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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
     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.

     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
     reference 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.