We need to support both REQ_FLUSH and REQ_FUA for bio based path since
it does not get the sequencing of REQ_FUA into REQ_FLUSH that request
based drivers can request.
REQ_FLUSH is emulated by:
A) If the bio has no data to write:
1. Send VIRTIO_BLK_T_FLUSH to device,
2. In the flush I/O completion handler, finish the bio
B) If the bio has data to write:
1. Send VIRTIO_BLK_T_FLUSH to device
2. In the flush I/O completion handler, send the actual write data to device
3. In the write I/O completion handler, finish the bio
REQ_FUA is emulated by:
1. Send the actual write data to device
2. In the write I/O completion handler, send VIRTIO_BLK_T_FLUSH to device
3. In the flush I/O completion handler, finish the bio
Changes in v7:
- Using vbr->flags to trace request type
- Dropped unnecessary struct virtio_blk *vblk parameter
- Reuse struct virtblk_req in bio done function
Cahnges in v6:
- Reworked REQ_FLUSH and REQ_FUA emulatation order
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Shaohua Li <shli@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Asias He <asias@xxxxxxxxxx>
---
drivers/block/virtio_blk.c | 272 +++++++++++++++++++++++++++++++--------------
1 file changed, 188 insertions(+), 84 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 95cfeed..2edfb5c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -58,10 +58,20 @@ struct virtblk_req
struct bio *bio;
struct virtio_blk_outhdr out_hdr;
struct virtio_scsi_inhdr in_hdr;
+ struct work_struct work;
+ struct virtio_blk *vblk;
+ int flags;
u8 status;
struct scatterlist sg[];
};
+enum {
+ VBLK_IS_FLUSH = 1,
+ VBLK_REQ_FLUSH = 2,
+ VBLK_REQ_DATA = 4,
+ VBLK_REQ_FUA = 8,
+};
+
static inline int virtblk_result(struct virtblk_req *vbr)
{
switch (vbr->status) {
@@ -74,9 +84,133 @@ static inline int virtblk_result(struct virtblk_req *vbr)
}
}
-static inline void virtblk_request_done(struct virtio_blk *vblk,
- struct virtblk_req *vbr)
+static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
+ gfp_t gfp_mask)
+{
+ struct virtblk_req *vbr;
+
+ vbr = mempool_alloc(vblk->pool, gfp_mask);
+ if (vbr && use_bio)
+ sg_init_table(vbr->sg, vblk->sg_elems);
+
+ vbr->vblk = vblk;
+
+ return vbr;
+}
+
+static void virtblk_add_buf_wait(struct virtio_blk *vblk,
+ struct virtblk_req *vbr,
+ unsigned long out,
+ unsigned long in)
+{
+ DEFINE_WAIT(wait);
+
+ for (;;) {
+ prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ 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);
+}
+
+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)
+{
+ 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));
+
+ virtblk_add_req(vbr, out, in);
+
+ return 0;
+}
+
+static int 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;
+ vbr->out_hdr.type = 0;
+ 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->out_hdr.type |= VIRTIO_BLK_T_OUT;
+ out += num;
+ } else {
+ vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
+ in += num;
+ }
+ }
+
+ virtblk_add_req(vbr, out, in);
+
+ return 0;
+}
+
+static void virtblk_bio_send_data_work(struct work_struct *work)
+{
+ struct virtblk_req *vbr;
+
+ vbr = container_of(work, struct virtblk_req, work);
+
+ virtblk_bio_send_data(vbr);
+}
+
+static void virtblk_bio_send_flush_work(struct work_struct *work)
+{
+ struct virtblk_req *vbr;
+
+ vbr = container_of(work, struct virtblk_req, work);
+
+ virtblk_bio_send_flush(vbr);
+}
+
+static inline void virtblk_request_done(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
struct request *req = vbr->req;
int error = virtblk_result(vbr);
@@ -92,17 +226,47 @@ static inline void virtblk_request_done(struct virtio_blk *vblk,
mempool_free(vbr, vblk->pool);
}
-static inline void virtblk_bio_done(struct virtio_blk *vblk,
- struct virtblk_req *vbr)
+static inline void virtblk_bio_flush_done(struct virtblk_req *vbr)
{
- bio_endio(vbr->bio, virtblk_result(vbr));
- mempool_free(vbr, vblk->pool);
+ struct virtio_blk *vblk = vbr->vblk;
