linux-kernel - [PATCH RFC 7/7] zram: Add recompress flag to read_block

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Message-Id: <20220905082323.2742399-8-senozhatsky@chromium.org>
Date:   Mon,  5 Sep 2022 17:23:23 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Minchan Kim <minchan@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCH RFC 7/7] zram: Add recompress flag to read_block_state()

Add a new flag to zram block state that shows if the page
was recompressed (using alternative compression algorithm).

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 Documentation/admin-guide/blockdev/zram.rst | 9 ++++++---
 drivers/block/zram/zram_drv.c               | 5 +++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index 88957fcb6ad7..70a3d0243b45 100644
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -466,9 +466,10 @@ pages of the process with*pagemap.
 If you enable the feature, you could see block state via
 /sys/kernel/debug/zram/zram0/block_state". The output is as follows::
 
-	  300    75.033841 .wh.
-	  301    63.806904 s...
-	  302    63.806919 ..hi
+	  300    75.033841 .wh..
+	  301    63.806904 s....
+	  302    63.806919 ..hi.
+	  303    62.801919 ....r
 
 First column
 	zram's block index.
@@ -485,6 +486,8 @@ Third column
 		huge page
 	i:
 		idle page
+	r:
+		recompressed page (secondary compression algorithm)
 
 First line of above example says 300th block is accessed at 75.033841sec
 and the block's state is huge so it is written back to the backing
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 8ed41514b8f0..f3948abce2f7 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -936,13 +936,14 @@ static ssize_t read_block_state(struct file *file, char __user *buf,
 
 		ts = ktime_to_timespec64(zram->table[index].ac_time);
 		copied = snprintf(kbuf + written, count,
-			"%12zd %12lld.%06lu %c%c%c%c\n",
+			"%12zd %12lld.%06lu %c%c%c%c%c\n",
 			index, (s64)ts.tv_sec,
 			ts.tv_nsec / NSEC_PER_USEC,
 			zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.',
 			zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.',
 			zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.',
-			zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.');
+			zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.',
+			zram_test_flag(zram, index, ZRAM_RECOMP) ? 'r' : '.');
 
 		if (count <= copied) {
 			zram_slot_unlock(zram, index);
-- 
2.37.2.789.g6183377224-goog