xfs: make sure to free the real-time inodes in the mount error path

When mount fails after allocating the real-time inodes we currently leak
them.  Add a new helper to free the real-time inodes which can be used by
both the mount and unmount path.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
diff --git a/fs/xfs/xfs_rtalloc.h b/fs/xfs/xfs_rtalloc.h
index 8d8dcd2..3bac681 100644
--- a/fs/xfs/xfs_rtalloc.h
+++ b/fs/xfs/xfs_rtalloc.h
@@ -108,6 +108,9 @@
 int					/* error */
 xfs_rtmount_init(
 	struct xfs_mount	*mp);	/* file system mount structure */
+void
+xfs_rtunmount_inodes(
+	struct xfs_mount	*mp);
 
 /*
  * Get the bitmap and summary inodes into the mount structure
@@ -146,6 +149,7 @@
 # define xfs_growfs_rt(mp,in)                           (ENOSYS)
 # define xfs_rtmount_init(m)    (((mp)->m_sb.sb_rblocks == 0)? 0 : (ENOSYS))
 # define xfs_rtmount_inodes(m)  (((mp)->m_sb.sb_rblocks == 0)? 0 : (ENOSYS))
+# define xfs_rtunmount_inodes(m)
 #endif	/* CONFIG_XFS_RT */
 
 #endif	/* __KERNEL__ */