From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Whitehouse <swhiteho@redhat.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
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>,
"cluster-devel@redhat.com" <cluster-devel@redhat.com>
Subject: Re: [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read
Date: Wed, 30 Oct 2019 11:54:35 +0100 [thread overview]
Message-ID: <CAHk-=wh4SKRxKQf5LawRMSijtjRVQevaFioBK+tOZAVPt7ek0Q@mail.gmail.com> (raw)
In-Reply-To: <f0140b13-cca2-af9e-eb4b-82eda134eb8f@redhat.com>
On Wed, Oct 30, 2019 at 11:35 AM Steven Whitehouse <swhiteho@redhat.com> wrote:
>
> NFS may be ok here, but it will break GFS2. There may be others too...
> OCFS2 is likely one. Not sure about CIFS either. Does it really matter
> that we might occasionally allocate a page and then free it again?
Why are gfs2 and cifs doing things wrong?
"readpage()" is not for synchrionizing metadata. Never has been. You
shouldn't treat it that way, and you shouldn't then make excuses for
filesystems that treat it that way.
Look at mmap, for example. It will do the SIGBUS handling before
calling readpage(). Same goes for the copyfile code. A filesystem that
thinks "I will update size at readpage" is already fundamentally
buggy.
We do _recheck_ the inode size under the page lock, but that's to
handle the races with truncate etc.
Linus
next prev parent reply other threads:[~2019-10-30 10:54 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 9:59 [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read Konstantin Khlebnikov
2019-10-28 12:39 ` Linus Torvalds
2019-10-28 12:42 ` Kirill A. Shutemov
2019-10-28 12:47 ` Linus Torvalds
2019-10-28 12:57 ` Kirill A. Shutemov
2019-10-29 14:25 ` Konstantin Khlebnikov
2019-10-29 16:52 ` Linus Torvalds
2019-10-30 6:50 ` Kirill A. Shutemov
2019-10-30 7:02 ` Linus Torvalds
2019-10-30 10:34 ` Steven Whitehouse
2019-10-30 10:54 ` Linus Torvalds [this message]
2019-10-31 11:40 ` Steven Whitehouse
2019-11-22 23:59 ` Andreas Grünbacher
2019-11-25 10:52 ` Steven Whitehouse
2019-11-25 17:05 ` Linus Torvalds
2019-11-27 15:41 ` Steven Whitehouse
2019-11-27 16:29 ` Andreas Gruenbacher
2019-11-27 17:29 ` Linus Torvalds
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