Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <157225677483.3442.4227193290486305330.stgit@buzz> <20191028124222.ld6u3dhhujfqcn7w@box>
In-Reply-To: <20191028124222.ld6u3dhhujfqcn7w@box>
From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 28 Oct 2019 13:47:16 +0100
Message-ID: <CAHk-=wgQ-Dcs2keNJPovTb4gG33M81yANH6KZM9d5NLUb-cJ1g@mail.gmail.com>
Subject: Re: [PATCH] mm/filemap: do not allocate cache pages beyond end of
 file at read
To:     "Kirill A. Shutemov" <kirill@shutemov.name>
Cc:     Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Linux-MM <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Steven Whitehouse <swhiteho@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Oct 28, 2019 at 1:42 PM Kirill A. Shutemov <kirill@shutemov.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