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zswap: allow initialization at boot without pool 

Allow zswap to initialize at boot even if it can't create its pool due
to a failure to create a zpool and/or compressor.  Allow those to be
created later, from the sysfs module param interface.

Link: http://lkml.kernel.org/r/20170124200259.16191-3-ddstreet@ieee.org
Signed-off-by: Dan Streetman <dan.streetman@canonical.com>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Dan Streetman 2017-02-27 14:26:47 -08:00 committed by Linus Torvalds
parent 01cddfe990
commit ae3d89a7e0
1 changed files with 34 additions and 12 deletions
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46
mm/zswap.c
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@ -185,6 +185,9 @@ static bool zswap_init_started;
/* fatal error during init */
static bool zswap_init_failed;
/* init completed, but couldn't create the initial pool */
static bool zswap_has_pool;
/*********************************
* helpers and fwd declarations
**********************************/
@ -424,7 +427,8 @@ static struct zswap_pool *__zswap_pool_current(void)
struct zswap_pool *pool;
pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
WARN_ON(!pool);
WARN_ONCE(!pool && zswap_has_pool,
"%s: no page storage pool!\n", __func__);
return pool;
}
@ -443,7 +447,7 @@ static struct zswap_pool *zswap_pool_current_get(void)
rcu_read_lock();
pool = __zswap_pool_current();
if (!pool || !zswap_pool_get(pool))
if (!zswap_pool_get(pool))
pool = NULL;
rcu_read_unlock();
@ -459,7 +463,9 @@ static struct zswap_pool *zswap_pool_last_get(void)
list_for_each_entry_rcu(pool, &zswap_pools, list)
last = pool;
if (!WARN_ON(!last) && !zswap_pool_get(last))
WARN_ONCE(!last && zswap_has_pool,
"%s: no page storage pool!\n", __func__);
if (!zswap_pool_get(last))
last = NULL;
rcu_read_unlock();
@ -582,6 +588,9 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
static int __must_check zswap_pool_get(struct zswap_pool *pool)
{
if (!pool)
return 0;
return kref_get_unless_zero(&pool->kref);
}
@ -639,7 +648,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
}
/* no change required */
if (!strcmp(s, *(char **)kp->arg))
if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
return 0;
/* if this is load-time (pre-init) param setting,
@ -685,6 +694,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
if (!ret) {
put_pool = zswap_pool_current();
list_add_rcu(&pool->list, &zswap_pools);
zswap_has_pool = true;
} else if (pool) {
/* add the possibly pre-existing pool to the end of the pools
* list; if it's new (and empty) then it'll be removed and
@ -692,6 +702,15 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
*/
list_add_tail_rcu(&pool->list, &zswap_pools);
put_pool = pool;
} else if (!zswap_has_pool) {
/* if initial pool creation failed, and this pool creation also
* failed, maybe both compressor and zpool params were bad.
* Allow changing this param, so pool creation will succeed
* when the other param is changed. We already verified this
* param is ok in the zpool_has_pool() or crypto_has_comp()
* checks above.
*/
ret = param_set_charp(s, kp);
}
spin_unlock(&zswap_pools_lock);
@ -724,6 +743,10 @@ static int zswap_enabled_param_set(const char *val,
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);
}
@ -1205,22 +1228,21 @@ static int __init init_zswap(void)
goto hp_fail;
pool = __zswap_pool_create_fallback();
if (!pool) {
if (pool) {
pr_info("loaded using pool %s/%s\n", pool->tfm_name,
zpool_get_type(pool->zpool));
list_add(&pool->list, &zswap_pools);
zswap_has_pool = true;
} else {
pr_err("pool creation failed\n");
goto pool_fail;
zswap_enabled = false;
}
pr_info("loaded using pool %s/%s\n", pool->tfm_name,
zpool_get_type(pool->zpool));
list_add(&pool->list, &zswap_pools);
frontswap_register_ops(&zswap_frontswap_ops);
if (zswap_debugfs_init())
pr_warn("debugfs initialization failed\n");
return 0;
pool_fail:
cpuhp_remove_state_nocalls(CPUHP_MM_ZSWP_POOL_PREPARE);
hp_fail:
cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
dstmem_fail: