1.\" 2.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd January 16, 2004 28.Dt G_CONSUMER 9 29.Os 30.Sh NAME 31.Nm g_new_consumer , 32.Nm g_destroy_consumer 33.Nd "GEOM consumers management" 34.Sh SYNOPSIS 35.In geom/geom.h 36.Ft "struct g_consumer *" 37.Fn g_new_consumer "struct g_geom *gp" 38.Ft void 39.Fn g_destroy_consumer "struct g_consumer *cp" 40.Sh DESCRIPTION 41A GEOM consumer is the backdoor through which a geom connects to 42another GEOM provider and through which I/O requests are sent. 43.Pp 44The 45.Fn g_new_consumer 46function creates a new consumer on geom 47.Fa gp . 48Before using the new consumer, it has to be attached to a provider with 49.Xr g_attach 9 50and opened with 51.Xr g_access 9 . 52.Pp 53The 54.Fn g_destroy_consumer 55function destroys the given consumer and cancels all related pending events. 56This function is the last stage of killing an unwanted consumer. 57.Sh RESTRICTIONS/CONDITIONS 58.Fn g_new_consumer : 59.Bl -item -offset indent 60.It 61The geom 62.Fa gp 63has to have an 64.Va orphan 65method defined. 66.It 67The topology lock has to be held. 68.El 69.Pp 70.Fn g_destroy_consumer : 71.Bl -item -offset indent 72.It 73The consumer must not be attached to a provider. 74.It 75The access count has to be 0. 76.It 77The topology lock has to be held. 78.El 79.Sh RETURN VALUES 80The 81.Fn g_new_consumer 82function 83returns a pointer to the newly created consumer. 84.Sh EXAMPLES 85Create consumer, attach it to given provider, gain read access and clean up. 86.Bd -literal -offset indent 87void 88some_function(struct g_geom *mygeom, struct g_provider *pp) 89{ 90 struct g_consumer *cp; 91 92 g_topology_assert(); 93 94 /* Create new consumer on 'mygeom' geom. */ 95 cp = g_new_consumer(mygeom); 96 /* Attach newly created consumer to given provider. */ 97 if (g_attach(cp, pp) != 0) { 98 g_destroy_consumer(cp); 99 return; 100 } 101 /* Open provider for reading through our consumer. */ 102 if (g_access(cp, 1, 0, 0) != 0) { 103 g_detach(cp); 104 g_destroy_consumer(cp); 105 return; 106 } 107 108 g_topology_unlock(); 109 /* 110 * Read data from provider. 111 */ 112 g_topology_lock(); 113 114 /* Disconnect from provider (release access count). */ 115 g_access(cp, -1, 0, 0); 116 /* Detach from provider. */ 117 g_detach(cp); 118 /* Destroy consumer. */ 119 g_destroy_consumer(cp); 120} 121.Ed 122.Sh SEE ALSO 123.Xr geom 4 , 124.Xr DECLARE_GEOM_CLASS 9 , 125.Xr g_access 9 , 126.Xr g_attach 9 , 127.Xr g_bio 9 , 128.Xr g_data 9 , 129.Xr g_event 9 , 130.Xr g_geom 9 , 131.Xr g_provider 9 , 132.Xr g_provider_by_name 9 , 133.Xr g_wither_geom 9 134.Sh AUTHORS 135.An -nosplit 136This manual page was written by 137.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org . 138