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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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reviewed-by: Asias He <asias@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-03-20 15:44:27 +10:30 committed by Rusty Russell
parent 5ee21a52c0
commit 8f39db9d37
1 changed files with 29 additions and 29 deletions
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58
drivers/block/virtio_blk.c
View File

@ -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;
}
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,
unsigned int out, unsigned int in)
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)