Changes since last update:
- fix various problems with the copy-on-write extent maps getting freed
  at the wrong time
- fix printk format specifier problems
- report zeroing operation outcomes instead of dropping them on the
  floor
- fix some crashes when dio operations partially fail
- fix a race condition between unwritten extent conversion & dio read
- fix some incorrect tests in the inode log item processing
- correct the delayed allocation space reservations on rmap filesystems
- fix some problems checking for dax support