autofs4: eliminate d_unhashed in path walk checks
Ian Kent [Wed, 16 Dec 2009 00:45:48 +0000 (16:45 -0800)]
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@themaw.net>
Cc: Sage Weil <sage@newdream.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andreas Dilger <adilger@sun.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Yehuda Saheh <yehuda@newdream.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/autofs4/root.c

index 81700f4..b6530f3 100644 (file)
@@ -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);