Re: [PATCH] zswap: dynamic pool creation

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On Thu, Jun 4, 2015 at 8:13 AM, Dan Streetman <ddstreet@xxxxxxxx> wrote:
> On Thu, Jun 4, 2015 at 8:02 AM, Dan Streetman <ddstreet@xxxxxxxx> wrote:
>> Add dynamic creation of pools.  Move the static crypto compression
>> per-cpu transforms into each pool.  Add a pointer to zswap_entry to
>> the pool it's in.
>
> Seth, as far as the design, from your previous comments I assume you
> were thinking of maintaining separate lists of zpools and compressors?
>  I do see how that will reduce duplication of zpools and compressors,
> but it also requires adding a new pointer to each zswap_entry, and
> increasing the amount of code to manage each list separately.  And the
> most common case in zswap will be just a single zpool and compressor,
> not repeatedly changing params.  What do you think?

Any opinion on this patch?  If you want, I can break it up so there's
a list of zpools and a list of compressors.  Either the combined way
(this patch) or separate lists works for me, as long as the params are
changeable at runtime :-)


>
>>
>> This is required by a separate patch which enables changing the
>> zswap zpool and compressor params at runtime.
>>
>> Signed-off-by: Dan Streetman <ddstreet@xxxxxxxx>
>> ---
>>  mm/zswap.c | 550 +++++++++++++++++++++++++++++++++++++++++++++----------------
>>  1 file changed, 408 insertions(+), 142 deletions(-)
>>
>> diff --git a/mm/zswap.c b/mm/zswap.c
>> index 2d5727b..fc93770 100644
>> --- a/mm/zswap.c
>> +++ b/mm/zswap.c
>> @@ -99,66 +99,19 @@ module_param_named(zpool, zswap_zpool_type, charp, 0444);
>>  static struct zpool *zswap_pool;
>>
>>  /*********************************
>> -* compression functions
>> +* data structures
>>  **********************************/
>> -/* per-cpu compression transforms */
>> -static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms;
>>
>> -enum comp_op {
>> -       ZSWAP_COMPOP_COMPRESS,
>> -       ZSWAP_COMPOP_DECOMPRESS
>> +struct zswap_pool {
>> +       struct zpool *zpool;
>> +       struct kref kref;
>> +       struct list_head list;
>> +       struct rcu_head rcu_head;
>> +       struct notifier_block notifier;
>> +       char tfm_name[CRYPTO_MAX_ALG_NAME];
>> +       struct crypto_comp * __percpu *tfm;
>>  };
>>
>> -static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
>> -                               u8 *dst, unsigned int *dlen)
>> -{
>> -       struct crypto_comp *tfm;
>> -       int ret;
>> -
>> -       tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu());
>> -       switch (op) {
>> -       case ZSWAP_COMPOP_COMPRESS:
>> -               ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
>> -               break;
>> -       case ZSWAP_COMPOP_DECOMPRESS:
>> -               ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
>> -               break;
>> -       default:
>> -               ret = -EINVAL;
>> -       }
>> -
>> -       put_cpu();
>> -       return ret;
>> -}
>> -
>> -static int __init zswap_comp_init(void)
>> -{
>> -       if (!crypto_has_comp(zswap_compressor, 0, 0)) {
>> -               pr_info("%s compressor not available\n", zswap_compressor);
>> -               /* fall back to default compressor */
>> -               zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
>> -               if (!crypto_has_comp(zswap_compressor, 0, 0))
>> -                       /* can't even load the default compressor */
>> -                       return -ENODEV;
>> -       }
>> -       pr_info("using %s compressor\n", zswap_compressor);
>> -
>> -       /* alloc percpu transforms */
>> -       zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
>> -       if (!zswap_comp_pcpu_tfms)
>> -               return -ENOMEM;
>> -       return 0;
>> -}
>> -
>> -static void __init zswap_comp_exit(void)
>> -{
>> -       /* free percpu transforms */
>> -       free_percpu(zswap_comp_pcpu_tfms);
>> -}
>> -
>> -/*********************************
>> -* data structures
>> -**********************************/
>>  /*
>>   * struct zswap_entry
>>   *
>> @@ -166,22 +119,24 @@ static void __init zswap_comp_exit(void)
>>   * page within zswap.
>>   *
>>   * rbnode - links the entry into red-black tree for the appropriate swap type
>> + * offset - the swap offset for the entry.  Index into the red-black tree.
>>   * refcount - the number of outstanding reference to the entry. This is needed
>>   *            to protect against premature freeing of the entry by code
>>   *            concurrent calls to load, invalidate, and writeback.  The lock
>>   *            for the zswap_tree structure that contains the entry must
>>   *            be held while changing the refcount.  Since the lock must
>>   *            be held, there is no reason to also make refcount atomic.
>> - * offset - the swap offset for the entry.  Index into the red-black tree.
>> - * handle - zpool allocation handle that stores the compressed page data
>>   * length - the length in bytes of the compressed page data.  Needed during
>>   *          decompression
>> + * pool - the zswap_pool the entry's data is in
>> + * handle - zpool allocation handle that stores the compressed page data
>>   */
>>  struct zswap_entry {
>>         struct rb_node rbnode;
>>         pgoff_t offset;
>>         int refcount;
>>         unsigned int length;
>> +       struct zswap_pool *pool;
>>         unsigned long handle;
>>  };
>>
>> @@ -201,6 +156,44 @@ struct zswap_tree {
>>
>>  static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
>>
>> +/* RCU-protected iteration */
>> +static LIST_HEAD(zswap_pools);
>> +/* protects zswap_pools list modification */
>> +static DEFINE_SPINLOCK(zswap_pools_lock);
>> +
>> +/*********************************
>> +* helpers and fwd declarations
>> +**********************************/
>> +
>> +#define zswap_pool_debug(msg, p)                               \
>> +       pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name,         \
>> +                zpool_get_type((p)->zpool))
>> +
>> +static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
>> +static int zswap_pool_get(struct zswap_pool *pool);
>> +static void zswap_pool_put(struct zswap_pool *pool);
>> +
>> +static bool zswap_is_full(void)
>> +{
>> +       return totalram_pages * zswap_max_pool_percent / 100 <
>> +               DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
>> +}
>> +
>> +static void zswap_update_total_size(void)
>> +{
>> +       struct zswap_pool *pool;
>> +       u64 total = 0;
>> +
>> +       rcu_read_lock();
>> +
>> +       list_for_each_entry_rcu(pool, &zswap_pools, list)
>> +               total += zpool_get_total_size(pool->zpool);
>> +
>> +       rcu_read_unlock();
>> +
>> +       zswap_pool_total_size = total;
>> +}
>> +
>>  /*********************************
>>  * zswap entry functions
>>  **********************************/
>> @@ -294,10 +287,11 @@ static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
>>   */
>>  static void zswap_free_entry(struct zswap_entry *entry)
>>  {
>> -       zpool_free(zswap_pool, entry->handle);
>> +       zpool_free(entry->pool->zpool, entry->handle);
>> +       zswap_pool_put(entry->pool);
>>         zswap_entry_cache_free(entry);
>>         atomic_dec(&zswap_stored_pages);
>> -       zswap_pool_total_size = zpool_get_total_size(zswap_pool);
>> +       zswap_update_total_size();
>>  }
>>
>>  /* caller must hold the tree lock */
>> @@ -339,35 +333,21 @@ static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
>>  **********************************/
>>  static DEFINE_PER_CPU(u8 *, zswap_dstmem);
>>
>> -static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
>> +static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu)
>>  {
>> -       struct crypto_comp *tfm;
>>         u8 *dst;
>>
>>         switch (action) {
>>         case CPU_UP_PREPARE:
>> -               tfm = crypto_alloc_comp(zswap_compressor, 0, 0);
>> -               if (IS_ERR(tfm)) {
>> -                       pr_err("can't allocate compressor transform\n");
>> -                       return NOTIFY_BAD;
>> -               }
>> -               *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm;
>>                 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
>>                 if (!dst) {
