Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull VFS fixes and cleanups from Al Viro.

Most of this is the series to remove sync_supers() and the
->write_supers VFS callback from Artem Bityutskiy.  One commit to do the
actual removal work, a whole series of commits to fix up stale comments
etc all over the tree.

There's also a regression fix for an incorrect use of mnt_drop_write()
in do_dentry_open().

* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  missed mnt_drop_write() in do_dentry_open()
  UBIFS: nuke pdflush from comments
  gfs2: nuke pdflush from comments
  drbd: nuke pdflush from comments
  nilfs2: nuke write_super from comments
  hfs: nuke write_super from comments
  vfs: nuke pdflush from comments
  jbd/jbd2: nuke write_super from comments
  btrfs: nuke pdflush from comments
  btrfs: nuke write_super from comments
  ext4: nuke pdflush from comments
  ext4: nuke write_super from comments
  ext3: nuke write_super from comments
  Documentation: fix the VM knobs descritpion WRT pdflush
  Documentation: get rid of write_super
  vfs: kill write_super and sync_supers