[PATCHv5 05/13] zram: Add recompress flag to read_block_state()

From: Sergey Senozhatsky
Date: Wed Nov 09 2022 - 06:51:27 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 c73b16930449..177a142c3146 100644
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -411,9 +411,10 @@ 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.
@@ -430,6 +431,8 @@ 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 749e4266dd72..560e2932021e 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -939,13 +939,14 @@ 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_get_priority(zram, index) ? 'r' : '.');

if (count <= copied) {
zram_slot_unlock(zram, index);
--
2.38.1.431.g37b22c650d-goog