Manual Pages  — VOP_ATTRIB

VOP_STAT() returns data in a format suitable for the stat(2) system call and by default is implemented as a wrapper around VOP_GETATTR(). Filesystems may want to implement their own variant for performance reasons.

For VOP_GETATTR() and VOP_SETATTR() the arguments are:

vp
	The vnode of the file.
vap
	The attributes of the file.
cred
	The user credentials of the calling thread.

For VOP_STAT() the arguments are:

vp
	The vnode of the file.
sb
	The attributes of the file.
active_cred
	The user credentials of the calling thread.
file_cred
	The credentials installed on the file description pointing to the vnode or NOCRED.
td
	The calling thread.

Attributes which are not being modified by VOP_SETATTR() should be set to the value VNOVAL; VATTR_NULL() may be used to clear all the values, and should generally be used to reset the contents of *vap prior to setting specific values.