From 066f4d82a67f621ddd547bfa4b9c94631d8457b0 Mon Sep 17 00:00:00 2001
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Thu, 29 May 2008 11:08:26 +0200
Subject: [PATCH] virtio_blk: check for hardsector size from host
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>
---
drivers/block/virtio_blk.c | 10 +++++++++-
include/linux/virtio_blk.h | 3 +++
2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index dd7ea203f940d..42251095134fa 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -196,6 +196,7 @@ static int virtblk_probe(struct virtio_device *vdev)
int err;
u64 cap;
u32 v;
+ u32 blk_size;
if (index_to_minor(index) >= 1 << MINORBITS)
return -ENOSPC;
@@ -290,6 +291,13 @@ static int virtblk_probe(struct virtio_device *vdev)
if (!err)
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);
return 0;
@@ -330,7 +338,7 @@ 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_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
};
static struct virtio_driver virtio_blk = {
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index 6a66c7f30bcb5..c1aef85243bf4 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -13,6 +13,7 @@
#define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
#define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */
#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
{
@@ -28,6 +29,8 @@ struct virtio_blk_config
__u8 heads;
__u8 sectors;
} geometry;
+ /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
+ __u32 blk_size;
} __attribute__((packed));
/* These two define direction. */
--
2.39.5