NAME¶
g_new_providerf
,
g_destroy_provider
,
g_error_provider
—
GEOM providers management
SYNOPSIS¶
#include
<geom/geom.h>
struct g_provider *
g_new_providerf
(
struct
g_geom *gp,
const char *fmt,
...);
void
g_destroy_provider
(
struct
g_provider *pp);
void
g_error_provider
(
struct
g_provider *pp,
int error);
DESCRIPTION¶
A GEOM provider is the front gate at which a geom offers service. A provider is
“a disk-like thing which appears in
/dev” – a logical disk in
other words. All providers have three main properties: name, sectorsize and
size.
The
g_new_providerf
() function creates a new
provider on given geom
gp. The name of the
provider, which will appear as device in
devfs(5), is created in a
printf(3)-like way from the rest of the
arguments. After creation, the caller has to set the provider's
mediasize and
sectorsize, as well as other desired
initializations, and then call
g_error_provider
() to reset the provider's
error, which is initially set to
ENXIO
.
The
g_destroy_provider
() function destroys
the given provider, cancels all related pending events and removes the
corresponding devfs entry.
The
g_error_provider
() function is used to
set the provider's error value. If set to a nonzero, all I/O requests will be
denied, as well as increasing its access count will not be possible (error
error will be returned).
RESTRICTIONS/CONDITIONS¶
g_new_provider
():
- The provider name should be unique, but this is not enforced by GEOM. If
the name is not unique, one will end up with two (or more) files with the
same name, which is a programmer error.
- The geom gp has to have a
start method defined.
- The topology lock has to be held.
g_destroy_provider
():
- The provider must not have consumers attached.
- The access count has to be 0.
- The topology lock has to be held.
RETURN VALUES¶
The
g_new_providerf
() function returns a
pointer to the newly created provider.
EXAMPLES¶
Create an example provider, set its parameters and make it usable.
struct g_provider *
create_example_provider(struct g_geom *gp)
{
struct g_provider *pp;
g_topology_lock();
pp = g_new_providerf(gp, "example_provider");
g_topology_unlock();
pp->mediasize = 65536;
pp->sectorsize = 512;
g_error_provider(pp, 0);
return (pp);
}
SEE ALSO¶
geom(4),
DECLARE_GEOM_CLASS(9),
g_access(9),
g_attach(9),
g_bio(9),
g_consumer(9),
g_data(9),
g_event(9),
g_geom(9),
g_provider_by_name(9),
g_wither_geom(9)
AUTHORS¶
This manual page was written by
Pawel Jakub
Dawidek ⟨pjd@FreeBSD.org⟩.