diff mbox series

[PATCHv4,1/9] zram: Preparation for multi-zcomp support

Message ID 20221018045533.2396670-2-senozhatsky@chromium.org (mailing list archive)
State New
Headers show
Series zram: Support multiple compression streams | expand

Commit Message

Sergey Senozhatsky Oct. 18, 2022, 4:55 a.m. UTC 
The patch turns compression streams and compressor algorithm
name struct zram members into arrays, so that we can have
multiple compression streams support (in the next patches).

The patch uses a rather explicit API for compressor selection:

- Get primary (default) compression stream
	zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP])
- Get secondary compression stream
	zcomp_stream_get(zram->comps[ZRAM_SECONDARY_ZCOMP])

We use similar API for compression streams put().

At this point we always have just one compression stream,
since CONFIG_ZRAM_MULTI_COMP is not yet defined.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 drivers/block/zram/zcomp.c    |  6 +--
 drivers/block/zram/zcomp.h    |  2 +-
 drivers/block/zram/zram_drv.c | 87 ++++++++++++++++++++++++-----------
 drivers/block/zram/zram_drv.h | 14 +++++-
 4 files changed, 77 insertions(+), 32 deletions(-)

Comments

Minchan Kim Nov. 2, 2022, 8:13 p.m. UTC | #1 
On Tue, Oct 18, 2022 at 01:55:25PM +0900, Sergey Senozhatsky wrote:
> The patch turns compression streams and compressor algorithm
> name struct zram members into arrays, so that we can have
> multiple compression streams support (in the next patches).
> 
> The patch uses a rather explicit API for compressor selection:
> 
> - Get primary (default) compression stream
> 	zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP])
> - Get secondary compression stream
> 	zcomp_stream_get(zram->comps[ZRAM_SECONDARY_ZCOMP])
> 
> We use similar API for compression streams put().
> 
> At this point we always have just one compression stream,
> since CONFIG_ZRAM_MULTI_COMP is not yet defined.
> 
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
>  drivers/block/zram/zcomp.c    |  6 +--
>  drivers/block/zram/zcomp.h    |  2 +-
>  drivers/block/zram/zram_drv.c | 87 ++++++++++++++++++++++++-----------
>  drivers/block/zram/zram_drv.h | 14 +++++-
>  4 files changed, 77 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
> index 0916de952e09..55af4efd7983 100644
> --- a/drivers/block/zram/zcomp.c
> +++ b/drivers/block/zram/zcomp.c
> @@ -206,7 +206,7 @@ void zcomp_destroy(struct zcomp *comp)
>   * case of allocation error, or any other error potentially
>   * returned by zcomp_init().
>   */
> -struct zcomp *zcomp_create(const char *compress)
> +struct zcomp *zcomp_create(const char *alg)
>  {
>  	struct zcomp *comp;
>  	int error;
> @@ -216,14 +216,14 @@ struct zcomp *zcomp_create(const char *compress)
>  	 * is not loaded yet. We must do it here, otherwise we are about to
>  	 * call /sbin/modprobe under CPU hot-plug lock.
>  	 */
> -	if (!zcomp_available_algorithm(compress))
> +	if (!zcomp_available_algorithm(alg))
>  		return ERR_PTR(-EINVAL);
>  
>  	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
>  	if (!comp)
>  		return ERR_PTR(-ENOMEM);
>  
> -	comp->name = compress;
> +	comp->name = alg;
>  	error = zcomp_init(comp);
>  	if (error) {
>  		kfree(comp);
> diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
> index 40f6420f4b2e..cdefdef93da8 100644
> --- a/drivers/block/zram/zcomp.h
> +++ b/drivers/block/zram/zcomp.h
> @@ -27,7 +27,7 @@ int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
>  ssize_t zcomp_available_show(const char *comp, char *buf);
>  bool zcomp_available_algorithm(const char *comp);
>  
> -struct zcomp *zcomp_create(const char *comp);
> +struct zcomp *zcomp_create(const char *alg);
>  void zcomp_destroy(struct zcomp *comp);
>  
>  struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 966aab902d19..770ea3489eb6 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -1007,36 +1007,53 @@ static ssize_t comp_algorithm_show(struct device *dev,
>  	struct zram *zram = dev_to_zram(dev);
>  
>  	down_read(&zram->init_lock);
> -	sz = zcomp_available_show(zram->compressor, buf);
> +	sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_ZCOMP], buf);
>  	up_read(&zram->init_lock);
>  
>  	return sz;
>  }
>  
> +static void comp_algorithm_set(struct zram *zram, u32 idx, const char *alg)
