virtio_blk: blk-mq support

Switch virtio-blk from the dual support for old-style requests and bios
to use the block-multiqueue.

Acked-by: Asias He <asias@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 65 insertions, 257 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 5cdf88b7ad9e..7455fe24bbbe 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -11,12 +11,11 @@
 #include <linux/string_helpers.h>
 #include <scsi/scsi_cmnd.h>
 #include <linux/idr.h>
+#include <linux/blk-mq.h>
+#include <linux/numa.h>
 
 #define PART_BITS 4
 
-static bool use_bio;
-module_param(use_bio, bool, S_IRUGO);
-
 static int major;
 static DEFINE_IDA(vd_index_ida);
 
@@ -26,13 +25,11 @@ struct virtio_blk
 {
         struct virtio_device *vdev;
         struct virtqueue *vq;
-        wait_queue_head_t queue_wait;
+        spinlock_t vq_lock;
 
         /* The disk structure for the kernel. */
         struct gendisk *disk;
 
-        mempool_t *pool;
-
         /* Process context for config space updates */
         struct work_struct config_work;
 
@@ -47,31 +44,17 @@ struct virtio_blk
 
         /* Ida index - used to track minor number allocations. */
         int index;
-
-        /* Scatterlist: can be too big for stack. */
-        struct scatterlist sg[/*sg_elems*/];
 };
 
 struct virtblk_req
 {
         struct request *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) {
@@ -84,22 +67,6 @@ static inline int virtblk_result(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)
-                return NULL;
-
-        vbr->vblk = vblk;
-        if (use_bio)
-                sg_init_table(vbr->sg, vblk->sg_elems);
-
-        return vbr;
-}
-
 static int __virtblk_add_req(struct virtqueue *vq,
                              struct virtblk_req *vbr,
                              struct scatterlist *data_sg,
@@ -143,83 +110,8 @@ static int __virtblk_add_req(struct virtqueue *vq,
         return virtqueue_add_sgs(vq, sgs, num_out, num_in, vbr, GFP_ATOMIC);
 }
 
-static void virtblk_add_req(struct virtblk_req *vbr, bool have_data)
-{
-        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, vbr->sg,
-                                                 have_data)) < 0)) {
-                prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
-                                          TASK_UNINTERRUPTIBLE);
-
-                spin_unlock_irq(vblk->disk->queue->queue_lock);
-                io_schedule();
-                spin_lock_irq(vblk->disk->queue->queue_lock);
-
-                finish_wait(&vblk->queue_wait, &wait);
-        }
-
-        virtqueue_kick(vblk->vq);
-        spin_unlock_irq(vblk->disk->queue->queue_lock);
-}
-
-static void virtblk_bio_send_flush(struct virtblk_req *vbr)
-{
-        vbr->flags |= VBLK_IS_FLUSH;
-        vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
-        vbr->out_hdr.sector = 0;
-        vbr->out_hdr.ioprio = 0;
-
-        virtblk_add_req(vbr, false);
-}
-
-static void virtblk_bio_send_data(struct virtblk_req *vbr)
-{
-        struct virtio_blk *vblk = vbr->vblk;
-        struct bio *bio = vbr->bio;
-        bool have_data;
-
-        vbr->flags &= ~VBLK_IS_FLUSH;
-        vbr->out_hdr.type = 0;
-        vbr->out_hdr.sector = bio->bi_sector;
-        vbr->out_hdr.ioprio = bio_prio(bio);
-
-        if (blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg)) {
-                have_data = true;
-                if (bio->bi_rw & REQ_WRITE)
-                        vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
-                else
-                        vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
-        } else
-                have_data = false;
-
-        virtblk_add_req(vbr, have_data);
-}
-
-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);
 
@@ -231,90 +123,43 @@ static inline void virtblk_request_done(struct virtblk_req *vbr)
                 req->errors = (error != 0);
         }
 
-        __blk_end_request_all(req, error);
-        mempool_free(vbr, vblk->pool);
-}
-
-static inline void virtblk_bio_flush_done(struct virtblk_req *vbr)
-{
-        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);
+        blk_mq_end_io(req, error);
 }
 
 static void virtblk_done(struct virtqueue *vq)
 {
         struct virtio_blk *vblk = vq->vdev->priv;
-        bool bio_done = false, req_done = false;
+        bool req_done = false;
         struct virtblk_req *vbr;
         unsigned long flags;
         unsigned int len;
 
