autofs_clear_leaf_automount_flags(): use ino->count instead of ->d_subdirs

We want to find out if the parent will become empty after we remove
the victim of rmdir().  Checking if the victim is the only element
of parent's ->d_subdirs is completely wrong - e.g. opening the parent
will end up with a cursor added to its ->d_parent and fooling the
check.

We do maintain ino->count - 0 for anything removed, 1 + number of
children for anything live.  Which gives us precisely what we need
for that check...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/autofs/root.c b/fs/autofs/root.c
index 29abafc..2065281 100644 (file)
--- a/fs/autofs/root.c
+++ b/fs/autofs/root.c
@@ -660,7 +660,6 @@ static void autofs_set_leaf_automount_flags(struct dentry *dentry)
 
 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 */
@@ -673,10 +672,7 @@ static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
        /* only consider parents below dentrys in the root */
        if (IS_ROOT(parent->d_parent))
                return;
-       d_child = &dentry->d_child;
-       /* Set parent managed if it's becoming empty */
-       if (d_child->next == &parent->d_subdirs &&
-           d_child->prev == &parent->d_subdirs)
+       if (atomic_read(&autofs_dentry_ino(parent)->count) == 2)
                managed_dentry_set_managed(parent);
 }