Merge tag 'for-5.4-rc7-tag' of git://git.kernel.org/pub/scm/linux/ker…

…nel/git/kdave/linux

Pull btrfs fix from David Sterba:
 "A fix for an older bug that has started to show up during testing
  (because of an updated test for rename exchange).

  It's an in-memory corruption caused by local variable leaking out of
  the function scope"

* tag 'for-5.4-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  Btrfs: fix log context list corruption after rename exchange operation

fs/btrfs/inode.c

@@ -9744,6 +9744,18 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 			commit_transaction = true;
 	}
 	if (commit_transaction) {
+		/*
+		 * We may have set commit_transaction when logging the new name
+		 * in the destination root, in which case we left the source
+		 * root context in the list of log contextes. So make sure we
+		 * remove it to avoid invalid memory accesses, since the context
+		 * was allocated in our stack frame.
+		 */
+		if (sync_log_root) {
+			mutex_lock(&root->log_mutex);
+			list_del_init(&ctx_root.list);
+			mutex_unlock(&root->log_mutex);
+		}
 		ret = btrfs_commit_transaction(trans);
 	} else {
 		int ret2;
@@ -9757,6 +9769,9 @@ static int btrfs_rename_exchange(struct inode *old_dir,
 	if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
 		up_read(&fs_info->subvol_sem);
 
+	ASSERT(list_empty(&ctx_root.list));
+	ASSERT(list_empty(&ctx_dest.list));
+
 	return ret;
 }