>>                         pr_err("can't allocate compressor buffer\n");
>> -                       crypto_free_comp(tfm);
>> -                       *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
>>                         return NOTIFY_BAD;
>>                 }
>>                 per_cpu(zswap_dstmem, cpu) = dst;
>>                 break;
>>         case CPU_DEAD:
>>         case CPU_UP_CANCELED:
>> -               tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu);
>> -               if (tfm) {
>> -                       crypto_free_comp(tfm);
>> -                       *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
>> -               }
>>                 dst = per_cpu(zswap_dstmem, cpu);
>>                 kfree(dst);
>>                 per_cpu(zswap_dstmem, cpu) = NULL;
>> @@ -378,43 +358,309 @@ static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
>>         return NOTIFY_OK;
>>  }
>>
>> -static int zswap_cpu_notifier(struct notifier_block *nb,
>> -                               unsigned long action, void *pcpu)
>> +static int zswap_cpu_dstmem_notifier(struct notifier_block *nb,
>> +                                    unsigned long action, void *pcpu)
>>  {
>> -       unsigned long cpu = (unsigned long)pcpu;
>> -       return __zswap_cpu_notifier(action, cpu);
>> +       return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu);
>>  }
>>
>> -static struct notifier_block zswap_cpu_notifier_block = {
>> -       .notifier_call = zswap_cpu_notifier
>> +static struct notifier_block zswap_dstmem_notifier = {
>> +       .notifier_call =        zswap_cpu_dstmem_notifier,
>>  };
>>
>> -static int __init zswap_cpu_init(void)
>> +static int __init zswap_cpu_dstmem_init(void)
>>  {
>>         unsigned long cpu;
>>
>>         cpu_notifier_register_begin();
>>         for_each_online_cpu(cpu)
>> -               if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK)
>> +               if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) ==
>> +                   NOTIFY_BAD)
>>                         goto cleanup;
>> -       __register_cpu_notifier(&zswap_cpu_notifier_block);
>> +       __register_cpu_notifier(&zswap_dstmem_notifier);
>>         cpu_notifier_register_done();
>>         return 0;
>>
>>  cleanup:
>>         for_each_online_cpu(cpu)
>> -               __zswap_cpu_notifier(CPU_UP_CANCELED, cpu);
>> +               __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
>>         cpu_notifier_register_done();
>>         return -ENOMEM;
>>  }
>>
>> +static void zswap_cpu_dstmem_destroy(void)
>> +{
>> +       unsigned long cpu;
>> +
>> +       cpu_notifier_register_begin();
>> +       for_each_online_cpu(cpu)
>> +               __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
>> +       __unregister_cpu_notifier(&zswap_dstmem_notifier);
>> +       cpu_notifier_register_done();
>> +}
>> +
>> +static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
>> +                                    unsigned long action, unsigned long cpu)
>> +{
>> +       struct crypto_comp *tfm;
>> +
>> +       switch (action) {
>> +       case CPU_UP_PREPARE:
>> +               if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
>> +                       break;
>> +               tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
>> +               if (IS_ERR_OR_NULL(tfm)) {
>> +                       pr_err("could not alloc crypto comp %s : %ld\n",
>> +                              pool->tfm_name, PTR_ERR(tfm));
>> +                       return NOTIFY_BAD;
>> +               }
>> +               *per_cpu_ptr(pool->tfm, cpu) = tfm;
>> +               break;
>> +       case CPU_DEAD:
>> +       case CPU_UP_CANCELED:
>> +               tfm = *per_cpu_ptr(pool->tfm, cpu);
>> +               if (!IS_ERR_OR_NULL(tfm))
>> +                       crypto_free_comp(tfm);
>> +               *per_cpu_ptr(pool->tfm, cpu) = NULL;
>> +               break;
>> +       default:
>> +               break;
>> +       }
>> +       return NOTIFY_OK;
>> +}
>> +
>> +static int zswap_cpu_comp_notifier(struct notifier_block *nb,
