[PATCH] zram: enable compaction support in zram

Sergey Senozhatsky
2015-04-17T01:07:36Z

Commit c72c6160d967 ("zram: move compact_store() to sysfs functions area")
was intended to be a cosmetic change that moved function around w/o any
functional change:
http://lkml.iu.edu/hypermail/linux/kernel/1503.1/01818.html

Unfortunately, on its way from mmotm to Linus's tree it was altered and turned
into "remove compaction support from zram" commit. I've managed to create a
mess of commits and Andrew had to pick some of the commits and hand edit them.

Fix it and learn my lessons.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
Documentation/blockdev/zram.txt | 2 +-
drivers/block/zram/zram_drv.c | 23 +++++++++++++++++++++++
2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 48a183e..bef4998 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -126,7 +126,7 @@ mem_used_max RW the maximum amount memory zram have consumed to
mem_limit RW the maximum amount of memory ZRAM can use to store
the compressed data
num_migrated RO the number of objects migrated migrated by compaction
-
+compact WO trigger memory compaction

WARNING
=======
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c94386a..f474cbe 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -261,6 +261,27 @@ static ssize_t comp_algorithm_store(struct device *dev,
return len;
}

+static ssize_t compact_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t len)
+{
+ unsigned long nr_migrated;
+ struct zram *zram = dev_to_zram(dev);
+ struct zram_meta *meta;
+
+ down_read(&zram->init_lock);
+ if (!init_done(zram)) {
+ up_read(&zram->init_lock);
+ return -EINVAL;
+ }
+
+ meta = zram->meta;
+ nr_migrated = zs_compact(meta->mem_pool);
+ atomic64_add(nr_migrated, &zram->stats.num_migrated);
+ up_read(&zram->init_lock);
+
+ return len;
+}
+
/* flag operations needs meta->tb_lock */
static int zram_test_flag(struct zram_meta *meta, u32 index,
enum zram_pageflags flag)
@@ -1038,6 +1059,7 @@ static const struct block_device_operations zram_devops = {
.owner = THIS_MODULE
};

+static DEVICE_ATTR_WO(compact);
static DEVICE_ATTR_RW(disksize);
static DEVICE_ATTR_RO(initstate);
static DEVICE_ATTR_WO(reset);
@@ -1114,6 +1136,7 @@ static struct attribute *zram_disk_attrs[] = {
&dev_attr_num_writes.attr,
&dev_attr_failed_reads.attr,
&dev_attr_failed_writes.attr,
+ &dev_attr_compact.attr,
&dev_attr_invalid_io.attr,
&dev_attr_notify_free.attr,
&dev_attr_zero_pages.attr,
--
2.4.0.rc1.29.gecc46a1