[PATCH v2 5/7] zram: support compaction

[Minchan Kim]

Now that zsmalloc supports compaction, zram can use it.
For the first step, this patch exports compact knob via sysfs
so user can do compaction via "echo 1 > /sys/block/zram0/compact".

Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-block-zram | 15 +++++++++++++++
 drivers/block/zram/zram_drv.c              | 25 +++++++++++++++++++++++++
 drivers/block/zram/zram_drv.h              |  1 +
 3 files changed, 41 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index a6148eaf91e5..bede9028a5a0 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -141,3 +141,18 @@ Description:
 		amount of memory ZRAM can use to store the compressed data.  The
 		limit could be changed in run time and "0" means disable the
 		limit.  No limit is the initial state.  Unit: bytes
+
+What:		/sys/block/zram<id>/compact
+Date:		August 2015
+Contact:	Minchan Kim <minchan@xxxxxxxxxx>
+Description:
+		The compact file is write-only and trigger compaction for
+		allocator zrm uses. The allocator moves some objects so that
+		it could free fragment space.
+
+What:		/sys/block/zram<id>/num_migrated
+Date:		August 2015
+Contact:	Minchan Kim <minchan@xxxxxxxxxx>
+Description:
+		The compact file is read-only and shows how many object
+		migrated by compaction.
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 871bd3550cb0..6ff6a5a8a769 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -246,6 +246,27 @@ 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)
@@ -1017,6 +1038,7 @@ 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);
@@ -1035,6 +1057,7 @@ ZRAM_ATTR_RO(invalid_io);
 ZRAM_ATTR_RO(notify_free);
 ZRAM_ATTR_RO(zero_pages);
 ZRAM_ATTR_RO(compr_data_size);
+ZRAM_ATTR_RO(num_migrated);
 
 static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_disksize.attr,
@@ -1044,6 +1067,8 @@ static struct attribute *zram_disk_attrs[] = {
 	&dev_attr_num_writes.attr,
 	&dev_attr_failed_reads.attr,
 	&dev_attr_failed_writes.attr,
+	&dev_attr_num_migrated.attr,
+	&dev_attr_compact.attr,
 	&dev_attr_invalid_io.attr,
 	&dev_attr_notify_free.attr,
 	&dev_attr_zero_pages.attr,
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 17056e589146..570c598f4ce9 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -84,6 +84,7 @@ struct zram_stats {
 	atomic64_t compr_data_size;	/* compressed size of pages stored */
 	atomic64_t num_reads;	/* failed + successful */
 	atomic64_t num_writes;	/* --do-- */
+	atomic64_t num_migrated;	/* no. of migrated object */
 	atomic64_t failed_reads;	/* can happen when memory is too low */
 	atomic64_t failed_writes;	/* can happen when memory is too low */
 	atomic64_t invalid_io;	/* non-page-aligned I/O requests */
-- 
1.9.1

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