[Xen-devel] [PATCH 3/5] blktap: Add queue access macros.

[Daniel Stodden <daniel.stodden@xxxxxxxxxx>]

Reduce request queue access in different contexts to a small set of
macros. Also simplifies transitions between different kernel versions.

Signed-off-by: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
---
 drivers/xen/blktap/device.c |   54 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/blktap/device.c b/drivers/xen/blktap/device.c
index 02e1fc8..4c4d682 100644
--- a/drivers/xen/blktap/device.c
+++ b/drivers/xen/blktap/device.c
@@ -103,6 +103,42 @@ static struct block_device_operations 
blktap_device_file_operations = {
        .getgeo    = blktap_device_getgeo
 };
 
+/* NB. __blktap holding the queue lock; blktap where unlocked */
+
+static inline struct request*
+__blktap_next_queued_rq(struct request_queue *q)
+{
+       return elv_next_request(q);
+}
+
+static inline void
+__blktap_dequeue_rq(struct request *rq)
+{
+       blkdev_dequeue_request(rq);
+}
+
+/* NB. err == 0 indicates success, failures < 0 */
+
+static inline void
+__blktap_end_queued_rq(struct request *rq, int err)
+{
+       __blk_end_request(rq, err, blk_rq_bytes(rq));
+}
+
+static inline void
+__blktap_end_rq(struct request *rq, int err)
+{
+       __blk_end_request(rq, err, blk_rq_bytes(rq));
+}
+
+static inline void
+blktap_end_rq(struct request *rq, int err)
+{
+       spin_lock_irq(rq->q->queue_lock);
+       __blktap_end_rq(rq, err);
+       spin_unlock_irq(rq->q->queue_lock);
+}
+
 void
 blktap_device_end_request(struct blktap *tap,
                          struct blktap_request *request,
@@ -119,9 +155,7 @@ blktap_device_end_request(struct blktap *tap,
                "end_request: op=%d error=%d bytes=%d\n",
                rq_data_dir(rq), error, blk_rq_bytes(rq));
 
-       spin_lock_irq(&tapdev->lock);
-       end_request(request->rq, !error);
-       spin_unlock_irq(&tapdev->lock);
+       blktap_end_rq(rq, error);
 }
 
 int
@@ -201,17 +235,17 @@ blktap_device_run_queue(struct blktap *tap)
        queue_flag_clear(QUEUE_FLAG_STOPPED, q);
 
        do {
-               rq = elv_next_request(q);
+               rq = __blktap_next_queued_rq(q);
                if (!rq)
                        break;
 
                if (!blk_fs_request(rq)) {
-                       end_queued_request(rq, 0);
+                       __blktap_end_queued_rq(rq, -EOPNOTSUPP);
                        continue;
                }
 
                if (blk_empty_barrier(rq)) {
-                       end_queued_request(rq, 1);
+                       __blktap_end_queued_rq(rq, 0);
                        continue;
                }
 
@@ -226,10 +260,10 @@ blktap_device_run_queue(struct blktap *tap)
                        break;
                }
 
-               blkdev_dequeue_request(req);
+               __blktap_dequeue_rq(rq);
 
                if (unlikely(err))
-                       end_request(rq, 0);
+                       __blktap_end_rq(rq, err);
        } while (1);
 
        spin_unlock_irq(&tapdev->lock);
@@ -365,11 +399,11 @@ blktap_device_fail_queue(struct blktap *tap)
        queue_flag_clear(QUEUE_FLAG_STOPPED, q);
 
        do {
-               struct request *rq = elv_next_request(q);
+               struct request *rq = __blktap_next_queued_rq(q);
                if (!rq)
                        break;
 
-               end_request(rq, -EIO);
+               __blktap_end_queued_rq(rq, -EIO);
        } while (1);
 
        spin_unlock_irq(&tapdev->lock);
-- 
1.7.0.4


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