From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932203Ab2BYCdA (ORCPT ); Fri, 24 Feb 2012 21:33:00 -0500 Received: from dcvr.yhbt.net ([64.71.152.64]:39964 "EHLO dcvr.yhbt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932132Ab2BYCc6 (ORCPT ); Fri, 24 Feb 2012 21:32:58 -0500 X-Greylist: delayed 346 seconds by postgrey-1.27 at vger.kernel.org; Fri, 24 Feb 2012 21:32:58 EST Date: Sat, 25 Feb 2012 02:27:10 +0000 From: Eric Wong To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] fadvise: avoid EINVAL if user input is valid Message-ID: <20120225022710.GA29455@dcvr.yhbt.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel is not required to act on fadvise, so fail silently and ignore advice as long as it has a valid descriptor and parameters. Cc: linux-mm@kvack.org Cc: Andrew Morton Signed-off-by: Eric Wong --- Of course I wouldn't knowingly call posix_fadvise() on a file in tmpfs, but a userspace app often doesn't know (nor should it care) what type of filesystem it's on. I encountered EINVAL while running the Ruby 1.9.3 test suite on a stock Debian wheezy installation. Wheezy uses tmpfs for "/tmp" by default and the test suite creates a temporary file to test the Ruby wrapper for posix_fadvise() on. mm/fadvise.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/mm/fadvise.c b/mm/fadvise.c index 469491e0..f9e48dd 100644 --- a/mm/fadvise.c +++ b/mm/fadvise.c @@ -43,13 +43,13 @@ SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice) goto out; } - mapping = file->f_mapping; - if (!mapping || len < 0) { + if (len < 0) { ret = -EINVAL; goto out; } - if (mapping->a_ops->get_xip_mem) { + mapping = file->f_mapping; + if (!mapping || mapping->a_ops->get_xip_mem) { switch (advice) { case POSIX_FADV_NORMAL: case POSIX_FADV_RANDOM: @@ -93,10 +93,9 @@ 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; + /* ignore the advice if readahead isn't possible (tmpfs) */ + if (!mapping->a_ops->readpage) break; - } /* First and last PARTIAL page! */ start_index = offset >> PAGE_CACHE_SHIFT; @@ -106,12 +105,8 @@ 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; + + force_page_cache_readahead(mapping, file, start_index, nrpages); break; case POSIX_FADV_NOREUSE: break; -- Eric Wong