Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934351AbZLKWen (ORCPT ); Fri, 11 Dec 2009 17:34:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756395AbZLKWds (ORCPT ); Fri, 11 Dec 2009 17:33:48 -0500 Received: from kroah.org ([198.145.64.141]:32800 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761546AbZLKWZE (ORCPT ); Fri, 11 Dec 2009 17:25:04 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: "Eric W. Biederman" , "Eric W. Biederman" , Greg Kroah-Hartman Subject: [PATCH 14/27] sysfs: Use dentry_ops instead of directly playing with the dcache Date: Fri, 11 Dec 2009 14:24:36 -0800 Message-Id: <1260570289-6997-14-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.6.5.3 In-Reply-To: <20091211212642.GA6624@kroah.com> References: <20091211212642.GA6624@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4225 Lines: 140 From: Eric W. Biederman Calling d_drop unconditionally when a sysfs_dirent is deleted has the potential to leak mounts, so instead implement dentry delete and revalidate operations that cause sysfs dentries to be removed at the appropriate time. Acked-by: Tejun Heo Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman Signed-off-by: Greg Kroah-Hartman --- fs/sysfs/dir.c | 73 +++++++++++++++++++++++++++++++++++-------------------- 1 files changed, 46 insertions(+), 27 deletions(-) diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c index 01a9a64..9ee130b 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -298,6 +298,46 @@ void release_sysfs_dirent(struct sysfs_dirent * sd) goto repeat; } +static int sysfs_dentry_delete(struct dentry *dentry) +{ + struct sysfs_dirent *sd = dentry->d_fsdata; + return !!(sd->s_flags & SYSFS_FLAG_REMOVED); +} + +static int sysfs_dentry_revalidate(struct dentry *dentry, struct nameidata *nd) +{ + struct sysfs_dirent *sd = dentry->d_fsdata; + int is_dir; + + mutex_lock(&sysfs_mutex); + + /* The sysfs dirent has been deleted */ + if (sd->s_flags & SYSFS_FLAG_REMOVED) + goto out_bad; + + mutex_unlock(&sysfs_mutex); +out_valid: + return 1; +out_bad: + /* Remove the dentry from the dcache hashes. + * If this is a deleted dentry we use d_drop instead of d_delete + * so sysfs doesn't need to cope with negative dentries. + */ + is_dir = (sysfs_type(sd) == SYSFS_DIR); + mutex_unlock(&sysfs_mutex); + if (is_dir) { + /* If we have submounts we must allow the vfs caches + * to lie about the state of the filesystem to prevent + * leaks and other nasty things. + */ + if (have_submounts(dentry)) + goto out_valid; + shrink_dcache_parent(dentry); + } + d_drop(dentry); + return 0; +} + static void sysfs_dentry_iput(struct dentry *dentry, struct inode *inode) { struct sysfs_dirent * sd = dentry->d_fsdata; @@ -307,6 +347,8 @@ static void sysfs_dentry_iput(struct dentry *dentry, struct inode *inode) } static const struct dentry_operations sysfs_dentry_ops = { + .d_revalidate = sysfs_dentry_revalidate, + .d_delete = sysfs_dentry_delete, .d_iput = sysfs_dentry_iput, }; @@ -527,44 +569,21 @@ void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd) } /** - * sysfs_drop_dentry - drop dentry for the specified sysfs_dirent + * sysfs_dec_nlink - Decrement link count for the specified sysfs_dirent * @sd: target sysfs_dirent * - * Drop dentry for @sd. @sd must have been unlinked from its + * Decrement nlink for @sd. @sd must have been unlinked from its * parent on entry to this function such that it can't be looked * up anymore. */ -static void sysfs_drop_dentry(struct sysfs_dirent *sd) +static void sysfs_dec_nlink(struct sysfs_dirent *sd) { struct inode *inode; - struct dentry *dentry; inode = ilookup(sysfs_sb, sd->s_ino); if (!inode) return; - /* Drop any existing dentries associated with sd. - * - * For the dentry to be properly freed we need to grab a - * reference to the dentry under the dcache lock, unhash it, - * and then put it. The playing with the dentry count allows - * dput to immediately free the dentry if it is not in use. - */ -repeat: - spin_lock(&dcache_lock); - list_for_each_entry(dentry, &inode->i_dentry, d_alias) { - if (d_unhashed(dentry)) - continue; - dget_locked(dentry); - spin_lock(&dentry->d_lock); - __d_drop(dentry); - spin_unlock(&dentry->d_lock); - spin_unlock(&dcache_lock); - dput(dentry); - goto repeat; - } - spin_unlock(&dcache_lock); - /* adjust nlink and update timestamp */ mutex_lock(&inode->i_mutex); @@ -611,7 +630,7 @@ void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt) acxt->removed = sd->s_sibling; sd->s_sibling = NULL; - sysfs_drop_dentry(sd); + sysfs_dec_nlink(sd); sysfs_deactivate(sd); unmap_bin_file(sd); sysfs_put(sd); -- 1.6.5.5 -- 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/