Commit e1489b4f authored by Ioannis Angelakopoulos's avatar Ioannis Angelakopoulos Committed by David Sterba
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btrfs: add lockdep annotations for num_writers wait event 



Annotate the num_writers wait event in fs/btrfs/transaction.c with
lockdep in order to catch deadlocks involving this wait event.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarIoannis Angelakopoulos <iangelak@fb.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ab9a323f

fs/btrfs/ctree.h

+6 −0
Original line number Diff line number Diff line
@@ -1092,6 +1092,12 @@ struct btrfs_fs_info { 
	/* Updates are not protected by any lock */

	struct btrfs_commit_stats commit_stats;



	/*

	 * Annotations for transaction events (structures are empty when

	 * compiled without lockdep).

	 */

	struct lockdep_map btrfs_trans_num_writers_map;



#ifdef CONFIG_BTRFS_FS_REF_VERIFY

	spinlock_t ref_verify_lock;

	struct rb_root block_tree;

fs/btrfs/disk-io.c

+2 −0
Original line number Diff line number Diff line
@@ -2990,6 +2990,8 @@ void btrfs_init_fs_info(struct btrfs_fs_info *fs_info) 
	mutex_init(&fs_info->zoned_data_reloc_io_lock);

	seqlock_init(&fs_info->profiles_lock);



	btrfs_lockdep_init_map(fs_info, btrfs_trans_num_writers);



	INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots);

	INIT_LIST_HEAD(&fs_info->space_info);

	INIT_LIST_HEAD(&fs_info->tree_mod_seq_list);

fs/btrfs/transaction.c

+33 −5
Original line number Diff line number Diff line
@@ -313,6 +313,7 @@ static noinline int join_transaction(struct btrfs_fs_info *fs_info, 
		atomic_inc(&cur_trans->num_writers);

		extwriter_counter_inc(cur_trans, type);

		spin_unlock(&fs_info->trans_lock);

		btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);

		return 0;

	}

	spin_unlock(&fs_info->trans_lock);
@@ -334,16 +335,20 @@ static noinline int join_transaction(struct btrfs_fs_info *fs_info, 
	if (!cur_trans)

		return -ENOMEM;



	btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers);



	spin_lock(&fs_info->trans_lock);

	if (fs_info->running_transaction) {

		/*

		 * someone started a transaction after we unlocked.  Make sure

		 * to redo the checks above

		 */

		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);

		kfree(cur_trans);

		goto loop;

	} else if (BTRFS_FS_ERROR(fs_info)) {

		spin_unlock(&fs_info->trans_lock);

		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);

		kfree(cur_trans);

		return -EROFS;

	}
@@ -1022,6 +1027,9 @@ static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, 
	extwriter_counter_dec(cur_trans, trans->type);



	cond_wake_up(&cur_trans->writer_wait);



	btrfs_lockdep_release(info, btrfs_trans_num_writers);



	btrfs_put_transaction(cur_trans);



	if (current->journal_info == trans)
@@ -1994,6 +2002,12 @@ static void cleanup_transaction(struct btrfs_trans_handle *trans, int err) 
	if (cur_trans == fs_info->running_transaction) {

		cur_trans->state = TRANS_STATE_COMMIT_DOING;

		spin_unlock(&fs_info->trans_lock);



		/*

		 * The thread has already released the lockdep map as reader

		 * already in btrfs_commit_transaction().

		 */

		btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);

		wait_event(cur_trans->writer_wait,

			   atomic_read(&cur_trans->num_writers) == 1);
@@ -2222,7 +2236,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 


			btrfs_put_transaction(prev_trans);

			if (ret)

				goto cleanup_transaction;

				goto lockdep_release;

		} else {

			spin_unlock(&fs_info->trans_lock);

		}
@@ -2236,7 +2250,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 
		 */

		if (BTRFS_FS_ERROR(fs_info)) {

			ret = -EROFS;

			goto cleanup_transaction;

			goto lockdep_release;

		}

	}
@@ -2250,19 +2264,21 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 


	ret = btrfs_start_delalloc_flush(fs_info);

	if (ret)

		goto cleanup_transaction;

		goto lockdep_release;



	ret = btrfs_run_delayed_items(trans);

	if (ret)

		goto cleanup_transaction;

		goto lockdep_release;



	wait_event(cur_trans->writer_wait,

		   extwriter_counter_read(cur_trans) == 0);



	/* some pending stuffs might be added after the previous flush. */

	ret = btrfs_run_delayed_items(trans);

	if (ret)

	if (ret) {

		btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);

		goto cleanup_transaction;

	}



	btrfs_wait_delalloc_flush(fs_info);
@@ -2284,6 +2300,14 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 
	add_pending_snapshot(trans);

	cur_trans->state = TRANS_STATE_COMMIT_DOING;

	spin_unlock(&fs_info->trans_lock);



	/*

	 * The thread has started/joined the transaction thus it holds the

	 * lockdep map as a reader. It has to release it before acquiring the

	 * lockdep map as a writer.

	 */

	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);

	btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers);

	wait_event(cur_trans->writer_wait,

		   atomic_read(&cur_trans->num_writers) == 1);
@@ -2515,6 +2539,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans) 
	cleanup_transaction(trans, ret);



	return ret;



lockdep_release:

	btrfs_lockdep_release(fs_info, btrfs_trans_num_writers);

	goto cleanup_transaction;

}



/*