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G_PROVIDER(9)	       FreeBSD Kernel Developer's Manual	 G_PROVIDER(9)

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, sector-
     size 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>.

FreeBSD	10.1		       January 16, 2004			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | RESTRICTIONS/CONDITIONS | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHORS

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