> +{
> +	/* Do not kfree() algs that we didn't allocate, IOW the default ones */
> +	if (zram->comp_algs[idx] != default_compressor)
> +		kfree(zram->comp_algs[idx]);
> +	zram->comp_algs[idx] = alg;
> +}
> +
>  static ssize_t comp_algorithm_store(struct device *dev,
>  		struct device_attribute *attr, const char *buf, size_t len)
>  {
>  	struct zram *zram = dev_to_zram(dev);
> -	char compressor[ARRAY_SIZE(zram->compressor)];
> +	char *compressor;
>  	size_t sz;
>  
> -	strscpy(compressor, buf, sizeof(compressor));
> +	sz = strlen(buf);
> +	if (sz >= CRYPTO_MAX_ALG_NAME)
> +		return -E2BIG;
> +
> +	compressor = kstrdup(buf, GFP_KERNEL);
> +	if (!compressor)
> +		return -ENOMEM;
> +
>  	/* ignore trailing newline */
> -	sz = strlen(compressor);
>  	if (sz > 0 && compressor[sz - 1] == '\n')
>  		compressor[sz - 1] = 0x00;
>  
> -	if (!zcomp_available_algorithm(compressor))
> +	if (!zcomp_available_algorithm(compressor)) {
> +		kfree(compressor);
>  		return -EINVAL;
> +	}
>  
>  	down_write(&zram->init_lock);
>  	if (init_done(zram)) {
>  		up_write(&zram->init_lock);
> +		kfree(compressor);
>  		pr_info("Can't change algorithm for initialized device\n");
>  		return -EBUSY;
>  	}
>  
> -	strcpy(zram->compressor, compressor);
> +	comp_algorithm_set(zram, ZRAM_PRIMARY_ZCOMP, compressor);
>  	up_write(&zram->init_lock);
>  	return len;
>  }
> @@ -1284,7 +1301,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
>  	size = zram_get_obj_size(zram, index);
>  
>  	if (size != PAGE_SIZE)
> -		zstrm = zcomp_stream_get(zram->comp);
> +		zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  
>  	src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
>  	if (size == PAGE_SIZE) {
> @@ -1296,7 +1313,7 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
>  		dst = kmap_atomic(page);
>  		ret = zcomp_decompress(zstrm, src, size, dst);
>  		kunmap_atomic(dst);
> -		zcomp_stream_put(zram->comp);
> +		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  	}
>  	zs_unmap_object(zram->mem_pool, handle);
>  	zram_slot_unlock(zram, index);
> @@ -1363,13 +1380,13 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
>  	kunmap_atomic(mem);
>  
>  compress_again:
> -	zstrm = zcomp_stream_get(zram->comp);
> +	zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  	src = kmap_atomic(page);
>  	ret = zcomp_compress(zstrm, src, &comp_len);
>  	kunmap_atomic(src);
>  
>  	if (unlikely(ret)) {
> -		zcomp_stream_put(zram->comp);
> +		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  		pr_err("Compression failed! err=%d\n", ret);
>  		zs_free(zram->mem_pool, handle);
>  		return ret;
> @@ -1397,7 +1414,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
>  				__GFP_HIGHMEM |
>  				__GFP_MOVABLE);
>  	if (IS_ERR((void *)handle)) {
> -		zcomp_stream_put(zram->comp);
> +		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  		atomic64_inc(&zram->stats.writestall);
>  		handle = zs_malloc(zram->mem_pool, comp_len,
>  				GFP_NOIO | __GFP_HIGHMEM |
> @@ -1414,14 +1431,14 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
>  		 * zstrm buffer back. It is necessary that the dereferencing
>  		 * of the zstrm variable below occurs correctly.
>  		 */
> -		zstrm = zcomp_stream_get(zram->comp);
> +		zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  	}
>  
>  	alloced_pages = zs_get_total_pages(zram->mem_pool);
>  	update_used_max(zram, alloced_pages);
>  
>  	if (zram->limit_pages && alloced_pages > zram->limit_pages) {
> -		zcomp_stream_put(zram->comp);
> +		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  		zs_free(zram->mem_pool, handle);
>  		return -ENOMEM;
>  	}
> @@ -1435,7 +1452,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
>  	if (comp_len == PAGE_SIZE)
>  		kunmap_atomic(src);
>  
> -	zcomp_stream_put(zram->comp);
> +	zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
>  	zs_unmap_object(zram->mem_pool, handle);
>  	atomic64_add(comp_len, &zram->stats.compr_data_size);
>  out:
> @@ -1710,6 +1727,20 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector,
>  	return ret;
>  }
>  
> +static void zram_destroy_comps(struct zram *zram)
> +{
> +	u32 idx;
> +
> +	for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
> +		struct zcomp *comp = zram->comps[idx];
> +
> +		zram->comps[idx] = NULL;
> +		if (IS_ERR_OR_NULL(comp))

