g_geom.9freebsd

Langue: en

Version: 308182 (debian - 07/07/09)

Section: 9 (Appels noyau Linux)


BSD mandoc

NAME

g_new_geomf g_destroy_geom - geom management

SYNOPSIS

In geom/geom.h Ft struct g_geom * Fn g_new_geomf struct g_class *mp const char *fmt ... Ft void Fn g_destroy_geom struct g_geom *gp

DESCRIPTION

The geom (do not confuse ``geom'' with ``GEOM'' is an instance of a GEOM class. For example: in a typical i386 Fx system, there will be one geom of class MBR for each disk. The geom's name is not really important, it is only used in the XML dump and for debugging purposes. There can be many geoms with the same name.

The Fn g_new_geomf function creates a new geom, which will be an instance of the class Fa mp . The geom's name is created in a printf(3) -like way from the rest of the arguments.

The Fn g_destroy_geom function destroys the given geom immediately and cancels all related pending events.

The Vt g_geom structure contains fields that should be set by the caller after geom creation, but before creating any providers or consumers related to this geom (not all are required):

Vt g_start_t * start
Pointer to a function used for I/O processing.
Vt g_spoiled_t * spoiled
Pointer to a function used for consumers spoiling.
Vt g_dumpconf_t * dumpconf
Pointer to a function used for configuration in XML format dumping.
Vt g_access_t * access
Pointer to a function used for access control.
Vt g_orphan_t * orphan
Pointer to a function used to inform about orphaned consumer.
Vt g_ioctl_t * ioctl
Pointer to a function used for handling ioctl requests.
Vt void * softc
Field for private use.

RESTRICTIONS/CONDITIONS

If you intend to use providers in this geom you must set field start of your geom.

If you are planning to use consumers in your geom you must set fields orphan and access for it.

Fn g_new_geomf :

Class
Fa mp must be valid (registered in GEOM).
The topology lock has to be held.

Fn g_destroy_geom :

The geom cannot posses any providers.
The geom cannot posses any consumers.
The topology lock has to be held.

RETURN VALUES

The Fn g_new_geomf function returns a pointer to the newly created geom.

EXAMPLES

Create an example geom.
 static struct geom *
 g_example_start(struct bio *bp)
 {
 
         [...]
 }
 
 static void
 g_example_orphan(struct g_consumer *cp)
 {
 
         g_topology_assert();
 
         [...]
 }
 
 static void
 g_example_spoiled(struct g_consumer *cp)
 {
 
         g_topology_assert();
 
         [...]
 }
 
 static void
 g_example_access(struct g_provider *pp, int dr, int dw, int de)
 {
 
         [...]
 }
 
 static struct g_geom *
 create_example_geom(struct g_class *myclass)
 {
         struct g_geom *gp;
 
         g_topology_lock();
         gp = g_new_geomf(myclass, "example_geom");
         g_topology_unlock();
         gp->start = g_example_start;
         gp->orphan = g_example_orphan;
         gp->spoiled = g_example_spoiled;
         gp->access = g_example_access;
         gp->softc = NULL;
 
         return (gp);
 }
 
 static int
 destroy_example_geom(struct g_geom *gp)
 {
 
         g_topology_lock();
         if (!LIST_EMPTY(&gp->provider) ||
             !LIST_EMPTY(&gp->consumer)) {
                 g_topology_unlock();
                 return (EBUSY);
         }
         g_destroy_geom(gp);
         g_topology_unlock();
 
         return (0);
 }
 

SEE ALSO

geom(4), DECLARE_GEOM_CLASS9, g_access9, g_attach9, g_bio9, g_consumer9, g_data9, g_event9, g_provider9, g_provider_by_name9, g_wither_geom9

AUTHORS

An -nosplit This manual page was written by An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .