From: Asias He Date: Wed, 8 Aug 2012 08:07:05 +0000 (+0800) Subject: virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path X-Git-Tag: next-20120822~50^2 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=ba05c7642bb3886ff66877dbd03c4d340c4feab3;p=karo-tx-linux.git virtio-blk: Add REQ_FLUSH and REQ_FUA support to bio path 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 Cc: Jens Axboe Cc: Christoph Hellwig Cc: Tejun Heo Cc: Shaohua Li Cc: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: virtualization@lists.linux-foundation.org Signed-off-by: Asias He Signed-off-by: Rusty Russell --- diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 95cfeeda4f3a..2edfb5cef4f2 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);