Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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$FreeBSD: head/share/man/man9/g_provider.9 125699 2004-02-11 10:06:18Z pjd $
.Dd January 16, 2004 .Dt g_provider 9 .Os .Sh NAME .Nm g_new_providerf , .Nm g_destroy_provider , .Nm g_error_provider .Nd "GEOM providers management" .Sh SYNOPSIS n geom/geom.h .Ft "struct g_provider *" .Fn g_new_providerf "struct g_geom *gp" "const char *fmt" ... .Ft void .Fn g_destroy_provider "struct g_provider *pp" .Ft void .Fn g_error_provider "struct g_provider *pp" "int error" .Sh DESCRIPTION The GEOM provider is the front gate at which a geom offers service. A provider is .Dq a disk-like thing which appears in Pa /dev - a logical disk in other words. All providers have three main properties: name, sectorsize and size.
p The .Fn g_new_providerf function creates a new provider and attaches it to geom .Fa gp . The provider name is created in a printf-like way from the rest of the arguments. After creation, the provider is unusable, because .Fn g_new_providerf sets its error to .Er ENXIO . The function .Fn g_error_provider should be used to reset this error, but before it is called, two fields should be set in the provider structure: .Va mediasize and .Va sectorsize as well as other initialization things should be done first.
p The .Fn g_destroy_provider function destroys the given provider, cancels all related pending events and removes corresponding devfs entry.
p The .Fn g_error_provider function is used to set a provider error value. If it set to a nonzero value, all I/O requests will be denied, increasing its access count will not be possible (error .Fa error will be returned). .Sh RESTRICTIONS/CONDITIONS .Fn g_new_provider : l -item -offset indent t 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 programmer error. t The geom related to the created provider must have .Fa start field defined. t The topology lock has to be held. .El
p .Fn g_destroy_provider : l -item -offset indent t No consumers have to be attached. t The access count has to be 0. t The topology lock has to be held. .El .Sh RETURN VALUES .Fn g_new_providerf returns a pointer to the newly created provider or .Dv NULL if an error occured. .Sh EXAMPLES Create an example provider, set its parameters and make it usable. d -literal -offset indent 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(); if (pp != NULL) { pp->mediasize = 65536; pp->sectorsize = 512; g_error_provider(pp, 0); } return (pp); } .Ed .Sh SEE ALSO .Xr DECLARE_GEOM_CLASS 9 , .Xr geom 4 , .Xr g_attach 9 , .Xr g_bio 9 , .Xr g_consumer 9 , .Xr g_data 9 , .Xr g_event 9 , .Xr g_geom 9 , .Xr g_provider_by_name 9 , .Xr g_wither_geom 9 .Sh AUTHORS .An -nosplit This manual page was written by .An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .