Commit 001d9273 authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Andrew Morton
Browse files

zram: add recompression algorithm sysfs knob 

Introduce recomp_algorithm sysfs knob that controls secondary algorithm
selection used for recompression.

We will support up to 3 secondary compression algorithms which are sorted
in order of their priority.  To select an algorithm user has to provide
its name and priority:

  echo "algo=zstd priority=1" > /sys/block/zramX/recomp_algorithm
  echo "algo=deflate priority=2" > /sys/block/zramX/recomp_algorithm

During recompression zram iterates through the list of registered
secondary algorithms in order of their priorities.

We also have a short version for cases when there is only
one secondary compression algorithm:

  echo "algo=zstd" > /sys/block/zramX/recomp_algorithm

This will register zstd as the secondary algorithm with priority 1.

Link: https://lkml.kernel.org/r/20221109115047.2921851-3-senozhatsky@chromium.org


Signed-off-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7ac07a26

drivers/block/zram/zram_drv.c

+105 −19
Original line number Diff line number Diff line
@@ -997,31 +997,28 @@ static ssize_t max_comp_streams_store(struct device *dev, 
	return len;

}



static ssize_t comp_algorithm_show(struct device *dev,

		struct device_attribute *attr, char *buf)

static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg)

{

	size_t sz;

	struct zram *zram = dev_to_zram(dev);

	/* Do not free statically defined compression algorithms */

	if (zram->comp_algs[prio] != default_compressor)

		kfree(zram->comp_algs[prio]);



	zram->comp_algs[prio] = alg;

}



static ssize_t __comp_algorithm_show(struct zram *zram, u32 prio, char *buf)

{

	ssize_t sz;



	down_read(&zram->init_lock);

	sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_COMP], buf);

	sz = zcomp_available_show(zram->comp_algs[prio], buf);

	up_read(&zram->init_lock);



	return sz;

}



static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg)

{

	/* Do not kfree() algs that we didn't allocate, IOW the default ones */

	if (zram->comp_algs[prio] != default_compressor)

		kfree(zram->comp_algs[prio]);

	zram->comp_algs[prio] = alg;

}



static ssize_t comp_algorithm_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t len)

static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)

{

	struct zram *zram = dev_to_zram(dev);

	char *compressor;

	size_t sz;
@@ -1050,11 +1047,94 @@ static ssize_t comp_algorithm_store(struct device *dev, 
		return -EBUSY;

	}



	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, compressor);

	comp_algorithm_set(zram, prio, compressor);

	up_write(&zram->init_lock);

	return len;

	return 0;

}



static ssize_t comp_algorithm_show(struct device *dev,

				   struct device_attribute *attr,

				   char *buf)

{

	struct zram *zram = dev_to_zram(dev);



	return __comp_algorithm_show(zram, ZRAM_PRIMARY_COMP, buf);

}



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);

	int ret;



	ret = __comp_algorithm_store(zram, ZRAM_PRIMARY_COMP, buf);

	return ret ? ret : len;

}



#ifdef CONFIG_ZRAM_MULTI_COMP

static ssize_t recomp_algorithm_show(struct device *dev,

				     struct device_attribute *attr,

				     char *buf)

{

	struct zram *zram = dev_to_zram(dev);

	ssize_t sz = 0;

	u32 prio;



	for (prio = ZRAM_SECONDARY_COMP; prio < ZRAM_MAX_COMPS; prio++) {

		if (!zram->comp_algs[prio])

			continue;



		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2, "#%d: ", prio);

		sz += __comp_algorithm_show(zram, prio, buf + sz);

	}



	return sz;

}



static ssize_t recomp_algorithm_store(struct device *dev,

				      struct device_attribute *attr,

				      const char *buf,

				      size_t len)

{

	struct zram *zram = dev_to_zram(dev);

	int prio = ZRAM_SECONDARY_COMP;

	char *args, *param, *val;

	char *alg = NULL;

	int ret;



	args = skip_spaces(buf);

	while (*args) {

		args = next_arg(args, &param, &val);



		if (!*val)

			return -EINVAL;



		if (!strcmp(param, "algo")) {

			alg = val;

			continue;

		}



		if (!strcmp(param, "priority")) {

			ret = kstrtoint(val, 10, &prio);

			if (ret)

				return ret;

			continue;

		}

	}



	if (!alg)

		return -EINVAL;



	if (prio < ZRAM_SECONDARY_COMP || prio >= ZRAM_MAX_COMPS)

		return -EINVAL;



	ret = __comp_algorithm_store(zram, prio, alg);

	return ret ? ret : len;

}

#endif



static ssize_t compact_store(struct device *dev,

		struct device_attribute *attr, const char *buf, size_t len)

{
@@ -1895,6 +1975,9 @@ static DEVICE_ATTR_WO(writeback); 
static DEVICE_ATTR_RW(writeback_limit);

static DEVICE_ATTR_RW(writeback_limit_enable);

#endif

#ifdef CONFIG_ZRAM_MULTI_COMP

static DEVICE_ATTR_RW(recomp_algorithm);

#endif



static struct attribute *zram_disk_attrs[] = {

	&dev_attr_disksize.attr,
@@ -1918,6 +2001,9 @@ static struct attribute *zram_disk_attrs[] = { 
	&dev_attr_bd_stat.attr,

#endif

	&dev_attr_debug_stat.attr,

#ifdef CONFIG_ZRAM_MULTI_COMP

	&dev_attr_recomp_algorithm.attr,

#endif

	NULL,

};
@@ -1997,7 +2083,7 @@ static int zram_add(void) 
	if (ret)

		goto out_cleanup_disk;



	zram->comp_algs[ZRAM_PRIMARY_COMP] = default_compressor;

	comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);



	zram_debugfs_register(zram);

	pr_info("Added device: %s\n", zram->disk->disk_name);