>> +                                  unsigned long action, void *pcpu)
>> +{
>> +       unsigned long cpu = (unsigned long)pcpu;
>> +       struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier);
>> +
>> +       return __zswap_cpu_comp_notifier(pool, action, cpu);
>> +}
>> +
>> +static int zswap_cpu_comp_init(struct zswap_pool *pool)
>> +{
>> +       unsigned long cpu;
>> +
>> +       memset(&pool->notifier, 0, sizeof(pool->notifier));
>> +       pool->notifier.notifier_call = zswap_cpu_comp_notifier;
>> +
>> +       cpu_notifier_register_begin();
>> +       for_each_online_cpu(cpu)
>> +               if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) ==
>> +                   NOTIFY_BAD)
>> +                       goto cleanup;
>> +       __register_cpu_notifier(&pool->notifier);
>> +       cpu_notifier_register_done();
>> +       return 0;
>> +
>> +cleanup:
>> +       for_each_online_cpu(cpu)
>> +               __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
>> +       cpu_notifier_register_done();
>> +       return -ENOMEM;
>> +}
>> +
>> +static void zswap_cpu_comp_destroy(struct zswap_pool *pool)
>> +{
>> +       unsigned long cpu;
>> +
>> +       cpu_notifier_register_begin();
>> +       for_each_online_cpu(cpu)
>> +               __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
>> +       __unregister_cpu_notifier(&pool->notifier);
>> +       cpu_notifier_register_done();
>> +}
>> +
>>  /*********************************
>> -* helpers
>> +* pool functions
>>  **********************************/
>> -static bool zswap_is_full(void)
>> +
>> +static struct zswap_pool *__zswap_pool_current(void)
>>  {
>> -       return totalram_pages * zswap_max_pool_percent / 100 <
>> -               DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
>> +       struct zswap_pool *pool;
>> +
>> +       pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
>> +       WARN_ON(!pool);
>> +
>> +       return pool;
>> +}
>> +
>> +static struct zswap_pool *zswap_pool_current(void)
>> +{
>> +       assert_spin_locked(&zswap_pools_lock);
>> +
>> +       return __zswap_pool_current();
>> +}
>> +
>> +static struct zswap_pool *zswap_pool_current_get(void)
>> +{
>> +       struct zswap_pool *pool;
>> +
>> +       rcu_read_lock();
>> +
>> +       pool = __zswap_pool_current();
>> +       if (!pool || !zswap_pool_get(pool))
>> +               pool = NULL;
>> +
>> +       rcu_read_unlock();
>> +
>> +       return pool;
>> +}
>> +
>> +static struct zswap_pool *zswap_pool_last_get(void)
>> +{
>> +       struct zswap_pool *pool, *last = NULL;
>> +
>> +       rcu_read_lock();
>> +
>> +       list_for_each_entry_rcu(pool, &zswap_pools, list)
>> +               last = pool;
>> +       if (!WARN_ON(!last) && !zswap_pool_get(last))
>> +               last = NULL;
>> +
>> +       rcu_read_unlock();
>> +
>> +       return last;
>> +}
>> +
>> +static struct zpool_ops zswap_zpool_ops = {
>> +       .evict = zswap_writeback_entry
>> +};
>> +
>> +static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
>> +{
>> +       struct zswap_pool *pool;
>> +
>> +       assert_spin_locked(&zswap_pools_lock);
>> +
>> +       list_for_each_entry_rcu(pool, &zswap_pools, list) {
>> +               if (strncmp(pool->tfm_name, compressor, sizeof(pool->tfm_name)))
>> +                       continue;
>> +               if (strncmp(zpool_get_type(pool->zpool), type,
>> +                           sizeof(zswap_zpool_type)))
>> +                       continue;
>> +               /* if we can't get it, it's about to be destroyed */
>> +               if (!zswap_pool_get(pool))
>> +                       continue;
>> +               return pool;
>> +       }
>> +
>> +       return NULL;
>> +}
>> +
>> +static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
>> +{
>> +       struct zswap_pool *pool;
>> +       gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
>> +
>> +       pool = kzalloc(sizeof(*pool), GFP_KERNEL);
>> +       if (!pool) {
>> +               pr_err("pool alloc failed\n");
>> +               return NULL;
>> +       }
>> +
