[PATCH] configfs: Consolidate locking around configfs_detach_prep() in configfs_rmdir()

It appears that configfs_rmdir() can protect configfs_detach_prep() retries with
less calls to {spin,mutex}_{lock,unlock}, and a cleaner code.

This patch does not change any behavior, except that it removes two useless
lock/unlock pairs having nothing inside to protect and providing a useless
barrier.

Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Joel Becker <Joel.Becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 7a8db78..8e93341 100644 (file)
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -1311,16 +1311,18 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
         * Ensure that no racing symlink() will make detach_prep() fail while
         * the new link is temporarily attached
         */
-       mutex_lock(&configfs_symlink_mutex);
-       spin_lock(&configfs_dirent_lock);
        do {
                struct mutex *wait_mutex;
 
+               mutex_lock(&configfs_symlink_mutex);
+               spin_lock(&configfs_dirent_lock);
                ret = configfs_detach_prep(dentry, &wait_mutex);
-               if (ret) {
+               if (ret)
                        configfs_detach_rollback(dentry);
-                       spin_unlock(&configfs_dirent_lock);
-                       mutex_unlock(&configfs_symlink_mutex);
+               spin_unlock(&configfs_dirent_lock);
+               mutex_unlock(&configfs_symlink_mutex);
+
+               if (ret) {
                        if (ret != -EAGAIN) {
                                config_item_put(parent_item);
                                return ret;
@@ -1329,13 +1331,8 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
                        /* Wait until the racing operation terminates */
                        mutex_lock(wait_mutex);
                        mutex_unlock(wait_mutex);
-
-                       mutex_lock(&configfs_symlink_mutex);
-                       spin_lock(&configfs_dirent_lock);
                }
        } while (ret == -EAGAIN);
-       spin_unlock(&configfs_dirent_lock);
-       mutex_unlock(&configfs_symlink_mutex);
 
        /* Get a working ref for the duration of this function */
        item = configfs_get_config_item(dentry);