fix the accounting.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/libxfs/xfs_ialloc.c

@@ -897,6 +897,7 @@ xfs_ialloc_ag_alloc(
 	be32_add_cpu(&agi->agi_freecount, newlen);
 	pag = xfs_perag_get(args.mp, agno);
 	pag->pagi_freecount += newlen;
+	pag->pagi_count += newlen;
 	xfs_perag_put(pag);
 	agi->agi_newino = cpu_to_be32(newino);
 
@@ -1991,6 +1992,7 @@ xfs_difree_inobt(
 		xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
 		pag = xfs_perag_get(mp, agno);
 		pag->pagi_freecount -= ilen - 1;
+		pag->pagi_count -= ilen;
 		xfs_perag_put(pag);
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
 		xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));