aboutsummaryrefslogtreecommitdiff
path: root/init/do_mounts.c
diff options
context:
space:
mode:
authorWill Drewry <wad@chromium.org>2010-08-31 15:47:07 -0500
committerJens Axboe <jaxboe@fusionio.com>2010-09-15 16:14:03 +0200
commitb5af921ec02333e943efb59aca4f56b78fc0e100 (patch)
treefcf966ccbee9c5f8b8f652100f033bc781b91b91 /init/do_mounts.c
parenteec7ecfede74bb996060efefd5c157acd5794e8a (diff)
downloadlinux-aarch64-b5af921ec02333e943efb59aca4f56b78fc0e100.tar.gz
init: add support for root devices specified by partition UUID
This is the third patch in a series which adds support for storing partition metadata, optionally, off of the hd_struct. One major use for that data is being able to resolve partition by other identities than just the index on a block device. Device enumeration varies by platform and there's a benefit to being able to use something like EFI GPT's GUIDs to determine the correct block device and partition to mount as the root. This change adds that support to root= by adding support for the following syntax: root=PARTUUID=hex-uuid Signed-off-by: Will Drewry <wad@chromium.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'init/do_mounts.c')
-rw-r--r--init/do_mounts.c66
1 files changed, 66 insertions, 0 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 02e3ca4fc527..804f9c6ba216 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -58,6 +58,60 @@ static int __init readwrite(char *str)
__setup("ro", readonly);
__setup("rw", readwrite);
+/**
+ * match_dev_by_uuid - callback for finding a partition using its uuid
+ * @dev: device passed in by the caller
+ * @data: opaque pointer to a 36 byte char array with a UUID
+ *
+ * Returns 1 if the device matches, and 0 otherwise.
+ */
+static int __init match_dev_by_uuid(struct device *dev, void *data)
+{
+ u8 *uuid = data;
+ struct hd_struct *part = dev_to_part(dev);
+
+ if (!part->info)
+ goto no_match;
+
+ if (memcmp(uuid, part->info->uuid, sizeof(part->info->uuid)))
+ goto no_match;
+
+ return 1;
+no_match:
+ return 0;
+}
+
+
+/**
+ * devt_from_partuuid - looks up the dev_t of a partition by its UUID
+ * @uuid: 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.
+ *
+ * Returns the matching dev_t on success or 0 on failure.
+ */
+static dev_t __init devt_from_partuuid(char *uuid_str)
+{
+ dev_t res = 0;
+ struct device *dev = NULL;
+ u8 uuid[16];
+
+ /* Pack the requested UUID in the expected format. */
+ part_pack_uuid(uuid_str, uuid);
+
+ dev = class_find_device(&block_class, NULL, uuid, &match_dev_by_uuid);
+ if (!dev)
+ goto done;
+
+ res = dev->devt;
+ put_device(dev);
+
+done:
+ return res;
+}
+
/*
* Convert a name into device number. We accept the following variants:
*
@@ -68,6 +122,8 @@ __setup("rw", readwrite);
* of partition - device number of disk plus the partition number
* 5) /dev/<disk_name>p<decimal> - same as the above, that form is
* 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.
*
* 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
@@ -82,6 +138,16 @@ dev_t name_to_dev_t(char *name)
dev_t res = 0;
int part;
+ if (strncmp(name, "PARTUUID=", 9) == 0) {
+ name += 9;
+ if (strlen(name) != 36)
+ goto fail;
+ res = devt_from_partuuid(name);
+ if (!res)
+ goto fail;
+ goto done;
+ }
+
if (strncmp(name, "/dev/", 5) != 0) {
unsigned maj, min;