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authorChristian Borntraeger <borntraeger@de.ibm.com>2008-05-16 11:17:03 +0200
committerRusty Russell <rusty@rustcorp.com.au>2008-05-30 15:09:44 +1000
commit3ef536095446552823fc488fec1c5451aab1260d (patch)
tree9d525f24f2bd07ce1b82f8b60673062e05c41c2e
parenta16ffe93c46dfca211434d00453ebb695025978b (diff)
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: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--drivers/block/virtio_blk.c6
-rw-r--r--include/linux/virtio_blk.h1
2 files changed, 6 insertions, 1 deletions
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c4804f3465d..dd7ea203f94 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -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 = {
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index d4695a3356d..b80919fad0e 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -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
{