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virtio_blk: allow read-only disks

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Hello Rusty,

sometimes it is useful to share a disk (e.g. usr). To avoid file system
corruption, the disk should be mounted read-only in that case. This patch
adds a new feature flag, that allows the host to specify, if the disk should
be considered read-only.

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
2008-05-16 11:17:03 +02:00
committed by Rusty Russell
parent a16ffe93c4
commit 3ef5360954
2 changed files with 6 additions and 1 deletions
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6
drivers/block/virtio_blk.c
View File

@@ -260,6 +260,10 @@ static int virtblk_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL); blk_queue_ordered(vblk->disk->queue, 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))
set_disk_ro(vblk->disk, 1);
/* Host must always specify the capacity. */ /* Host must always specify the capacity. */
vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity), vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
&cap, sizeof(cap)); &cap, sizeof(cap));
@@ -326,7 +330,7 @@ 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_GEOMETRY, VIRTIO_BLK_F_RO,
}; };
static struct virtio_driver virtio_blk = { static struct virtio_driver virtio_blk = {

1
include/linux/virtio_blk.h
View File

@@ -10,6 +10,7 @@
#define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */ #define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
#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 */
struct virtio_blk_config struct virtio_blk_config
{ {