linux-kernel - Re: [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read

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Message-ID: <CAHk-=wgQ-Dcs2keNJPovTb4gG33M81yANH6KZM9d5NLUb-cJ1g@mail.gmail.com>
Date:   Mon, 28 Oct 2019 13:47:16 +0100
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     "Kirill A. Shutemov" <kirill@...temov.name>
Cc:     Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Linux-MM <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Johannes Weiner <hannes@...xchg.org>,
        Steven Whitehouse <swhiteho@...hat.com>
Subject: Re: [PATCH] mm/filemap: do not allocate cache pages beyond end of
 file at read

On Mon, Oct 28, 2019 at 1:42 PM Kirill A. Shutemov <kirill@...temov.name> wrote:
>
> I've tried something of this sort back in 2013:
>
> http://lore.kernel.org/r/1377099441-2224-1-git-send-email-kirill.shutemov@linux.intel.com
>
> and I've got push back.
>
> Apparently, some filesystems may not have valid i_size before >readpage().
> Not sure if it's still the case...

Well, I agree that there might be some network filesystem that might
have inode sizes that are stale, but if that's the case then I don't
think your previous patch works either.

It too will avoid the readpage() if the read position is beyond i_size.

No?

               Linus