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https://github.com/torvalds/linux
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block: virtio-blk: support multi virt queues per virtio-blk device
Firstly this patch supports more than one virtual queues for virtio-blk device. Secondly this patch maps the virtual queue to blk-mq's hardware queue. With this approach, both scalability and performance can be improved. Signed-off-by: Ming Lei <ming.lei@canonical.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lei
Jens Axboe
parent
cb553215d5
commit
6a27b656fc
1 changed files with 84 additions and 20 deletions
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@ -15,17 +15,22 @@
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#include <linux/numa.h>
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#define PART_BITS 4
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#define VQ_NAME_LEN 16
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static int major;
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static DEFINE_IDA(vd_index_ida);
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static struct workqueue_struct *virtblk_wq;
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struct virtio_blk_vq {
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struct virtqueue *vq;
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spinlock_t lock;
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char name[VQ_NAME_LEN];
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} ____cacheline_aligned_in_smp;
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struct virtio_blk
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{
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struct virtio_device *vdev;
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struct virtqueue *vq;
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spinlock_t vq_lock;
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/* The disk structure for the kernel. */
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struct gendisk *disk;
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@ -47,6 +52,10 @@ struct virtio_blk
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/* Ida index - used to track minor number allocations. */
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int index;
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/* num of vqs */
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int num_vqs;
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struct virtio_blk_vq *vqs;
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};
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struct virtblk_req
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@ -133,14 +142,15 @@ static void virtblk_done(struct virtqueue *vq)
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{
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struct virtio_blk *vblk = vq->vdev->priv;
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bool req_done = false;
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int qid = vq->index;
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struct virtblk_req *vbr;
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unsigned long flags;
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unsigned int len;
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spin_lock_irqsave(&vblk->vq_lock, flags);
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spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
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do {
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virtqueue_disable_cb(vq);
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while ((vbr = virtqueue_get_buf(vblk->vq, &len)) != NULL) {
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while ((vbr = virtqueue_get_buf(vblk->vqs[qid].vq, &len)) != NULL) {
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blk_mq_complete_request(vbr->req);
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req_done = true;
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}
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@ -151,7 +161,7 @@ static void virtblk_done(struct virtqueue *vq)
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/* In case queue is stopped waiting for more buffers. */
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if (req_done)
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blk_mq_start_stopped_hw_queues(vblk->disk->queue, true);
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spin_unlock_irqrestore(&vblk->vq_lock, flags);
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spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
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}
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static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
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@ -160,6 +170,7 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
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struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
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unsigned long flags;
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unsigned int num;
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int qid = hctx->queue_num;
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const bool last = (req->cmd_flags & REQ_END) != 0;
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int err;
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bool notify = false;
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@ -202,12 +213,12 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
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vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
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}
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spin_lock_irqsave(&vblk->vq_lock, flags);
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err = __virtblk_add_req(vblk->vq, vbr, vbr->sg, num);
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spin_lock_irqsave(&vblk->vqs[qid].lock, flags);
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err = __virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num);
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if (err) {
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virtqueue_kick(vblk->vq);
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virtqueue_kick(vblk->vqs[qid].vq);
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blk_mq_stop_hw_queue(hctx);
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spin_unlock_irqrestore(&vblk->vq_lock, flags);
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spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
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/* Out of mem doesn't actually happen, since we fall back
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* to direct descriptors */
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if (err == -ENOMEM || err == -ENOSPC)
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@ -215,12 +226,12 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx, struct request *req)
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return BLK_MQ_RQ_QUEUE_ERROR;
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}
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if (last && virtqueue_kick_prepare(vblk->vq))
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if (last && virtqueue_kick_prepare(vblk->vqs[qid].vq))
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notify = true;
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spin_unlock_irqrestore(&vblk->vq_lock, flags);
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spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags);
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if (notify)
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virtqueue_notify(vblk->vq);
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virtqueue_notify(vblk->vqs[qid].vq);
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return BLK_MQ_RQ_QUEUE_OK;
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}
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@ -377,12 +388,64 @@ static void virtblk_config_changed(struct virtio_device *vdev)
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static int init_vq(struct virtio_blk *vblk)
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{
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int err = 0;
