From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@linux-foundation.org,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
nicolas.dichtel@6wind.com, raven@themaw.net,
Christian Brauner <christian@brauner.io>,
keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
linux-block@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2]
Date: Sun, 27 Oct 2019 08:22:23 -0700 [thread overview]
Message-ID: <20191027152223.GA21194@infradead.org> (raw)
In-Reply-To: <30394.1571936252@warthog.procyon.org.uk>
On Thu, Oct 24, 2019 at 05:57:32PM +0100, David Howells wrote:
> pipe: Add fsync() support
>
> The keyrings testsuite needs the ability to wait for all the outstanding
> notifications in the queue to have been processed so that it can then go
> through them to find out whether the notifications it expected have been
> emitted.
>
> Implement fsync() support for pipes to provide this. The tailmost buffer
> at the point of calling is marked and fsync adds itself to the list of
> waiters, noting the tail position to be waited for and marking the buffer
> as no longer mergeable. Then when the buffer is consumed, if the flag is
> set, any matching waiters are woken up.
I am _really_ worried about overloading fsync for this behavior. fsync
hasn't done anything for 50 years, and suddenly adding any action
is not helpful. If you can't use FIONREAD please add a new ioctls
instead, and document it properly.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@linux-foundation.org,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Peter Zijlstra <peterz@infradead.org>,
nicolas.dichtel@6wind.com, raven@themaw.net,
Christian Brauner <christian@brauner.io>,
keyrings@vger.kernel.org, linux-usb@vger.kernel.org,
linux-block@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 11/10] pipe: Add fsync() support [ver #2]
Date: Sun, 27 Oct 2019 15:22:23 +0000 [thread overview]
Message-ID: <20191027152223.GA21194@infradead.org> (raw)
In-Reply-To: <30394.1571936252@warthog.procyon.org.uk>
On Thu, Oct 24, 2019 at 05:57:32PM +0100, David Howells wrote:
> pipe: Add fsync() support
>
> The keyrings testsuite needs the ability to wait for all the outstanding
> notifications in the queue to have been processed so that it can then go
> through them to find out whether the notifications it expected have been
> emitted.
>
> Implement fsync() support for pipes to provide this. The tailmost buffer
> at the point of calling is marked and fsync adds itself to the list of
> waiters, noting the tail position to be waited for and marking the buffer
> as no longer mergeable. Then when the buffer is consumed, if the flag is
> set, any matching waiters are woken up.
I am _really_ worried about overloading fsync for this behavior. fsync
hasn't done anything for 50 years, and suddenly adding any action
is not helpful. If you can't use FIONREAD please add a new ioctls
instead, and document it properly.
next prev parent reply other threads:[~2019-10-27 15:22 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-23 20:17 [RFC PATCH 00/10] pipe: Notification queue preparation [ver #2] David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 01/10] pipe: Reduce #inclusion of pipe_fs_i.h " David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 02/10] Remove the nr_exclusive argument from __wake_up_sync_key() " David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 03/10] Add wake_up_interruptible_sync_poll_locked() " David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length " David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-26 0:29 ` kbuild test robot
2019-10-26 0:50 ` kbuild test robot
2019-10-26 14:58 ` [pipe] 6567a02d20: BUG:kernel_NULL_pointer_dereference,address kernel test robot
2019-10-26 14:58 ` kernel test robot
