VOP_OPEN(9)	       FreeBSD Kernel Developer's Manual	   VOP_OPEN(9)

NAME
     VOP_OPEN, VOP_CLOSE -- open or close a file

SYNOPSIS
     #include <sys/param.h>
     #include <sys/vnode.h>

     int
     VOP_OPEN(struct vnode *vp, int mode, struct ucred *cred,

	 struct thread *td, struct file *fp);

     int
     VOP_CLOSE(struct vnode *vp, int mode, struct ucred *cred,

	 struct thread *td);

DESCRIPTION
     The VOP_OPEN() entry point is called before a file is accessed by a
     process and the VOP_CLOSE() entry point is called after a file is fin-
     ished with by the process.

     The arguments are:

     vp    The vnode of the file.

     mode  The access mode required by the calling process.

     td    The thread which is accessing the file.

     fp    The file being opened.

     Pointer to the file fp is useful for file systems which require such
     information, e.g., fdescfs(5).  Use `NULL' as fp argument to VOP_OPEN()
     for in-kernel opens.

     The access mode is a set of flags, including FREAD, FWRITE, O_NONBLOCK,
     O_APPEND.

LOCKS
     VOP_OPEN() expects vp to be locked on entry and will leave it locked on
     return.

     VOP_CLOSE() expects at least a reference to be associated with the vnode
     and does not care whether the vnode is locked or not.  The lock and ref-
     erence state is left unchanged on return.	Note that vn_close expects an
     unlocked, referenced vnode and will dereference the vnode prior to
     returning.

RETURN VALUES
     Zero is returned on success, otherwise an error code is returned.

PSEUDOCODE
     int
     vop_open(struct vnode *vp, int mode, struct ucred *cred, struct thread *td,

	 struct file *fp)
     {

	 /*
	  * Most file systems don't do much here.
	  */

	 return 0;
     }

SEE ALSO
     vnode(9), VOP_LOOKUP(9)

AUTHORS
     This manual page was written by Doug Rabson.

FreeBSD 7.2			 June 5, 2007			   FreeBSD 7.2

NAME - SYNOPSIS - DESCRIPTION - LOCKS - RETURN VALUES - PSEUDOCODE - 
SEE ALSO - AUTHORS -