VOP_CLOSE9

Usage

Overview

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 finished 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.

Additionally, VOP_OPEN() can accept a file descriptor number in fdidx; this is useful for file systems which require such information, e.g., fdescfs(5).

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 reference state is left unchanged on return. Note that vn_close expects an unlocked, referenced vnode and will dereference the vnode prior to returning.

Implementation notes

The fdidx argument to VOP_OPEN() is currently unused, use ‘-1’ for the meantime; however, this will change in future.

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)
{
    /*
     * Most file systems don't do much here.
     */
    return 0;
}