xfs: using GFP_NOFS for blkdev_issue_flush

Issuing a block device flush request in transaction context using GFP_KERNEL
directly can cause deadlocks due to memory reclaim recursion. Use GFP_NOFS to
avoid recursion from reclaim context.
Signed-off-by: NShaohua Li <shli@fusionio.com>
Reviewed-by: NMark Tinguely <tinguely@sgi.com>
Signed-off-by: NBen Myers <bpm@sgi.com>

fs/xfs/xfs_super.c

@@ -622,7 +622,7 @@ void
 xfs_blkdev_issue_flush(
 	xfs_buftarg_t		*buftarg)
 {
-	blkdev_issue_flush(buftarg->bt_bdev, GFP_KERNEL, NULL);
+	blkdev_issue_flush(buftarg->bt_bdev, GFP_NOFS, NULL);
 }
 
 STATIC void