DECLARE_GEOM_CLASS (9)
Leading comments
Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the d...
NAME
DECLARE_GEOM_CLASS - GEOM class declaration macroSYNOPSIS
In geom/geom.h Fn DECLARE_GEOM_CLASS class mod_nameDESCRIPTION
The Fn DECLARE_GEOM_CLASS macro registers a GEOM class in GEOM. A GEOM class itself implements one particular kind of transformation. Typical examples are: MBR disk partition, BSD disklabel and RAID5 classes. Fn DECLARE_GEOM_CLASS can be used both for compiled in and loaded as kld(4) modules GEOM classes and it is the only official way for class registration.The arguments to Fn DECLARE_GEOM_CLASS are:
- Fa class
- The Vt g_class structure which describes a GEOM class.
- Fa mod_name
- A kernel module name (not a class name!).
Structure Vt g_class contains data describing the class. They are:
- Vt const char * name
- Class name.
- Vt g_taste_t * taste
-
Pointer to function used for taste event handling.
If it is
non- NULL
it is called in three situations:
- On class activation, all existing providers are offered for tasting.
- When new provider is created it is offered for tasting.
- After last write access to a provider is closed it is offered for retasting
- (on first write open event ``spoil'' was sent).
- Vt g_config_t * config
- This field is not used anymore, its functionality was replaced by the ctlreq field.
- Vt g_ctl_req_t * ctlreq
- Pointer to function used for handling events from userland applications.
- Vt g_init_t * init
- Pointer to function which is called right after class registration.
- Vt g_fini_t * fini
- Pointer to function which is called right before class deregistration.
- Vt g_ctl_destroy_geom_t * destroy_geom
- Pointer to a function which is called for every geom on class unload. If this field is not set, the class can not be unloaded.
Only a Fa name field is required; the rest are optional.
RESTRICTIONS/CONDITIONS
The fields of Vt g_class should always be initialized using C99-style field naming (see the initialization of example_class below).EXAMPLES
Example class declaration.
static struct g_geom *
g_example_taste(struct g_class *mp, struct g_provider *pp,
int flags __unused)
{
g_topology_assert();
[...]
}
static void
g_example_ctlreq(struct gctl_req *req, struct g_class *cp,
char const *verb)
{
[...]
}
static int
g_example_destroy_geom(struct gctl_req *req, struct g_class *cp,
struct g_geom *gp)
{
g_topology_assert();
[...]
}
static void
g_example_init(struct g_class *mp)
{
[...]
}
static void
g_example_fini(struct g_class *mp)
{
[...]
}
struct g_class example_class = {
.name = "EXAMPLE",
.taste = g_example_taste,
.ctlreq = g_example_ctlreq,
.init = g_example_init,
.fini = g_example_fini,
.destroy_geom = g_example_destroy_geom
};
DECLARE_GEOM_CLASS(example_class, g_example);