block: store partition_meta_info.uuid as a string

This will allow other types of UUID to be stored here, aside from true
UUIDs.  This also simplifies code that uses this field, since it's usually
constructed from a, used as a, or compared to other, strings.

Note: A simplistic approach here would be to set uuid_str[36]=0 whenever a
/PARTNROFF option was found to be present.  However, this modifies the
input string, and causes subsequent calls to devt_from_partuuid() not to
see the /PARTNROFF option, which causes different results.  In order to
avoid misleading future maintainers, this parameter is marked const.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 17 insertions, 11 deletions

diff --git a/init/do_mounts.c b/init/do_mounts.c
index f8a66424360d..b28ec5819325 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -69,23 +69,28 @@ __setup("ro", readonly);
 __setup("rw", readwrite);
 
 #ifdef CONFIG_BLOCK
+struct uuidcmp {
+        const char *uuid;
+        int len;
+};
+
 /**
  * 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
+ * @data:       opaque pointer to the desired struct uuidcmp to match
  *
  * Returns 1 if the device matches, and 0 otherwise.
  */
 static int match_dev_by_uuid(struct device *dev, void *data)
 {
-        u8 *uuid = data;
+        struct uuidcmp *cmp = 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;
+        if (strncasecmp(cmp->uuid, part->info->uuid, cmp->len))
+                goto no_match;
 
         return 1;
 no_match:
@@ -95,7 +100,7 @@ no_match:
 
 /**
  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
- * @uuid:       min 36 byte char array containing a hex ascii UUID
+ * @uuid:       char array containing 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
@@ -106,11 +111,11 @@ no_match:
  *
  * Returns the matching dev_t on success or 0 on failure.
  */
-static dev_t devt_from_partuuid(char *uuid_str)
+static dev_t devt_from_partuuid(const char *uuid_str)
 {
         dev_t res = 0;
+        struct uuidcmp cmp;
         struct device *dev = NULL;
-        u8 uuid[16];
         struct gendisk *disk;
         struct hd_struct *part;
         int offset = 0;
@@ -118,6 +123,9 @@ static dev_t devt_from_partuuid(char *uuid_str)
         if (strlen(uuid_str) < 36)
                 goto done;
 
+        cmp.uuid = uuid_str;
+        cmp.len = 36;
+
         /* Check for optional partition number offset attributes. */
         if (uuid_str[36]) {
                 char c = 0;
@@ -134,10 +142,8 @@ static dev_t devt_from_partuuid(char *uuid_str)
                 }
         }
 
-        /* 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);
+        dev = class_find_device(&block_class, NULL, &cmp,
+                                &match_dev_by_uuid);
         if (!dev)
                 goto done;