gpt: Drop PARTITION_LINUX_GENERIC and PARTITION_USER_HOME

These don't have an inherent purpose, and aren't used throughout
the codebase, so let's simplify things and remove these.

See https://github.com/systemd/systemd/pull/24803#discussion_r1028190421
for more information.

src/shared/dissect-image.c

@@ -811,7 +811,8 @@ static int dissect_image(
                                 if (pflags & SD_GPT_FLAG_NO_AUTO)
                                         continue;
 
-                        } else if (type.designator == PARTITION_LINUX_GENERIC) {
+                        /* We don't have a designator for SD_GPT_LINUX_GENERIC so check the UUID instead. */
+                        } else if (sd_id128_equal(type.uuid, SD_GPT_LINUX_GENERIC)) {
 
                                 check_partition_flags(node, pflags,
                                                       SD_GPT_FLAG_NO_AUTO | SD_GPT_FLAG_READ_ONLY | SD_GPT_FLAG_GROWFS);

src/shared/gpt.c

@@ -73,8 +73,6 @@ static const char *const partition_designator_table[_PARTITION_DESIGNATOR_MAX] =
         [PARTITION_USR_VERITY_SIG]            = "usr-verity-sig",
         [PARTITION_TMP]                       = "tmp",
         [PARTITION_VAR]                       = "var",
-        [PARTITION_USER_HOME]                 = "user-home",
-        [PARTITION_LINUX_GENERIC]             = "linux-generic",
 };
 
 DEFINE_STRING_TABLE_LOOKUP(partition_designator, PartitionDesignator);
@@ -144,8 +142,8 @@ const GptPartitionType gpt_partition_type_table[] = {
         { SD_GPT_SRV,                    "srv",           _ARCHITECTURE_INVALID, .designator = PARTITION_SRV },
         { SD_GPT_VAR,                    "var",           _ARCHITECTURE_INVALID, .designator = PARTITION_VAR },
         { SD_GPT_TMP,                    "tmp",           _ARCHITECTURE_INVALID, .designator = PARTITION_TMP },
-        { SD_GPT_USER_HOME,              "user-home",     _ARCHITECTURE_INVALID, .designator = PARTITION_USER_HOME },
-        { SD_GPT_LINUX_GENERIC,          "linux-generic", _ARCHITECTURE_INVALID, .designator = PARTITION_LINUX_GENERIC },
+        { SD_GPT_USER_HOME,              "user-home",     _ARCHITECTURE_INVALID, .designator = _PARTITION_DESIGNATOR_INVALID },
+        { SD_GPT_LINUX_GENERIC,          "linux-generic", _ARCHITECTURE_INVALID, .designator = _PARTITION_DESIGNATOR_INVALID },
         {}
 };
 

src/shared/gpt.h

@@ -24,8 +24,6 @@ typedef enum PartitionDesignator {
         PARTITION_USR_VERITY_SIG,
         PARTITION_TMP,
         PARTITION_VAR,
-        PARTITION_USER_HOME,
-        PARTITION_LINUX_GENERIC,
         _PARTITION_DESIGNATOR_MAX,
         _PARTITION_DESIGNATOR_INVALID = -EINVAL,
 } PartitionDesignator;