md: Call blk_queue_flush() to establish flush/fua support

Before 2.6.37, the md layer had a mechanism for catching I/Os with the
barrier flag set, and translating the barrier into barriers for all
the underlying devices.  With 2.6.37, I/O barriers have become plain
old flushes, and the md code was updated to reflect this.  However,
one piece was left out -- the md layer does not tell the block layer
that it supports flushes or FUA access at all, which results in md
silently dropping flush requests.

Since the support already seems there, just add this one piece of
bookkeeping.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 7b9e229a05e219497c82ebebb97fc3fb00f7ac75..84c46a161927999ebfc6c5d56d98e76247e66ae4 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4338,6 +4338,8 @@ static int md_alloc(dev_t dev, char *name)
        if (mddev->kobj.sd &&
            sysfs_create_group(&mddev->kobj, &md_bitmap_group))
                printk(KERN_DEBUG "pointless warning\n");
+
+       blk_queue_flush(mddev->queue, REQ_FLUSH | REQ_FUA);
  abort:
        mutex_unlock(&disks_mutex);
        if (!error && mddev->kobj.sd) {