[PATCH v1 4/8] crypto: acomp - Add API to get a compression algorithm's batch-size.

[Kanchana P. Sridhar]

This commit adds a @batch_size data member to struct acomp_alg.

An acomp_alg compression algorithm that supports batching of
compressions and decompressions must provide a @batch_size greater
than 1, representing the maximum batch-size that the compressor
supports, so that kernel users of crypto_acomp, such as zswap, can
allocate resources for submitting multiple compress/decompress jobs that
can be batched, and invoke batching of [de]compressions.

The new crypto_acomp_batch_size() API queries the crypto_acomp's
acomp_alg for the batch-size. If the acomp_alg has registered a
@batch_size greater than 1, this is returned. If not, a default of "1"
is returned.

zswap can invoke crypto_acomp_batch_size() to query the maximum number
of requests that can be batch [de]compressed. Based on this, zswap
can use the minimum of any zswap-specific upper limits for batch-size
and the compressor's max @batch_size, to allocate batching resources.

This enables zswap to compress/decompress multiple pages as a batch
to improve swapout/swapin performance and memory savings.

Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
Signed-off-by: Kanchana P. Sridhar <kanchanapsridhar2026@xxxxxxxxx>
---
 crypto/acompress.c                  | 14 ++++++++++++++
 include/crypto/acompress.h          | 12 ++++++++++++
 include/crypto/internal/acompress.h |  3 +++
 3 files changed, 29 insertions(+)

diff --git a/crypto/acompress.c b/crypto/acompress.c
index 8c9a76073159..192ea996e779 100644
--- a/crypto/acompress.c
+++ b/crypto/acompress.c
@@ -318,6 +318,20 @@ int crypto_acomp_decompress(struct acomp_req *req)
 }
 EXPORT_SYMBOL_GPL(crypto_acomp_decompress);
 
+unsigned int crypto_acomp_batch_size(struct crypto_acomp *tfm)
+{
+	if (acomp_is_async(tfm) &&
+		(crypto_comp_alg_common(tfm)->base.cra_flags & CRYPTO_ALG_TYPE_ACOMPRESS)) {
+		struct acomp_alg *alg = crypto_acomp_alg(tfm);
+
+		if (alg && alg->batch_size > 1)
+			return alg->batch_size;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(crypto_acomp_batch_size);
+
 void comp_prepare_alg(struct comp_alg_common *alg)
 {
 	struct crypto_alg *base = &alg->base;
diff --git a/include/crypto/acompress.h b/include/crypto/acompress.h
index fc0665b77a8f..06578c4367f6 100644
--- a/include/crypto/acompress.h
+++ b/include/crypto/acompress.h
@@ -593,6 +593,18 @@ int crypto_acomp_compress(struct acomp_req *req);
  */
 int crypto_acomp_decompress(struct acomp_req *req);
 
+/**
+ * crypto_acomp_batch_size() -- Get the algorithm's batch size
+ *
+ * Function returns the algorithm's batch size for batching operations
+ *
+ * @tfm:	ACOMPRESS tfm handle allocated with crypto_alloc_acomp()
+ *
+ * Return:	@tfm's acomp_alg's @batch_size, if it has defined a
+ *		@batch_size greater than 1; else return 1.
+ */
+unsigned int crypto_acomp_batch_size(struct crypto_acomp *tfm);
+
 static inline struct acomp_req *acomp_request_on_stack_init(
 	char *buf, struct crypto_acomp *tfm)
 {
diff --git a/include/crypto/internal/acompress.h b/include/crypto/internal/acompress.h
index 93ae59623f13..b790722c263a 100644
--- a/include/crypto/internal/acompress.h
+++ b/include/crypto/internal/acompress.h
@@ -28,6 +28,8 @@
  *
  * @compress:	Function performs a compress operation
  * @decompress:	Function performs a de-compress operation
+ * @batch_size:	Maximum batch-size for batching compress/decompress
+ *		operations.
  * @init:	Initialize the cryptographic transformation object.
  *		This function is used to initialize the cryptographic
  *		transformation object. This function is called only once at
@@ -47,6 +49,7 @@
 struct acomp_alg {
 	int (*compress)(struct acomp_req *req);
 	int (*decompress)(struct acomp_req *req);
+	unsigned int batch_size;
 	int (*init)(struct crypto_acomp *tfm);
 	void (*exit)(struct crypto_acomp *tfm);
 
-- 
2.39.5