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Date:   Wed, 8 Jan 2020 04:04:44 -0800
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Chao Yu <yuchao0@huawei.com>
Cc:     linux-kernel@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH] f2fs: add a way to turn off ipu bio cache
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 <afddac87-b7c5-f68c-4e55-3705be311cf6@huawei.com>
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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@kernel.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.

> 
> Reviewed-by: Chao Yu <yuchao0@huawei.com>
> 
> Thanks,
> 
> > +			       0x40: F2FS_IPU_NOCACHE disables bio caches.
> >  
> >   min_ipu_util                 This parameter controls the threshold to trigger
> >                                in-place-updates. The number indicates percentage
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index a9519532c029..311fe4937f6a 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -3289,7 +3289,7 @@ int f2fs_inplace_write_data(struct f2fs_io_info *fio)
> >  
> >  	stat_inc_inplace_blocks(fio->sbi);
> >  
> > -	if (fio->bio)
> > +	if (fio->bio && !(SM_I(sbi)->ipu_policy & (1 << F2FS_IPU_NOCACHE)))
> >  		err = f2fs_merge_page_bio(fio);
> >  	else
> >  		err = f2fs_submit_page_bio(fio);
> > diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> > index a1b3951367cd..02e620470eef 100644
> > --- a/fs/f2fs/segment.h
> > +++ b/fs/f2fs/segment.h
> > @@ -623,6 +623,7 @@ enum {
> >  	F2FS_IPU_SSR_UTIL,
> >  	F2FS_IPU_FSYNC,
> >  	F2FS_IPU_ASYNC,
> > +	F2FS_IPU_NOCACHE,
> >  };
> >  
> >  static inline unsigned int curseg_segno(struct f2fs_sb_info *sbi,
> >