xfs: Make inode32 a remountable option

As inode64 is the default option now, and was also made remountable
previously, inode32 can also be remounted on-the-fly when it is needed.
Signed-off-by: NCarlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>

fs/xfs/xfs_super.c

@@ -122,13 +122,18 @@ mempool_t *xfs_ioend_pool;
  * in the future, too.
  */
 enum {
-	Opt_barrier, Opt_nobarrier, Opt_inode64, Opt_err
+	Opt_barrier,
+	Opt_nobarrier,
+	Opt_inode64,
+	Opt_inode32,
+	Opt_err
 };
 
 static const match_table_t tokens = {
 	{Opt_barrier, "barrier"},
 	{Opt_nobarrier, "nobarrier"},
 	{Opt_inode64, "inode64"},
+	{Opt_inode32, "inode32"},
 	{Opt_err, NULL}
 };
 
@@ -1141,6 +1146,9 @@ xfs_fs_remount(
 		case Opt_inode64:
 			mp->m_maxagi = xfs_set_inode64(mp);
 			break;
+		case Opt_inode32:
+			mp->m_maxagi = xfs_set_inode32(mp);
+			break;
 		default:
 			/*
 			 * Logically we would return an error here to prevent