[XFS] sort out opening and closing of the block devices

Currently closing the rt/log block device is done in the wrong spot, and
far too early. So revampt it:

- xfs_blkdev_put moved out of xfs_free_buftarg into the caller so that

it is done after tearing down the buftarg completely.

- call to xfs_unmountfs_close moved from xfs_mountfs into caller so

that it's done after tearing down the filesystem completely.

- xfs_unmountfs_close is renamed to xfs_close_devices and made static

in xfs_super.c

- opening of the block devices is split into a helper xfs_open_devices

that is symetric in use to xfs_close_devices

- xfs_unmountfs can now lose struct cred

- error handling around device opening sanitized in xfs_fs_fill_super

SGI-PV: 981951
SGI-Modid: xfs-linux-melb:xfs-kern:31193a

Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index ee5df5f..c67f8a9 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -1278,7 +1278,7 @@
  * log and makes sure that incore structures are freed.
  */
 int
-xfs_unmountfs(xfs_mount_t *mp, struct cred *cr)
+xfs_unmountfs(xfs_mount_t *mp)
 {
 	__uint64_t	resblks;
 	int		error = 0;
@@ -1345,7 +1345,6 @@
 	 */
 	ASSERT(mp->m_inodes == NULL);
 
-	xfs_unmountfs_close(mp, cr);
 	if ((mp->m_flags & XFS_MOUNT_NOUUID) == 0)
 		uuid_table_remove(&mp->m_sb.sb_uuid);
 
@@ -1356,16 +1355,6 @@
 	return 0;
 }
 
-void
-xfs_unmountfs_close(xfs_mount_t *mp, struct cred *cr)
-{
-	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
-		xfs_free_buftarg(mp->m_logdev_targp, 1);
-	if (mp->m_rtdev_targp)
-		xfs_free_buftarg(mp->m_rtdev_targp, 1);
-	xfs_free_buftarg(mp->m_ddev_targp, 0);
-}
-
 STATIC void
 xfs_unmountfs_wait(xfs_mount_t *mp)
 {