[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>

1 files changed, 7 insertions, 10 deletions

diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 7a8db78a91d2..8e93341f3e82 100644
--- 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);