fs: dcache scale d_unhashed

Protect d_unhashed(dentry) condition with d_lock. This means keeping
DCACHE_UNHASHED bit in synch with hash manipulations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index da6061a..e58b4c3 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -121,6 +121,7 @@
 	struct config_item * item = NULL;
 
 	spin_lock(&dcache_lock);
+	spin_lock(&dentry->d_lock);
 	if (!d_unhashed(dentry)) {
 		struct configfs_dirent * sd = dentry->d_fsdata;
 		if (sd->s_type & CONFIGFS_ITEM_LINK) {
@@ -129,6 +130,7 @@
 		} else
 			item = config_item_get(sd->s_element);
 	}
+	spin_unlock(&dentry->d_lock);
 	spin_unlock(&dcache_lock);
 
 	return item;