From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756266AbYFQRiF (ORCPT ); Tue, 17 Jun 2008 13:38:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755825AbYFQRh3 (ORCPT ); Tue, 17 Jun 2008 13:37:29 -0400 Received: from bohort.kerlabs.com ([62.160.40.57]:60135 "EHLO bohort.kerlabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755511AbYFQRh2 (ORCPT ); Tue, 17 Jun 2008 13:37:28 -0400 From: Louis Rilling To: Joel.Becker@oracle.com Cc: linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com, Louis Rilling Subject: [BUGFIX][PATCH 3/3] configfs: Fix failing symlink() making rmdir() fail Date: Tue, 17 Jun 2008 19:37:23 +0200 Message-Id: <1213724243-29183-4-git-send-email-louis.rilling@kerlabs.com> X-Mailer: git-send-email 1.5.5.3 In-Reply-To: <1213724243-29183-1-git-send-email-louis.rilling@kerlabs.com> References: <1213724243-29183-1-git-send-email-louis.rilling@kerlabs.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On a similar pattern as mkdir() vs rmdir(), a failing symlink() may make rmdir() fail for the symlink's parent and the symlink's target as well. failing symlink() making target's rmdir() fail: process 1: process 2: symlink("A/S" -> "B") allow_link() create_link() attach to "B" links list rmdir("B") detach_prep("B") error because of new link configfs_create_link("A", "S") error (eg -ENOMEM) failing symlink() making parent's rmdir() fail: process 1: process 2: symlink("A/D/S" -> "B") allow_link() create_link() attach to "B" links list configfs_create_link("A/D", "S") make_dirent("A/D", "S") rmdir("A") detach_prep("A") detach_prep("A/D") error because of "S" create("S") error (eg -ENOMEM) 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. Signed-off-by: Louis Rilling --- fs/configfs/symlink.c | 39 +++++++++++++++++++++++++++++---------- 1 files changed, 29 insertions(+), 10 deletions(-) diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c index 58722a9..0c5e650 100644 --- a/fs/configfs/symlink.c +++ b/fs/configfs/symlink.c @@ -69,6 +69,7 @@ static int create_link(struct config_item *parent_item, struct config_item *item, struct dentry *dentry) { + struct configfs_dirent *parent_sd = parent_item->ci_dentry->d_fsdata; struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata; struct configfs_symlink *sl; int ret; @@ -77,24 +78,42 @@ static int create_link(struct config_item *parent_item, 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 -EPERM; - } - list_add(&sl->sl_list, &target_sd->s_links); + /* + * Force rmdir() of parent_item to wait until we know if we + * succeed. + */ + parent_sd->s_type |= CONFIGFS_USET_ATTACHING; spin_unlock(&configfs_dirent_lock); + ret = configfs_create_link(sl, parent_item->ci_dentry, dentry); - if (ret) { - spin_lock(&configfs_dirent_lock); - list_del_init(&sl->sl_list); + + spin_lock(&configfs_dirent_lock); + parent_sd->s_type &= ~CONFIGFS_USET_ATTACHING; + + if (ret || target_sd->s_type & CONFIGFS_USET_DROPPING) { + struct configfs_dirent *sd = NULL; + + if (!ret) { + sd = dentry->d_fsdata; + list_del_init(&sd->s_sibling); + } spin_unlock(&configfs_dirent_lock); + + if (!ret) { + configfs_drop_dentry(sd, dentry->d_parent); + d_delete(dentry); + configfs_put(sd); + } config_item_put(item); kfree(sl); + return ret ? ret : -EPERM; } + + list_add(&sl->sl_list, &target_sd->s_links); + spin_unlock(&configfs_dirent_lock); } return ret; -- 1.5.5.3