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-rw-r--r--init/do_mounts.c48
1 files changed, 43 insertions, 5 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index c0851a8e030c..0f6e1d985a3b 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -28,7 +28,7 @@ int __initdata rd_doload; /* 1 = load RAM disk, 0 = don't load */
int root_mountflags = MS_RDONLY | MS_SILENT;
static char * __initdata root_device_name;
static char __initdata saved_root_name[64];
-static int __initdata root_wait;
+static int root_wait;
dev_t ROOT_DEV;
@@ -85,12 +85,15 @@ no_match:
/**
* devt_from_partuuid - looks up the dev_t of a partition by its UUID
- * @uuid: 36 byte char array containing a hex ascii UUID
+ * @uuid: min 36 byte char array containing a hex ascii UUID
*
* The function will return the first partition which contains a matching
* UUID value in its partition_meta_info struct. This does not search
* by filesystem UUIDs.
*
+ * If @uuid is followed by a "/PARTNROFF=%d", then the number will be
+ * extracted and used as an offset from the partition identified by the UUID.
+ *
* Returns the matching dev_t on success or 0 on failure.
*/
static dev_t devt_from_partuuid(char *uuid_str)
@@ -98,6 +101,28 @@ static dev_t devt_from_partuuid(char *uuid_str)
dev_t res = 0;
struct device *dev = NULL;
u8 uuid[16];
+ struct gendisk *disk;
+ struct hd_struct *part;
+ int offset = 0;
+
+ if (strlen(uuid_str) < 36)
+ goto done;
+
+ /* Check for optional partition number offset attributes. */
+ if (uuid_str[36]) {
+ char c = 0;
+ /* Explicitly fail on poor PARTUUID syntax. */
+ if (sscanf(&uuid_str[36],
+ "/PARTNROFF=%d%c", &offset, &c) != 1) {
+ printk(KERN_ERR "VFS: PARTUUID= is invalid.\n"
+ "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
+ if (root_wait)
+ printk(KERN_ERR
+ "Disabling rootwait; root= is invalid.\n");
+ root_wait = 0;
+ goto done;
+ }
+ }
/* Pack the requested UUID in the expected format. */
part_pack_uuid(uuid_str, uuid);
@@ -107,8 +132,21 @@ static dev_t devt_from_partuuid(char *uuid_str)
goto done;
res = dev->devt;
- put_device(dev);
+ /* Attempt to find the partition by offset. */
+ if (!offset)
+ goto no_offset;
+
+ res = 0;
+ disk = part_to_disk(dev_to_part(dev));
+ part = disk_get_part(disk, dev_to_part(dev)->partno + offset);
+ if (part) {
+ res = part_devt(part);
+ put_device(part_to_dev(part));
+ }
+
+no_offset:
+ put_device(dev);
done:
return res;
}
@@ -126,6 +164,8 @@ done:
* used when disk name of partitioned disk ends on a digit.
* 6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
* unique id of a partition if the partition table provides it.
+ * 7) PARTUUID=<UUID>/PARTNROFF=<int> to select a partition in relation to
+ * a partition with a known unique id.
*
* If name doesn't have fall into the categories above, we return (0,0).
* block_class is used to check if something is a disk name. If the disk
@@ -143,8 +183,6 @@ dev_t name_to_dev_t(char *name)
#ifdef CONFIG_BLOCK
if (strncmp(name, "PARTUUID=", 9) == 0) {
name += 9;
- if (strlen(name) != 36)
- goto fail;
res = devt_from_partuuid(name);
if (!res)
goto fail;

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