From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx177.postini.com [74.125.245.177]) by kanga.kvack.org (Postfix) with SMTP id BBC0C6B006C for ; Wed, 20 Jun 2012 02:31:33 -0400 (EDT) Message-ID: <4FE16E50.9030304@cn.fujitsu.com> Date: Wed, 20 Jun 2012 14:31:44 +0800 From: Wanlong Gao Reply-To: gaowanlong@cn.fujitsu.com MIME-Version: 1.0 Subject: Re: [PATCH] mm, fadvise: don't return -EINVAL when filesystem has no optimization way References: <1339792575-17637-1-git-send-email-kosaki.motohiro@gmail.com> In-Reply-To: <1339792575-17637-1-git-send-email-kosaki.motohiro@gmail.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: kosaki.motohiro@gmail.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, KOSAKI Motohiro , Hugh Dickins , Andrew Morton , Hillf Danton , Eric Wong On 06/16/2012 04:36 AM, kosaki.motohiro@gmail.com wrote: > From: KOSAKI Motohiro > > 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. > But in fact, force_page_cache_readahead() only require > a target filesystem has either ->readpage or ->readpages. > 2) return -EINVAL when filesystem don't have ->readpage. > But, posix says, it should be retrieved a hint. Thus fadvise() > should return 0 if filesystem has no optimization way. > Especially, userland application don't know a filesystem type > of TMPDIR directory as Eric pointed out. Then, userland can't > avoid this error. We shouldn't encourage to ignore syscall > 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 > Cc: Andrew Morton > Cc: Hillf Danton > Signed-off-by: Eric Wong > Tested-by: Eric Wong > Signed-off-by: KOSAKI Motohiro > --- > mm/fadvise.c | 18 +++++++----------- > 1 files changed, 7 insertions(+), 11 deletions(-) > > diff --git a/mm/fadvise.c b/mm/fadvise.c > index 469491e..33e6baf 100644 > --- a/mm/fadvise.c > +++ b/mm/fadvise.c > @@ -93,11 +93,6 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > spin_unlock(&file->f_lock); > break; > case POSIX_FADV_WILLNEED: > - if (!mapping->a_ops->readpage) { > - ret = -EINVAL; > - break; > - } Why not check both readpage and readpages, if they are not here, just beak and no following force_page_cache_readahead ? Thanks, Wanlong Gao > - > /* First and last PARTIAL page! */ > start_index = offset >> PAGE_CACHE_SHIFT; > end_index = endbyte >> PAGE_CACHE_SHIFT; > @@ -106,12 +101,13 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) > nrpages = end_index - start_index + 1; > if (!nrpages) > nrpages = ~0UL; > - > - ret = force_page_cache_readahead(mapping, file, > - start_index, > - nrpages); > - if (ret > 0) > - ret = 0; > + > + /* > + * Ignore return value because fadvise() shall return > + * success even if filesystem can't retrieve a hint, > + */ > + force_page_cache_readahead(mapping, file, start_index, > + nrpages); > break; > case POSIX_FADV_NOREUSE: > break; > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org