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    SubjectRe: [PATCH] zswap: dynamic pool creation
    On Wed, Jun 17, 2015 at 07:13:31PM -0400, Dan Streetman wrote:
    > On Wed, Jun 10, 2015 at 4:54 PM, Dan Streetman <ddstreet@ieee.org> wrote:
    > > On Thu, Jun 4, 2015 at 8:13 AM, Dan Streetman <ddstreet@ieee.org> wrote:
    > >> On Thu, Jun 4, 2015 at 8:02 AM, Dan Streetman <ddstreet@ieee.org> 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 :-)
    >
    > You on vacation Seth? Let me know what direction you prefer for this...

    I think it is as good as it can be. Complicated, but I don't know of a
    way to make it less so if we want to be able to do this (which is a
    separate discussion).

    Seth

    >
    > >
    > >
    > >>
    > >>>
    > >>> This is required by a separate patch which enables changing the
    > >>> zswap zpool and compressor params at runtime.
    > >>>
    > >>> Signed-off-by: Dan Streetman <ddstreet@ieee.org>
    > >>> ---
    > >>> 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
    > >>>
    >
    > --
    > To unsubscribe, send a message with 'unsubscribe linux-mm' in
    > the body to majordomo@kvack.org. For more info on Linux MM,
    > see: http://www.linux-mm.org/ .
    > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>


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