path: root/drivers/block/virtio_blk.c

//#define DEBUG
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/virtio.h>
#include <linux/virtio_blk.h>
#include <linux/scatterlist.h>
#include <linux/string_helpers.h>
#include <scsi/scsi_cmnd.h>
#include <linux/idr.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);

struct workqueue_struct *virtblk_wq;

struct virtio_blk
{
	struct virtio_device *vdev;
	struct virtqueue *vq;
	wait_queue_head_t queue_wait;

	/* The disk structure for the kernel. */
	struct gendisk *disk;

	mempool_t *pool;

	/* Process context for config space updates */
	struct work_struct config_work;

	/* Lock for config space updates */
	struct mutex config_lock;

	/* enable config space updates */
	bool config_enable;

	/* What host tells us, plus 2 for header & tailer. */
	unsigned int sg_elems;

	/* 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) {
	case VIRTIO_BLK_S_OK:
		return 0;
	case VIRTIO_BLK_S_UNSUPP:
		return -ENOTTY;
	default:
		return -EIO;
	}
}

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 && use_bio)
		sg_init_table(vbr->sg, vblk->sg_elems);

	vbr->vblk = vblk;

	return vbr;
}

static void virtblk_add_buf_wait(struct virtio_blk *vblk,
				 struct virtblk_req *vbr,
				 unsigned long out,
				 unsigned long in)
{
	DEFINE_WAIT(wait);

	for (;;) {
		prepare_to_wait_exclusive(&vblk->queue_wait, &wait,
					  TASK_UNINTERRUPTIBLE);

		spin_lock_irq(vblk->disk->queue->queue_lock);
		if (virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
				      GFP_ATOMIC) < 0) {
			spin_unlock_irq(vblk->disk->queue->queue_lock);
			io_schedule();
		} else {
			virtqueue_kick(vblk->vq);
			spin_unlock_irq(vblk->disk->queue->queue_lock);
			break;
		}

	}

	finish_wait(&vblk->queue_wait, &wait);
}

static inline void virtblk_add_req(struct virtblk_req *vbr,
				   unsigned int out, unsigned int in)
{
	struct virtio_blk *vblk = vbr->vblk;

	spin_lock_irq(vblk->disk->queue->queue_lock);
	if (unlikely(virtqueue_add_buf(vblk->vq, vbr->sg, out, in, vbr,
					GFP_ATOMIC) < 0)) {
		spin_unlock_irq(vblk->disk->queue->queue_lock);
		virtblk_add_buf_wait(vblk, vbr, out, in);
		return;
	}
	virtqueue_kick(vblk->vq);
	spin_unlock_irq(vblk->disk->queue->queue_lock);
}

static int virtblk_bio_send_flush(struct virtblk_req *vbr)
{
	unsigned int out = 0, in = 0;

	vbr->flags |= VBLK_IS_FLUSH;
	vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH;
	vbr->out_hdr.sector = 0;
	vbr->out_hdr.ioprio = 0;
	sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr));
	sg_set_buf(&vbr->sg[out + in++], &vbr->