diff options
| -rw-r--r-- | drivers/block/Kconfig | 6 | ||||
| -rw-r--r-- | drivers/block/Makefile | 1 | ||||
| -rw-r--r-- | drivers/block/virtio_blk.c | 308 | ||||
| -rw-r--r-- | include/linux/Kbuild | 1 | ||||
| -rw-r--r-- | include/linux/virtio_blk.h | 51 |
5 files changed, 367 insertions, 0 deletions
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index ce4b1e4..4d0119e 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -425,4 +425,10 @@ config XEN_BLKDEV_FRONTEND block device driver. It communicates with a back-end driver in another domain which drives the actual block device. +config VIRTIO_BLK + tristate "Virtio block driver (EXPERIMENTAL)" + depends on EXPERIMENTAL && VIRTIO + ---help--- + This is the virtual block driver for lguest. Say Y or M. + endif # BLK_DEV diff --git a/drivers/block/Makefile b/drivers/block/Makefile index 014e721..d199eba 100644 --- a/drivers/block/Makefile +++ b/drivers/block/Makefile @@ -25,6 +25,7 @@ obj-$(CONFIG_SUNVDC) += sunvdc.o obj-$(CONFIG_BLK_DEV_UMEM) += umem.o obj-$(CONFIG_BLK_DEV_NBD) += nbd.o obj-$(CONFIG_BLK_DEV_CRYPTOLOOP) += cryptoloop.o +obj-$(CONFIG_VIRTIO_BLK) += virtio_blk.o obj-$(CONFIG_VIODASD) += viodasd.o obj-$(CONFIG_BLK_DEV_SX8) += sx8.o diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c new file mode 100644 index 0000000..a901eee --- /dev/null +++ b/drivers/block/virtio_blk.c @@ -0,0 +1,308 @@ +//#define DEBUG +#include <linux/spinlock.h> +#include <linux/blkdev.h> +#include <linux/hdreg.h> +#include <linux/virtio.h> +#include <linux/virtio_blk.h> +#include <linux/virtio_blk.h> + +static unsigned char virtblk_index = 'a'; +struct virtio_blk +{ + spinlock_t lock; + + struct virtio_device *vdev; + struct virtqueue *vq; + + /* The disk structure for the kernel. */ + struct gendisk *disk; + + /* Request tracking. */ + struct list_head reqs; + + mempool_t *pool; + + /* Scatterlist: can be too big for stack. */ + struct scatterlist sg[3+MAX_PHYS_SEGMENTS]; +}; + +struct virtblk_req +{ + struct list_head list; + struct request *req; + struct virtio_blk_outhdr out_hdr; + struct virtio_blk_inhdr in_hdr; +}; + +static bool blk_done(struct virtqueue *vq) +{ + struct virtio_blk *vblk = vq->vdev->priv; + struct virtblk_req *vbr; + unsigned int len; + unsigned long flags; + + spin_lock_irqsave(&vblk->lock, flags); + while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) { + int uptodate; + switch (vbr->in_hdr.status) { + case VIRTIO_BLK_S_OK: + uptodate = 1; + break; + case VIRTIO_BLK_S_UNSUPP: + uptodate = -ENOTTY; + break; + default: + uptodate = 0; + break; + } + + end_dequeued_request(vbr->req, uptodate); + list_del(&vbr->list); + mempool_free(vbr, vblk->pool); + } + /* In case queue is stopped waiting for more buffers. */ + blk_start_queue(vblk->disk->queue); + spin_unlock_irqrestore(&vblk->lock, flags); + return true; +} + +static bool do_req(struct request_queue *q, struct virtio_blk *vblk, + struct request *req) +{ + unsigned long num, out, in; + struct virtblk_req *vbr; + + vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); + if (!vbr) + /* When another request finishes we'll try again. */ + return false; + + vbr->req = req; + if (blk_fs_request(vbr->req)) { + vbr->out_hdr.type = 0; + vbr->out_hdr.sector = vbr->req->sector; + vbr->out_hdr.ioprio = vbr->req->ioprio; + } else if (blk_pc_request(vbr->req)) { + vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD; + vbr->out_hdr.sector = 0; + vbr->out_hdr.ioprio = vbr->req->ioprio; + } else { + /* We don't put anything else in the queue. */ + BUG(); + } + + if (blk_barrier_rq(vbr->req)) + vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; + + /* We have to zero this, otherwise blk_rq_map_sg gets upset. */ + memset(vblk->sg, 0, sizeof(vblk->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->in_hdr, sizeof(vbr->in_hdr)); + + if (rq_data_dir(vbr->req) == WRITE) { + vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; + out = 1 + num; + in = 1; + } else { + vbr->out_hdr.type |= VIRTIO_BLK_T_IN; + out = 1; + in = 1 + num; + } + + if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { + mempool_free(vbr, vblk->pool); + return false; + } + + list_add_tail(&vbr->list, &vblk->reqs); + return true; +} + +static void do_virtblk_request(struct request_queue *q) +{ + struct virtio_blk *vblk = NULL; + struct request *req; + unsigned int issued = 0; + + while ((req = elv_next_request(q)) != NULL) { + vblk = req->rq_disk->private_data; + BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg)); + + /* 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; + } + blkdev_dequeue_request(req); + issued++; + } + + if (issued) + vblk->vq->vq_ops->kick(vblk->vq); +} + +static int virtblk_ioctl(struct inode *inode, struct file *filp, + unsigned cmd, unsigned long data) +{ + return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue, + inode->i_bdev->bd_disk, cmd, + (void __user *)data); +} + +static struct block_device_operations virtblk_fops = { + .ioctl = virtblk_ioctl, + .owner = THIS_MODULE, +}; + +static int virtblk_probe(struct virtio_device *vdev) +{ + struct virtio_blk *vblk; + int err, major; + void *token; + unsigned int len; + u64 cap; + u32 v; + + vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL); + if (!vblk) { + err = -ENOMEM; + goto out; + } + + INIT_LIST_HEAD(&vblk->reqs); + spin_lock_init(&vblk->lock); + vblk->vdev = vdev; + + /* We expect one virtqueue, for output. */ + vblk->vq = vdev->config->find_vq(vdev, blk_done); + if (IS_ERR(vblk->vq)) { + err = PTR_ERR(vblk->vq); + goto out_free_vblk; + } + + vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req)); + if (!vblk->pool) { + err = -ENOMEM; + goto out_free_vq; + } + + major = register_blkdev(0, "virtblk"); + if (major < 0) { + err = major; + goto out_mempool; + } + + /* FIXME: How many partitions? How long is a piece of string? */ + vblk->disk = alloc_disk(1 << 4); + if (!vblk->disk) { + err = -ENOMEM; + goto out_unregister_blkdev; + } + + vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock); + if (!vblk->disk->queue) { + err = -ENOMEM; + goto out_put_disk; + } + + sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++); + vblk->disk->major = major; + vblk->disk->first_minor = 0; + vblk->disk->private_data = vblk; + vblk->disk->fops = &virtblk_fops; + + /* If barriers are supported, tell block layer that queue is ordered */ + token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len); + if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER)) + blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); + + err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap); + if (err) { + dev_err(&vdev->dev, "Bad/missing capacity in config\n"); + goto out_put_disk; + } + + /* If capacity is too big, truncate with warning. */ + if ((sector_t)cap != cap) { + dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n", + (unsigned long long)cap); + cap = (sector_t)-1; + } + set_capacity(vblk->disk, cap); + + err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v); + if (!err) + blk_queue_max_segment_size(vblk->disk->queue, v); + else if (err != -ENOENT) { + dev_err(&vdev->dev, "Bad SIZE_MAX in config\n"); + goto out_put_disk; + } + + err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v); + if (!err) + blk_queue_max_hw_segments(vblk->disk->queue, v); + else if (err != -ENOENT) { + dev_err(&vdev->dev, "Bad SEG_MAX in config\n"); + goto out_put_disk; + } + + add_disk(vblk->disk); + return 0; + +out_put_disk: + put_disk(vblk->disk); +out_unregister_blkdev: + unregister_blkdev(major, "virtblk"); +out_mempool: + mempool_destroy(vblk->pool); +out_free_vq: + vdev->config->del_vq(vblk->vq); +out_free_vblk: + kfree(vblk); +out: + return err; +} + +static void virtblk_remove(struct virtio_device *vdev) +{ + struct virtio_blk *vblk = vdev->priv; + int major = vblk->disk->major; + + BUG_ON(!list_empty(&vblk->reqs)); + blk_cleanup_queue(vblk->disk->queue); + put_disk(vblk->disk); + unregister_blkdev(major, "virtblk"); + mempool_destroy(vblk->pool); + kfree(vblk); +} + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static struct virtio_driver virtio_blk = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = virtblk_probe, + .remove = __devexit_p(virtblk_remove), +}; + +static int __init init(void) +{ + return register_virtio_driver(&virtio_blk); +} + +static void __exit fini(void) +{ + unregister_virtio_driver(&virtio_blk); +} +module_init(init); +module_exit(fini); + +MODULE_DEVICE_TABLE(virtio, id_table); +MODULE_DESCRIPTION("Virtio block driver"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/Kbuild b/include/linux/Kbuild index b101588..6a65231 100644 --- a/include/linux/Kbuild +++ b/include/linux/Kbuild @@ -344,6 +344,7 @@ unifdef-y += utsname.h unifdef-y += videodev2.h unifdef-y += videodev.h unifdef-y += virtio_config.h +unifdef-y += virtio_blk.h unifdef-y += virtio_net.h unifdef-y += wait.h unifdef-y += wanrouter.h diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h new file mode 100644 index 0000000..7bd2bce --- /dev/null +++ b/include/linux/virtio_blk.h @@ -0,0 +1,51 @@ +#ifndef _LINUX_VIRTIO_BLK_H +#define _LINUX_VIRTIO_BLK_H +#include <linux/virtio_config.h> + +/* The ID for virtio_block */ +#define VIRTIO_ID_BLOCK 2 + +/* Feature bits */ +#define VIRTIO_CONFIG_BLK_F 0x40 +#define VIRTIO_BLK_F_BARRIER 1 /* Does host support barriers? */ + +/* The capacity (in 512-byte sectors). */ +#define VIRTIO_CONFIG_BLK_F_CAPACITY 0x41 +/* The maximum segment size. */ +#define VIRTIO_CONFIG_BLK_F_SIZE_MAX 0x42 +/* The maximum number of segments. */ +#define VIRTIO_CONFIG_BLK_F_SEG_MAX 0x43 + +/* These two define direction. */ +#define VIRTIO_BLK_T_IN 0 +#define VIRTIO_BLK_T_OUT 1 + +/* This bit says it's a scsi command, not an actual read or write. */ +#define VIRTIO_BLK_T_SCSI_CMD 2 + +/* Barrier before this op. */ +#define VIRTIO_BLK_T_BARRIER 0x80000000 + +/* This is the first element of the read scatter-gather list. */ +struct virtio_blk_outhdr +{ + /* VIRTIO_BLK_T* */ + __u32 type; + /* io priority. */ + __u32 ioprio; + /* Sector (ie. 512 byte offset) */ + __u64 sector; + /* Where to put reply. */ + __u64 id; +}; + +#define VIRTIO_BLK_S_OK 0 +#define VIRTIO_BLK_S_IOERR 1 +#define VIRTIO_BLK_S_UNSUPP 2 + +/* This is the first element of the write scatter-gather list */ +struct virtio_blk_inhdr +{ + unsigned char status; +}; +#endif /* _LINUX_VIRTIO_BLK_H */ |
