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

drivers/block/virtio_blk.c

+5 −1
Original line number Diff line number Diff line
@@ -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 = {

include/linux/virtio_blk.h

+1 −0
Original line number Diff line number Diff line
@@ -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

{