Re: [PATCH] zswap: dynamic pool creation

[Dan Streetman]

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?

>
> 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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