xfs: bug fixes for 3.15-rc2

Data corruption fixes:
- fix a bunch of delayed allocation state mismatches
- fix collapse/zero range bugs
- fix a direct IO block mapping bug @ EOF

Other fixes:
- fix a use after free on metadata IO error
- fix a use after free on IO error during unmount
- fix an incorrect error sign on direct IO write errors
- add missing O_TMPFILE inode security context initialisation