xfs: reduce code duplication handling inode32/64 options

Add xfs_set_inode32() to be used to enable inode32 allocation mode. this
will reduce the amount of duplicated code needed to mount/remount a
filesystem with inode32 option.  This patch also changes
xfs_set_inode64() to return the maximum AG number that inodes can be
allocated instead of set mp->m_maxagi by itself, so that the behaviour
is the same as xfs_set_inode32().  This simplifies code that calls these
functions and needs to know the maximum AG that inodes can be allocated
in.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_super.h b/fs/xfs/xfs_super.h
index 09b0c26..9de4a92 100644
--- a/fs/xfs/xfs_super.h
+++ b/fs/xfs/xfs_super.h
@@ -75,6 +75,8 @@
 extern __uint64_t xfs_max_file_offset(unsigned int);
 
 extern void xfs_blkdev_issue_flush(struct xfs_buftarg *);
+extern xfs_agnumber_t xfs_set_inode32(struct xfs_mount *);
+extern xfs_agnumber_t xfs_set_inode64(struct xfs_mount *);
 
 extern const struct export_operations xfs_export_operations;
 extern const struct xattr_handler *xfs_xattr_handlers[];