tree c339f2f4a59e403c7f9bfa8d137663c6bf260537
parent 31153d81284934601d08110ac7698fd9a535e4c0
author Chris Mason <chris.mason@oracle.com> 1217273571 -0400
committer Chris Mason <chris.mason@oracle.com> 1222355045 -0400

Btrfs: Leaf reference cache update

This changes the reference cache to make a single cache per root
instead of one cache per transaction, and to key by the byte number
of the disk block instead of the keys inside.

This makes it much less likely to have cache misses if a snapshot
or something has an extra reference on a higher node or a leaf while
the first transaction that added the leaf into the cache is dropping.

Some throttling is added to functions that free blocks heavily so they
wait for old transactions to drop.

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