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.
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 124 ++++++++++++++++++++++++++++------
1 file changed, 105 insertions(+), 19 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 5371ed63c785..56026a6deb70 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1000,31 +1000,28 @@ 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)
+static int __comp_algorithm_store(struct zram *zram, u32 prio, const char *buf)
{
- /* 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)
-{
- struct zram *zram = dev_to_zram(dev);
char *compressor;
size_t sz;
@@ -1053,11 +1050,94 @@ 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, ¶m, &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)
{
@@ -1898,6 +1978,9 @@ 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,
@@ -1921,6 +2004,9 @@ 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,
};
@@ -2000,7 +2086,7 @@ 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);
--
2.38.1.431.g37b22c650d-goog
