btrfs: reloc: use btrfs_backref_iter infrastructure

In the core function of relocation, build_backref_tree, it needs to
iterate all backref items of one tree block.

Use btrfs_backref_iter infrastructure to do the loop and make the code
more readable.

The backref items look would be much more easier to read:

	ret = btrfs_backref_iter_start(iter, cur->bytenr);
	for (; ret == 0; ret = btrfs_backref_iter_next(iter)) {
		/* The really important work */
	}

Reviewed-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>

0 files changed, 0 insertions, 0 deletions