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

Patch series "Delay the initializaton of zswap".

In the initialization of zswap, about 18MB memory will be allocated for
zswap_pool.  Since not all users use zswap, the memory may be wasted.
Save the memory for these users by delaying the initialization of zswap to
first enablement.

This patch (of 3):

zswap_init_started indicates that the initialization is started.  And
zswap_init_failed indicates that the initialization is failed.  As we will
support to init zswap after system startup, it's necessary to add a state
to indicate the initialization is complete and succeed to avoid
concurrency issues.  Since we don't care about the difference between init
started with init completion.  We only need three states: uninitialized,
initial failed, initial succeed.

Link: https://lkml.kernel.org/r/20220825142037.3214152-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20220825142037.3214152-2-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/zswap.c b/mm/zswap.c
index 2d48fd59cc7ab67e0d22781012fa06bb37c54a93..84e38300f571e2f82621937e1cacfa76fb09a520 100644 (file)
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -214,11 +214,12 @@ 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;
+#define ZSWAP_UNINIT           0
+#define ZSWAP_INIT_SUCCEED     1
+#define ZSWAP_INIT_FAILED      2
 
-/* fatal error during init */
-static bool zswap_init_failed;
+/* init state */
+static int zswap_init_state;
 
 /* init completed, but couldn't create the initial pool */
 static bool zswap_has_pool;
@@ -772,7 +773,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
        char *s = strstrip((char *)val);
        int ret;
 
-       if (zswap_init_failed) {
+       if (zswap_init_state == ZSWAP_INIT_FAILED) {
                pr_err("can't set param, initialization failed\n");
                return -ENODEV;
        }
@@ -784,7 +785,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
        /* if this is load-time (pre-init) param setting,
         * don't create a pool; that's done during init.
         */
-       if (!zswap_init_started)
+       if (zswap_init_state == ZSWAP_UNINIT)
                return param_set_charp(s, kp);
 
        if (!type) {
@@ -875,11 +876,11 @@ 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) {
+       if (zswap_init_state == ZSWAP_INIT_FAILED) {
                pr_err("can't enable, initialization failed\n");
                return -ENODEV;
        }
-       if (!zswap_has_pool && zswap_init_started) {
+       if (!zswap_has_pool && zswap_init_state == ZSWAP_INIT_SUCCEED) {
                pr_err("can't enable, no pool configured\n");
                return -ENODEV;
        }
@@ -1476,8 +1477,6 @@ static int __init init_zswap(void)
        struct zswap_pool *pool;
        int ret;
 
-       zswap_init_started = true;
-
        if (zswap_entry_cache_create()) {
                pr_err("entry cache creation failed\n");
                goto cache_fail;
@@ -1517,6 +1516,7 @@ 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:
@@ -1530,7 +1530,7 @@ dstmem_fail:
        zswap_entry_cache_destroy();
 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;
 }