xfs: only issues a cache flush on unmount if barriers are enabled

Currently we unconditionally issue a flush from xfs_free_buftarg, but
since 2.6.29-rc1 this gives a warning in the style of

	end_request: I/O error, dev vdb, sector 0

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Felix Blyakher <felixb@sgi.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index cb329edc925b..aa1016bb9134 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -34,6 +34,12 @@
 #include <linux/backing-dev.h>
 #include <linux/freezer.h>
 
+#include "xfs_sb.h"
+#include "xfs_inum.h"
+#include "xfs_ag.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+
 static kmem_zone_t *xfs_buf_zone;
 STATIC int xfsbufd(void *);
 STATIC int xfsbufd_wakeup(int, gfp_t);
@@ -1435,10 +1441,12 @@ xfs_unregister_buftarg(
 
 void
 xfs_free_buftarg(
-        xfs_buftarg_t           *btp)
+        struct xfs_mount        *mp,
+        struct xfs_buftarg      *btp)
 {
         xfs_flush_buftarg(btp, 1);
-        xfs_blkdev_issue_flush(btp);
+        if (mp->m_flags & XFS_MOUNT_BARRIER)
+                xfs_blkdev_issue_flush(btp);
         xfs_free_bufhash(btp);
         iput(btp->bt_mapping->host);