drbd: drop drbd_md_flush

The only user of drbd_md_flush was bm_rw(),
and it is always followed by either a drbd_md_sync(),
or an al_write_transaction(), which, if so configured,
both end up submiting a FLUSH|FUA request anyways.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

drivers/block/drbd/drbd_bitmap.c

@@ -1155,9 +1155,7 @@ static int bm_rw(struct drbd_device *device, int rw, unsigned flags, unsigned la
 		err = -EIO; /* Disk timeout/force-detach during IO... */
 
 	now = jiffies;
-	if (rw == WRITE) {
-		drbd_md_flush(device);
-	} else /* rw == READ */ {
+	if (rw == READ) {
 		b->bm_set = bm_count_bits(b);
 		drbd_info(device, "recounting of set bits took additional %lu jiffies\n",
 		     jiffies - now);

drivers/block/drbd/drbd_int.h

@@ -2182,25 +2182,6 @@ static inline int drbd_queue_order_type(struct drbd_device *device)
 	return QUEUE_ORDERED_NONE;
 }
 
-static inline void drbd_md_flush(struct drbd_device *device)
-{
-	int r;
-
-	if (device->ldev == NULL) {
-		drbd_warn(device, "device->ldev == NULL in drbd_md_flush\n");
-		return;
-	}
-
-	if (test_bit(MD_NO_FUA, &device->flags))
-		return;
-
-	r = blkdev_issue_flush(device->ldev->md_bdev, GFP_NOIO, NULL);
-	if (r) {
-		set_bit(MD_NO_FUA, &device->flags);
-		drbd_err(device, "meta data flush failed with status %d, disabling md-flushes\n", r);
-	}
-}
-
 static inline struct drbd_connection *first_connection(struct drbd_resource *resource)
 {
 	return list_first_entry_or_null(&resource->connections,