Commit 3ef53609 authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Rusty Russell

virtio_blk: allow read-only disks

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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent a16ffe93
No related merge requests found
......@@ -260,6 +260,10 @@ static int virtblk_probe(struct virtio_device *vdev)
if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER))
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. */
vdev->config->get(vdev, offsetof(struct virtio_blk_config, capacity),
&cap, sizeof(cap));
......@@ -326,7 +330,7 @@ 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_GEOMETRY, VIRTIO_BLK_F_RO,
};
static struct virtio_driver virtio_blk = {
......
......@@ -10,6 +10,7 @@
#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_GEOMETRY 4 /* Legacy geometry available */
#define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
struct virtio_blk_config
{
......
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