[v5,10/12] mm: zswap: Allocate pool batching resources if the crypto_alg supports batching.

diff --git a/mm/zswap.c b/mm/zswap.c
index 9718c33f8192..99cd78891fd0 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -78,6 +78,13 @@  static bool zswap_pool_reached_full;
 
 #define ZSWAP_PARAM_UNSET ""
 
+/*
+ * For compression batching of large folios:
+ * Maximum number of acomp compress requests that will be processed
+ * in a batch, iff the zswap compressor supports batching.
+ */
+#define ZSWAP_MAX_BATCH_SIZE 8U
+
 static int zswap_setup(void);
 
 /* Enable/disable zswap */
@@ -143,9 +150,10 @@  bool zswap_never_enabled(void)
 
 struct crypto_acomp_ctx {
 	struct crypto_acomp *acomp;
-	struct acomp_req *req;
+	struct acomp_req **reqs;
+	u8 **buffers;
+	unsigned int nr_reqs;
 	struct crypto_wait wait;
-	u8 *buffer;
 	struct mutex mutex;
 	bool is_sleepable;
 };
@@ -818,49 +826,88 @@  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_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
 	struct crypto_acomp *acomp;
-	struct acomp_req *req;
-	int ret;
+	unsigned int nr_reqs = 1;
+	int ret = -ENOMEM;
+	int i, j;
 
 	mutex_init(&acomp_ctx->mutex);
-
-	acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
-	if (!acomp_ctx->buffer)
-		return -ENOMEM;
+	acomp_ctx->nr_reqs = 0;
 
 	acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
 	if (IS_ERR(acomp)) {
 		pr_err("could not alloc crypto acomp %s : %ld\n",
 				pool->tfm_name, PTR_ERR(acomp));
-		ret = PTR_ERR(acomp);
-		goto acomp_fail;
+		return PTR_ERR(acomp);
 	}
 	acomp_ctx->acomp = acomp;
 	acomp_ctx->is_sleepable = acomp_is_async(acomp);
 
-	req = acomp_request_alloc(acomp_ctx->acomp);
-	if (!req) {
-		pr_err("could not alloc crypto acomp_request %s\n",
-		       pool->tfm_name);
-		ret = -ENOMEM;
+	/*
+	 * Create the necessary batching resources if the crypto acomp alg
+	 * implements the batch_compress and batch_decompress API.
+	 */
+	if (acomp_has_async_batching(acomp)) {
+		nr_reqs = min(ZSWAP_MAX_BATCH_SIZE, crypto_acomp_batch_size(acomp));
+		pr_info_once("Creating acomp_ctx with %d reqs/buffers for batching since crypto acomp\n%s has registered batch_compress() and batch_decompress().\n",
+			nr_reqs, pool->tfm_name);
+	}
+
+	acomp_ctx->buffers = kmalloc_node(nr_reqs * sizeof(u8 *), GFP_KERNEL, cpu_to_node(cpu));
+	if (!acomp_ctx->buffers)
+		goto buf_fail;
+
+	for (i = 0; i < nr_reqs; ++i) {
+		acomp_ctx->buffers[i] = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+		if (!acomp_ctx->buffers[i]) {
+			for (j = 0; j < i; ++j)
+				kfree(acomp_ctx->buffers[j]);
+			kfree(acomp_ctx->buffers);
+			ret = -ENOMEM;
+			goto buf_fail;
+		}
+	}
+
+	acomp_ctx->reqs = kmalloc_node(nr_reqs * sizeof(struct acomp_req *), GFP_KERNEL, cpu_to_node(cpu));
+	if (!acomp_ctx->reqs)
 		goto req_fail;
+
+	for (i = 0; i < nr_reqs; ++i) {
+		acomp_ctx->reqs[i] = acomp_request_alloc(acomp_ctx->acomp);
+		if (!acomp_ctx->reqs[i]) {
+			pr_err("could not alloc crypto acomp_request reqs[%d] %s\n",
+			       i, pool->tfm_name);
+			for (j = 0; j < i; ++j)
+				acomp_request_free(acomp_ctx->reqs[j]);
+			kfree(acomp_ctx->reqs);
+			ret = -ENOMEM;
+			goto req_fail;
+		}
 	}
-	acomp_ctx->req = req;
 
