ext4: add data structures for the extent status tree

This patch adds two structures that supports extent status tree, extent_status
and ext4_es_tree.  Currently extent_status is used to track a delay extent for
an inode, which record the start block and the length of the delay extent.
ext4_es_tree is used to store all extent_status for an inode in memory.

Signed-off-by: Yongqiang Yang <[email protected]>
Signed-off-by: Allison Henderson <[email protected]>
Signed-off-by: Zheng Liu <[email protected]>
Signed-off-by: "Theodore Ts'o" <[email protected]>
2 files changed