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>
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 51042f0ba7..7eff828 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -243,10 +243,12 @@
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 @@
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 @@
/* 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 @@
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 @@
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 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
};
/*
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index fd294c5..e52029e 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -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 @@
__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));
/*