DECLARE_GEOM_CLASS —
GEOM class declaration macro
#include
<geom/geom.h>
DECLARE_GEOM_CLASS(
class,
mod_name);
The
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.
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
DECLARE_GEOM_CLASS() are:
- class
- The g_class structure
which describes a GEOM class.
- mod_name
- A kernel module name (not a class name!).
Structure
g_class contains data describing the
class. They are:
-
const char *
name
- Class name.
-
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).
-
g_config_t *
config
- This field is not used anymore, its functionality was
replaced by the ctlreq field.
-
g_ctl_req_t *
ctlreq
- Pointer to function used for handling events from userland
applications.
-
g_init_t *
init
- Pointer to function which is called right after class
registration.
-
g_fini_t *
fini
- Pointer to function which is called right before class
deregistration.
-
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
name field is required; the rest are
optional.
The fields of
g_class should always be
initialized using C99-style field naming (see the initialization of
example_class below).
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);
geom(4),
g_attach(9),
g_bio(9),
g_consumer(9),
g_data(9),
g_event(9),
g_geom(9),
g_provider(9),
g_provider_by_name(9),
g_wither_geom(9)
This manual page was written by
Pawel Jakub
Dawidek
<
[email protected]>.