virtio-blk: reorganize virtblk_add_req

Right now, both virtblk_add_req and virtblk_add_req_wait call
virtqueue_add_buf.  To prepare for the next patches, abstract the call
to virtqueue_add_buf into a new function __virtblk_add_req, and include
the waiting logic directly in virtblk_add_req.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Asias He <asias@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 922bcb9..b271650 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -100,50 +100,39 @@ static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
        return vbr;
 }
 
-static void virtblk_add_buf_wait(struct virtio_blk *vblk,
-                                struct virtblk_req *vbr,
-                                unsigned long out,
-                                unsigned long in)
+static inline int __virtblk_add_req(struct virtqueue *vq,
+                            struct virtblk_req *vbr,
+                            unsigned long out,
+                            unsigned long in)
 {
+       return virtqueue_add_buf(vq, vbr->sg, out, in, vbr, GFP_ATOMIC);
+}
+
+static void virtblk_add_req(struct virtblk_req *vbr,
+                           unsigned int out, unsigned int in)
+{
+       struct virtio_blk *vblk = vbr->vblk;
        DEFINE_WAIT(wait);
+       int ret;
 
-       for (;;) {
+       spin_lock_irq(vblk->disk->queue->queue_lock);
+       while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr,
+                                                out, in)) < 0)) {
                prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
                                          TASK_UNINTERRUPTIBLE);
 
+               spin_unlock_irq(vblk->disk->queue->queue_lock);
+               io_schedule();
                spin_lock_irq(vblk->disk->queue->queue_lock);
-               if (virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
-                                     GFP_ATOMIC) < 0) {
-                       spin_unlock_irq(vblk->disk->queue->queue_lock);
-                       io_schedule();
-               } else {
-                       virtqueue_kick(vblk->vq);
-                       spin_unlock_irq(vblk->disk->queue->queue_lock);
-                       break;
-               }
 
+               finish_wait(&vblk->queue_wait, &wait);
        }
 
-       finish_wait(&vblk->queue_wait, &wait);
-}
-
-static inline void virtblk_add_req(struct virtblk_req *vbr,
-                                  unsigned int out, unsigned int in)
-{
-       struct virtio_blk *vblk = vbr->vblk;
-
-       spin_lock_irq(vblk->disk->queue->queue_lock);
-       if (unlikely(virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
-                                       GFP_ATOMIC) < 0)) {
-               spin_unlock_irq(vblk->disk->queue->queue_lock);
-               virtblk_add_buf_wait(vblk, vbr, out, in);
-               return;
-       }
        virtqueue_kick(vblk->vq);
        spin_unlock_irq(vblk->disk->queue->queue_lock);
 }
 
-static int virtblk_bio_send_flush(struct virtblk_req *vbr)
+static void virtblk_bio_send_flush(struct virtblk_req *vbr)
 {
        unsigned int out = 0, in = 0;
 
@@ -155,11 +144,9 @@ static int virtblk_bio_send_flush(struct virtblk_req *vbr)
        sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status));
 
        virtblk_add_req(vbr, out, in);
-
-       return 0;
 }
 
-static int virtblk_bio_send_data(struct virtblk_req *vbr)
+static void virtblk_bio_send_data(struct virtblk_req *vbr)
 {
        struct virtio_blk *vblk = vbr->vblk;
        unsigned int num, out = 0, in = 0;
@@ -188,8 +175,6 @@ static int virtblk_bio_send_data(struct virtblk_req *vbr)
        }
 
        virtblk_add_req(vbr, out, in);
-
-       return 0;
 }
 
 static void virtblk_bio_send_data_work(struct work_struct *work)