[PATCH] zram: add stat to gather incompressible pages since zram set up

[Minchan Kim <minchan@kernel.org>]

Currently, zram supports the stat via /sys/block/zram/mm_stat to
represent how many of incompressible pages are stored at the
moment but it couldn't show how many times incompressible pages
were wrote down since zram set up. It's also good indication to
see how zram is effective in the system.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 Documentation/admin-guide/blockdev/zram.rst | 1 +
 drivers/block/zram/zram_drv.c               | 6 ++++--
 drivers/block/zram/zram_drv.h               | 1 +
 3 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index 8f3cfa42e443..03f1105b21b7 100644
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -266,6 +266,7 @@ The mm_stat file represents the device's mm statistics. It consists of a single
                   No memory is allocated for such pages.
  pages_compacted  the number of pages freed during compaction
  huge_pages	  the number of incompressible pages
+ huge_pages_since the number of incompressible pages since zram set up
  ================ =============================================================
 
 File /sys/block/zram<id>/bd_stat
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 23350210a2a2..ac4d19f6571c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1084,7 +1084,7 @@ static ssize_t mm_stat_show(struct device *dev,
 	max_used = atomic_long_read(&zram->stats.max_used_pages);
 
 	ret = scnprintf(buf, PAGE_SIZE,
-			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu\n",
+			"%8llu %8llu %8llu %8lu %8ld %8llu %8lu %8llu %8llu\n",
 			orig_size << PAGE_SHIFT,
 			(u64)atomic64_read(&zram->stats.compr_data_size),
 			mem_used << PAGE_SHIFT,
@@ -1092,7 +1092,8 @@ static ssize_t mm_stat_show(struct device *dev,
 			max_used << PAGE_SHIFT,
 			(u64)atomic64_read(&zram->stats.same_pages),
 			pool_stats.pages_compacted,
-			(u64)atomic64_read(&zram->stats.huge_pages));
+			(u64)atomic64_read(&zram->stats.huge_pages),
+			(u64)atomic64_read(&zram->stats.huge_pages_since));
 	up_read(&zram->init_lock);
 
 	return ret;
@@ -1424,6 +1425,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 	if (comp_len == PAGE_SIZE) {
 		zram_set_flag(zram, index, ZRAM_HUGE);
 		atomic64_inc(&zram->stats.huge_pages);
+		atomic64_inc(&zram->stats.huge_pages_since);
 	}
 
 	if (flags) {
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index f2fd46daa760..9cabcbb13fd9 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -78,6 +78,7 @@ struct zram_stats {
 	atomic64_t notify_free;	/* no. of swap slot free notifications */
 	atomic64_t same_pages;		/* no. of same element filled pages */
 	atomic64_t huge_pages;		/* no. of huge pages */
+	atomic64_t huge_pages_since;	/* no. of huge pages since zram set up */
 	atomic64_t pages_stored;	/* no. of pages currently stored */
 	atomic_long_t max_used_pages;	/* no. of maximum pages stored */
 	atomic64_t writestall;		/* no. of write slow paths */
-- 
2.29.2.454.gaff20da3a2-goog