Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932402AbZJNJ7P (ORCPT ); Wed, 14 Oct 2009 05:59:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758226AbZJNJ7O (ORCPT ); Wed, 14 Oct 2009 05:59:14 -0400 Received: from acsinet12.oracle.com ([141.146.126.234]:20061 "EHLO acsinet12.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758327AbZJNJ7M (ORCPT ); Wed, 14 Oct 2009 05:59:12 -0400 From: Joel Becker To: ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, hch@infradead.org, torvalds@linux-foundation.org Subject: [PATCH 1/2] vfs: Add MAY_CREATE to the permission() flags. Date: Wed, 14 Oct 2009 02:57:40 -0700 Message-Id: <1255514261-25823-2-git-send-email-joel.becker@oracle.com> X-Mailer: git-send-email 1.5.6.5 In-Reply-To: <1255514261-25823-1-git-send-email-joel.becker@oracle.com> References: <1255514261-25823-1-git-send-email-joel.becker@oracle.com> X-Source-IP: acsmt353.oracle.com [141.146.40.153] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090209.4AD5A09A.0146:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2037 Lines: 56 A simple rule of system calls is that you cannot return -ERESTARTSYS after you've made non-idempotent changes. ocfs2 has run into this with open(O_CREAT|O_EXCL). Once you've created the file, you can't restart the open(), because O_CREAT|O_EXCL will trigger -EEXIST. The problem is that ocfs2 is catching the signal ->permission(), called by may_open(). This happens after ->create() has successfully created the file. ocfs2_permission() has to get a cluster lock, and this is what can be interrupted by a signal. Now, obviously we want to block signals in the O_CREAT|O_EXCL case, but ocfs2_permission() has no way of knowing it just got called from open_namei_create(). So we add the MAY_CREATE flag to permission(). open_namei_create() will pass it to may_open(), and then ocfs2 can block signals in ocfs2_permission() as appropriate. The same is true of any other filesystem that has to do work in may_open(). Signed-off-by: Joel Becker --- fs/namei.c | 2 +- include/linux/fs.h | 1 + 2 files changed, 2 insertions(+), 1 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index d11f404..d54cb98 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1623,7 +1623,7 @@ out_unlock: if (error) return error; /* Don't check for write permission, don't truncate */ - return may_open(&nd->path, 0, flag & ~O_TRUNC); + return may_open(&nd->path, MAY_CREATE, flag & ~O_TRUNC); } /* diff --git a/include/linux/fs.h b/include/linux/fs.h index 2620a8c..b1a454c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -53,6 +53,7 @@ struct inodes_stat_t { #define MAY_APPEND 8 #define MAY_ACCESS 16 #define MAY_OPEN 32 +#define MAY_CREATE 64 /* * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond -- 1.6.3.3 -- 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/