Commit fa9ad6e2 authored by Johannes Weiner's avatar Johannes Weiner Committed by Andrew Morton
Browse files

mm: zswap: break out zwap_compress() 

zswap_store() is long and mixes work at the zswap layer with work at
the backend and compression layer. Move compression & backend work to
zswap_compress(), mirroring zswap_decompress().

Link: https://lkml.kernel.org/r/20240130014208.565554-8-hannes@cmpxchg.org


Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarNhat Pham <nphamcs@gmail.com>
Acked-by: default avatarYosry Ahmed <yosryahmed@google.com>
Reviewed-by: default avatarChengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ff2972aa

mm/zswap.c

+77 −68
Original line number Diff line number Diff line
@@ -1315,6 +1315,79 @@ static int zswap_enabled_param_set(const char *val, 
	return ret;

}



static bool zswap_compress(struct folio *folio, struct zswap_entry *entry)

{

	struct crypto_acomp_ctx *acomp_ctx;

	struct scatterlist input, output;

	unsigned int dlen = PAGE_SIZE;

	unsigned long handle;

	struct zpool *zpool;

	char *buf;

	gfp_t gfp;

	int ret;

	u8 *dst;



	acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);



	mutex_lock(&acomp_ctx->mutex);



	dst = acomp_ctx->buffer;

	sg_init_table(&input, 1);

	sg_set_page(&input, &folio->page, PAGE_SIZE, 0);



	/*

	 * We need PAGE_SIZE * 2 here since there maybe over-compression case,

	 * and hardware-accelerators may won't check the dst buffer size, so

	 * giving the dst buffer with enough length to avoid buffer overflow.

	 */

	sg_init_one(&output, dst, PAGE_SIZE * 2);

	acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);



	/*

	 * it maybe looks a little bit silly that we send an asynchronous request,

	 * then wait for its completion synchronously. This makes the process look

	 * synchronous in fact.

	 * Theoretically, acomp supports users send multiple acomp requests in one

	 * acomp instance, then get those requests done simultaneously. but in this

	 * case, zswap actually does store and load page by page, there is no

	 * existing method to send the second page before the first page is done

	 * in one thread doing zwap.

	 * but in different threads running on different cpu, we have different

	 * acomp instance, so multiple threads can do (de)compression in parallel.

	 */

	ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);

	dlen = acomp_ctx->req->dlen;

	if (ret) {

		zswap_reject_compress_fail++;

		goto unlock;

	}



	zpool = zswap_find_zpool(entry);

	gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;

	if (zpool_malloc_support_movable(zpool))

		gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;

	ret = zpool_malloc(zpool, dlen, gfp, &handle);

	if (ret == -ENOSPC) {

		zswap_reject_compress_poor++;

		goto unlock;

	}

	if (ret) {

		zswap_reject_alloc_fail++;

		goto unlock;

	}



	buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO);

	memcpy(buf, dst, dlen);

	zpool_unmap_handle(zpool, handle);



	entry->handle = handle;

	entry->length = dlen;



unlock:

	mutex_unlock(&acomp_ctx->mutex);

	return ret == 0;

}



static void zswap_decompress(struct zswap_entry *entry, struct page *page)

{

	struct zpool *zpool = zswap_find_zpool(entry);
@@ -1471,18 +1544,11 @@ bool zswap_store(struct folio *folio) 
	struct page *page = &folio->page;

	struct zswap_tree *tree = swap_zswap_tree(swp);

	struct zswap_entry *entry, *dupentry;

	struct scatterlist input, output;

	struct crypto_acomp_ctx *acomp_ctx;

	struct obj_cgroup *objcg = NULL;

	struct mem_cgroup *memcg = NULL;

	struct zswap_pool *pool;

	struct zpool *zpool;

	unsigned int dlen = PAGE_SIZE;

	unsigned long handle, value;

	char *buf;

	u8 *src, *dst;

	gfp_t gfp;

	int ret;

	unsigned long value;

	u8 *src;



	VM_WARN_ON_ONCE(!folio_test_locked(folio));

	VM_WARN_ON_ONCE(!folio_test_swapcache(folio));
@@ -1568,65 +1634,10 @@ bool zswap_store(struct folio *folio) 
		mem_cgroup_put(memcg);

	}



	/* compress */

	acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);



	mutex_lock(&acomp_ctx->mutex);



	dst = acomp_ctx->buffer;

	sg_init_table(&input, 1);

	sg_set_page(&input, &folio->page, PAGE_SIZE, 0);



	/*

	 * We need PAGE_SIZE * 2 here since there maybe over-compression case,

	 * and hardware-accelerators may won't check the dst buffer size, so

	 * giving the dst buffer with enough length to avoid buffer overflow.

	 */

	sg_init_one(&output, dst, PAGE_SIZE * 2);

	acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);

	/*

	 * it maybe looks a little bit silly that we send an asynchronous request,

	 * then wait for its completion synchronously. This makes the process look

	 * synchronous in fact.

	 * Theoretically, acomp supports users send multiple acomp requests in one

	 * acomp instance, then get those requests done simultaneously. but in this

	 * case, zswap actually does store and load page by page, there is no

	 * existing method to send the second page before the first page is done

	 * in one thread doing zwap.

	 * but in different threads running on different cpu, we have different

	 * acomp instance, so multiple threads can do (de)compression in parallel.

	 */

	ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);

	dlen = acomp_ctx->req->dlen;



	if (ret) {

		zswap_reject_compress_fail++;

		goto put_dstmem;

	}



	/* store */

	zpool = zswap_find_zpool(entry);

	gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;

	if (zpool_malloc_support_movable(zpool))

		gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;

	ret = zpool_malloc(zpool, dlen, gfp, &handle);

	if (ret == -ENOSPC) {

		zswap_reject_compress_poor++;

		goto put_dstmem;

	}

	if (ret) {

		zswap_reject_alloc_fail++;

		goto put_dstmem;

	}

	buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO);

	memcpy(buf, dst, dlen);

	zpool_unmap_handle(zpool, handle);

	mutex_unlock(&acomp_ctx->mutex);

	if (!zswap_compress(folio, entry))

		goto put_pool;



	/* populate entry */

	entry->swpentry = swp;

	entry->handle = handle;

	entry->length = dlen;



insert_entry:

	entry->objcg = objcg;
@@ -1663,8 +1674,6 @@ bool zswap_store(struct folio *folio) 


	return true;



put_dstmem:

	mutex_unlock(&acomp_ctx->mutex);

put_pool:

	zswap_pool_put(entry->pool);

freepage: