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g_attach.9freebsd
Langue: en
Version: 309498 (debian - 07/07/09)
Section: 9 (Appels noyau Linux)
BSD mandoc
NAME
g_attach g_detach - attach/detach GEOM consumers to/from providersSYNOPSIS
In geom/geom.h Ft int Fn g_attach struct g_consumer *cp struct g_provider *pp Ft void Fn g_detach struct g_consumer *cpDESCRIPTION
The Fn g_attach function attaches given consumer Fa cp to given provider Fa pp , thus establishing a communication channel between the consumer and the provider that allows to change access counts and perform I/O operations.The Fn g_detach function detaches given consumer Fa cp from its corresponding provider, tearing down the communication channel between them.
RESTRICTIONS/CONDITIONS
Fn g_attach :- The consumer must not be attached to a provider.
- The operation must not create a topology loop.
- The topology lock has to be held.
Fn g_detach :
- The consumer has to be attached.
- The access count has to be 0.
- There must be no active requests.
- The topology lock has to be held.
RETURN VALUES
The Fn g_attach function returns 0 if successful; otherwise an error code is returned.EXAMPLES
Create a consumer, attach it to a 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); }
ERRORS
Possible errors:- Bq Er ELOOP
- The operation creates a topology loop.
SEE ALSO
geom(4), DECLARE_GEOM_CLASS9, g_access9, g_bio9, g_consumer9, g_data9, g_event9, g_geom9, g_provider9, g_provider_by_name9, g_wither_geom9AUTHORS
An -nosplit This manual page was written by An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .Contenus ©2006-2024 Benjamin Poulain
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