mm/zswap: replace zswap_init_{started/failed} with zswap_init_state

The zswap_init_started variable name has a bit confusing.  Actually, there
are three state: uninitialized, initial failed and initial succeed.  Add a
new variable zswap_init_state to replace zswap_init_{started/failed}.

Link: https://lkml.kernel.org/r/20230403121318.1876082-3-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/zswap.c

@@ -214,11 +214,13 @@ static DEFINE_SPINLOCK(zswap_pools_lock);
 /* pool counter to provide unique names to zpool */
 static atomic_t zswap_pools_count = ATOMIC_INIT(0);
 
-/* used by param callback function */
-static bool zswap_init_started;
+enum zswap_init_type {
+	ZSWAP_UNINIT,
+	ZSWAP_INIT_SUCCEED,
+	ZSWAP_INIT_FAILED
+};
 
-/* fatal error during init */
-static bool zswap_init_failed;
+static enum zswap_init_type zswap_init_state;
 
 /* init completed, but couldn't create the initial pool */
 static bool zswap_has_pool;
@@ -761,21 +763,22 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
 	char *s = strstrip((char *)val);
 	int ret;
 
-	if (zswap_init_failed) {
+	switch (zswap_init_state) {
+	case ZSWAP_UNINIT:
+		/* if this is load-time (pre-init) param setting,
+		 * don't create a pool; that's done during init.
+		 */
+		return param_set_charp(s, kp);
+	case ZSWAP_INIT_SUCCEED:
+		/* no change required */
+		if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
+			return 0;
+		break;
+	case ZSWAP_INIT_FAILED:
 		pr_err("can't set param, initialization failed\n");
 		return -ENODEV;
 	}
 
-	/* no change required */
-	if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
-		return 0;
-
-	/* if this is load-time (pre-init) param setting,
-	 * don't create a pool; that's done during init.
-	 */
-	if (!zswap_init_started)
-		return param_set_charp(s, kp);
-
 	if (!type) {
 		if (!zpool_has_pool(s)) {
 			pr_err("zpool %s not available\n", s);
@@ -864,16 +867,19 @@ static int zswap_zpool_param_set(const char *val,
 static int zswap_enabled_param_set(const char *val,
 				   const struct kernel_param *kp)
 {
-	if (zswap_init_failed) {
+	switch (zswap_init_state) {
+	case ZSWAP_UNINIT:
+		return param_set_bool(val, kp);
+	case ZSWAP_INIT_SUCCEED:
+		if (!zswap_has_pool) {
+			pr_err("can't enable, no pool configured\n");
+			return -ENODEV;
+		} else
+			return param_set_bool(val, kp);
+	case ZSWAP_INIT_FAILED:
 		pr_err("can't enable, initialization failed\n");
 		return -ENODEV;
 	}
-	if (!zswap_has_pool && zswap_init_started) {
-		pr_err("can't enable, no pool configured\n");
-		return -ENODEV;
-	}
-
-	return param_set_bool(val, kp);
 }
 
 /*********************************
@@ -1476,8 +1482,6 @@ static int __init init_zswap(void)
 	struct zswap_pool *pool;
 	int ret;
 
-	zswap_init_started = true;
-
 	zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
 	if (!zswap_entry_cache) {
 		pr_err("entry cache creation failed\n");
@@ -1518,6 +1522,7 @@ static int __init init_zswap(void)
 		goto destroy_wq;
 	if (zswap_debugfs_init())
 		pr_warn("debugfs initialization failed\n");
+	zswap_init_state = ZSWAP_INIT_SUCCEED;
 	return 0;
 
 destroy_wq:
@@ -1531,7 +1536,7 @@ static int __init init_zswap(void)
 	kmem_cache_destroy(zswap_entry_cache);
 cache_fail:
 	/* if built-in, we aren't unloaded on failure; don't allow use */
-	zswap_init_failed = true;
+	zswap_init_state = ZSWAP_INIT_FAILED;
 	zswap_enabled = false;
 	return -ENOMEM;
 }