Commit 59b0713a authored Nov 09, 2018 by Filipe Manana Committed by David Sterba Dec 17, 2018

Btrfs: simpler and more efficient cleanup of a log tree's extent io tree



We currently are in a loop finding each range (corresponding to a btree
node/leaf) in a log root's extent io tree and then clean it up. This is a
waste of time since we are traversing the extent io tree's rb_tree more
times then needed (one for a range lookup and another for cleaning it up)
without any good reason.

We free the log trees when we are in the critical section of a transaction
commit (the transaction state is set to TRANS_STATE_COMMIT_DOING), so it's
of great convenience to do everything as fast as possible in order to
reduce the time we block other tasks from starting a new transaction.

So fix this by traversing the extent io tree once and cleaning up all its
records in one go while traversing it.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 46cc775e

fs/btrfs/tree-log.c

+2 −14

Original line number	Diff line number	Diff line
		@@ -3201,8 +3201,6 @@ static void free_log_tree(struct btrfs_trans_handle *trans,
		struct btrfs_root *log)
		{
		int ret;
		u64 start;
		u64 end;
		struct walk_control wc = {
		.free = 1,
		.process_func = process_one_buffer
		@@ -3216,18 +3214,8 @@ static void free_log_tree(struct btrfs_trans_handle *trans,
		btrfs_handle_fs_error(log->fs_info, ret, NULL);
		}

		while (1) {
		ret = find_first_extent_bit(&log->dirty_log_pages,
		0, &start, &end,
		EXTENT_DIRTY \| EXTENT_NEW \| EXTENT_NEED_WAIT,
		NULL);
		if (ret)
		break;

		clear_extent_bits(&log->dirty_log_pages, start, end,
		clear_extent_bits(&log->dirty_log_pages, 0, (u64)-1,
		EXTENT_DIRTY \| EXTENT_NEW \| EXTENT_NEED_WAIT);
		}

		free_extent_buffer(log->node);
		kfree(log);
		}