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.Dd January 16, 2004 26.Dt G_CONSUMER 9 27.Os 28.Sh NAME 29.Nm g_new_consumer , 30.Nm g_destroy_consumer 31.Nd "GEOM consumers management" 32.Sh SYNOPSIS 33.In geom/geom.h 34.Ft "struct g_consumer *" 35.Fn g_new_consumer "struct g_geom *gp" 36.Ft void 37.Fn g_destroy_consumer "struct g_consumer *cp" 38.Sh DESCRIPTION 39A GEOM consumer is the backdoor through which a geom connects to 40another GEOM provider and through which I/O requests are sent. 41.Pp 42The 43.Fn g_new_consumer 44function creates a new consumer on geom 45.Fa gp . 46Before using the new consumer, it has to be attached to a provider with 47.Xr g_attach 9 48and opened with 49.Xr g_access 9 . 50.Pp 51The 52.Fn g_destroy_consumer 53function destroys the given consumer and cancels all related pending events. 54This function is the last stage of killing an unwanted consumer. 55.Sh RESTRICTIONS/CONDITIONS 56.Fn g_new_consumer : 57.Bl -item -offset indent 58.It 59The geom 60.Fa gp 61has to have an 62.Va orphan 63method defined. 64.It 65The topology lock has to be held. 66.El 67.Pp 68.Fn g_destroy_consumer : 69.Bl -item -offset indent 70.It 71The consumer must not be attached to a provider. 72.It 73The access count has to be 0. 74.It 75The topology lock has to be held. 76.El 77.Sh RETURN VALUES 78The 79.Fn g_new_consumer 80function 81returns a pointer to the newly created consumer. 82.Sh EXAMPLES 83Create consumer, attach it to given provider, gain read access and clean up. 84.Bd -literal -offset indent 85void 86some_function(struct g_geom *mygeom, struct g_provider *pp) 87{ 88 struct g_consumer *cp; 89 90 g_topology_assert(); 91 92 /* Create new consumer on 'mygeom' geom. */ 93 cp = g_new_consumer(mygeom); 94 /* Attach newly created consumer to given provider. */ 95 if (g_attach(cp, pp) != 0) { 96 g_destroy_consumer(cp); 97 return; 98 } 99 /* Open provider for reading through our consumer. */ 100 if (g_access(cp, 1, 0, 0) != 0) { 101 g_detach(cp); 102 g_destroy_consumer(cp); 103 return; 104 } 105 106 g_topology_unlock(); 107 /* 108 * Read data from provider. 109 */ 110 g_topology_lock(); 111 112 /* Disconnect from provider (release access count). */ 113 g_access(cp, -1, 0, 0); 114 /* Detach from provider. */ 115 g_detach(cp); 116 /* Destroy consumer. */ 117 g_destroy_consumer(cp); 118} 119.Ed 120.Sh SEE ALSO 121.Xr geom 4 , 122.Xr DECLARE_GEOM_CLASS 9 , 123.Xr g_access 9 , 124.Xr g_attach 9 , 125.Xr g_bio 9 , 126.Xr g_data 9 , 127.Xr g_event 9 , 128.Xr g_geom 9 , 129.Xr g_provider 9 , 130.Xr g_provider_by_name 9 , 131.Xr g_wither_geom 9 132.Sh AUTHORS 133.An -nosplit 134This manual page was written by 135.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org . 136