fs: provide rcu-walk aware permission i_ops

Documentation/filesystems/Locking

Documentation/filesystems/path-lookup.txt

Documentation/filesystems/porting

Documentation/filesystems/vfs.txt

drivers/staging/smbfs/file.c

fs/9p/acl.c

fs/9p/acl.h

fs/afs/internal.h

fs/afs/security.c

fs/bad_inode.c

fs/btrfs/acl.c

fs/btrfs/ctree.h

fs/btrfs/inode.c

fs/ceph/inode.c

fs/ceph/super.h

fs/cifs/cifsfs.c

fs/coda/dir.c

fs/coda/pioctl.c

fs/ecryptfs/inode.c

fs/ext2/acl.c