>> +       pool->zpool = zpool_create_pool(type, "zswap", gfp, &zswap_zpool_ops);
>> +       if (!pool->zpool) {
>> +               pr_err("%s zpool not available\n", type);
>> +               goto error;
>> +       }
>> +       pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
>> +
>> +       strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
>> +       pool->tfm = alloc_percpu(struct crypto_comp *);
>> +       if (!pool->tfm) {
>> +               pr_err("percpu alloc failed\n");
>> +               goto error;
>> +       }
>> +
>> +       if (zswap_cpu_comp_init(pool))
>> +               goto error;
>> +       pr_debug("using %s compressor\n", pool->tfm_name);
>> +
>> +       /* being the current pool takes 1 ref; this func expects the
>> +        * caller to always add the new pool as the current pool
>> +        */
>> +       kref_init(&pool->kref);
>> +       INIT_LIST_HEAD(&pool->list);
>> +
>> +       zswap_pool_debug("created", pool);
>> +
>> +       return pool;
>> +
>> +error:
>> +       free_percpu(pool->tfm);
>> +       if (pool->zpool)
>> +               zpool_destroy_pool(pool->zpool);
>> +       kfree(pool);
>> +       return NULL;
>> +}
>> +
>> +static struct zswap_pool *__zswap_pool_create_fallback(void)
>> +{
>> +       if (!crypto_has_comp(zswap_compressor, 0, 0)) {
>> +               pr_err("compressor %s not available, using default %s\n",
>> +                      zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
>> +               strncpy(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT,
>> +                       sizeof(zswap_compressor));
>> +       }
>> +       if (!zpool_has_pool(zswap_zpool_type)) {
>> +               pr_err("zpool %s not available, using default %s\n",
>> +                      zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
>> +               strncpy(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT,
>> +                       sizeof(zswap_zpool_type));
>> +       }
>> +
>> +       return zswap_pool_create(zswap_zpool_type, zswap_compressor);
>> +}
>> +
>> +static void zswap_pool_destroy(struct zswap_pool *pool)
>> +{
>> +       zswap_pool_debug("destroying", pool);
>> +
>> +       zswap_cpu_comp_destroy(pool);
>> +       free_percpu(pool->tfm);
>> +       zpool_destroy_pool(pool->zpool);
>> +       kfree(pool);
>> +}
>> +
>> +static int __must_check zswap_pool_get(struct zswap_pool *pool)
>> +{
>> +       return kref_get_unless_zero(&pool->kref);
>> +}
>> +
>> +static void __zswap_pool_release(struct rcu_head *head)
>> +{
>> +       struct zswap_pool *pool = container_of(head, typeof(*pool), rcu_head);
>> +
>> +       /* nobody should have been able to get a kref... */
>> +       WARN_ON(kref_get_unless_zero(&pool->kref));
>> +
>> +       /* pool is now off zswap_pools list and has no references. */
>> +       zswap_pool_destroy(pool);
>> +}
>> +
>> +static void __zswap_pool_empty(struct kref *kref)
>> +{
>> +       struct zswap_pool *pool;
>> +
>> +       pool = container_of(kref, typeof(*pool), kref);
>> +
>> +       spin_lock(&zswap_pools_lock);
>> +
>> +       WARN_ON(pool == zswap_pool_current());
>> +
>> +       list_del_rcu(&pool->list);
>> +       call_rcu(&pool->rcu_head, __zswap_pool_release);
>> +
>> +       spin_unlock(&zswap_pools_lock);
>> +}
>> +
>> +static void zswap_pool_put(struct zswap_pool *pool)
>> +{
>> +       kref_put(&pool->kref, __zswap_pool_empty);
>> +}
>> +
>>  }
>>
>>  /*********************************
>> @@ -538,6 +784,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
>>         pgoff_t offset;
>>         struct zswap_entry *entry;
>>         struct page *page;
>> +       struct crypto_comp *tfm;
>>         u8 *src, *dst;
>>         unsigned int dlen;
>>         int ret;
>> @@ -578,13 +825,15 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
>>         case ZSWAP_SWAPCACHE_NEW: /* page is locked */
>>                 /* decompress */
>>                 dlen = PAGE_SIZE;
>> -               src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
>> +               src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
