Re: [RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support

From: Seth Jennings
Date: Tue Feb 14 2017 - 11:21:08 EST

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In reply to: Mahipal Challa: "[RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support"
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On Tue, Feb 14, 2017 at 9:40 AM, Mahipal Challa
<mahipalreddy2006@xxxxxxxxx> wrote:
> This adds the support for kernel's crypto new acomp/scomp framework
> to zswap.
>
> Signed-off-by: Mahipal Challa <Mahipal.Challa@xxxxxxxxxx>
> Signed-off-by: Vishnu Nair <Vishnu.Nair@xxxxxxxxxx>
> ---
> mm/zswap.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 99 insertions(+), 30 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 067a0d6..d08631b 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -33,6 +33,8 @@
> #include <linux/rbtree.h>
> #include <linux/swap.h>
> #include <linux/crypto.h>
> +#include <crypto/acompress.h>
> +#include <linux/scatterlist.h>
> #include <linux/mempool.h>
> #include <linux/zpool.h>
>
> @@ -114,7 +116,8 @@ static int zswap_compressor_param_set(const char *,
>
> struct zswap_pool {
> struct zpool *zpool;
> - struct crypto_comp * __percpu *tfm;
> + struct crypto_acomp * __percpu *acomp;
> + struct acomp_req * __percpu *acomp_req;
> struct kref kref;
> struct list_head list;
> struct work_struct work;
> @@ -379,30 +382,49 @@ static int zswap_dstmem_dead(unsigned int cpu)
> static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
> {
> struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
> - struct crypto_comp *tfm;
> + struct crypto_acomp *acomp;
> + struct acomp_req *acomp_req;
>
> - if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
> + if (WARN_ON(*per_cpu_ptr(pool->acomp, cpu)))
> return 0;
> + if (WARN_ON(*per_cpu_ptr(pool->acomp_req, cpu)))
> + return 0;
> +
> + acomp = crypto_alloc_acomp(pool->tfm_name, 0, 0);
> + if (IS_ERR_OR_NULL(acomp)) {
> + pr_err("could not alloc crypto acomp %s : %ld\n",
> + pool->tfm_name, PTR_ERR(acomp));
> + return -ENOMEM;
> + }
> + *per_cpu_ptr(pool->acomp, cpu) = acomp;
>
> - 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));
> + acomp_req = acomp_request_alloc(acomp);
> + if (IS_ERR_OR_NULL(acomp_req)) {
> + pr_err("could not alloc crypto acomp %s : %ld\n",
> + pool->tfm_name, PTR_ERR(acomp));
> return -ENOMEM;
> }
> - *per_cpu_ptr(pool->tfm, cpu) = tfm;
> + *per_cpu_ptr(pool->acomp_req, cpu) = acomp_req;
> +
> return 0;
> }
>
> static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
> {
> struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
> - struct crypto_comp *tfm;
> + struct crypto_acomp *acomp;
> + struct acomp_req *acomp_req;
> +
> + acomp_req = *per_cpu_ptr(pool->acomp_req, cpu);
> + if (!IS_ERR_OR_NULL(acomp_req))
> + acomp_request_free(acomp_req);
> + *per_cpu_ptr(pool->acomp_req, cpu) = NULL;
> +
> + acomp = *per_cpu_ptr(pool->acomp, cpu);
> + if (!IS_ERR_OR_NULL(acomp))
> + crypto_free_acomp(acomp);
> + *per_cpu_ptr(pool->acomp, cpu) = NULL;
>
> - tfm = *per_cpu_ptr(pool->tfm, cpu);
> - if (!IS_ERR_OR_NULL(tfm))
> - crypto_free_comp(tfm);
> - *per_cpu_ptr(pool->tfm, cpu) = NULL;
> return 0;
> }
>
> @@ -503,8 +525,14 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> 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) {
> + pool->acomp = alloc_percpu(struct crypto_acomp *);
> + if (!pool->acomp) {
> + pr_err("percpu alloc failed\n");
> + goto error;
> + }
> +
> + pool->acomp_req = alloc_percpu(struct acomp_req *);
> + if (!pool->acomp_req) {
> pr_err("percpu alloc failed\n");
> goto error;
> }
> @@ -526,7 +554,8 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> return pool;
>
> error:
> - free_percpu(pool->tfm);
> + free_percpu(pool->acomp_req);
> + free_percpu(pool->acomp);
> if (pool->zpool)
> zpool_destroy_pool(pool->zpool);
> kfree(pool);
> @@ -566,7 +595,8 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
> zswap_pool_debug("destroying", pool);
>
> cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
> - free_percpu(pool->tfm);
> + free_percpu(pool->acomp_req);
> + free_percpu(pool->acomp);
> zpool_destroy_pool(pool->zpool);
> kfree(pool);
> }
> @@ -763,7 +793,8 @@ 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;
> + struct scatterlist input, output;
> + struct acomp_req *req;
> u8 *src, *dst;
> unsigned int dlen;
> int ret;
> @@ -803,14 +834,23 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
>
> case ZSWAP_SWAPCACHE_NEW: /* page is locked */
> /* decompress */
> + req = *get_cpu_ptr(entry->pool->acomp_req);
> dlen = PAGE_SIZE;
> src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
> ZPOOL_MM_RO) + sizeof(struct zswap_header);
> dst = kmap_atomic(page);
> - tfm = *get_cpu_ptr(entry->pool->tfm);
> - ret = crypto_comp_decompress(tfm, src, entry->length,
> - dst, &dlen);
> - put_cpu_ptr(entry->pool->tfm);
> +
> + sg_init_one(&input, src, entry->length);
> + sg_init_one(&output, dst, dlen);
> + acomp_request_set_params(req, &input, &output, entry->length,
> + dlen);
> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
> + NULL, NULL);
> +
> + ret = crypto_acomp_decompress(req);

