From 3ef536095446552823fc488fec1c5451aab1260d Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 16 May 2008 11:17:03 +0200 Subject: [PATCH] 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 Signed-off-by: Rusty Russell --- drivers/block/virtio_blk.c | 6 +++++- include/linux/virtio_blk.h | 1 + 2 files changed, 6 insertions(+), 1 deletion(-) 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 { -- 2.20.1