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Commit 8f39db9d authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Rusty Russell
Browse files

virtio-blk: use virtqueue_add_sgs on bio path 



(This is a respin of Paolo Bonzini's patch, but it calls
virtqueue_add_sgs() instead of his multi-part API).

Move the creation of the request header and response footer to
__virtblk_add_req.  vbr->sg only contains the data scatterlist,
the header/footer are added separately using virtqueue_add_sgs().

With this change, virtio-blk (with use_bio) is not relying anymore on
the virtio functions ignoring the end markers in a scatterlist.
The next patch will do the same for the other path.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Reviewed-by: default avatarAsias He <asias@redhat.com>
parent 5ee21a52

drivers/block/virtio_blk.c

+29 −29
Original line number Diff line number Diff line
@@ -62,6 +62,7 @@ struct virtblk_req 
	struct virtio_blk *vblk;

	int flags;

	u8 status;

	int nents;

	struct scatterlist sg[];

};
@@ -100,24 +101,36 @@ static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk, 
	return vbr;

}



static inline int __virtblk_add_req(struct virtqueue *vq,

			     struct virtblk_req *vbr,

			     unsigned long out,

			     unsigned long in)

static int __virtblk_add_req(struct virtqueue *vq,

			     struct virtblk_req *vbr)

{

	return virtqueue_add_buf(vq, vbr->sg, out, in, vbr, GFP_ATOMIC);

	struct scatterlist hdr, status, *sgs[3];

	unsigned int num_out = 0, num_in = 0;



	sg_init_one(&hdr, &vbr->out_hdr, sizeof(vbr->out_hdr));

	sgs[num_out++] = &hdr;



	if (vbr->nents) {

		if (vbr->out_hdr.type & VIRTIO_BLK_T_OUT)

			sgs[num_out++] = vbr->sg;

		else

			sgs[num_out + num_in++] = vbr->sg;

	}



static void virtblk_add_req(struct virtblk_req *vbr,

			    unsigned int out, unsigned int in)

	sg_init_one(&status, &vbr->status, sizeof(vbr->status));

	sgs[num_out + num_in++] = &status;



	return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);

}



static void virtblk_add_req(struct virtblk_req *vbr)

{

	struct virtio_blk *vblk = vbr->vblk;

	DEFINE_WAIT(wait);

	int ret;



	spin_lock_irq(vblk->disk->queue->queue_lock);

	while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr,

						 out, in)) < 0)) {

	while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr)) < 0)) {

		prepare_to_wait_exclusive(&vblk->queue_wait, &wait,

					  TASK_UNINTERRUPTIBLE);
@@ -134,22 +147,18 @@ static void virtblk_add_req(struct virtblk_req *vbr, 


static void virtblk_bio_send_flush(struct virtblk_req *vbr)

{

	unsigned int out = 0, in = 0;



	vbr->flags |= VBLK_IS_FLUSH;

	vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;

	vbr->out_hdr.sector = 0;

	vbr->out_hdr.ioprio = 0;

	sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));

	sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status));

	vbr->nents = 0;



	virtblk_add_req(vbr, out, in);

	virtblk_add_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;

	struct bio *bio = vbr->bio;



	vbr->flags &= ~VBLK_IS_FLUSH;
@@ -157,24 +166,15 @@ static void virtblk_bio_send_data(struct virtblk_req *vbr) 
	vbr->out_hdr.sector = bio->bi_sector;

	vbr->out_hdr.ioprio = bio_prio(bio);



	sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));



	num = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg + out);



	sg_set_buf(&vbr->sg[num + out + in++], &vbr->status,

		   sizeof(vbr->status));



	if (num) {

		if (bio->bi_rw & REQ_WRITE) {

	vbr->nents = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg);

	if (vbr->nents) {

		if (bio->bi_rw & REQ_WRITE)

			vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;

			out += num;

		} else {

		else

			vbr->out_hdr.type |= VIRTIO_BLK_T_IN;

			in += num;

		}

	}



	virtblk_add_req(vbr, out, in);

	virtblk_add_req(vbr);

}



static void virtblk_bio_send_data_work(struct work_struct *work)