The XFS pull request for Linux 3.9 reads, "Please pull these XFS updates for 3.9-rc1. Here there are primarily fixes for regressions and bugs, but there are a few cleanups too. There are fixes for compound buffers, quota asserts, dir v2 block compaction, mount behavior, use-after-free with AIO, swap extents, an unmount hang, speculative preallocation, write verifiers, the allocator stack switch, recursion on xa_lock, an xfs_buf_find oops, and a memory barrier in xfs_ifunlock."
There isn't anything too compelling in pouring over the individual changes making up the XFS file-system pull request for Linux 3.9, but for those using this file-system it looks to improve the stability and reliability.
For those that missed it there are XFS file-system benchmarks within F2FS File-System Shows Hope, Runs Against Btrfs & EXT4. There will surely be new benchmarks of XFS on Linux 3.9 when the time comes.