766ca4428d
struct request has an ioprio member but it is never updated because currently bios do not hold io context information. The implication of this is that virtio_blk ends up passing useless information to the backend driver. That said, some IO schedulers such as CFQ do store io context information in struct request, but use private members for that, which means that that information cannot be directly accessed in a IO scheduler-independent way. This patch adds a function to obtain the ioprio of a request. We should avoid accessing ioprio directly and use this function instead, so that its users do not have to care about future changes in block layer structures or what the currently active IO controller is. This patch does not introduce any functional changes but paves the way for future clean-ups and enhancements. Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
372 lines
8.9 KiB
C
372 lines
8.9 KiB
C
//#define DEBUG
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#include <linux/spinlock.h>
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#include <linux/blkdev.h>
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#include <linux/hdreg.h>
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#include <linux/virtio.h>
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#include <linux/virtio_blk.h>
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#include <linux/scatterlist.h>
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#define VIRTIO_MAX_SG (3+MAX_PHYS_SEGMENTS)
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#define PART_BITS 4
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static int major, index;
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struct virtio_blk
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{
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spinlock_t lock;
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struct virtio_device *vdev;
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struct virtqueue *vq;
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/* The disk structure for the kernel. */
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struct gendisk *disk;
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/* Request tracking. */
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struct list_head reqs;
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mempool_t *pool;
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/* Scatterlist: can be too big for stack. */
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struct scatterlist sg[VIRTIO_MAX_SG];
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};
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struct virtblk_req
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{
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struct list_head list;
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struct request *req;
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struct virtio_blk_outhdr out_hdr;
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u8 status;
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};
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static void blk_done(struct virtqueue *vq)
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{
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struct virtio_blk *vblk = vq->vdev->priv;
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struct virtblk_req *vbr;
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unsigned int len;
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unsigned long flags;
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spin_lock_irqsave(&vblk->lock, flags);
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while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
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int uptodate;
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switch (vbr->status) {
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case VIRTIO_BLK_S_OK:
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uptodate = 1;
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break;
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case VIRTIO_BLK_S_UNSUPP:
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uptodate = -ENOTTY;
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break;
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default:
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uptodate = 0;
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break;
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}
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end_dequeued_request(vbr->req, uptodate);
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list_del(&vbr->list);
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mempool_free(vbr, vblk->pool);
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}
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/* In case queue is stopped waiting for more buffers. */
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blk_start_queue(vblk->disk->queue);
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spin_unlock_irqrestore(&vblk->lock, flags);
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}
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static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
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struct request *req)
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{
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unsigned long num, out, in;
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struct virtblk_req *vbr;
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vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
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if (!vbr)
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/* When another request finishes we'll try again. */
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return false;
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vbr->req = req;
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if (blk_fs_request(vbr->req)) {
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vbr->out_hdr.type = 0;
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vbr->out_hdr.sector = vbr->req->sector;
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vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
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} else if (blk_pc_request(vbr->req)) {
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vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
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vbr->out_hdr.sector = 0;
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vbr->out_hdr.ioprio = req_get_ioprio(vbr->req);
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} else {
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/* We don't put anything else in the queue. */
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BUG();
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}
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if (blk_barrier_rq(vbr->req))
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vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
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/* This init could be done at vblk creation time */
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sg_init_table(vblk->sg, VIRTIO_MAX_SG);
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sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
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num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
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sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status));
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if (rq_data_dir(vbr->req) == WRITE) {
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vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
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out = 1 + num;
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in = 1;
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} else {
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vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
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out = 1;
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in = 1 + num;
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}
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if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
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mempool_free(vbr, vblk->pool);
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return false;
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}
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list_add_tail(&vbr->list, &vblk->reqs);
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return true;
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}
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static void do_virtblk_request(struct request_queue *q)
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{
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struct virtio_blk *vblk = NULL;
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struct request *req;
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unsigned int issued = 0;
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while ((req = elv_next_request(q)) != NULL) {
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vblk = req->rq_disk->private_data;
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BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
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/* If this request fails, stop queue and wait for something to
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finish to restart it. */
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if (!do_req(q, vblk, req)) {
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blk_stop_queue(q);
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break;
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}
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blkdev_dequeue_request(req);
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issued++;
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}
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if (issued)
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vblk->vq->vq_ops->kick(vblk->vq);
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}
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static int virtblk_ioctl(struct inode *inode, struct file *filp,
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unsigned cmd, unsigned long data)
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{
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return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
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inode->i_bdev->bd_disk, cmd,
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(void __user *)data);
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}
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/* We provide getgeo only to please some old bootloader/partitioning tools */
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static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
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{
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struct virtio_blk *vblk = bd->bd_disk->private_data;
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struct virtio_blk_geometry vgeo;
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int err;
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/* see if the host passed in geometry config */
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err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
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offsetof(struct virtio_blk_config, geometry),
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&vgeo);
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if (!err) {
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geo->heads = vgeo.heads;
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geo->sectors = vgeo.sectors;
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geo->cylinders = vgeo.cylinders;
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} else {
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/* some standard values, similar to sd */
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geo->heads = 1 << 6;
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geo->sectors = 1 << 5;
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geo->cylinders = get_capacity(bd->bd_disk) >> 11;
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}
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return 0;
