tux3: Add ->leaf_pre_write() callback to btree_write()

For overwrite mode, we don't want to dirty leaf if all extents are
exists already.

But, current btree_write() dirty leaf unconditionally. So, this adds
->leaf_pre_write() callback before dirty leaf.

With this, leaf operations can control whether leaf is dirtied or not.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
4 files changed