->permission() sanitizing: document API changes

so the i_size should not change when hole punching, even when puching the end of

a file off.

--

[mandatory]

--

[mandatory]

	->get_sb() is gone.  Switch to use of ->mount().  Typically it's just

a matter of switching from calling get_sb_... to mount_... and changing the

function type.  If you were doing it manually, just switch from setting ->mnt_root

to some pointer to returning that pointer.  On errors return ERR_PTR(...).

--

[mandatory]

	->permission(), generic_permission() and ->check_acl() have lost flags

argument; instead of passing IPERM_FLAG_RCU we add MAY_NOT_BLOCK into mask.

	generic_permission() has also lost the check_acl argument; if you want

non-NULL to be used for that inode, put it into ->i_op->check_acl.