[PATCHv4 7/9] zram: add pages_per_pool_page device attribute

Sergey Senozhatsky
2022-10-31T05:41:37Z

Add a new sysfs knob that allows user-space to set
zsmalloc pages per-zspage limit value on per-device
basis.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
drivers/block/zram/zram_drv.c | 44 ++++++++++++++++++++++++++++++++++-
drivers/block/zram/zram_drv.h | 2 ++
2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index bec02f636bce..cf9d3474b80c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1180,6 +1180,45 @@ static ssize_t mm_stat_show(struct device *dev,
return ret;
}

+static ssize_t pages_per_pool_page_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ u32 val;
+ struct zram *zram = dev_to_zram(dev);
+
+ down_read(&zram->init_lock);
+ val = zram->pages_per_pool_page;
+ up_read(&zram->init_lock);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", val);
+}
+
+static ssize_t pages_per_pool_page_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t len)
+{
+ struct zram *zram = dev_to_zram(dev);
+ u32 val;
+
+ if (kstrtou32(buf, 10, &val))
+ return -EINVAL;
+
+ if (val < ZS_MIN_PAGES_PER_ZSPAGE || val > ZS_MAX_PAGES_PER_ZSPAGE)
+ return -EINVAL;
+
+ down_read(&zram->init_lock);
+ if (init_done(zram)) {
+ up_read(&zram->init_lock);
+ return -EINVAL;
+ }
+
+ zram->pages_per_pool_page = val;
+ up_read(&zram->init_lock);
+
+ return len;
+}
+
#ifdef CONFIG_ZRAM_WRITEBACK
#define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12)))
static ssize_t bd_stat_show(struct device *dev,
@@ -1248,7 +1287,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 disksize)
return false;

zram->mem_pool = zs_create_pool(zram->disk->disk_name,
- ZS_DEFAULT_PAGES_PER_ZSPAGE);
+ zram->pages_per_pool_page);
if (!zram->mem_pool) {
vfree(zram->table);
return false;
@@ -2174,6 +2213,7 @@ static DEVICE_ATTR_RW(writeback_limit_enable);
static DEVICE_ATTR_RW(recomp_algorithm);
static DEVICE_ATTR_WO(recompress);
#endif
+static DEVICE_ATTR_RW(pages_per_pool_page);

static struct attribute *zram_disk_attrs[] = {
&dev_attr_disksize.attr,
@@ -2201,6 +2241,7 @@ static struct attribute *zram_disk_attrs[] = {
&dev_attr_recomp_algorithm.attr,
&dev_attr_recompress.attr,
#endif
+ &dev_attr_pages_per_pool_page.attr,
NULL,
};

@@ -2238,6 +2279,7 @@ static int zram_add(void)
goto out_free_idr;
}

+ zram->pages_per_pool_page = ZS_DEFAULT_PAGES_PER_ZSPAGE;
zram->disk->major = zram_major;
zram->disk->first_minor = device_id;
zram->disk->minors = 1;
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 9d6fcfdf7aa7..bdfc9bf0bdd5 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -120,6 +120,8 @@ struct zram {
*/
u64 disksize; /* bytes */
const char *comp_algs[ZRAM_MAX_ZCOMPS];
+
+ u32 pages_per_pool_page;
/*
* Pages that compress to sizes equal or greater than this are stored
* uncompressed in memory.
--
2.38.1.273.g43a17bfeac-goog