-        spin_lock_irqsave(vblk->disk->queue->queue_lock, flags);
+        spin_lock_irqsave(&vblk->vq_lock, flags);
         do {
                 virtqueue_disable_cb(vq);
                 while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
-                        if (vbr->bio) {
-                                virtblk_bio_done(vbr);
-                                bio_done = true;
-                        } else {
-                                virtblk_request_done(vbr);
-                                req_done = true;
-                        }
+                        virtblk_request_done(vbr);
+                        req_done = true;
                 }
         } while (!virtqueue_enable_cb(vq));
+        spin_unlock_irqrestore(&vblk->vq_lock, flags);
+
         /* In case queue is stopped waiting for more buffers. */
         if (req_done)
-                blk_start_queue(vblk->disk->queue);
-        spin_unlock_irqrestore(vblk->disk->queue->queue_lock, flags);
-
-        if (bio_done)
-                wake_up(&vblk->queue_wait);
+                blk_mq_start_stopped_hw_queues(vblk->disk->queue);
 }
 
-static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
-                   struct request *req)
+static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
 {
+        struct virtio_blk *vblk = hctx->queue->queuedata;
+        struct virtblk_req *vbr = req->special;
+        unsigned long flags;
         unsigned int num;
-        struct virtblk_req *vbr;
+        const bool last = (req->cmd_flags & REQ_END) != 0;
 
-        vbr = virtblk_alloc_req(vblk, GFP_ATOMIC);
-        if (!vbr)
-                /* When another request finishes we'll try again. */
-                return false;
+        BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
 
         vbr->req = req;
-        vbr->bio = NULL;
         if (req->cmd_flags & REQ_FLUSH) {
                 vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
                 vbr->out_hdr.sector = 0;
@@ -342,7 +187,7 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
                 }
         }
 
-        num = blk_rq_map_sg(q, vbr->req, vblk->sg);
+        num = blk_rq_map_sg(hctx->queue, vbr->req, vbr->sg);
         if (num) {
                 if (rq_data_dir(vbr->req) == WRITE)
                         vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
@@ -350,63 +195,18 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
                         vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
         }
 
-        if (__virtblk_add_req(vblk->vq, vbr, vblk->sg, num) < 0) {
-                mempool_free(vbr, vblk->pool);
-                return false;
-        }
-
-        return true;
-}
-
-static void virtblk_request(struct request_queue *q)
-{
-        struct virtio_blk *vblk = q->queuedata;
-        struct request *req;
-        unsigned int issued = 0;
-
-        while ((req = blk_peek_request(q)) != NULL) {
-                BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
-
-                /* If this request fails, stop queue and wait for something to
-                   finish to restart it. */
-                if (!do_req(q, vblk, req)) {
-                        blk_stop_queue(q);
-                        break;
-                }
-                blk_start_request(req);
-                issued++;
-        }
-
-        if (issued)
+        spin_lock_irqsave(&vblk->vq_lock, flags);
+        if (__virtblk_add_req(vblk->vq, vbr, vbr->sg, num) < 0) {
+                spin_unlock_irqrestore(&vblk->vq_lock, flags);
+                blk_mq_stop_hw_queue(hctx);
                 virtqueue_kick(vblk->vq);
-}
-
-static void virtblk_make_request(struct request_queue *q, struct bio *bio)
-{
-        struct virtio_blk *vblk = q->queuedata;
-        struct virtblk_req *vbr;
-
-        BUG_ON(bio->bi_phys_segments + 2 > vblk->sg_elems);
-
-        vbr = virtblk_alloc_req(vblk, GFP_NOIO);
-        if (!vbr) {
-                bio_endio(bio, -ENOMEM);
-                return;
+                return BLK_MQ_RQ_QUEUE_BUSY;
         }
+        spin_unlock_irqrestore(&vblk->vq_lock, flags);
 
-        vbr->bio = bio;
-        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);
+        if (last)
+                virtqueue_kick(vblk->vq);
+        return BLK_MQ_RQ_QUEUE_OK;
 }
 
 /* return id (s/n) string for *disk to *id_str
@@ -680,12 +480,35 @@ static const struct device_attribute dev_attr_cache_type_rw =
         __ATTR(cache_type, S_IRUGO|S_IWUSR,
                virtblk_cache_type_show, virtblk_cache_type_store);
 
