All of lore.kernel.org
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@osdl.org>
To: Joel Becker <Joel.Becker@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>,
	Ulrich Drepper <drepper@redhat.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: statfs() / statvfs() syscall ballsup...
Date: Fri, 10 Oct 2003 10:51:52 -0700 (PDT)	[thread overview]
Message-ID: <Pine.LNX.4.44.0310101046060.20420-100000@home.osdl.org> (raw)
In-Reply-To: <20031010173344.GC29301@ca-server1.us.oracle.com>


On Fri, 10 Oct 2003, Joel Becker wrote:
> 
> 	I know that, I agree with it, and I said as much a few emails
> past.  Linux should refuse to corrupt your data.  But you've taken the
> tack "It is unsafe today, so we should abandon it altogether, never mind
> fixing it.", which doesn't logically follow.

No, we've fixed it, the problem is that it ends up being a lot of extra
complexity that isn't obvious when just initially looking at it. For
example, just the IO scheduler ended up having serious problems with
overlapping IO requests. That's in addition to all the issues with
out-of-sync ordering etc that could cause direct_io reads to bypass
regular writes and read stuff off the disk that was a potential security
issue.

So right now we have extra code and extra complexity (which implies not
only potential for more bugs, but there are performance worries etc that
can impact even users that don't need it).

And these are fundamental problems to DIRECT_IO. Which means that likely
at some point we will _have_ to actually implement DIRECT_IO entirely
through the page cache to make sure that it's safe. So my bet is that
eventually we'll make DIRECT_IO just be an awkward way to do page cache
manipulation.

And maybe it works out ok. And we'll clearly have to keep it working. The 
issue is whether there are better interfaces. And I think there are bound 
to be.

		Linus


  reply	other threads:[~2003-10-10 17:52 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-09 22:16 Trond Myklebust
2003-10-09 22:26 ` Linus Torvalds
2003-10-09 23:19   ` Ulrich Drepper
2003-10-10  0:22     ` viro
2003-10-10  4:49       ` Jamie Lokier
2003-10-10  5:26         ` Trond Myklebust
2003-10-10 12:37           ` Jamie Lokier
2003-10-10 13:46             ` Trond Myklebust
2003-10-10 14:35               ` Jamie Lokier
2003-10-10 15:32                 ` Misc NFSv4 (was Re: statfs() / statvfs() syscall ballsup...) Trond Myklebust
2003-10-10 15:53                   ` Jamie Lokier
2003-10-10 16:07                     ` Trond Myklebust
2003-10-10 15:55                   ` Michael Shuey
2003-10-10 16:20                     ` Trond Myklebust
2003-10-10 16:45                     ` J. Bruce Fields
2003-10-10 14:39               ` statfs() / statvfs() syscall ballsup Jamie Lokier
2003-10-09 23:31   ` Trond Myklebust
2003-10-10 12:27   ` Joel Becker
2003-10-10 14:59     ` Linus Torvalds
2003-10-10 15:27       ` Joel Becker
2003-10-10 16:00         ` Linus Torvalds
2003-10-10 16:26           ` Joel Becker
2003-10-10 16:50             ` Linus Torvalds
2003-10-10 17:33               ` Joel Becker
2003-10-10 17:51                 ` Linus Torvalds [this message]
2003-10-10 18:13                   ` Joel Becker
2003-10-10 16:27           ` Valdis.Kletnieks
2003-10-10 16:33           ` Chris Friesen
2003-10-10 17:04             ` Linus Torvalds
2003-10-10 17:07               ` Linus Torvalds
2003-10-10 17:21                 ` Joel Becker
2003-10-10 16:01         ` Jamie Lokier
2003-10-10 16:33           ` Joel Becker
2003-10-10 16:58             ` Chris Friesen
2003-10-10 17:05               ` Trond Myklebust
2003-10-10 17:20               ` Joel Becker
2003-10-10 17:33                 ` Chris Friesen
2003-10-10 17:40                 ` Linus Torvalds
2003-10-10 17:54                   ` Trond Myklebust
2003-10-10 18:05                     ` Linus Torvalds
2003-10-10 20:40                       ` Trond Myklebust
2003-10-10 21:09                         ` Linus Torvalds
2003-10-10 22:17                           ` Trond Myklebust
2003-10-11  2:53                     ` Andrew Morton
2003-10-11  3:47                       ` Trond Myklebust
2003-10-10 18:05                   ` Joel Becker
2003-10-10 18:31                     ` Andrea Arcangeli
2003-10-10 20:33                     ` Helge Hafting
2003-10-10 20:07             ` Jamie Lokier
2003-10-12 15:31             ` Greg Stark
2003-10-12 16:13               ` Linus Torvalds
2003-10-12 22:09                 ` Greg Stark
2003-10-13  8:45                   ` Helge Hafting
2003-10-15 13:25                     ` Ingo Oeser
2003-10-15 15:03                       ` Greg Stark
2003-10-15 18:37                         ` Helge Hafting
2003-10-16 10:29                         ` Ingo Oeser
2003-10-16 14:02                           ` Greg Stark
2003-10-21 11:47                             ` Ingo Oeser
2003-10-10 18:20           ` Andrea Arcangeli
2003-10-10 18:36             ` Linus Torvalds
2003-10-10 19:03               ` Andrea Arcangeli
2003-10-09 23:16 ` Andreas Dilger
2003-10-09 23:24   ` Linus Torvalds

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Pine.LNX.4.44.0310101046060.20420-100000@home.osdl.org \
    --to=torvalds@osdl.org \
    --cc=Joel.Becker@oracle.com \
    --cc=drepper@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=trond.myklebust@fys.uio.no \
    --subject='Re: statfs() / statvfs() syscall ballsup...' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.