From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: readahead: fix do_readahead for no readpage(s)
Date: Tue, 28 Jan 2014 13:53:16 +0200 [thread overview]
Message-ID: <20140128115316.GA22934@node.dhcp.inet.fi> (raw)
In-Reply-To: <1390907659-11675-1-git-send-email-mark.rutland@arm.com>
On Tue, Jan 28, 2014 at 11:14:19AM +0000, Mark Rutland wrote:
> Commit 63d0f0a3c7e1 (mm/readahead.c:do_readhead(): don't check for
> ->readpage) unintentionally made do_readahead return 0 for all valid
> files regardless of whether readahead was supported, rather than the
> expected -EINVAL. This gets forwarded on to userspace, and results in
> sys_readahead appearing to succeed in cases that don't make sense (e.g.
> when called on pipes or sockets). This issue is detected by the LTP
> readahead01 testcase.
>
> As the exact return value of force_page_cache_readahead is currently
> never used, we can simplify it to return only 0 or -EINVAL (when
> readpage or readpages is missing). With that in place we can simply
> forward on the return value of force_page_cache_readahead in
> do_readahead.
>
> This patch performs said change, restoring the expected semantics.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
next prev parent reply other threads:[~2014-01-28 11:53 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-28 11:14 [PATCH] mm: readahead: fix do_readahead for no readpage(s) Mark Rutland
2014-01-28 11:53 ` Kirill A. Shutemov [this message]
2014-01-28 20:03 ` Andrew Morton
2014-01-28 21:01 ` Kirill A. Shutemov
2014-01-28 21:09 ` Andrew Morton
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