linux-kernel - Re: [f2fs-dev] [PATCH] f2fs: add a way to turn off ipu bio cache

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Message-ID: <20200108231840.GB42219@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Wed, 8 Jan 2020 15:18:40 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: add a way to turn off ipu bio cache

On 01/08, Chao Yu wrote:
> On 2020/1/8 20:04, Jaegeuk Kim wrote:
> > On 01/08, Chao Yu wrote:
> >> On 2020/1/7 10:07, Jaegeuk Kim wrote:
> >>> Setting 0x40 in /sys/fs/f2fs/dev/ipu_policy gives a way to turn off
> >>> bio cache, which is useufl to check whether block layer using hardware
> >>> encryption engine merges IOs correctly.
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> >>> ---
> >>>  Documentation/filesystems/f2fs.txt | 1 +
> >>>  fs/f2fs/segment.c                  | 2 +-
> >>>  fs/f2fs/segment.h                  | 1 +
> >>>  3 files changed, 3 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
> >>> index 41b5aa94b30f..cd93bcc34726 100644
> >>> --- a/Documentation/filesystems/f2fs.txt
> >>> +++ b/Documentation/filesystems/f2fs.txt
> >>> @@ -335,6 +335,7 @@ Files in /sys/fs/f2fs/<devname>
> >>>                                 0x01: F2FS_IPU_FORCE, 0x02: F2FS_IPU_SSR,
> >>>                                 0x04: F2FS_IPU_UTIL,  0x08: F2FS_IPU_SSR_UTIL,
> >>>                                 0x10: F2FS_IPU_FSYNC.
> >>
> >> . -> ,
> > 
> > Actually, we can't do it. I revised it a bit instead.
> 
> One more question, why skipping 0x20 bit position?

It seems original patch missed to add comment.

>From f9447095de55a3cda1023a37a5e1cb6dd2f54ebb Mon Sep 17 00:00:00 2001
From: Jaegeuk Kim <jaegeuk@...nel.org>
Date: Wed, 8 Jan 2020 15:10:02 -0800
Subject: [PATCH] f2fs: update f2fs document regarding to fsync_mode

This patch adds missing fsync_mode entry in f2fs document.

Fixes: 04485987f053 ("f2fs: introduce async IPU policy")
Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 Documentation/filesystems/f2fs.txt | 3 ++-
 fs/f2fs/segment.h                  | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index b80a7b69f210..ee61ace30276 100644
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -334,7 +334,8 @@ Files in /sys/fs/f2fs/<devname>
                               updates in f2fs. User can set:
                                0x01: F2FS_IPU_FORCE, 0x02: F2FS_IPU_SSR,
                                0x04: F2FS_IPU_UTIL,  0x08: F2FS_IPU_SSR_UTIL,
-                               0x10: F2FS_IPU_FSYNC, 0x40: F2FS_IPU_NOCACHE.
+                               0x10: F2FS_IPU_FSYNC, 0x20: F2FS_IPU_ASYNC,
+                               0x40: F2FS_IPU_NOCACHE.
                               Refer segment.h for details.
 
  min_ipu_util                 This parameter controls the threshold to trigger
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index 5e6cd8d8411d..459dc3901a57 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -607,9 +607,10 @@ static inline int utilization(struct f2fs_sb_info *sbi)
  *                     threashold,
  * F2FS_IPU_FSYNC - activated in fsync path only for high performance flash
  *                     storages. IPU will be triggered only if the # of dirty
- *                     pages over min_fsync_blocks.
+ *                     pages over min_fsync_blocks. (=default option)
+ * F2FS_IPU_ASYNC - do IPU given by asynchronous write requests.
  * F2FS_IPU_NOCACHE - disable IPU bio cache.
- * F2FS_IPUT_DISABLE - disable IPU. (=default option)
+ * F2FS_IPUT_DISABLE - disable IPU. (=default option in LFS mode)
  */
 #define DEF_MIN_IPU_UTIL	70
 #define DEF_MIN_FSYNC_BLOCKS	8
-- 
2.24.0.525.g8f36a354ae-goog