zram: support compaction

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@kernel.org>
Cc: Juneho Choi <juno.choi@lge.com>
Cc: Gunho Lee <gunho.lee@lge.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjennings@variantweb.net>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 26 insertions, 0 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 871bd3550cb0..1626961fdb2f 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -63,6 +63,27 @@ static inline struct zram *dev_to_zram(struct device *dev)
         return (struct zram *)dev_to_disk(dev)->private_data;
 }
 
+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;
+}
+
 static ssize_t disksize_show(struct device *dev,
                 struct device_attribute *attr, char *buf)
 {
@@ -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 */