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virtio_blk: add block topology support 

Allow reading various alignment values from the config page.  This
allows the guest to much better align I/O requests depending on the
storage topology.

Note that the formats for the config values appear a bit messed up,
but we follow the formats used by ATA and SCSI so they are expected in
the storage world.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Christoph Hellwig 2010-02-24 14:22:25 -06:00 committed by Rusty Russell
parent d57ed95da4
commit 69740c8ba8
2 changed files with 59 additions and 15 deletions
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61
drivers/block/virtio_blk.c
View File

@ -243,10 +243,12 @@ static int index_to_minor(int index)
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
struct request_queue *q;
int err;
u64 cap;
u32 v;
u32 blk_size, sg_elems;
u32 v, blk_size, sg_elems, opt_io_size;
u16 min_io_size;
u8 physical_block_exp, alignment_offset;
if (index_to_minor(index) >= 1 << MINORBITS)
return -ENOSPC;
@ -293,13 +295,13 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
goto out_mempool;
}
vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
if (!vblk->disk->queue) {
q = vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
if (!q) {
err = -ENOMEM;
goto out_put_disk;
}
vblk->disk->queue->queuedata = vblk;
q->queuedata = vblk;
if (index < 26) {
sprintf(vblk->disk->disk_name, "vd%c", 'a' + index % 26);
@ -323,10 +325,10 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
/* If barriers are supported, tell block layer that queue is ordered */
if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_DRAIN_FLUSH,
blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH,
virtblk_prepare_flush);
else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
blk_queue_ordered(q, QUEUE_ORDERED_TAG, NULL);
/* If disk is read-only in the host, the guest should obey */
if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO))
@ -345,14 +347,14 @@ static int __devinit 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);
blk_queue_max_phys_segments(q, vblk->sg_elems-2);
blk_queue_max_hw_segments(q, vblk->sg_elems-2);
/* No need to bounce any requests */
blk_queue_bounce_limit(vblk->disk->queue, BLK_BOUNCE_ANY);
blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
/* No real sector limit. */
blk_queue_max_sectors(vblk->disk->queue, -1U);
blk_queue_max_sectors(q, -1U);
/* Host can optionally specify maximum segment size and number of
* segments. */
@ -360,16 +362,45 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
offsetof(struct virtio_blk_config, size_max),
&v);
if (!err)
blk_queue_max_segment_size(vblk->disk->queue, v);
blk_queue_max_segment_size(q, v);
else
blk_queue_max_segment_size(vblk->disk->queue, -1U);
blk_queue_max_segment_size(q, -1U);
/* 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),
&blk_size);
if (!err)
blk_queue_logical_block_size(vblk->disk->queue, blk_size);
blk_queue_logical_block_size(q, blk_size);
else
blk_size = queue_logical_block_size(q);
/* Use topology information if available */
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, physical_block_exp),
&physical_block_exp);
if (!err && physical_block_exp)
blk_queue_physical_block_size(q,
blk_size * (1 << physical_block_exp));
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, alignment_offset),
&alignment_offset);
if (!err && alignment_offset)
blk_queue_alignment_offset(q, blk_size * alignment_offset);
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, min_io_size),
&min_io_size);
if (!err && min_io_size)
blk_queue_io_min(q, blk_size * min_io_size);
err = virtio_config_val(vdev, VIRTIO_BLK_F_TOPOLOGY,
offsetof(struct virtio_blk_config, opt_io_size),
&opt_io_size);
if (!err && opt_io_size)
blk_queue_io_opt(q, blk_size * opt_io_size);
add_disk(vblk->disk);
return 0;
@ -412,7 +443,7 @@ static struct virtio_device_id id_table[] = {
static unsigned int features[] = {
VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH
VIRTIO_BLK_F_SCSI, VIRTIO_BLK_F_FLUSH, VIRTIO_BLK_F_TOPOLOGY
};
/*

13
include/linux/virtio_blk.h
View File

@ -15,6 +15,7 @@
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
#define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
#define VIRTIO_BLK_F_FLUSH 9 /* Cache flush command support */
#define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
struct virtio_blk_config {
/* The capacity (in 512-byte sectors). */
@ -29,8 +30,20 @@ struct virtio_blk_config {
__u8 heads;
__u8 sectors;
} geometry;
/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
__u32 blk_size;
/* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY */
/* exponent for physical block per logical block. */
__u8 physical_block_exp;
/* alignment offset in logical blocks. */
__u8 alignment_offset;
/* minimum I/O size without performance penalty in logical blocks. */
__u16 min_io_size;
/* optimal sustained I/O size in logical blocks. */
__u32 opt_io_size;
} __attribute__((packed));
/*