[PATCH RFC 7/7] zram: Add recompress flag to read_block_state()

From: Sergey Senozhatsky
Date: Mon Sep 05 2022 - 04:24:30 EST


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@xxxxxxxxxxxx>
---
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