linux-kernel - Re: [f2fs-dev] [PATCH 2/2] f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS

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Message-ID: <CACOAw_xaJ6pfT_EDqCSaL8UnBVkktXK5N_GXuHT+xzu1ufVacg@mail.gmail.com>
Date:   Fri, 27 Nov 2020 08:46:47 +0900
From:   Daeho Jeong <daeho43@...il.com>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Chao Yu <yuchao0@...wei.com>, Daeho Jeong <daehojeong@...gle.com>,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE

Chao,

Got it~

Eric,

Actually, I wanted to detour the internal readahead mechanism using
page_cache_ra_unbounded() to generate cluster size aligned read
requests.
But, page_cache_async_readahead() or page_cache_sync_readahead() can
be also good enough, since those can compensate for the misaligned
reads reading more pages in advance.

Thanks,

2020년 11월 27일 (금) 오전 2:49, Eric Biggers <ebiggers@...nel.org>님이 작성:
>
> On Thu, Nov 26, 2020 at 02:04:41PM +0900, Daeho Jeong wrote:
> > Eric,
> >
> > do_page_cache_ra() is defined in mm/internal.h for internal use
> > between in mm, so we cannot use this one right now.
> > So, I think we could use page_cache_ra_unbounded(), because we already
> > check i_size boundary on our own.
> > What do you think?
>
> What about page_cache_async_readahead() or page_cache_sync_readahead()?
>
> - Eric