From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757324AbZEUAaI (ORCPT ); Wed, 20 May 2009 20:30:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755785AbZEUA2b (ORCPT ); Wed, 20 May 2009 20:28:31 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:46321 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753900AbZEUA2R (ORCPT ); Wed, 20 May 2009 20:28:17 -0400 From: "Eric W. Biederman" To: Andrew Morton , Greg Kroah-Hartman Cc: , Tejun Heo , Cornelia Huck , , "Eric W. Biederman" , "Eric W. Biederman" Subject: [PATCH 06/20] sysfs: Use dentry_ops instead of directly playing with the dcache Date: Wed, 20 May 2009 17:28:00 -0700 Message-Id: <1242865694-2100-6-git-send-email-ebiederm@xmission.com> X-Mailer: git-send-email 1.6.1.2.350.g88cc In-Reply-To: <1242865694-2100-5-git-send-email-ebiederm@xmission.com> References: <1242865694-2100-1-git-send-email-ebiederm@xmission.com> <1242865694-2100-2-git-send-email-ebiederm@xmission.com> <1242865694-2100-3-git-send-email-ebiederm@xmission.com> <1242865694-2100-4-git-send-email-ebiederm@xmission.com> <1242865694-2100-5-git-send-email-ebiederm@xmission.com> X-XM-SPF: eid=;;;mid=;;;hst=in02.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: akpm@linux-foundation.org, gregkh@suse.de, linux-kernel@vger.kernel.org, tj@kernel.org, cornelia.huck@de.ibm.com, linux-fsdevel@vger.kernel.org, ebiederm@xmission.com, ebiederm@aristanetworks.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Version: 4.2.1 (built Thu, 25 Oct 2007 00:26:12 +0000) X-SA-Exim-Scanned: No (on in02.mta.xmission.com); Unknown failure Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Signed-off-by: Eric W. Biederman --- 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 01b1e40..8dd2abf 100644 --- a/fs/sysfs/dir.c +++ b/fs/sysfs/dir.c @@ -294,6 +294,46 @@ 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; @@ -303,6 +343,8 @@ 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, }; @@ -493,44 +535,21 @@ 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); @@ -577,7 +596,7 @@ 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); -- 1.6.1.2.350.g88cc