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G_CONSUMER(9FREEBSD) - man page online | system kernel interfaces

GEOM consumers management.

Chapter
January 16, 2004
G_CONSUMER(9)                     BSD Kernel Developer's Manual                     G_CONSUMER(9)

NAME g_new_consumer, g_destroy_consumer — GEOM consumers management
SYNOPSIS #include <geom/geom.h> struct g_consumer * g_new_consumer(struct g_geom *gp); void g_destroy_consumer(struct g_consumer *cp);
DESCRIPTION A GEOM consumer is the backdoor through which a geom connects to another GEOM provider and through which I/O requests are sent. The g_new_consumer() function creates a new consumer on geom gp. Before using the new con‐ sumer, it has to be attached to a provider with g_attach(9) and opened with g_access(9). The g_destroy_consumer() function destroys the given consumer and cancels all related pend‐ ing events. This function is the last stage of killing an unwanted consumer. RESTRICTIONS/CONDITIONS g_new_consumer(): The geom gp has to have an orphan method defined. The topology lock has to be held. g_destroy_consumer(): The consumer must not be attached to a provider. The access count has to be 0. The topology lock has to be held.
RETURN VALUES The g_new_consumer() function returns a pointer to the newly created consumer.
EXAMPLES Create consumer, attach it to given provider, gain read access and clean up. void some_function(struct g_geom *mygeom, struct g_provider *pp) { struct g_consumer *cp; g_topology_assert(); /* Create new consumer on 'mygeom' geom. */ cp = g_new_consumer(mygeom); /* Attach newly created consumer to given provider. */ if (g_attach(cp, pp) != 0) { g_destroy_consumer(cp); return; } /* Open provider for reading through our consumer. */ if (g_access(cp, 1, 0, 0) != 0) { g_detach(cp); g_destroy_consumer(cp); return; } g_topology_unlock(); /* * Read data from provider. */ g_topology_lock(); /* Disconnect from provider (release access count). */ g_access(cp, -1, 0, 0); /* Detach from provider. */ g_detach(cp); /* Destroy consumer. */ g_destroy_consumer(cp); }
SEE ALSO geom(4), DECLARE_GEOM_CLASS(9), g_access(9), g_attach(9), g_bio(9), g_data(9), g_event(9), g_geom(9), g_provider(9), g_provider_by_name(9), g_wither_geom(9)
AUTHORS This manual page was written by Pawel Jakub Dawidek <@FreeBSD.org>.
BSD January 16, 2004 BSD
This manual Reference Other manuals
g_consumer(9freebsd) referred by DECLARE_GEOM_CLASS(9freebsd) | g_access(9freebsd) | g_attach(9freebsd) | g_bio(9freebsd) | g_cancel_event(9freebsd) | g_clone_bio(9freebsd) | g_data(9freebsd) | g_destroy_bio(9freebsd) | g_destroy_consumer(9freebsd) | g_destroy_geom(9freebsd) | g_destroy_provider(9freebsd) | g_detach(9freebsd) | g_error_provider(9freebsd) | g_event(9freebsd) | g_geom(9freebsd) | g_new_bio(9freebsd) | g_new_consumer(9freebsd) | g_new_geomf(9freebsd) | g_new_providerf(9freebsd) | g_post_event(9freebsd)
refer to DECLARE_GEOM_CLASS(9freebsd) | g_access(9freebsd) | g_attach(9freebsd) | g_bio(9freebsd) | g_data(9freebsd) | g_event(9freebsd) | g_geom(9freebsd) | g_provider(9freebsd) | g_provider_by_name(9freebsd) | g_wither_geom(9freebsd)