[PATCH v2 8/8] zram: use decompress_noctx

[Joonsoo Kim <js1304@gmail.com>]

Crypto subsystem supports noctx API which doesn't require tfm.
To get tfm in zram, we need zstrm and it is limited resource.
If we uses noctx API, we don't need to get zstrm so that
we get much better performance when zstrm is insufficient.

This patch restores zram's performance to the time that zram
doesn't use crypto subsystem.

Following is zram's read performance number.

* iozone -t 4 -R -r 16K -s 60M -I +Z -i 0 -i 1
* max_stream is set to 1
* Output is in Kbytes/sec

zram-base vs zram-crypto vs zram-crypto-noctx

Read		10411701.88	6426911.62	9423894.38
Re-read		10017386.62	6428218.88	11000063.50

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 drivers/block/zram/zcomp.c    | 28 +++++++++++++++++++++++++++-
 drivers/block/zram/zcomp.h    |  9 ++++++++-
 drivers/block/zram/zram_drv.c |  9 +++++----
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index d2734f2..86b0c9b 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -291,8 +291,12 @@ bool zcomp_set_max_streams(struct zcomp *comp, int num_strm)
 	return comp->set_max_streams(comp, num_strm);
 }
 
-struct zcomp_strm *zcomp_strm_find(struct zcomp *comp)
+struct zcomp_strm *zcomp_strm_find(struct zcomp *comp, bool decomp)
 {
+	/* We don't need decompression context so zstrm neither */
+	if (decomp && test_bit(ZCOMP_DECOMPRESS_NOCTX, &comp->flags))
+		return NULL;
+
 	return comp->strm_find(comp);
 }
 
@@ -307,6 +311,11 @@ int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
 {
 	*dst_len = PAGE_SIZE << 1;
 
+	if (!zstrm) {
+		return crypto_comp_compress_noctx(comp->alg, src, PAGE_SIZE,
+							dst, dst_len);
+	}
+
 	return crypto_comp_compress(zstrm->tfm, src, PAGE_SIZE, dst, dst_len);
 }
 
@@ -316,12 +325,18 @@ int zcomp_decompress(struct zcomp *comp, struct zcomp_strm *zstrm,
 {
 	unsigned int size = PAGE_SIZE;
 
+	if (!zstrm) {
+		return crypto_comp_decompress_noctx(comp->alg, src, src_len,
+							dst, &size);
+	}
+
 	return crypto_comp_decompress(zstrm->tfm, src, src_len,	dst, &size);
 }
 
 void zcomp_destroy(struct zcomp *comp)
 {
 	comp->destroy(comp);
+	crypto_put_comp(comp->alg);
 	kfree(comp);
 }
 
@@ -344,12 +359,23 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
 		return ERR_PTR(-ENOMEM);
 
 	comp->name = compress;
+	comp->alg = crypto_get_comp(compress, 0, 0);
+	if (!comp->alg) {
+		kfree(comp);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (crypto_has_compress_noctx(comp->alg))
+		set_bit(ZCOMP_COMPRESS_NOCTX, &comp->flags);
+	if (crypto_has_decompress_noctx(comp->alg))
+		set_bit(ZCOMP_DECOMPRESS_NOCTX, &comp->flags);
 
 	if (max_strm > 1)
 		zcomp_strm_multi_create(comp, max_strm);
 	else
 		zcomp_strm_single_create(comp);
 	if (!comp->stream) {
+		crypto_put_comp(comp->alg);
 		kfree(comp);
 		return ERR_PTR(-ENOMEM);
 	}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index c47db4d..6c137c8 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -13,6 +13,11 @@
 #include <linux/crypto.h>
 #include <linux/mutex.h>
 
+enum {
+	ZCOMP_COMPRESS_NOCTX,
+	ZCOMP_DECOMPRESS_NOCTX,
+};
+
 struct zcomp_strm {
 	struct crypto_comp *tfm;
 
@@ -27,6 +32,8 @@ struct zcomp_strm {
 struct zcomp {
 	void *stream;
 	const char *name;
+	struct crypto_alg *alg;
+	unsigned long flags;
 
 	struct zcomp_strm *(*strm_find)(struct zcomp *comp);
 	void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm);
@@ -39,7 +46,7 @@ ssize_t zcomp_available_show(const char *comp, char *buf);
 struct zcomp *zcomp_create(const char *comp, int max_strm);
 void zcomp_destroy(struct zcomp *comp);
 
-struct zcomp_strm *zcomp_strm_find(struct zcomp *comp);
+struct zcomp_strm *zcomp_strm_find(struct zcomp *comp, bool decomp);
 void zcomp_strm_release(struct zcomp *comp, struct zcomp_strm *zstrm);
 
 int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index b3044d3..8283bd3 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -623,7 +623,7 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 		/* Use  a temporary buffer to decompress the page */
 		uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
 
-	zstrm = zcomp_strm_find(zram->comp);
+	zstrm = zcomp_strm_find(zram->comp, true);
 	user_mem = kmap_atomic(page);
 	if (!is_partial_io(bvec))
 		uncmem = user_mem;
@@ -647,7 +647,8 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
 	ret = 0;
 out_cleanup:
 	kunmap_atomic(user_mem);
-	zcomp_strm_release(zram->comp, zstrm);
+	if (zstrm)
+		zcomp_strm_release(zram->comp, zstrm);
 	if (is_partial_io(bvec))
 		kfree(uncmem);
 	return ret;
@@ -676,14 +677,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
 			ret = -ENOMEM;
 			goto out;
 		}
-		zstrm = zcomp_strm_find(zram->comp);
+		zstrm = zcomp_strm_find(zram->comp, true);
 		ret = zram_decompress_page(zram, zstrm, uncmem, index);
 		if (ret)
 			goto out;
 	}
 
 	if (!zstrm)
-		zstrm = zcomp_strm_find(zram->comp);
+		zstrm = zcomp_strm_find(zram->comp, false);
 	user_mem = kmap_atomic(page);
 
 	if (is_partial_io(bvec)) {
-- 
1.9.1