xen/blkback: Don't let in-flight requests defer pending ones.

[pandora-kernel.git] / drivers / block / xen-blkback / blkback.c

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index 5cf2993..f0537f3 100644 (file)
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -458,7 +458,8 @@ static void end_block_io_op(struct bio *bio, int error)
  * (which has the sectors we want, number of them, grant references, etc),
  * and transmute  it to the block API to hand it over to the proper block disk.
  */
-static int do_block_io_op(struct xen_blkif *blkif)
+static int
+__do_block_io_op(struct xen_blkif *blkif)
 {
        union blkif_back_rings *blk_rings = &blkif->blk_rings;
        struct blkif_request req;
@@ -515,6 +516,23 @@ static int do_block_io_op(struct xen_blkif *blkif)
        return more_to_do;
 }
 
+static int
+do_block_io_op(struct xen_blkif *blkif)
+{
+       union blkif_back_rings *blk_rings = &blkif->blk_rings;
+       int more_to_do;
+
+       do {
+               more_to_do = __do_block_io_op(blkif);
+               if (more_to_do)
+                       break;
+
+               RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
+       } while (more_to_do);
+
+       return more_to_do;
+}
+
 /*
  * Transmutation of the 'struct blkif_request' to a proper 'struct bio'
  * and call the 'submit_bio' to pass it to the underlying storage.
@@ -700,7 +718,6 @@ static void make_response(struct xen_blkif *blkif, u64 id,
        struct blkif_response  resp;
        unsigned long     flags;
        union blkif_back_rings *blk_rings = &blkif->blk_rings;
-       int more_to_do = 0;
        int notify;
 
        resp.id        = id;
@@ -727,22 +744,7 @@ static void make_response(struct xen_blkif *blkif, u64 id,
        }
        blk_rings->common.rsp_prod_pvt++;
        RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&blk_rings->common, notify);
-       if (blk_rings->common.rsp_prod_pvt == blk_rings->common.req_cons) {
-               /*
-                * Tail check for pending requests. Allows frontend to avoid
-                * notifications if requests are already in flight (lower
-                * overheads and promotes batching).
-                */
-               RING_FINAL_CHECK_FOR_REQUESTS(&blk_rings->common, more_to_do);
-
-       } else if (RING_HAS_UNCONSUMED_REQUESTS(&blk_rings->common)) {
-               more_to_do = 1;
-       }
-
        spin_unlock_irqrestore(&blkif->blk_ring_lock, flags);
-
-       if (more_to_do)
-               blkif_notify_work(blkif);
        if (notify)
                notify_remote_via_irq(blkif->irq);
 }