Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:24788 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755737Ab0I3SQs (ORCPT ); Thu, 30 Sep 2010 14:16:48 -0400 From: David Howells Subject: [PATCH 16/17] autofs4 - add v4 pseudo direct mount support To: viro@ftp.linux.org.uk, jmoyer@redhat.com Cc: linux-fs@vger.kernel.org, autofs@linux.kernel.org, linux-kernel@vger.kernel.org, linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Ian Kent , David Howells Date: Thu, 30 Sep 2010 19:16:17 +0100 Message-ID: <20100930181617.30939.37248.stgit@warthog.procyon.org.uk> In-Reply-To: <20100930181455.30939.53914.stgit@warthog.procyon.org.uk> References: <20100930181455.30939.53914.stgit@warthog.procyon.org.uk> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 From: Ian Kent Version 4 of autofs provides a pseudo direct mount implementation that relies on directories at the leaves of a directory tree under an indirect mount to trigger mounts. This patch adds support for that functionality. Signed-off-by: Ian Kent Signed-off-by: David Howells --- fs/autofs4/root.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 60 insertions(+), 0 deletions(-) diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 3b38794..135d713 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -629,6 +629,60 @@ static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry) return 0; } +/* + * Version 4 of autofs provides a pseudo direct mount implementation + * that relies on directories at the leaves of a directory tree under + * an indirect mount to trigger mounts. To allow for this we need to + * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves + * of the directory tree. There is no need to clear the automount flag + * following a mount or restore it after an expire because these mounts + * are always covered. However, it is neccessary to ensure that these + * flags are clear on non-empty directories to avoid unnecessary calls + * during path walks. + */ +static void autofs_set_leaf_automount_flags(struct dentry *dentry) +{ + struct dentry *parent; + + /* root and dentrys in the root are already handled */ + if (IS_ROOT(dentry->d_parent)) + return; + + managed_dentry_set_managed(dentry); + + parent = dentry->d_parent; + /* only consider parents below dentrys in the root */ + if (IS_ROOT(parent->d_parent)) + return; + managed_dentry_clear_managed(parent); + return; +} + +static void autofs_clear_leaf_automount_flags(struct dentry *dentry) +{ + struct list_head *d_child; + struct dentry *parent; + + /* flags for dentrys in the root are handled elsewhere */ + if (IS_ROOT(dentry->d_parent)) + return; + + managed_dentry_clear_managed(dentry); + + parent = dentry->d_parent; + /* only consider parents below dentrys in the root */ + if (IS_ROOT(parent->d_parent)) + return; + d_child = &dentry->d_u.d_child; + spin_lock(&dcache_lock); + /* Set parent managed if it's becoming empty */ + if (d_child->next == &parent->d_subdirs && + d_child->prev == &parent->d_subdirs) + managed_dentry_set_managed(parent); + spin_unlock(&dcache_lock); + return; +} + static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry) { struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb); @@ -652,6 +706,9 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry) spin_unlock(&dentry->d_lock); spin_unlock(&dcache_lock); + if (sbi->version < 5) + autofs_clear_leaf_automount_flags(dentry); + if (atomic_dec_and_test(&ino->count)) { p_ino = autofs4_dentry_ino(dentry->d_parent); if (p_ino && dentry->d_parent != dentry) @@ -694,6 +751,9 @@ static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode) } d_add(dentry, inode); + if (sbi->version < 5) + autofs_set_leaf_automount_flags(dentry); + dentry->d_fsdata = ino; ino->dentry = dget(dentry); atomic_inc(&ino->count);