NAME

       VOP_CREATEVOBJECT, VOP_DESTROYVOBJECT, VOP_GETVOBJECT — VM object interaction

SYNOPSIS

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

       int
       VOP_CREATEVOBJECT(struct vnode *vp, struct ucred *cred, struct thread *td);

       int
       VOP_DESTROYVOBJECT(struct vnode *vp);

       int
       VOP_GETVOBJECT(struct vnode *vp, struct vm_object **objpp);

DESCRIPTION

       These calls are used to control the association of a VM object with a particular vnode.

       The arguments specific to these functions are:

       vp     The vnode of the file.

       objpp  The  VM  object  being  returned,  or NULL if the caller wants to test for the existence of the VM
              object.

       VFS(9) invokes VOP_CREATEVOBJECT() when it needs to create a VM object  for  the  given  vnode(9).   File
       system  code  may  pass  this  call  down to the underlying file system.  This VOP can be called multiple
       times, and file system code should ignore any additional calls, exiting with a zero return code.

       VOP_DESTROYVOBJECT() is called when a vnode(9) is recycled.

       VOP_GETVOBJECT() should be used by all kernel code to get a VM object.  The returned VM object may belong
       to a different file system in the case of stacked mounts.

       VFS(9) has three functions which perform standard operations  by  creating  and  destroying  VM  objects.
       These functions are: vop_stdcreatevobject(), vop_stddestroyvobject() and vop_stdgetvobject().

       Note: a vnode(9) should be locked on entry and must be left locked on exit.

RETURN VALUES

       The VOP_CREATEVOBJECT(), VOP_DESTROYVOBJECT() and VOP_GETVOBJECT() functions return zero on success, or a
       non-zero value on failure.  Zero is returned on success, otherwise an error is returned.

EXAMPLES

       By default, file systems leave VM object handling to the vop_std*() functions.

SEE ALSO

       vnode(9), VOP_GETPAGES(9), VOP_PUTPAGES(9)

AUTHORS

       This manual page was written by Boris Popov.

Debian                                         September 10, 2000                           VOP_CREATEVOBJECT(9)