nit:

Why don't you use just NULL check? I don't see any error setting
for zram->comps(Maybe later patch? Will keep check)?
Sergey Senozhatsky Nov. 3, 2022, 2:40 a.m. UTC | #2 
On (22/11/02 13:13), Minchan Kim wrote:
[..]
> >  
> > +static void zram_destroy_comps(struct zram *zram)
> > +{
> > +	u32 idx;
> > +
> > +	for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
> > +		struct zcomp *comp = zram->comps[idx];
> > +
> > +		zram->comps[idx] = NULL;
> > +		if (IS_ERR_OR_NULL(comp))
> 
> nit:
> 
> Why don't you use just NULL check? I don't see any error setting
> for zram->comps(Maybe later patch? Will keep check)?

A defense measure. zcomp_create() returns err pointer, so here
I check for err and nil just in case (if somehow someday we
accidentally have err values stored in comps). It's cheap and
safer than NULL.
diff mbox series

Patch

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 0916de952e09..55af4efd7983 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -206,7 +206,7 @@  void zcomp_destroy(struct zcomp *comp)
  * case of allocation error, or any other error potentially
  * returned by zcomp_init().
  */
-struct zcomp *zcomp_create(const char *compress)
+struct zcomp *zcomp_create(const char *alg)
 {
 	struct zcomp *comp;
 	int error;
@@ -216,14 +216,14 @@  struct zcomp *zcomp_create(const char *compress)
 	 * is not loaded yet. We must do it here, otherwise we are about to
 	 * call /sbin/modprobe under CPU hot-plug lock.
 	 */
-	if (!zcomp_available_algorithm(compress))
+	if (!zcomp_available_algorithm(alg))
 		return ERR_PTR(-EINVAL);
 
 	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
 	if (!comp)
 		return ERR_PTR(-ENOMEM);
 
-	comp->name = compress;
+	comp->name = alg;
 	error = zcomp_init(comp);
 	if (error) {
 		kfree(comp);
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 40f6420f4b2e..cdefdef93da8 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -27,7 +27,7 @@  int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
 ssize_t zcomp_available_show(const char *comp, char *buf);
 bool zcomp_available_algorithm(const char *comp);
 
-struct zcomp *zcomp_create(const char *comp);
+struct zcomp *zcomp_create(const char *alg);
 void zcomp_destroy(struct zcomp *comp);
 
 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 966aab902d19..770ea3489eb6 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1007,36 +1007,53 @@  static ssize_t comp_algorithm_show(struct device *dev,
 	struct zram *zram = dev_to_zram(dev);
 
 	down_read(&zram->init_lock);
-	sz = zcomp_available_show(zram->compressor, buf);
+	sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_ZCOMP], buf);
 	up_read(&zram->init_lock);
 
 	return sz;
 }
 
+static void comp_algorithm_set(struct zram *zram, u32 idx, const char *alg)
+{
+	/* Do not kfree() algs that we didn't allocate, IOW the default ones */
+	if (zram->comp_algs[idx] != default_compressor)
+		kfree(zram->comp_algs[idx]);
+	zram->comp_algs[idx] = alg;
+}
+
 static ssize_t comp_algorithm_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
-	char compressor[ARRAY_SIZE(zram->compressor)];
+	char *compressor;
 	size_t sz;
 
