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Commit 8b3a0ca0 authored by Hyunchul Lee's avatar Hyunchul Lee Committed by Jaegeuk Kim
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f2fs: Add the 'whint_mode' mount option to f2fs documentation 



Signed-off-by: default avatarHyunchul Lee <cheol.lee@lge.com>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: Add the write-hint policy in f2fs doc.]
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent f2e703f9

Documentation/filesystems/f2fs.txt

+66 −0
Original line number Diff line number Diff line
@@ -174,6 +174,12 @@ offgrpjquota Turn off group journelled quota. 
offprjjquota           Turn off project journelled quota.

quota                  Enable plain user disk quota accounting.

noquota                Disable all plain disk quota option.

whint_mode=%s          Control which write hints are passed down to block

                       layer. This supports "off", "user-based", and

                       "fs-based".  In "off" mode (default), f2fs does not pass

                       down hints. In "user-based" mode, f2fs tries to pass

                       down hints given by users. And in "fs-based" mode, f2fs

                       passes down hints with its policy.



================================================================================

DEBUGFS ENTRIES
@@ -611,3 +617,63 @@ algorithm. 
In order to identify whether the data in the victim segment are valid or not,

F2FS manages a bitmap. Each bit represents the validity of a block, and the

bitmap is composed of a bit stream covering whole blocks in main area.



Write-hint Policy

-----------------



1) whint_mode=off. F2FS only passes down WRITE_LIFE_NOT_SET.



2) whint_mode=user-based. F2FS tries to pass down hints given by

users.



User                  F2FS                     Block

----                  ----                     -----

                      META                     WRITE_LIFE_NOT_SET

                      HOT_NODE                 "

                      WARM_NODE                "

                      COLD_NODE                "

*ioctl(COLD)          COLD_DATA                WRITE_LIFE_EXTREME

*extension list       "                        "



-- buffered io

WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME

WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT

WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET

WRITE_LIFE_NONE       "                        "

WRITE_LIFE_MEDIUM     "                        "

WRITE_LIFE_LONG       "                        "



-- direct io

WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME

WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT

WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET

WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE

WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM

WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG



3) whint_mode=fs-based. F2FS passes down hints with its policy.



User                  F2FS                     Block

----                  ----                     -----

                      META                     WRITE_LIFE_MEDIUM;

                      HOT_NODE                 WRITE_LIFE_NOT_SET

                      WARM_NODE                "

                      COLD_NODE                WRITE_LIFE_NONE

ioctl(COLD)           COLD_DATA                WRITE_LIFE_EXTREME

extension list        "                        "



-- buffered io

WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME

WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT

WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_LONG

WRITE_LIFE_NONE       "                        "

WRITE_LIFE_MEDIUM     "                        "

WRITE_LIFE_LONG       "                        "



-- direct io

WRITE_LIFE_EXTREME    COLD_DATA                WRITE_LIFE_EXTREME

WRITE_LIFE_SHORT      HOT_DATA                 WRITE_LIFE_SHORT

WRITE_LIFE_NOT_SET    WARM_DATA                WRITE_LIFE_NOT_SET

WRITE_LIFE_NONE       "                        WRITE_LIFE_NONE

WRITE_LIFE_MEDIUM     "                        WRITE_LIFE_MEDIUM

WRITE_LIFE_LONG       "                        WRITE_LIFE_LONG