2019-10-26 14:58 ` kernel test robot
2019-10-27 14:03 ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length [ver #2] Linus Torvalds
2019-10-27 14:03 ` Linus Torvalds
2019-10-30 16:19 ` Ilya Dryomov
2019-10-30 16:19 ` Ilya Dryomov
2019-10-30 20:35 ` Rasmus Villemoes
2019-10-30 20:35 ` Rasmus Villemoes
2019-10-30 22:16 ` Ilya Dryomov
2019-10-30 22:16 ` Ilya Dryomov
2019-10-30 22:38 ` Rasmus Villemoes
2019-10-30 22:38 ` Rasmus Villemoes
2019-10-31 15:11 ` David Howells
2019-10-31 15:57 ` Ilya Dryomov
2019-10-31 15:57 ` Ilya Dryomov
2019-11-01 14:53 ` David Howells
2019-10-31 14:57 ` David Howells
2019-11-03 11:17 ` Matthew Wilcox
2019-11-03 11:17 ` Matthew Wilcox
2019-12-06 21:47 ` Johannes Hirte
2019-12-06 21:47 ` Johannes Hirte
2019-12-06 22:14 ` Linus Torvalds
2019-12-06 22:14 ` Linus Torvalds
2019-12-07 0:00 ` Johannes Hirte
2019-12-07 0:00 ` Johannes Hirte
2019-12-07 1:03 ` Linus Torvalds
2019-12-07 1:03 ` Linus Torvalds
2019-12-08 17:56 ` Johannes Hirte
2019-12-08 17:56 ` Johannes Hirte
2019-12-08 18:10 ` Linus Torvalds
2019-12-08 18:10 ` Linus Torvalds
2019-12-07 6:47 ` Linus Torvalds
2019-12-07 6:47 ` Linus Torvalds
2019-12-06 22:15 ` David Howells
2019-10-23 20:17 ` [RFC PATCH 05/10] pipe: Allow pipes to have kernel-reserved slots " David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:17 ` David Howells
2019-10-23 20:18 ` [RFC PATCH 06/10] pipe: Advance tail pointer inside of wait spinlock in pipe_read() " David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` [RFC PATCH 07/10] pipe: Conditionalise wakeup " David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` David Howells
2019-10-27 15:57 ` Konstantin Khlebnikov
2019-10-27 15:57 ` Konstantin Khlebnikov
2019-10-31 15:21 ` David Howells
2019-10-31 16:38 ` David Howells
2019-11-03 11:04 ` Konstantin Khlebnikov
2019-11-03 11:04 ` Konstantin Khlebnikov
2019-10-23 20:18 ` [RFC PATCH 08/10] pipe: Rearrange sequence in pipe_write() to preallocate slot " David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` [RFC PATCH 09/10] pipe: Remove redundant wakeup from pipe_write() " David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` [RFC PATCH 10/10] pipe: Check for ring full inside of the spinlock in " David Howells
2019-10-23 20:18 ` David Howells
2019-10-23 20:18 ` David Howells
2019-10-24 10:32 ` [RFC PATCH 04/10] pipe: Use head and tail pointers for the ring, not cursor and length " David Howells
2019-10-24 10:32 ` David Howells
2019-10-24 13:14 ` [RFC PATCH 00/10] pipe: Notification queue preparation " Peter Zijlstra
2019-10-24 13:14 ` Peter Zijlstra
2019-10-24 16:57 ` [RFC PATCH 11/10] pipe: Add fsync() support " David Howells
2019-10-24 16:57 ` David Howells
2019-10-24 21:29 ` Linus Torvalds
2019-10-24 21:29 ` Linus Torvalds
2019-10-25 8:34 ` David Howells
2019-10-25 8:34 ` David Howells
2019-10-27 15:22 ` Christoph Hellwig [this message]
2019-10-27 15:22 ` Christoph Hellwig
2019-10-27 16:04 ` Konstantin Khlebnikov
2019-10-27 16:04 ` Konstantin Khlebnikov
2019-10-31 15:13 ` David Howells
2019-10-31 15:15 ` David Howells
2019-11-02 18:53 ` Linus Torvalds
2019-11-02 18:53 ` Linus Torvalds
2019-11-02 19:34 ` David Howells
2019-11-02 20:31 ` Andy Lutomirski
2019-11-02 20:31 ` Andy Lutomirski
2019-11-02 22:03 ` Linus Torvalds
2019-11-02 22:03 ` Linus Torvalds
2019-11-02 22:09 ` Linus Torvalds
2019-11-02 22:09 ` Linus Torvalds
2019-11-02 22:30 ` Andy Lutomirski
2019-11-02 22:30 ` Andy Lutomirski
2019-11-02 23:02 ` Linus Torvalds
2019-11-02 23:02 ` Linus Torvalds
2019-11-02 23:09 ` Linus Torvalds
2019-11-02 23:09 ` Linus Torvalds
2019-11-02 23:14 ` Andy Lutomirski
2019-11-02 23:14 ` Andy Lutomirski
2019-11-03 12:02 ` Konstantin Khlebnikov
2019-11-03 12:02 ` Konstantin Khlebnikov
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