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authorSergey Senozhatsky <senozhatsky@chromium.org>2022-11-09 20:50:46 +0900
committerAndrew Morton <akpm@linux-foundation.org>2022-11-30 15:58:53 -0800
commitb46f9ea3cb351587b2cfc68f7211f7a7cc5b6673 (patch)
treedaf5737bdb1ea5c912e3d308ca2aeefee9037d8a
parent443dd798062c1549e790539e572cbda4b7a8df30 (diff)
zram: add incompressible writeback
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>
-rw-r--r--Documentation/admin-guide/blockdev/zram.rst7
-rw-r--r--drivers/block/zram/zram_drv.c18
2 files changed, 18 insertions, 7 deletions
diff --git a/Documentation/admin-guide/blockdev/zram.rst b/Documentation/admin-guide/blockdev/zram.rst
index d898b7ace33d..f14c8c2e42f3 100644
--- a/Documentation/admin-guide/blockdev/zram.rst
+++ b/Documentation/admin-guide/blockdev/zram.rst
@@ -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
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 798c421fdd36..25b7ff2b56bf 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -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.