From: Andi Kleen <andi@firstfloor.org>
To: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Cc: Josef Bacik <josef@redhat.com>,
sandeen@redhat.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] Perform check in iov_iter_fault_in_readable() by check_readable_bytes()
Date: Fri, 15 May 2009 08:56:00 +0200 [thread overview]
Message-ID: <87k54iq2gv.fsf@basil.nowhere.org> (raw)
In-Reply-To: <1242317939-15392-3-git-send-email-v.mayatskih@gmail.com> (Vitaly Mayatskikh's message of "Thu, 14 May 2009 18:19:01 +0200")
Vitaly Mayatskikh <v.mayatskih@gmail.com> writes:
> This patch changes iov_iter_fault_in_readable() to use check_readable_bytes()
> instead of fault_in_pages_readable(). It allows iov_iter_fault_in_readable()
> callers to know how much data is accessible and proceed with it. It makes
> sys_write() more POSIX-friendly.
Can you describe how it makes it POSIX friendly?
My understanding was that EFAULT behaviour was undefined in POSIX.
The obvious hole in the patch is that all these checks are not race
free -- they don't pin pages -- so if there's a parallel unmap even
with your change they can still fail in the middle.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2009-05-15 6:56 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-14 16:18 [PATCH 0/2] sys_write() should write all valid data Vitaly Mayatskikh
2009-05-14 16:19 ` [PATCH 1/2] Introduce check_readable_bytes() Vitaly Mayatskikh
2009-05-14 17:40 ` Josef Bacik
2009-05-14 17:57 ` Vitaly Mayatskikh
2009-05-14 16:19 ` [PATCH 2/2] Perform check in iov_iter_fault_in_readable() by check_readable_bytes() Vitaly Mayatskikh
2009-05-15 6:56 ` Andi Kleen [this message]
2009-05-15 7:56 ` Vitaly Mayatskikh
2009-05-15 9:38 ` Andi Kleen
2009-05-15 11:56 ` Vitaly Mayatskikh
2009-05-15 12:19 ` Andi Kleen
2009-05-15 13:43 ` Jamie Lokier
2009-05-15 14:01 ` Andi Kleen
2009-05-15 14:37 ` Jamie Lokier
2009-05-18 8:31 ` Alan Cox
2009-05-18 9:48 ` Jamie Lokier
2009-05-18 10:03 ` Alan Cox
2009-05-18 10:16 ` Andi Kleen
2009-05-19 8:55 ` Pavel Machek
2009-05-14 18:02 ` [PATCH 0/2] sys_write() should write all valid data Josef Bacik
2009-05-14 18:48 ` Vitaly Mayatskikh
2009-05-14 19:05 ` Josef Bacik
2009-05-15 6:52 ` Andi Kleen
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