+
+ if (vbr->flags & VBLK_REQ_DATA) {
+ /* Send out the actual write data */
+ INIT_WORK(&vbr->work, virtblk_bio_send_data_work);
+ queue_work(virtblk_wq, &vbr->work);
+ } else {
+ bio_endio(vbr->bio, virtblk_result(vbr));
+ mempool_free(vbr, vblk->pool);
+ }
+}
+
+static inline void virtblk_bio_data_done(struct virtblk_req *vbr)
+{
+ struct virtio_blk *vblk = vbr->vblk;
+
+ if (unlikely(vbr->flags & VBLK_REQ_FUA)) {
+ /* Send out a flush before end the bio */
+ vbr->flags &= ~VBLK_REQ_DATA;
+ INIT_WORK(&vbr->work, virtblk_bio_send_flush_work);
+ queue_work(virtblk_wq, &vbr->work);
+ } else {
+ bio_endio(vbr->bio, virtblk_result(vbr));
+ mempool_free(vbr, vblk->pool);
+ }
+}
+
+static inline void virtblk_bio_done(struct virtblk_req *vbr)
+{
+ if (unlikely(vbr->flags & VBLK_IS_FLUSH))
+ virtblk_bio_flush_done(vbr);
+ else
+ virtblk_bio_data_done(vbr);
}
static void virtblk_done(struct virtqueue *vq)
{
struct virtio_blk *vblk = vq->vdev->priv;
- unsigned long bio_done = 0, req_done = 0;
+ bool bio_done = false, req_done = false;
struct virtblk_req *vbr;
unsigned long flags;
unsigned int len;
@@ -110,11 +274,11 @@ static void virtblk_done(struct virtqueue *vq)
spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
if (vbr->bio) {
- virtblk_bio_done(vblk, vbr);
- bio_done++;
+ virtblk_bio_done(vbr);
+ bio_done = true;
} else {
- virtblk_request_done(vblk, vbr);
- req_done++;
+ virtblk_request_done(vbr);
+ req_done = true;
}
}
/* In case queue is stopped waiting for more buffers. */
@@ -126,18 +290,6 @@ static void virtblk_done(struct virtqueue *vq)
wake_up(&vblk->queue_wait);
}
-static inline struct virtblk_req *virtblk_alloc_req(struct virtio_blk *vblk,
- gfp_t gfp_mask)
-{
- struct virtblk_req *vbr;
-
- vbr = mempool_alloc(vblk->pool, gfp_mask);
- if (vbr && use_bio)
- sg_init_table(vbr->sg, vblk->sg_elems);
-
- return vbr;
-}
-
static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
struct request *req)
{
@@ -242,41 +394,12 @@ static void virtblk_request(struct request_queue *q)
virtqueue_kick(vblk->vq);
}
-static void virtblk_add_buf_wait(struct virtio_blk *vblk,
- struct virtblk_req *vbr,
- unsigned long out,
- unsigned long in)
-{
- DEFINE_WAIT(wait);
-
- for (;;) {
- prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
- TASK_UNINTERRUPTIBLE);
-
- 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);
-}
-
static void virtblk_make_request(struct request_queue *q, struct bio *bio)
{
struct virtio_blk *vblk = q->queuedata;
- unsigned int num, out = 0, in = 0;
struct virtblk_req *vbr;
BUG_ON(bio->bi_phys_segments + 2 > vblk->sg_elems);
- BUG_ON(bio->bi_rw & (REQ_FLUSH | REQ_FUA));
vbr = virtblk_alloc_req(vblk, GFP_NOIO);
if (!vbr) {
@@ -285,37 +408,18 @@ static void virtblk_make_request(struct request_queue *q, struct bio *bio)
}
vbr->bio = bio;
- vbr->req = NULL;
- vbr->out_hdr.type = 0;
- 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(q, 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->out_hdr.type |= VIRTIO_BLK_T_OUT;
- out += num;
- } else {
- vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
- in += num;
- }
- }
-
- 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);
+ vbr->flags = 0;
+ if (bio->bi_rw & REQ_FLUSH)
+ vbr->flags |= VBLK_REQ_FLUSH;
+ if (bio->bi_rw & REQ_FUA)
+ vbr->flags |= VBLK_REQ_FUA;
+ if (bio->bi_size)
+ vbr->flags |= VBLK_REQ_DATA;
+
+ if (unlikely(vbr->flags & VBLK_REQ_FLUSH))
+ virtblk_bio_send_flush(vbr);
+ else
+ virtblk_bio_send_data(vbr);
}
/* return id (s/n) string for *disk to *id_str
@@ -529,7 +633,7 @@ static void virtblk_update_cache_mode(struct virtio_device *vdev)
u8 writeback = virtblk_get_cache_mode(vdev);
struct virtio_blk *vblk = vdev->priv;
- if (writeback && !use_bio)
+ if (writeback)
blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
else
blk_queue_flush(vblk->disk->queue, 0);
--
1.7.11.2
--
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