virtio_blk: remove nents member.

It's simply a flag as to whether we have data now, so make it an
explicit function parameter rather than a member of struct
virtblk_req.

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

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index cc88b29..6472395 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -62,7 +62,6 @@ struct virtblk_req
        struct virtio_blk *vblk;
        int flags;
        u8 status;
-       int nents;
        struct scatterlist sg[];
 };
 
@@ -104,7 +103,7 @@ static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
 static int __virtblk_add_req(struct virtqueue *vq,
                             struct virtblk_req *vbr,
                             struct scatterlist *data_sg,
-                            unsigned data_nents)
+                            bool have_data)
 {
        struct scatterlist hdr, status, cmd, sense, inhdr, *sgs[6];
        unsigned int num_out = 0, num_in = 0;
@@ -124,7 +123,7 @@ static int __virtblk_add_req(struct virtqueue *vq,
                sgs[num_out++] = &cmd;
        }
 
-       if (data_nents) {
+       if (have_data) {
                if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)
                        sgs[num_out++] = data_sg;
                else
@@ -144,7 +143,7 @@ static int __virtblk_add_req(struct virtqueue *vq,
        return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 }
 
-static void virtblk_add_req(struct virtblk_req *vbr)
+static void virtblk_add_req(struct virtblk_req *vbr, bool have_data)
 {
        struct virtio_blk *vblk = vbr->vblk;
        DEFINE_WAIT(wait);
@@ -152,7 +151,7 @@ static void virtblk_add_req(struct virtblk_req *vbr)
 
        spin_lock_irq(vblk->disk->queue->queue_lock);
        while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, vbr->sg,
-                                                vbr->nents)) < 0)) {
+                                                have_data)) < 0)) {
                prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
                                          TASK_UNINTERRUPTIBLE);
 
@@ -173,30 +172,31 @@ static void virtblk_bio_send_flush(struct virtblk_req *vbr)
        vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
        vbr->out_hdr.sector = 0;
        vbr->out_hdr.ioprio = 0;
-       vbr->nents = 0;
 
-       virtblk_add_req(vbr);
+       virtblk_add_req(vbr, false);
 }
 
 static void virtblk_bio_send_data(struct virtblk_req *vbr)
 {
        struct virtio_blk *vblk = vbr->vblk;
        struct bio *bio = vbr->bio;
+       bool have_data;
 
        vbr->flags &= ~VBLK_IS_FLUSH;
        vbr->out_hdr.type = 0;
        vbr->out_hdr.sector = bio->bi_sector;
        vbr->out_hdr.ioprio = bio_prio(bio);
 
-       vbr->nents = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg);
-       if (vbr->nents) {
+       if (blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg)) {
+               have_data = true;
                if (bio->bi_rw & REQ_WRITE)
                        vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
                else
                        vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
-       }
+       } else
+               have_data = false;
 
-       virtblk_add_req(vbr);
+       virtblk_add_req(vbr, have_data);
 }
 
 static void virtblk_bio_send_data_work(struct work_struct *work)