block: fix part_pack_uuid() build error

Commit "85865c1f ima: add policy support for file system uuid"
introduced a CONFIG_BLOCK dependency.  This patch defines a
wrapper called blk_part_pack_uuid(), which returns -EINVAL,
when CONFIG_BLOCK is not defined.

security/integrity/ima/ima_policy.c:538:4: error: implicit declaration
of function 'part_pack_uuid' [-Werror=implicit-function-declaration]

Changelog v2:
- Reference commit number in patch description
Changelog v1:
- rename ima_part_pack_uuid() to blk_part_pack_uuid()
- resolve scripts/checkpatch.pl warnings
Changelog v0:
- fix UUID scripts/Lindent msgs
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: James Morris <james.l.morris@oracle.com>

include/linux/genhd.h

@@ -231,6 +231,12 @@ static inline void part_pack_uuid(const u8 *uuid_str, u8 *to)
 	}
 }
 
+static inline int blk_part_pack_uuid(const u8 *uuid_str, u8 *to)
+{
+	part_pack_uuid(uuid_str, to);
+	return 0;
+}
+
 static inline int disk_max_parts(struct gendisk *disk)
 {
 	if (disk->flags & GENHD_FL_EXT_DEVT)
@@ -718,6 +724,10 @@ static inline dev_t blk_lookup_devt(const char *name, int partno)
 	return devt;
 }
 
+static inline int blk_part_pack_uuid(const u8 *uuid_str, u8 *to)
+{
+	return -EINVAL;
+}
 #endif /* CONFIG_BLOCK */
 
 #endif /* _LINUX_GENHD_H */

security/integrity/ima/ima_policy.c

@@ -535,9 +535,10 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 				break;
 			}
 
-			part_pack_uuid(args[0].from, entry->fsuuid);
+			result = blk_part_pack_uuid(args[0].from,
+						    entry->fsuuid);
+			if (!result)
 				entry->flags |= IMA_FSUUID;
-			result = 0;
 			break;
 		case Opt_uid:
 			ima_log_string(ab, "uid", args[0].from);