+	/*
+	 * The crypto_wait is used only in fully synchronous, i.e., with scomp
+	 * or non-poll mode of acomp, hence there is only one "wait" per
+	 * acomp_ctx, with callback set to reqs[0], under the assumption that
+	 * there is at least 1 request per acomp_ctx.
+	 */
 	crypto_init_wait(&acomp_ctx->wait);
 	/*
 	 * if the backend of acomp is async zip, crypto_req_done() will wakeup
 	 * crypto_wait_req(); if the backend of acomp is scomp, the callback
 	 * won't be called, crypto_wait_req() will return without blocking.
 	 */
-	acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+	acomp_request_set_callback(acomp_ctx->reqs[0], CRYPTO_TFM_REQ_MAY_BACKLOG,
 				   crypto_req_done, &acomp_ctx->wait);
 
+	acomp_ctx->nr_reqs = nr_reqs;
 	return 0;
 
 req_fail:
+	for (i = 0; i < nr_reqs; ++i)
+		kfree(acomp_ctx->buffers[i]);
+	kfree(acomp_ctx->buffers);
+buf_fail:
 	crypto_free_acomp(acomp_ctx->acomp);
-acomp_fail:
-	kfree(acomp_ctx->buffer);
 	return ret;
 }
 
@@ -870,11 +917,22 @@  static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
 	struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
 
 	if (!IS_ERR_OR_NULL(acomp_ctx)) {
-		if (!IS_ERR_OR_NULL(acomp_ctx->req))
-			acomp_request_free(acomp_ctx->req);
+		int i;
+
+		for (i = 0; i < acomp_ctx->nr_reqs; ++i)
+			if (!IS_ERR_OR_NULL(acomp_ctx->reqs[i]))
+				acomp_request_free(acomp_ctx->reqs[i]);
+		kfree(acomp_ctx->reqs);
+
+		for (i = 0; i < acomp_ctx->nr_reqs; ++i)
+			kfree(acomp_ctx->buffers[i]);
+		kfree(acomp_ctx->buffers);
+
 		if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
 			crypto_free_acomp(acomp_ctx->acomp);
-		kfree(acomp_ctx->buffer);
+
+		acomp_ctx->nr_reqs = 0;
+		acomp_ctx = NULL;
 	}
 
 	return 0;
@@ -897,7 +955,7 @@  static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 
 	mutex_lock(&acomp_ctx->mutex);
 
-	dst = acomp_ctx->buffer;
+	dst = acomp_ctx->buffers[0];
 	sg_init_table(&input, 1);
 	sg_set_page(&input, page, PAGE_SIZE, 0);
 
@@ -907,7 +965,7 @@  static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	 * 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);
+	acomp_request_set_params(acomp_ctx->reqs[0], &input, &output, PAGE_SIZE, dlen);
 
 	/*
 	 * it maybe looks a little bit silly that we send an asynchronous request,
@@ -921,8 +979,8 @@  static bool zswap_compress(struct page *page, struct zswap_entry *entry,
 	 * but in different threads running on different cpu, we have different
 	 * acomp instance, so multiple threads can do (de)compression in parallel.
 	 */
-	comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
-	dlen = acomp_ctx->req->dlen;
+	comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->reqs[0]), &acomp_ctx->wait);
+	dlen = acomp_ctx->reqs[0]->dlen;
 	if (comp_ret)
 		goto unlock;
 
@@ -975,20 +1033,20 @@  static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
 	 */
 	if ((acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) ||
 	    !virt_addr_valid(src)) {
-		memcpy(acomp_ctx->buffer, src, entry->length);
-		src = acomp_ctx->buffer;
+		memcpy(acomp_ctx->buffers[0], src, entry->length);
+		src = acomp_ctx->buffers[0];
 		zpool_unmap_handle(zpool, entry->handle);
 	}
 
 	sg_init_one(&input, src, entry->length);
 	sg_init_table(&output, 1);
 	sg_set_folio(&output, folio, PAGE_SIZE, 0);
-	acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE);
-	BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait));
-	BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
+	acomp_request_set_params(acomp_ctx->reqs[0], &input, &output, entry->length, PAGE_SIZE);
+	BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->reqs[0]), &acomp_ctx->wait));
+	BUG_ON(acomp_ctx->reqs[0]->dlen != PAGE_SIZE);
 	mutex_unlock(&acomp_ctx->mutex);
 
-	if (src != acomp_ctx->buffer)
+	if (src != acomp_ctx->buffers[0])
 		zpool_unmap_handle(zpool, entry->handle);
 }