-	strscpy(compressor, buf, sizeof(compressor));
+	sz = strlen(buf);
+	if (sz >= CRYPTO_MAX_ALG_NAME)
+		return -E2BIG;
+
+	compressor = kstrdup(buf, GFP_KERNEL);
+	if (!compressor)
+		return -ENOMEM;
+
 	/* ignore trailing newline */
-	sz = strlen(compressor);
 	if (sz > 0 && compressor[sz - 1] == '\n')
 		compressor[sz - 1] = 0x00;
 
-	if (!zcomp_available_algorithm(compressor))
+	if (!zcomp_available_algorithm(compressor)) {
+		kfree(compressor);
 		return -EINVAL;
+	}
 
 	down_write(&zram->init_lock);
 	if (init_done(zram)) {
 		up_write(&zram->init_lock);
+		kfree(compressor);
 		pr_info("Can't change algorithm for initialized device\n");
 		return -EBUSY;
 	}
 
-	strcpy(zram->compressor, compressor);
+	comp_algorithm_set(zram, ZRAM_PRIMARY_ZCOMP, compressor);
 	up_write(&zram->init_lock);
 	return len;
 }
@@ -1284,7 +1301,7 @@  static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
 	size = zram_get_obj_size(zram, index);
 
 	if (size != PAGE_SIZE)
-		zstrm = zcomp_stream_get(zram->comp);
+		zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 
 	src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
 	if (size == PAGE_SIZE) {
@@ -1296,7 +1313,7 @@  static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
 		dst = kmap_atomic(page);
 		ret = zcomp_decompress(zstrm, src, size, dst);
 		kunmap_atomic(dst);
-		zcomp_stream_put(zram->comp);
+		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 	}
 	zs_unmap_object(zram->mem_pool, handle);
 	zram_slot_unlock(zram, index);
@@ -1363,13 +1380,13 @@  static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 	kunmap_atomic(mem);
 
 compress_again:
-	zstrm = zcomp_stream_get(zram->comp);
+	zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 	src = kmap_atomic(page);
 	ret = zcomp_compress(zstrm, src, &comp_len);
 	kunmap_atomic(src);
 
 	if (unlikely(ret)) {
-		zcomp_stream_put(zram->comp);
+		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 		pr_err("Compression failed! err=%d\n", ret);
 		zs_free(zram->mem_pool, handle);
 		return ret;
@@ -1397,7 +1414,7 @@  static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 				__GFP_HIGHMEM |
 				__GFP_MOVABLE);
 	if (IS_ERR((void *)handle)) {
-		zcomp_stream_put(zram->comp);
+		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 		atomic64_inc(&zram->stats.writestall);
 		handle = zs_malloc(zram->mem_pool, comp_len,
 				GFP_NOIO | __GFP_HIGHMEM |
@@ -1414,14 +1431,14 @@  static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 		 * zstrm buffer back. It is necessary that the dereferencing
 		 * of the zstrm variable below occurs correctly.
 		 */
-		zstrm = zcomp_stream_get(zram->comp);
+		zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 	}
 
 	alloced_pages = zs_get_total_pages(zram->mem_pool);
 	update_used_max(zram, alloced_pages);
 
 	if (zram->limit_pages && alloced_pages > zram->limit_pages) {
-		zcomp_stream_put(zram->comp);
+		zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 		zs_free(zram->mem_pool, handle);
 		return -ENOMEM;
 	}
@@ -1435,7 +1452,7 @@  static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 	if (comp_len == PAGE_SIZE)
 		kunmap_atomic(src);
 
-	zcomp_stream_put(zram->comp);
+	zcomp_stream_put(zram->comps[ZRAM_PRIMARY_ZCOMP]);
 	zs_unmap_object(zram->mem_pool, handle);
 	atomic64_add(comp_len, &zram->stats.compr_data_size);
 out:
@@ -1710,6 +1727,20 @@  static int zram_rw_page(struct block_device *bdev, sector_t sector,
 	return ret;
 }
 
+static void zram_destroy_comps(struct zram *zram)
+{
+	u32 idx;
+
+	for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
+		struct zcomp *comp = zram->comps[idx];
+
+		zram->comps[idx] = NULL;
+		if (IS_ERR_OR_NULL(comp))
+			continue;
+		zcomp_destroy(comp);
+	}
+}
+
 static void zram_reset_device(struct zram *zram)
 {
 	down_write(&zram->init_lock);
@@ -1727,11 +1758,11 @@  static void zram_reset_device(struct zram *zram)
 	/* I/O operation under all of CPU are done so let's free */
 	zram_meta_free(zram, zram->disksize);
 	zram->disksize = 0;
+	zram_destroy_comps(zram);
 	memset(&zram->stats, 0, sizeof(zram->stats));
-	zcomp_destroy(zram->comp);
-	zram->comp = NULL;
 	reset_bdev(zram);
 
+	comp_algorithm_set(zram, ZRAM_PRIMARY_ZCOMP, default_compressor);
 	up_write(&zram->init_lock);
 }
 
@@ -1742,6 +1773,7 @@  static ssize_t disksize_store(struct device *dev,
 	struct zcomp *comp;
 	struct zram *zram = dev_to_zram(dev);
 	int err;
+	u32 idx;
 
 	disksize = memparse(buf, NULL);
 	if (!disksize)
@@ -1760,22 +1792,25 @@  static ssize_t disksize_store(struct device *dev,
 		goto out_unlock;
 	}
 
-	comp = zcomp_create(zram->compressor);
-	if (IS_ERR(comp)) {
-		pr_err("Cannot initialise %s compressing backend\n",
-				zram->compressor);
-		err = PTR_ERR(comp);
-		goto out_free_meta;
-	}
+	for (idx = 0; idx < ZRAM_MAX_ZCOMPS; idx++) {
+		comp = zcomp_create(zram->comp_algs[idx]);
+		if (IS_ERR(comp)) {
+			pr_err("Cannot initialise %s compressing backend\n",
+			       zram->comp_algs[idx]);
+			err = PTR_ERR(comp);
+			goto out_free_comps;
+		}
 
-	zram->comp = comp;
+		zram->comps[idx] = comp;
+	}
 	zram->disksize = disksize;
 	set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT);
 	up_write(&zram->init_lock);
 
 	return len;
 
-out_free_meta:
+out_free_comps:
+	zram_destroy_comps(zram);
 	zram_meta_free(zram, disksize);
 out_unlock:
 	up_write(&zram->init_lock);
@@ -1962,7 +1997,7 @@  static int zram_add(void)
 	if (ret)
 		goto out_cleanup_disk;
 
-	strscpy(zram->compressor, default_compressor, sizeof(zram->compressor));
+	zram->comp_algs[ZRAM_PRIMARY_ZCOMP] = default_compressor;
 
 	zram_debugfs_register(zram);
 	pr_info("Added device: %s\n", zram->disk->disk_name);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index a2bda53020fd..4044ddbb2326 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -89,10 +89,20 @@  struct zram_stats {
 #endif
 };
 
+#ifdef CONFIG_ZRAM_MULTI_COMP
+#define ZRAM_PRIMARY_ZCOMP	0
+#define ZRAM_SECONDARY_ZCOMP	1
+#define ZRAM_MAX_ZCOMPS	2
+#else
+#define ZRAM_PRIMARY_ZCOMP	0
+#define ZRAM_SECONDARY_ZCOMP	0
+#define ZRAM_MAX_ZCOMPS	1
+#endif
+
 struct zram {
 	struct zram_table_entry *table;
 	struct zs_pool *mem_pool;
-	struct zcomp *comp;
+	struct zcomp *comps[ZRAM_MAX_ZCOMPS];
 	struct gendisk *disk;
 	/* Prevent concurrent execution of device init */
 	struct rw_semaphore init_lock;
@@ -107,7 +117,7 @@  struct zram {
 	 * we can store in a disk.
 	 */
 	u64 disksize;	/* bytes */
-	char compressor[CRYPTO_MAX_ALG_NAME];
+	const char *comp_algs[ZRAM_MAX_ZCOMPS];
 	/*
 	 * zram is claimed so open request will be failed
 	 */