From: Benjamin LaHaise <bcrl@kvack.org>
To: "Michael K. Edwards" <medwards.linux@gmail.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: sys_write() racy for multi-threaded append?
Date: Thu, 8 Mar 2007 20:34:05 -0500 [thread overview]
Message-ID: <20070309013405.GI6209@kvack.org> (raw)
In-Reply-To: <f2b55d220703081645vc78905cj56afbc58ad2113d8@mail.gmail.com>
> Actually, I think it would make the kernel (negligibly) faster to bump
> f_pos before the vfs_write() call. Unless fget_light sets fput_needed
> or the write doesn't complete cleanly, you won't have to touch the
> file table entry again after vfs_write() returns. You can adjust
Any number of things can cause a short write to occur, and rewinding the
file position after the fact is just as bad. A sane app has to either
serialise the writes itself or use a thread safe API like pwrite().
-ben
--
"Time is of no importance, Mr. President, only life is important."
Don't Email: <zyntrop@kvack.org>.
next prev parent reply other threads:[~2007-03-09 1:34 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-08 23:08 sys_write() racy for multi-threaded append? Michael K. Edwards
2007-03-08 23:43 ` Eric Dumazet
2007-03-08 23:57 ` Michael K. Edwards
2007-03-09 0:15 ` Eric Dumazet
2007-03-09 0:45 ` Michael K. Edwards
2007-03-09 1:34 ` Benjamin LaHaise [this message]
2007-03-09 12:19 ` Michael K. Edwards
2007-03-09 13:44 ` Eric Dumazet
2007-03-09 14:10 ` Alan Cox
2007-03-09 14:59 ` Benjamin LaHaise
2007-03-10 6:43 ` Michael K. Edwards
2007-03-09 5:53 ` Eric Dumazet
2007-03-09 11:52 ` Michael K. Edwards
2007-03-09 0:43 ` Alan Cox
[not found] <7WzUo-1zl-21@gated-at.bofh.it>
[not found] ` <7WAx2-2pg-21@gated-at.bofh.it>
[not found] ` <7WAGF-2Bx-9@gated-at.bofh.it>
[not found] ` <7WB07-3g5-33@gated-at.bofh.it>
[not found] ` <7WBt7-3SZ-23@gated-at.bofh.it>
2007-03-12 7:53 ` Bodo Eggert
2007-03-12 16:26 ` Michael K. Edwards
2007-03-12 18:48 ` Bodo Eggert
2007-03-13 0:46 ` Michael K. Edwards
2007-03-13 2:24 ` Alan Cox
2007-03-13 7:25 ` Michael K. Edwards
2007-03-13 7:42 ` David Miller
2007-03-13 16:24 ` Michael K. Edwards
2007-03-13 17:59 ` Michael K. Edwards
2007-03-13 19:09 ` Christoph Hellwig
2007-03-13 23:40 ` Michael K. Edwards
2007-03-14 0:09 ` Michael K. Edwards
2007-03-13 13:15 ` Alan Cox
2007-03-14 20:09 ` Michael K. Edwards
2007-03-16 16:43 ` Frank Ch. Eigler
2007-03-16 17:25 ` Alan Cox
2007-03-13 14:00 ` David M. Lloyd
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