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int i;
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vq_callback_t **callbacks;
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const char **names;
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struct virtqueue **vqs;
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unsigned short num_vqs;
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struct virtio_device *vdev = vblk->vdev;
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/* We expect one virtqueue, for output. */
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vblk->vq = virtio_find_single_vq(vblk->vdev, virtblk_done, "requests");
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if (IS_ERR(vblk->vq))
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err = PTR_ERR(vblk->vq);
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err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ,
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struct virtio_blk_config, num_queues,
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&num_vqs);
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if (err)
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num_vqs = 1;
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vblk->vqs = kmalloc(sizeof(*vblk->vqs) * num_vqs, GFP_KERNEL);
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if (!vblk->vqs) {
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err = -ENOMEM;
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goto out;
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}
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names = kmalloc(sizeof(*names) * num_vqs, GFP_KERNEL);
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if (!names)
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goto err_names;
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callbacks = kmalloc(sizeof(*callbacks) * num_vqs, GFP_KERNEL);
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if (!callbacks)
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goto err_callbacks;
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vqs = kmalloc(sizeof(*vqs) * num_vqs, GFP_KERNEL);
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if (!vqs)
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goto err_vqs;
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for (i = 0; i < num_vqs; i++) {
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callbacks[i] = virtblk_done;
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snprintf(vblk->vqs[i].name, VQ_NAME_LEN, "req.%d", i);
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names[i] = vblk->vqs[i].name;
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}
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/* Discover virtqueues and write information to configuration. */
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err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names);
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if (err)
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goto err_find_vqs;
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for (i = 0; i < num_vqs; i++) {
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spin_lock_init(&vblk->vqs[i].lock);
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vblk->vqs[i].vq = vqs[i];
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}
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vblk->num_vqs = num_vqs;
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err_find_vqs:
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kfree(vqs);
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err_vqs:
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kfree(callbacks);
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err_callbacks:
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kfree(names);
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err_names:
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if (err)
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kfree(vblk->vqs);
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out:
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return err;
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}
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@ -551,7 +614,6 @@ static int virtblk_probe(struct virtio_device *vdev)
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err = init_vq(vblk);
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if (err)
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goto out_free_vblk;
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spin_lock_init(&vblk->vq_lock);
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/* FIXME: How many partitions? How long is a piece of string? */
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vblk->disk = alloc_disk(1 << PART_BITS);
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@ -562,7 +624,7 @@ static int virtblk_probe(struct virtio_device *vdev)
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/* Default queue sizing is to fill the ring. */
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if (!virtblk_queue_depth) {
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virtblk_queue_depth = vblk->vq->num_free;
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virtblk_queue_depth = vblk->vqs[0].vq->num_free;
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/* ... but without indirect descs, we use 2 descs per req */
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if (!virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC))
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virtblk_queue_depth /= 2;
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@ -570,7 +632,6 @@ static int virtblk_probe(struct virtio_device *vdev)
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memset(&vblk->tag_set, 0, sizeof(vblk->tag_set));
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vblk->tag_set.ops = &virtio_mq_ops;
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vblk->tag_set.nr_hw_queues = 1;
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vblk->tag_set.queue_depth = virtblk_queue_depth;
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vblk->tag_set.numa_node = NUMA_NO_NODE;
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vblk->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
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@ -578,6 +639,7 @@ static int virtblk_probe(struct virtio_device *vdev)
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sizeof(struct virtblk_req) +
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sizeof(struct scatterlist) * sg_elems;
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vblk->tag_set.driver_data = vblk;
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vblk->tag_set.nr_hw_queues = vblk->num_vqs;
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err = blk_mq_alloc_tag_set(&vblk->tag_set);
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if (err)
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@ -727,6 +789,7 @@ static void virtblk_remove(struct virtio_device *vdev)
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refc = atomic_read(&disk_to_dev(vblk->disk)->kobj.kref.refcount);
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put_disk(vblk->disk);
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vdev->config->del_vqs(vdev);
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kfree(vblk->vqs);
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kfree(vblk);
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/* Only free device id if we don't have any users */
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@ -777,7 +840,8 @@ static const struct virtio_device_id id_table[] = {
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static unsigned int features[] = {
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VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
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VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE, VIRTIO_BLK_F_SCSI,
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VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE
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VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
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VIRTIO_BLK_F_MQ,
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};
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static struct virtio_driver virtio_blk = {
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