Btrfs: snapshot-aware defrag
This comes from one of btrfs's project ideas, As we defragment files, we break any sharing from other snapshots. The balancing code will preserve the sharing, and defrag needs to grow this as well. Now we're able to fill the blank with this patch, in which we make full use of backref walking stuff. Here is the basic idea, o set the writeback ranges started by defragment with flag EXTENT_DEFRAG o at endio, after we finish updating fs tree, we use backref walking to find all parents of the ranges and re-link them with the new COWed file layout by adding corresponding backrefs. Signed-off-by:Li Zefan <lizf@cn.fujitsu.com> Signed-off-by:
Liu Bo <bo.li.liu@oracle.com> Signed-off-by:
Chris Mason <chris.mason@fusionio.com>
parent
86db2578
Please register or sign in to comment