btrfs: don't clobber errors in add_remap_tree_entries()

btrfs: don't clobber errors in add_remap_tree_entries()

In add_remap_tree_entries(), we only process a certain number of entries
at a time, meaning we may need to loop.

But because we weren't checking the return value of btrfs_insert_empty_items()
within the loop, this meant that if the last iteration of the loop
succeeded but a previous iteration failed, we were erroneously returning
0.

Fix this by breaking the loop early if btrfs_insert_empty_items() fails.

Fixes: b56f35560b82 ("btrfs: handle setting up relocation of block group with remap-tree")
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>