zram: add incompressible flag to read_block_state()

Add a new flag to zram block state that shows if the page is
incompressible: that none of the algorithm (including secondary ones)
could compress it.

Link: https://lkml.kernel.org/r/20221109115047.2921851-14-senozhatsky@chromium.org
Suggested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index f14c8c2e42f3eaec8cdc8ff391682ded9a7886ea..e4551579cb128e15c91b0461f4e899d944553ead 100644 (file)
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -497,10 +497,11 @@ 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.
-         303    62.801919 ....r
+         300    75.033841 .wh...
+         301    63.806904 s.....
+         302    63.806919 ..hi..
+         303    62.801919 ....r.
+         304   146.781902 ..hi.n
 
 First column
        zram's block index.
@@ -519,6 +520,8 @@ Third column
                idle page
        r:
                recompressed page (secondary compression algorithm)
+       n:
+               none (including secondary) of algorithms could compress it
 
 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 25b7ff2b56bf34f7d3a2cb0eb002925cebd56f87..9d33801e8ba874679a32fb695bde56cba9052780 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -946,14 +946,16 @@ 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%c\n",
+                       "%12zd %12lld.%06lu %c%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_get_priority(zram, index) ? 'r' : '.');
+                       zram_get_priority(zram, index) ? 'r' : '.',
+                       zram_test_flag(zram, index,
+                                      ZRAM_INCOMPRESSIBLE) ? 'n' : '.');
 
                if (count <= copied) {
                        zram_slot_unlock(zram, index);