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zram: add incompressible writeback

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Add support for incompressible pages writeback:

  echo incompressible > /sys/block/zramX/writeback

Link: https://lkml.kernel.org/r/20221109115047.2921851-13-senozhatsky@chromium.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>
This commit is contained in:
Sergey Senozhatsky 2022-11-09 20:50:46 +09:00 committed by Andrew Morton
parent 443dd79806
commit b46f9ea3cb
2 changed files with 18 additions and 7 deletions
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7
Documentation/admin-guide/blockdev/zram.rst
View file

@ -348,8 +348,13 @@ this can be accomplished with::
echo huge_idle > /sys/block/zramX/writeback
If a user chooses to writeback only incompressible pages (pages that none of
algorithms can compress) this can be accomplished with::
echo incompressible > /sys/block/zramX/writeback
If an admin wants to write a specific page in zram device to the backing device,
they could write a page index into the interface.
they could write a page index into the interface::
echo "page_index=1251" > /sys/block/zramX/writeback

18
drivers/block/zram/zram_drv.c
View file

@ -645,10 +645,10 @@ static int read_from_bdev_async(struct zram *zram, struct bio_vec *bvec,
#define PAGE_WB_SIG "page_index="
#define PAGE_WRITEBACK 0
#define HUGE_WRITEBACK (1<<0)
#define IDLE_WRITEBACK (1<<1)
#define PAGE_WRITEBACK 0
#define HUGE_WRITEBACK (1<<0)
#define IDLE_WRITEBACK (1<<1)
#define INCOMPRESSIBLE_WRITEBACK (1<<2)
static ssize_t writeback_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
@ -669,6 +669,8 @@ static ssize_t writeback_store(struct device *dev,
mode = HUGE_WRITEBACK;
else if (sysfs_streq(buf, "huge_idle"))
mode = IDLE_WRITEBACK | HUGE_WRITEBACK;
else if (sysfs_streq(buf, "incompressible"))
mode = INCOMPRESSIBLE_WRITEBACK;
else {
if (strncmp(buf, PAGE_WB_SIG, sizeof(PAGE_WB_SIG) - 1))
return -EINVAL;
@ -731,11 +733,15 @@ static ssize_t writeback_store(struct device *dev,
goto next;
if (mode & IDLE_WRITEBACK &&
!zram_test_flag(zram, index, ZRAM_IDLE))
!zram_test_flag(zram, index, ZRAM_IDLE))
goto next;
if (mode & HUGE_WRITEBACK &&
!zram_test_flag(zram, index, ZRAM_HUGE))
!zram_test_flag(zram, index, ZRAM_HUGE))
goto next;
if (mode & INCOMPRESSIBLE_WRITEBACK &&
!zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE))
goto next;
/*
* Clearing ZRAM_UNDER_WB is duty of caller.
* IOW, zram_free_page never clear it.