I assume all of these crypto_acomp_[compress|decompress] calls are
actually synchronous,
not asynchronous as the name suggests. Otherwise, this would blow up
quite spectacularly
since all the resources we use in the call get derefed/unmapped below.

Could an async algorithm be implement/used that would break this assumption?

Seth

> +
> + dlen = req->dlen;
> + put_cpu_ptr(entry->pool->acomp_req);
> kunmap_atomic(dst);
> zpool_unmap_handle(entry->pool->zpool, entry->handle);
> BUG_ON(ret);
> @@ -886,7 +926,8 @@ 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;
> + struct scatterlist input, output;
> + struct acomp_req *req;
> int ret;
> unsigned int dlen = PAGE_SIZE, len;
> unsigned long handle;
> @@ -925,12 +966,27 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> }
>
> /* compress */
> + req = *get_cpu_ptr(entry->pool->acomp_req);
> + if (!req) {
> + put_cpu_ptr(entry->pool->acomp_req);
> + ret = -EINVAL;
> + goto freepage;
> + }
> +
> dst = get_cpu_var(zswap_dstmem);
> - tfm = *get_cpu_ptr(entry->pool->tfm);
> src = kmap_atomic(page);
> - ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
> +
> + sg_init_one(&input, src, PAGE_SIZE);
> + /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
> + sg_init_one(&output, dst, PAGE_SIZE * 2);
> + acomp_request_set_params(req, &input, &output, PAGE_SIZE, dlen);
> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, NULL,
> + NULL);
> +
> + ret = crypto_acomp_compress(req);
> kunmap_atomic(src);
> - put_cpu_ptr(entry->pool->tfm);
> + put_cpu_ptr(entry->pool->acomp_req);
> + dlen = req->dlen;
> if (ret) {
> ret = -EINVAL;
> goto put_dstmem;
> @@ -998,7 +1054,8 @@ 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;
> + struct scatterlist input, output;
> + struct acomp_req *req;
> u8 *src, *dst;
> unsigned int dlen;
> int ret;
> @@ -1014,13 +1071,25 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
> spin_unlock(&tree->lock);
>
> /* decompress */
> + req = *get_cpu_ptr(entry->pool->acomp_req);
> + if (!req) {
> + put_cpu_ptr(entry->pool->acomp_req);
> + return -1;
> + }
> dlen = PAGE_SIZE;
> src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
> ZPOOL_MM_RO) + sizeof(struct zswap_header);
> dst = kmap_atomic(page);
> - tfm = *get_cpu_ptr(entry->pool->tfm);
> - ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
> - put_cpu_ptr(entry->pool->tfm);
> +
> + sg_init_one(&input, src, entry->length);
> + sg_init_one(&output, dst, dlen);
> + acomp_request_set_params(req, &input, &output, entry->length, dlen);
> + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, NULL,
> + NULL);
> +
> + ret = crypto_acomp_decompress(req);
> +
> + put_cpu_ptr(entry->pool->acomp_req);
> kunmap_atomic(dst);
> zpool_unmap_handle(entry->pool->zpool, entry->handle);
> BUG_ON(ret);
> --
> 1.8.3.1
>

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In reply to: Mahipal Challa: "[RFC PATCH v1 1/1] mm: zswap - Add crypto acomp/scomp framework support"
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