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virtio_blk: check for hardsector size from host

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Currently virtio_blk assumes a 512 byte hard sector size. This can cause
trouble / performance issues if the backing has a different block size
(like a file on an ext3 file system formatted with 4k block size or a dasd).

Lets add a feature flag that tells the guest to use a different hard sector
size than 512 byte.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Christian Borntraeger
2008-05-29 11:08:26 +02:00
committed by Rusty Russell
parent e962fa660d
commit 066f4d82a6
2 changed files with 12 additions and 1 deletions
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10
drivers/block/virtio_blk.c
View File

@@ -196,6 +196,7 @@ static int virtblk_probe(struct virtio_device *vdev)
int err; int err;
u64 cap; u64 cap;
u32 v; u32 v;
u32 blk_size;
if (index_to_minor(index) >= 1 << MINORBITS) if (index_to_minor(index) >= 1 << MINORBITS)
return -ENOSPC; return -ENOSPC;
@@ -290,6 +291,13 @@ static int virtblk_probe(struct virtio_device *vdev)
if (!err) if (!err)
blk_queue_max_hw_segments(vblk->disk->queue, v); blk_queue_max_hw_segments(vblk->disk->queue, v);
/* 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_hardsect_size(vblk->disk->queue, blk_size);
add_disk(vblk->disk); add_disk(vblk->disk);
return 0; return 0;
@@ -330,7 +338,7 @@ static struct virtio_device_id id_table[] = {
static unsigned int features[] = { static unsigned int features[] = {
VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, 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_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
}; };
static struct virtio_driver virtio_blk = { static struct virtio_driver virtio_blk = {

3
include/linux/virtio_blk.h
View File

@@ -13,6 +13,7 @@
#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */ #define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
#define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */ #define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */
#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */ #define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
#define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
struct virtio_blk_config struct virtio_blk_config
{ {
@@ -28,6 +29,8 @@ struct virtio_blk_config
__u8 heads; __u8 heads;
__u8 sectors; __u8 sectors;
} geometry; } geometry;
/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
__u32 blk_size;
} __attribute__((packed)); } __attribute__((packed));
/* These two define direction. */ /* These two define direction. */