+static struct blk_mq_ops virtio_mq_ops = {
+        .queue_rq       = virtio_queue_rq,
+        .map_queue      = blk_mq_map_queue,
+        .alloc_hctx     = blk_mq_alloc_single_hw_queue,
+        .free_hctx      = blk_mq_free_single_hw_queue,
+};
+
+static struct blk_mq_reg virtio_mq_reg = {
+        .ops            = &virtio_mq_ops,
+        .nr_hw_queues   = 1,
+        .queue_depth    = 64,
+        .numa_node      = NUMA_NO_NODE,
+        .flags          = BLK_MQ_F_SHOULD_MERGE,
+};
+
+static void virtblk_init_vbr(void *data, struct blk_mq_hw_ctx *hctx,
+                             struct request *rq, unsigned int nr)
+{
+        struct virtio_blk *vblk = data;
+        struct virtblk_req *vbr = rq->special;
+
+        sg_init_table(vbr->sg, vblk->sg_elems);
+}
+
 static int virtblk_probe(struct virtio_device *vdev)
 {
         struct virtio_blk *vblk;
         struct request_queue *q;
         int err, index;
-        int pool_size;
 
         u64 cap;
         u32 v, blk_size, sg_elems, opt_io_size;
@@ -709,17 +532,14 @@ static int virtblk_probe(struct virtio_device *vdev)
 
         /* We need an extra sg elements at head and tail. */
         sg_elems += 2;
-        vdev->priv = vblk = kmalloc(sizeof(*vblk) +
-                                    sizeof(vblk->sg[0]) * sg_elems, GFP_KERNEL);
+        vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
         if (!vblk) {
                 err = -ENOMEM;
                 goto out_free_index;
         }
 
-        init_waitqueue_head(&vblk->queue_wait);
         vblk->vdev = vdev;
         vblk->sg_elems = sg_elems;
-        sg_init_table(vblk->sg, vblk->sg_elems);
         mutex_init(&vblk->config_lock);
 
         INIT_WORK(&vblk->config_work, virtblk_config_changed_work);
@@ -728,31 +548,27 @@ static int virtblk_probe(struct virtio_device *vdev)
         err = init_vq(vblk);
         if (err)
                 goto out_free_vblk;
-
-        pool_size = sizeof(struct virtblk_req);
-        if (use_bio)
-                pool_size += sizeof(struct scatterlist) * sg_elems;
-        vblk->pool = mempool_create_kmalloc_pool(1, pool_size);
-        if (!vblk->pool) {
-                err = -ENOMEM;
-                goto out_free_vq;
-        }
+        spin_lock_init(&vblk->vq_lock);
 
         /* FIXME: How many partitions?  How long is a piece of string? */
         vblk->disk = alloc_disk(1 << PART_BITS);
         if (!vblk->disk) {
                 err = -ENOMEM;
-                goto out_mempool;
+                goto out_free_vq;
         }
 
-        q = vblk->disk->queue = blk_init_queue(virtblk_request, NULL);
+        virtio_mq_reg.cmd_size =
+                sizeof(struct virtblk_req) +
+                sizeof(struct scatterlist) * sg_elems;
+
+        q = vblk->disk->queue = blk_mq_init_queue(&virtio_mq_reg, vblk);
         if (!q) {
                 err = -ENOMEM;
                 goto out_put_disk;
         }
 
-        if (use_bio)
-                blk_queue_make_request(q, virtblk_make_request);
+        blk_mq_init_commands(q, virtblk_init_vbr, vblk);
+
         q->queuedata = vblk;
 
         virtblk_name_format("vd", index, vblk->disk->disk_name, DISK_NAME_LEN);
@@ -857,8 +673,6 @@ out_del_disk:
         blk_cleanup_queue(vblk->disk->queue);
 out_put_disk:
         put_disk(vblk->disk);
-out_mempool:
-        mempool_destroy(vblk->pool);
 out_free_vq:
         vdev->config->del_vqs(vdev);
 out_free_vblk:
@@ -890,7 +704,6 @@ static void virtblk_remove(struct virtio_device *vdev)
 
         refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
         put_disk(vblk->disk);
-        mempool_destroy(vblk->pool);
         vdev->config->del_vqs(vdev);
         kfree(vblk);
 
@@ -914,10 +727,7 @@ static int virtblk_freeze(struct virtio_device *vdev)
 
         flush_work(&vblk->config_work);
 
-        spin_lock_irq(vblk->disk->queue->queue_lock);
-        blk_stop_queue(vblk->disk->queue);
-        spin_unlock_irq(vblk->disk->queue->queue_lock);
-        blk_sync_queue(vblk->disk->queue);
+        blk_mq_stop_hw_queues(vblk->disk->queue);
 
         vdev->config->del_vqs(vdev);
         return 0;
@@ -930,11 +740,9 @@ static int virtblk_restore(struct virtio_device *vdev)
 
         vblk->config_enable = true;
         ret = init_vq(vdev->priv);
-        if (!ret) {
-                spin_lock_irq(vblk->disk->queue->queue_lock);
-                blk_start_queue(vblk->disk->queue);
-                spin_unlock_irq(vblk->disk->queue->queue_lock);
-        }
+        if (!ret)
+                blk_mq_start_stopped_hw_queues(vblk->disk->queue);
+
         return ret;
 }
 #endif