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}
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static struct block_device_operations virtblk_fops = {
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.ioctl = virtblk_ioctl,
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.owner = THIS_MODULE,
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.getgeo = virtblk_getgeo,
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};
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static int index_to_minor(int index)
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{
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return index << PART_BITS;
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}
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static int virtblk_probe(struct virtio_device *vdev)
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{
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struct virtio_blk *vblk;
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int err;
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u64 cap;
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u32 v;
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u32 blk_size;
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if (index_to_minor(index) >= 1 << MINORBITS)
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return -ENOSPC;
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vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
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if (!vblk) {
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err = -ENOMEM;
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goto out;
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}
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INIT_LIST_HEAD(&vblk->reqs);
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spin_lock_init(&vblk->lock);
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vblk->vdev = vdev;
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/* We expect one virtqueue, for output. */
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vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);
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if (IS_ERR(vblk->vq)) {
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err = PTR_ERR(vblk->vq);
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goto out_free_vblk;
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}
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vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
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if (!vblk->pool) {
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err = -ENOMEM;
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goto out_free_vq;
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}
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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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if (!vblk->disk) {
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err = -ENOMEM;
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goto out_mempool;
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}
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vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
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if (!vblk->disk->queue) {
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err = -ENOMEM;
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goto out_put_disk;
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}
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if (index < 26) {
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sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
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} else if (index < (26 + 1) * 26) {
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sprintf(vblk->disk->disk_name, "vd%c%c",
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'a' + index / 26 - 1, 'a' + index % 26);
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} else {
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const unsigned int m1 = (index / 26 - 1) / 26 - 1;
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const unsigned int m2 = (index / 26 - 1) % 26;
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const unsigned int m3 = index % 26;
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sprintf(vblk->disk->disk_name, "vd%c%c%c",
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'a' + m1, 'a' + m2, 'a' + m3);
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}
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vblk->disk->major = major;
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vblk->disk->first_minor = index_to_minor(index);
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vblk->disk->private_data = vblk;
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vblk->disk->fops = &virtblk_fops;
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vblk->disk->driverfs_dev = &vdev->dev;
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index++;
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/* If barriers are supported, tell block layer that queue is ordered */
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if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
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blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
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/* If disk is read-only in the host, the guest should obey */
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if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
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set_disk_ro(vblk->disk, 1);
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/* Host must always specify the capacity. */
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vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
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&cap, sizeof(cap));
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/* If capacity is too big, truncate with warning. */
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if ((sector_t)cap != cap) {
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dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
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(unsigned long long)cap);
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cap = (sector_t)-1;
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}
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set_capacity(vblk->disk, cap);
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/* Host can optionally specify maximum segment size and number of
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* segments. */
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err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,
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offsetof(struct virtio_blk_config, size_max),
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&v);
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if (!err)
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blk_queue_max_segment_size(vblk->disk->queue, v);
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err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,
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offsetof(struct virtio_blk_config, seg_max),
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&v);
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if (!err)
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blk_queue_max_hw_segments(vblk->disk->queue, v);
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/* Host can optionally specify the block size of the device */
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err = virtio_config_val(vdev, VIRTIO_BLK_F_BLK_SIZE,
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offsetof(struct virtio_blk_config, blk_size),
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&blk_size);
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if (!err)
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blk_queue_hardsect_size(vblk->disk->queue, blk_size);
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add_disk(vblk->disk);
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return 0;
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out_put_disk:
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put_disk(vblk->disk);
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out_mempool:
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mempool_destroy(vblk->pool);
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out_free_vq:
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vdev->config->del_vq(vblk->vq);
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out_free_vblk:
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kfree(vblk);
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out:
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return err;
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}
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static void virtblk_remove(struct virtio_device *vdev)
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{
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struct virtio_blk *vblk = vdev->priv;
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/* Nothing should be pending. */
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BUG_ON(!list_empty(&vblk->reqs));
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/* Stop all the virtqueues. */
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vdev->config->reset(vdev);
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del_gendisk(vblk->disk);
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blk_cleanup_queue(vblk->disk->queue);
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put_disk(vblk->disk);
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mempool_destroy(vblk->pool);
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vdev->config->del_vq(vblk->vq);
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kfree(vblk);
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}
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
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{ 0 },
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};
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static unsigned int features[] = {
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VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
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VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
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};
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static struct virtio_driver virtio_blk = {
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.feature_table = features,
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.feature_table_size = ARRAY_SIZE(features),
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.driver.name = KBUILD_MODNAME,
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.driver.owner = THIS_MODULE,
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.id_table = id_table,
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.probe = virtblk_probe,
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.remove = __devexit_p(virtblk_remove),
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};
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static int __init init(void)
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{
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major = register_blkdev(0, "virtblk");
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if (major < 0)
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return major;
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return register_virtio_driver(&virtio_blk);
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}
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static void __exit fini(void)
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{
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unregister_blkdev(major, "virtblk");
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unregister_virtio_driver(&virtio_blk);
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}
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module_init(init);
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module_exit(fini);
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MODULE_DEVICE_TABLE(virtio, id_table);
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MODULE_DESCRIPTION("Virtio block driver");
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MODULE_LICENSE("GPL");
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