tree 825efe2a79dbca8d61256183f3526a5b5dc40dc6
parent a1b32a5932cfac7c38b442582285f3da2a09dfd8
author Chris Mason <chris.mason@oracle.com> 1220645591 -0400
committer Chris Mason <chris.mason@oracle.com> 1222355047 -0400

Btrfs: Add a write ahead tree log to optimize synchronous operations

File syncs and directory syncs are optimized by copying their
items into a special (copy-on-write) log tree.  There is one log tree per
subvolume and the btrfs super block points to a tree of log tree roots.

After a crash, items are copied out of the log tree and back into the
subvolume.  See tree-log.c for all the details.

Signed-off-by: Chris Mason <chris.mason@oracle.com>