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Date: Thu, 7 Feb 2013 13:22:28 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Wanlong Gao <gaowanlong@...fujitsu.com>, asias@...hat.com,
Rusty Russell <rusty@...tcorp.com.au>, mst@...hat.com,
kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org
Subject: [RFC PATCH 4/8] virtio-blk: use virtqueue_start_buf on req path
This is similar to the previous patch, but a bit more radical
because the bio and req paths now share the buffer construction
code. Because the req path doesn't use vbr->sg, however, we
need to add a couple of arguments to __virtblk_add_req.
We also need to teach __virtblk_add_req how to build SCSI command
requests.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
drivers/block/virtio_blk.c | 73 +++++++++++++++++++++++---------------------
1 files changed, 38 insertions(+), 35 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 538cc40..5896b4d 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -102,19 +102,27 @@ 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 virtblk_req *vbr,
+ struct scatterlist *io_sg,
+ unsigned io_sg_count)
{
struct virtqueue_buf buf;
struct scatterlist sg;
enum dma_data_direction dir;
int ret;
+ int type = vbr->out_hdr.type & ~VIRTIO_BLK_T_OUT;
unsigned int count = 2;
unsigned int count_sg = 2;
- if (vbr->sg_count) {
+ if (type == VIRTIO_BLK_T_SCSI_CMD) {
+ BUG_ON(use_bio);
+ count_sg += 3;
+ count += 3;
+ }
+ if (io_sg_count) {
count_sg++;
- count += vbr->sg_count;
+ count += io_sg_count;
}
ret = virtqueue_start_buf(vq, &buf, vbr, count, count_sg, GFP_ATOMIC);
@@ -125,14 +133,32 @@ static int __virtblk_add_req(struct virtqueue *vq,
sg_init_one(&sg, &vbr->out_hdr, sizeof(vbr->out_hdr));
virtqueue_add_sg_single(&buf, &sg, dir);
- if (vbr->sg_count) {
+ /*
+ * If this is a packet command we need a couple of additional headers.
+ * Behind the normal outhdr we put a segment with the scsi command
+ * block, and before the normal inhdr we put the sense data and the
+ * inhdr with additional status information before the normal inhdr.
+ */
+ if (type == VIRTIO_BLK_T_SCSI_CMD) {
+ sg_init_one(&sg, vbr->req->cmd, vbr->req->cmd_len);
+ virtqueue_add_sg_single(&buf, &sg, dir);
+ }
+
+ if (io_sg_count) {
if ((vbr->out_hdr.type & VIRTIO_BLK_T_OUT) == 0)
dir = DMA_FROM_DEVICE;
- virtqueue_add_sg(&buf, vbr->sg, vbr->sg_count, dir);
+ virtqueue_add_sg(&buf, io_sg, io_sg_count, dir);
}
dir = DMA_FROM_DEVICE;
+ if (type == VIRTIO_BLK_T_SCSI_CMD) {
+ sg_init_one(&sg, vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
+ virtqueue_add_sg_single(&buf, &sg, dir);
+ sg_init_one(&sg, &vbr->in_hdr, sizeof(vbr->in_hdr));
+ virtqueue_add_sg_single(&buf, &sg, dir);
+ }
+
sg_init_one(&sg, &vbr->status, sizeof(vbr->status));
virtqueue_add_sg_single(&buf, &sg, dir);
@@ -147,7 +173,8 @@ static void virtblk_add_req(struct virtblk_req *vbr)
int ret;
spin_lock_irq(vblk->disk->queue->queue_lock);
- while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr)) < 0)) {
+ while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, vbr->sg,
+ vbr->sg_count)) < 0)) {
prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
TASK_UNINTERRUPTIBLE);
@@ -300,7 +327,7 @@ static void virtblk_done(struct virtqueue *vq)
static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
struct request *req)
{
- unsigned long num, out = 0, in = 0;
+ unsigned int num;
struct virtblk_req *vbr;
vbr = virtblk_alloc_req(vblk, GFP_ATOMIC);
@@ -337,40 +364,16 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
}
}
- sg_set_buf(&vblk->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
-
- /*
- * If this is a packet command we need a couple of additional headers.
- * Behind the normal outhdr we put a segment with the scsi command
- * block, and before the normal inhdr we put the sense data and the
- * inhdr with additional status information before the normal inhdr.
- */
- if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC)
- sg_set_buf(&vblk->sg[out++], vbr->req->cmd, vbr->req->cmd_len);
-
- num = blk_rq_map_sg(q, vbr->req, vblk->sg + out);
-
- if (vbr->req->cmd_type == REQ_TYPE_BLOCK_PC) {
- sg_set_buf(&vblk->sg[num + out + in++], vbr->req->sense, SCSI_SENSE_BUFFERSIZE);
- sg_set_buf(&vblk->sg[num + out + in++], &vbr->in_hdr,
- sizeof(vbr->in_hdr));
- }
-
- sg_set_buf(&vblk->sg[num + out + in++], &vbr->status,
- sizeof(vbr->status));
+ num = blk_rq_map_sg(q, vbr->req, vblk->sg);
if (num) {
- if (rq_data_dir(vbr->req) == WRITE) {
+ if (rq_data_dir(vbr->req) == WRITE)
vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
- out += num;
- } else {
+ else
vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
- in += num;
- }
}
- if (virtqueue_add_buf(vblk->vq, vblk->sg, out, in, vbr,
- GFP_ATOMIC) < 0) {
+ if (__virtblk_add_req(vblk->vq, vbr, vblk->sg, num) < 0) {
mempool_free(vbr, vblk->pool);
return false;
}
--
1.7.1
--
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