Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759589AbYFQWRQ (ORCPT ); Tue, 17 Jun 2008 18:17:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757676AbYFQWQ7 (ORCPT ); Tue, 17 Jun 2008 18:16:59 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:58245 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757488AbYFQWQ6 (ORCPT ); Tue, 17 Jun 2008 18:16:58 -0400 Date: Tue, 17 Jun 2008 15:15:28 -0700 From: Joel Becker To: Louis Rilling Cc: linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: Re: [BUGFIX][PATCH 3/3] configfs: Fix failing symlink() making rmdir() fail Message-ID: <20080617221528.GA29091@mail.oracle.com> Mail-Followup-To: Louis Rilling , linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com References: <1213724243-29183-1-git-send-email-louis.rilling@kerlabs.com> <1213724243-29183-4-git-send-email-louis.rilling@kerlabs.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1213724243-29183-4-git-send-email-louis.rilling@kerlabs.com> X-Burt-Line: Trees are cool. X-Red-Smith: Ninety feet between bases is perhaps as close as man has ever come to perfection. User-Agent: Mutt/1.5.18 (2008-05-17) X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2401 Lines: 66 On Tue, Jun 17, 2008 at 07:37:23PM +0200, Louis Rilling wrote: > For the parent's rmdir() case, we can use the same solution as with mkdir() vs > rmdir(). For the target's rmdir() case, we cannot, since we do not and cannot > lock the target's inode while in symlink(). Fortunately, once create_link() > terminates, no further operation can fail in symlink(). So we first reorder the > operations in create_link() to attach the new symlink to its target in last > place, and second handle symlink creation failure the same way as a new item > creation failure. Oh, no, ugh. We don't want to create vfs objects first and ask questions later. Otherwise we wouldn't need ATTACHING - we'd just create the symlink, then check dropping. If you have ATTACHING set, the rmdir cannot continue - you can check dropping at that time. That is, you keep the DROPPING check where it is - if it is already set, you know that rmdir() is going to complete successfully. You can bail before even calling configfs_create_link(). If, however, it isn't set, your ATTACHING protects you from rmdir throughout. sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); if (sl) { sl->sl_target = config_item_get(item); spin_lock(&configfs_dirent_lock); if (target_sd->s_type & CONFIGFS_USET_DROPPING) { spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); return -ENOENT; /* * Force rmdir() of parent_item to wait until we know * if we succeed. */ parent_sd->s_type |= CONFIGFS_USET_ATTACHING; } list_add(&sl->sl_list, &target_sd->s_links); spin_unlock(&configfs_dirent_lock); ret = configfs_create_link(sl, parent_item->ci_dentry, dentry); spin_lock(&configfs_dirent_lock); parent_sd->s_type &= ~CONFIGFS_USET_ATTACHING; if (ret) { list_del_init(&sl->sl_list); spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); } else spin_unlock(&configfs_dirent_lock); } return ret; -- "When arrows don't penetrate, see... Cupid grabs the pistol." Joel Becker Principal Software Developer Oracle E-mail: joel.becker@oracle.com Phone: (650) 506-8127 -- 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/