xfs: update for 4.1-rc1 This update contains: o RENAME_WHITEOUT support o conversion of per-cpu superblock accounting to use generic counters o new inode mmap lock so that we can lock page faults out of truncate, hole punch and other direct extent manipulation functions to avoid racing mmap writes from causing data corruption o rework of direct IO submission and completion to solve data corruption issue when running concurrent extending DIO writes. Also solves problem of running IO completion transactions in interrupt context during size extending AIO writes. o FALLOC_FL_INSERT_RANGE support for inserting holes into a file via direct extent manipulation to avoid needing to copy data within the file o attribute block header field overflow fix for 64k block size filesystems o Lots of changes to log messaging to be more informative and concise when errors occur. Also prevent a lot of unnecessary log spamming due to cascading failures in error conditions. o lots of cleanups and bug fixes