1 files changed, 18 insertions, 17 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 0d710c9d403b..f0faefca032f 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -13,7 +13,6 @@
  * blk_queue_ordered - does this queue support ordered writes
  * @q:        the request queue
  * @ordered:  one of QUEUE_ORDERED_*
- * @prepare_flush_fn: rq setup helper for cache flush ordered writes
  *
  * Description:
  *   For journalled file systems, doing ordered writes on a commit
@@ -22,15 +21,8 @@
  *   feature should call this function and indicate so.
  *
  **/
-int blk_queue_ordered(struct request_queue *q, unsigned ordered,
-                      prepare_flush_fn *prepare_flush_fn)
+int blk_queue_ordered(struct request_queue *q, unsigned ordered)
 {
-        if (!prepare_flush_fn && (ordered & (QUEUE_ORDERED_DO_PREFLUSH |
-                                             QUEUE_ORDERED_DO_POSTFLUSH))) {
-                printk(KERN_ERR "%s: prepare_flush_fn required\n", __func__);
-                return -EINVAL;
-        }
-
         if (ordered != QUEUE_ORDERED_NONE &&
             ordered != QUEUE_ORDERED_DRAIN &&
             ordered != QUEUE_ORDERED_DRAIN_FLUSH &&
@@ -44,7 +36,6 @@ int blk_queue_ordered(struct request_queue *q, unsigned ordered,
 
         q->ordered = ordered;
         q->next_ordered = ordered;
-        q->prepare_flush_fn = prepare_flush_fn;
 
         return 0;
 }
@@ -79,7 +70,7 @@ unsigned blk_ordered_req_seq(struct request *rq)
          *
          * http://thread.gmane.org/gmane.linux.kernel/537473
          */
-        if (!blk_fs_request(rq))
+        if (rq->cmd_type != REQ_TYPE_FS)
                 return QUEUE_ORDSEQ_DRAIN;
 
         if ((rq->cmd_flags & REQ_ORDERED_COLOR) ==
@@ -143,10 +134,10 @@ static void queue_flush(struct request_queue *q, unsigned which)
         }
 
         blk_rq_init(q, rq);
-        rq->cmd_flags = REQ_HARDBARRIER;
-        rq->rq_disk = q->bar_rq.rq_disk;
+        rq->cmd_type = REQ_TYPE_FS;
+        rq->cmd_flags = REQ_HARDBARRIER | REQ_FLUSH;
+        rq->rq_disk = q->orig_bar_rq->rq_disk;
         rq->end_io = end_io;
-        q->prepare_flush_fn(q, rq);
 
         elv_insert(q, rq, ELEVATOR_INSERT_FRONT);
 }
@@ -203,7 +194,7 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp)
                 /* initialize proxy request and queue it */
                 blk_rq_init(q, rq);
                 if (bio_data_dir(q->orig_bar_rq->bio) == WRITE)
-                        rq->cmd_flags |= REQ_RW;
+                        rq->cmd_flags |= REQ_WRITE;
                 if (q->ordered & QUEUE_ORDERED_DO_FUA)
                         rq->cmd_flags |= REQ_FUA;
                 init_request_from_bio(rq, q->orig_bar_rq->bio);
@@ -236,7 +227,8 @@ static inline bool start_ordered(struct request_queue *q, struct request **rqp)
 bool blk_do_ordered(struct request_queue *q, struct request **rqp)
 {
         struct request *rq = *rqp;
-        const int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
+        const int is_barrier = rq->cmd_type == REQ_TYPE_FS &&
+                                (rq->cmd_flags & REQ_HARDBARRIER);
 
         if (!q->ordseq) {
                 if (!is_barrier)
@@ -261,7 +253,7 @@ bool blk_do_ordered(struct request_queue *q, struct request **rqp)
          */
 
         /* Special requests are not subject to ordering rules. */
-        if (!blk_fs_request(rq) &&
+        if (rq->cmd_type != REQ_TYPE_FS &&
             rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
                 return true;
 
@@ -319,6 +311,15 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
         if (!q)
                 return -ENXIO;
 
+        /*
+         * some block devices may not have their queue correctly set up here
+         * (e.g. loop device without a backing file) and so issuing a flush
+         * here will panic. Ensure there is a request function before issuing
+         * the barrier.
+         */
+        if (!q->make_request_fn)
+                return -ENXIO;
+
         bio = bio_alloc(gfp_mask, 0);
         bio->bi_end_io = bio_end_empty_barrier;
         bio->bi_bdev = bdev;