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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Date: Wed, 20 Jun 2012 01:01:25 -0400
Message-ID: <CAHGf_=qmCdfv0jxOqdrHduTgnjPxgBT7oTdhkywSCCRAKu3A-A@mail.gmail.com>
Subject: Re: [PATCH] mm, fadvise: don't return -EINVAL when filesystem has no
 optimization way
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Sender: owner-linux-mm@kvack.org
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To: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Hugh Dickins <hughd@google.com>, Andrew Morton <akpm@linux-foundation.org>, Hillf Danton <dhillf@gmail.com>, Eric Wong <normalperson@yhbt.net>

On Fri, Jun 15, 2012 at 4:36 PM,  <kosaki.motohiro@gmail.com> wrote:
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>
> Eric Wong reported his test suite was fail when /tmp is tmpfs.
>
> https://lkml.org/lkml/2012/2/24/479
>
> Current,input check of POSIX_FADV_WILLNEED has two problems.
>
> 1) require a_ops->readpage.
> =A0 But in fact, force_page_cache_readahead() only require
> =A0 a target filesystem has either ->readpage or ->readpages.
> 2) return -EINVAL when filesystem don't have ->readpage.
> =A0 But, posix says, it should be retrieved a hint. Thus fadvise()
> =A0 should return 0 if filesystem has no optimization way.
> =A0 Especially, userland application don't know a filesystem type
> =A0 of TMPDIR directory as Eric pointed out. Then, userland can't
> =A0 avoid this error. We shouldn't encourage to ignore syscall
> =A0 return value.
>
> Thus, this patch change a return value to 0 when filesytem don't
> support readahead.
>
> Cc: linux-mm@kvack.org
> Cc: Hugh Dickins <hughd@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Hillf Danton <dhillf@gmail.com>
> Signed-off-by: Eric Wong <normalperson@yhbt.net>
> Tested-by: Eric Wong <normalperson@yhbt.net>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> ---

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