zfs: default device name to vblk0.1 if vdev_path different than /dev/…

…vblk*

This patch allows mounting OSv zfs image on Linux host and/or modifying and
using again to boot OSv. It also allows mounting ZFS disks created on Linux
host.

Typically when mounting OSv image on Linux, the zpool utility would
change so called vdev_path from /dev/vblk0.1 to /dev/nbd0p2
and OSv would fail mounting it afterwards as it tries open device
using the vdev_path stored on the disk. This patch effectively
validates the vdev_path to make sure it starts with /dev/vblk.

Fixes #918

Signed-off-by: Waldemar Kozaczuk <[email protected]>
Message-Id: <[email protected]>

bsd/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_disk.c

@@ -56,6 +56,7 @@ vdev_disk_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
 {
 	struct vdev_disk *dvd;
 	int error;
+	char *device_name;
 
 	/*
 	 * We must have a pathname, and it must be absolute.
@@ -72,7 +73,11 @@ vdev_disk_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
 	if (vd->vdev_tsd == NULL) {
 		dvd = vd->vdev_tsd = kmem_zalloc(sizeof(struct vdev_disk), KM_SLEEP);
 
-		error = device_open(vd->vdev_path + 5, DO_RDWR, &dvd->device);
+		device_name = vd->vdev_path + 5;
+		if (strncmp(device_name, "vblk", 4) != 0) {
+			device_name = "vblk0.1";
+		}
+		error = device_open(device_name, DO_RDWR, &dvd->device);
 		if (error) {
 			vd->vdev_stat.vs_aux = VDEV_AUX_OPEN_FAILED;
 			return error;