linux-kernel - [RFC PATCH 08/11] autofs4 - eliminate d

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Message-ID: <20090924082212.22151.76953.stgit@zeus.themaw.net>
Date:	Thu, 24 Sep 2009 16:22:12 +0800
From:	Ian Kent <raven@...maw.net>
To:	Sage Weil <sage@...dream.net>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Al Viro <viro@...IV.linux.org.uk>,
	Christoph Hellwig <hch@...radead.org>,
	Andreas Dilger <adilger@....com>,
	Yehuda Saheh <yehuda@...dream.net>,
	Jim Garlick <garlick@...l.gov>
Subject: [RFC PATCH 08/11] autofs4 - eliminate d_unhashed in path walk checks

We unhash the dentry (in a subsequent patch) in ->d_revalidate() in
order to send mount requests to ->lookup(). But then we can not rely
on d_unhased() to give reliable results because it may be called at
any time by any code path. The d_unhashed() function is used by
__simple_empty() in the path walking callbacks but autofs mount
point dentrys should have no directories at all so a list_empty()
on d_subdirs should be (and is) sufficient.

Signed-off-by: Ian Kent <raven@...maw.net>
---

 fs/autofs4/root.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 81700f4..b6530f3 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -133,7 +133,7 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
 	 * it.
 	 */
 	spin_lock(&dcache_lock);
-	if (!d_mountpoint(dentry) && __simple_empty(dentry)) {
+	if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
 		spin_unlock(&dcache_lock);
 		return -ENOENT;
 	}
@@ -257,7 +257,7 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
 	 * mount it again.
 	 */
 	if (ino->flags & AUTOFS_INF_PENDING ||
-	    (!d_mountpoint(dentry) && __simple_empty(dentry))) {
+	    (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs))) {
 		spin_unlock(&dcache_lock);
 		spin_unlock(&sbi->fs_lock);
 
@@ -340,8 +340,7 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 	/* Check for a non-mountpoint directory with no contents */
 	spin_lock(&dcache_lock);
 	if (S_ISDIR(dentry->d_inode->i_mode) &&
-	    !d_mountpoint(dentry) && 
-	    __simple_empty(dentry)) {
+	    !d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
 		DPRINTK("dentry=%p %.*s, emptydir",
 			 dentry, dentry->d_name.len, dentry->d_name.name);
 		spin_unlock(&dcache_lock);

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