>>                                 ZPOOL_MM_RO) + sizeof(struct zswap_header);
>>                 dst = kmap_atomic(page);
>> -               ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
>> -                               entry->length, dst, &dlen);
>> +               tfm = *get_cpu_ptr(entry->pool->tfm);
>> +               ret = crypto_comp_decompress(tfm, src, entry->length,
>> +                                            dst, &dlen);
>> +               put_cpu_ptr(entry->pool->tfm);
>>                 kunmap_atomic(dst);
>> -               zpool_unmap_handle(zswap_pool, entry->handle);
>> +               zpool_unmap_handle(entry->pool->zpool, entry->handle);
>>                 BUG_ON(ret);
>>                 BUG_ON(dlen != PAGE_SIZE);
>>
>> @@ -633,6 +882,22 @@ end:
>>         return ret;
>>  }
>>
>> +static int zswap_shrink(void)
>> +{
>> +       struct zswap_pool *pool;
>> +       int ret;
>> +
>> +       pool = zswap_pool_last_get();
>> +       if (!pool)
>> +               return -ENOENT;
>> +
>> +       ret = zpool_shrink(pool->zpool, 1, NULL);
>> +
>> +       zswap_pool_put(pool);
>> +
>> +       return ret;
>> +}
>> +
>>  /*********************************
>>  * frontswap hooks
>>  **********************************/
>> @@ -642,6 +907,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>>  {
>>         struct zswap_tree *tree = zswap_trees[type];
>>         struct zswap_entry *entry, *dupentry;
>> +       struct crypto_comp *tfm;
>>         int ret;
>>         unsigned int dlen = PAGE_SIZE, len;
>>         unsigned long handle;
>> @@ -657,7 +923,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>>         /* reclaim space if needed */
>>         if (zswap_is_full()) {
>>                 zswap_pool_limit_hit++;
>> -               if (zpool_shrink(zswap_pool, 1, NULL)) {
>> +               if (zswap_shrink()) {
>>                         zswap_reject_reclaim_fail++;
>>                         ret = -ENOMEM;
>>                         goto reject;
>> @@ -672,33 +938,42 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>>                 goto reject;
>>         }
>>
>> +       /* if entry is successfully added, it keeps the reference */
>> +       entry->pool = zswap_pool_current_get();
>> +       if (!entry->pool) {
>> +               ret = -EINVAL;
>> +               goto freepage;
>> +       }
>> +
>>         /* compress */
>>         dst = get_cpu_var(zswap_dstmem);
>> +       tfm = *get_cpu_ptr(entry->pool->tfm);
>>         src = kmap_atomic(page);
>> -       ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen);
>> +       ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
>>         kunmap_atomic(src);
>> +       put_cpu_ptr(entry->pool->tfm);
>>         if (ret) {
>>                 ret = -EINVAL;
>> -               goto freepage;
>> +               goto put_dstmem;
>>         }
>>
>>         /* store */
>>         len = dlen + sizeof(struct zswap_header);
>> -       ret = zpool_malloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
>> -               &handle);
>> +       ret = zpool_malloc(entry->pool->zpool, len,
>> +                          __GFP_NORETRY | __GFP_NOWARN, &handle);
>>         if (ret == -ENOSPC) {
>>                 zswap_reject_compress_poor++;
>> -               goto freepage;
>> +               goto put_dstmem;
>>         }
>>         if (ret) {
>>                 zswap_reject_alloc_fail++;
>> -               goto freepage;
>> +               goto put_dstmem;
>>         }
>> -       zhdr = zpool_map_handle(zswap_pool, handle, ZPOOL_MM_RW);
>> +       zhdr = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW);
>>         zhdr->swpentry = swp_entry(type, offset);
>>         buf = (u8 *)(zhdr + 1);
>>         memcpy(buf, dst, dlen);
>> -       zpool_unmap_handle(zswap_pool, handle);
>> +       zpool_unmap_handle(entry->pool->zpool, handle);
>>         put_cpu_var(zswap_dstmem);
>>
>>         /* populate entry */
>> @@ -721,12 +996,14 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
>>
>>         /* update stats */
>>         atomic_inc(&zswap_stored_pages);
>> -       zswap_pool_total_size = zpool_get_total_size(zswap_pool);
