diff options
| -rw-r--r-- | drivers/block/virtio_blk.c | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 0e2ade6..7b9b38a 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -6,7 +6,6 @@ #include <linux/virtio_blk.h> #include <linux/scatterlist.h> -#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS) #define PART_BITS 4 static int major, index; @@ -26,8 +25,11 @@ struct virtio_blk mempool_t *pool; + /* What host tells us, plus 2 for header & tailer. */ + unsigned int sg_elems; + /* Scatterlist: can be too big for stack. */ - struct scatterlist sg[VIRTIO_MAX_SG]; + struct scatterlist sg[/*sg_elems*/]; }; struct virtblk_req @@ -97,8 +99,6 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk, if (blk_barrier_rq(vbr->req)) vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; - /* This init could be done at vblk creation time */ - sg_init_table(vblk->sg, VIRTIO_MAX_SG); sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status)); @@ -130,7 +130,7 @@ static void do_virtblk_request(struct request_queue *q) while ((req = elv_next_request(q)) != NULL) { vblk = req->rq_disk->private_data; - BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg)); + 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. */ @@ -196,12 +196,22 @@ static int virtblk_probe(struct virtio_device *vdev) int err; u64 cap; u32 v; - u32 blk_size; + u32 blk_size, sg_elems; if (index_to_minor(index) >= 1 << MINORBITS) return -ENOSPC; - vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); + /* We need to know how many segments before we allocate. */ + err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, + offsetof(struct virtio_blk_config, seg_max), + &sg_elems); + if (err) + sg_elems = 1; + + /* 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); if (!vblk) { err = -ENOMEM; goto out; @@ -210,6 +220,8 @@ static int virtblk_probe(struct virtio_device *vdev) INIT_LIST_HEAD(&vblk->reqs); spin_lock_init(&vblk->lock); vblk->vdev = vdev; + vblk->sg_elems = sg_elems; + sg_init_table(vblk->sg, vblk->sg_elems); /* We expect one virtqueue, for output. */ vblk->vq = vdev->config->find_vq(vdev, 0, blk_done); @@ -277,6 +289,10 @@ static int virtblk_probe(struct virtio_device *vdev) } set_capacity(vblk->disk, cap); + /* We can handle whatever the host told us to handle. */ + blk_queue_max_phys_segments(vblk->disk->queue, vblk->sg_elems-2); + blk_queue_max_hw_segments(vblk->disk->queue, vblk->sg_elems-2); + /* No real sector limit. */ blk_queue_max_sectors(vblk->disk->queue, -1U); @@ -290,12 +306,6 @@ static int virtblk_probe(struct virtio_device *vdev) else blk_queue_max_segment_size(vblk->disk->queue, -1UL); - err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX, - offsetof(struct virtio_blk_config, seg_max), - &v); - if (!err) - blk_queue_max_hw_segments(vblk->disk->queue, v); - /* Host can optionally specify the block size of the device */ err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE, offsetof(struct virtio_blk_config, blk_size), |