Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757827Ab2FOUgf (ORCPT ); Fri, 15 Jun 2012 16:36:35 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:54586 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757589Ab2FOUge (ORCPT ); Fri, 15 Jun 2012 16:36:34 -0400 From: kosaki.motohiro@gmail.com To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, KOSAKI Motohiro , Hugh Dickins , Andrew Morton , Hillf Danton , Eric Wong Subject: [PATCH] mm, fadvise: don't return -EINVAL when filesystem has no optimization way Date: Fri, 15 Jun 2012 16:36:15 -0400 Message-Id: <1339792575-17637-1-git-send-email-kosaki.motohiro@gmail.com> X-Mailer: git-send-email 1.7.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2515 Lines: 77 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; - } - /* 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; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/