>> +       zswap_update_total_size();
>>
>>         return 0;
>>
>> -freepage:
>> +put_dstmem:
>>         put_cpu_var(zswap_dstmem);
>> +       zswap_pool_put(entry->pool);
>> +freepage:
>>         zswap_entry_cache_free(entry);
>>  reject:
>>         return ret;
>> @@ -741,6 +1018,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
>>  {
>>         struct zswap_tree *tree = zswap_trees[type];
>>         struct zswap_entry *entry;
>> +       struct crypto_comp *tfm;
>>         u8 *src, *dst;
>>         unsigned int dlen;
>>         int ret;
>> @@ -757,13 +1035,14 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
>>
>>         /* decompress */
>>         dlen = PAGE_SIZE;
>> -       src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
>> +       src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
>>                         ZPOOL_MM_RO) + sizeof(struct zswap_header);
>>         dst = kmap_atomic(page);
>> -       ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length,
>> -               dst, &dlen);
>> +       tfm = *get_cpu_ptr(entry->pool->tfm);
>> +       ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
>> +       put_cpu_ptr(entry->pool->tfm);
>>         kunmap_atomic(dst);
>> -       zpool_unmap_handle(zswap_pool, entry->handle);
>> +       zpool_unmap_handle(entry->pool->zpool, entry->handle);
>>         BUG_ON(ret);
>>
>>         spin_lock(&tree->lock);
>> @@ -816,10 +1095,6 @@ static void zswap_frontswap_invalidate_area(unsigned type)
>>         zswap_trees[type] = NULL;
>>  }
>>
>> -static struct zpool_ops zswap_zpool_ops = {
>> -       .evict = zswap_writeback_entry
>> -};
>> -
>>  static void zswap_frontswap_init(unsigned type)
>>  {
>>         struct zswap_tree *tree;
>> @@ -900,49 +1175,40 @@ static void __exit zswap_debugfs_exit(void) { }
>>  **********************************/
>>  static int __init init_zswap(void)
>>  {
>> -       gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
>> +       struct zswap_pool *pool;
>>
>> -       pr_info("loading zswap\n");
>> -
>> -       zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
>> -                                       &zswap_zpool_ops);
>> -       if (!zswap_pool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
>> -               pr_info("%s zpool not available\n", zswap_zpool_type);
>> -               zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
>> -               zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
>> -                                       &zswap_zpool_ops);
>> -       }
>> -       if (!zswap_pool) {
>> -               pr_err("%s zpool not available\n", zswap_zpool_type);
>> -               pr_err("zpool creation failed\n");
>> -               goto error;
>> -       }
>> -       pr_info("using %s pool\n", zswap_zpool_type);
>> +       pr_info("loading\n");
>>
>>         if (zswap_entry_cache_create()) {
>>                 pr_err("entry cache creation failed\n");
>> -               goto cachefail;
>> +               goto cache_fail;
>>         }
>> -       if (zswap_comp_init()) {
>> -               pr_err("compressor initialization failed\n");
>> -               goto compfail;
>> +
>> +       if (zswap_cpu_dstmem_init()) {
>> +               pr_err("dstmem alloc failed\n");
>> +               goto dstmem_fail;
>>         }
>> -       if (zswap_cpu_init()) {
>> -               pr_err("per-cpu initialization failed\n");
>> -               goto pcpufail;
>> +
>> +       pool = __zswap_pool_create_fallback();
>> +       if (!pool) {
>> +               pr_err("pool creation failed\n");
>> +               goto pool_fail;
>>         }
>> +       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;
>> -pcpufail:
>> -       zswap_comp_exit();
>> -compfail:
>> +
>> +pool_fail:
>> +       zswap_cpu_dstmem_destroy();
>> +dstmem_fail:
>>         zswap_entry_cache_destroy();
>> -cachefail:
>> -       zpool_destroy_pool(zswap_pool);
>> -error:
>> +cache_fail:
>>         return -ENOMEM;
>>  }
>>  /* must be late so crypto has time to come up */
>> --
>> 2.1.0
>>

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