Merge branch 'writeback' of git://git.kernel.dk/linux-2.6-block

* 'writeback' of git://git.kernel.dk/linux-2.6-block:
  writeback: fix possible bdi writeback refcounting problem
  writeback: Fix bdi use after free in wb_work_complete()
  writeback: improve scalability of bdi writeback work queues
  writeback: remove smp_mb(), it's not needed with list_add_tail_rcu()
  writeback: use schedule_timeout_interruptible()
  writeback: add comments to bdi_work structure
  writeback: splice dirty inode entries to default bdi on bdi_destroy()
  writeback: separate starting of sync vs opportunistic writeback
  writeback: inline allocation failure handling in bdi_alloc_queue_work()
  writeback: use RCU to protect bdi_list
  writeback: only use bdi_writeback_all() for WB_SYNC_NONE writeout
  fs: Assign bdi in super_block
  writeback: make wb_writeback() take an argument structure
  writeback: merely wakeup flusher thread if work allocation fails for WB_SYNC_NONE
  writeback: get rid of wbc->for_writepages
  fs: remove bdev->bd_inode_backing_dev_info