xref: /freebsd/share/man/man9/g_geom.9 (revision acd546f01e58354af049455472980c6c4a52e18b)
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25.Dd April 24, 2016
26.Dt G_GEOM 9
27.Os
28.Sh NAME
29.Nm g_new_geomf ,
30.Nm g_new_geom ,
31.Nm g_destroy_geom
32.Nd "geom management"
33.Sh SYNOPSIS
34.In geom/geom.h
35.Ft "struct g_geom *"
36.Fn g_new_geomf "struct g_class *mp" "const char *fmt" ...
37.Ft "struct g_geom *"
38.Fn g_new_geom "struct g_class *mp" "const char *name"
39.Ft void
40.Fn g_destroy_geom "struct g_geom *gp"
41.Sh DESCRIPTION
42The geom (do not confuse
43.Dq geom
44with
45.Dq GEOM )
46is an instance of a GEOM class.
47For example: in a typical i386
48.Fx
49system, there will be one geom
50of class MBR for each disk.
51The geom's name is not really important, it is only used in the XML
52dump and for debugging purposes.
53There can be many geoms with the same name.
54.Pp
55The
56.Fn g_new_geomf
57function creates a new geom, which will be an instance of the class
58.Fa mp .
59The geom's name is created in a
60.Xr printf 3 Ns
61-like way from the rest of the arguments.
62.Pp
63The
64.Fn g_new_geom
65function is very similar to
66.Fn g_new_geomf
67except that it accepts a regular string instead of a
68.Xr printf 3 Ns
69-like format strng as the geom's name.
70.Pp
71The
72.Fn g_destroy_geom
73function destroys the given geom immediately and cancels all related pending
74events.
75.Pp
76The
77.Vt g_geom
78structure
79contains fields that should be set by the caller after geom creation, but before
80creating any providers or consumers related to this geom (not all are required):
81.Bl -tag -offset indent -width indent
82.It Vt "g_start_t *" Va start
83Pointer to a function used for I/O processing.
84.It Vt "g_spoiled_t *" Va spoiled
85Pointer to a function used for consumers spoiling.
86.It Vt "g_dumpconf_t *" Va dumpconf
87Pointer to a function used for configuration in XML format dumping.
88.It Vt "g_access_t *" Va access
89Pointer to a function used for access control.
90.It Vt "g_orphan_t *" Va orphan
91Pointer to a function used to inform about orphaned consumer.
92.It Vt "g_ioctl_t *" Va ioctl
93Pointer to a function used for handling ioctl requests.
94.It Vt "void *" Va softc
95Field for private use.
96.El
97.Sh RESTRICTIONS/CONDITIONS
98If you intend to use providers in this geom you must set field
99.Va start
100of your geom.
101.Pp
102If you are planning to use consumers in your geom you must set fields
103.Va orphan
104and
105.Va access
106for it.
107.Pp
108.Fn g_new_geomf
109and
110.Fn g_new_geom :
111.Bl -item -offset indent
112.It
113Class
114.Fa mp
115must be valid (registered in GEOM).
116.It
117The topology lock has to be held.
118.El
119.Pp
120.Fn g_destroy_geom :
121.Bl -item -offset indent
122.It
123The geom cannot possess any providers.
124.It
125The geom cannot possess any consumers.
126.It
127The topology lock has to be held.
128.El
129.Sh RETURN VALUES
130The
131.Fn g_new_geomf
132function
133returns a pointer to the newly created geom.
134.Sh EXAMPLES
135Create an example geom.
136.Bd -literal -offset indent
137static void
138g_example_start(struct bio *bp)
139{
140
141	[...]
142}
143
144static void
145g_example_orphan(struct g_consumer *cp)
146{
147
148	g_topology_assert();
149
150	[...]
151}
152
153static void
154g_example_spoiled(struct g_consumer *cp)
155{
156
157	g_topology_assert();
158
159	[...]
160}
161
162static int
163g_example_access(struct g_provider *pp, int dr, int dw, int de)
164{
165
166	[...]
167}
168
169static struct g_geom *
170create_example_geom(struct g_class *myclass)
171{
172	struct g_geom *gp;
173
174	g_topology_lock();
175	gp = g_new_geomf(myclass, "example_geom");
176	g_topology_unlock();
177	gp->start = g_example_start;
178	gp->orphan = g_example_orphan;
179	gp->spoiled = g_example_spoiled;
180	gp->access = g_example_access;
181	gp->softc = NULL;
182
183	return (gp);
184}
185
186static int
187destroy_example_geom(struct g_geom *gp)
188{
189
190	g_topology_lock();
191	if (!LIST_EMPTY(&gp->provider) ||
192	    !LIST_EMPTY(&gp->consumer)) {
193		g_topology_unlock();
194		return (EBUSY);
195	}
196	g_destroy_geom(gp);
197	g_topology_unlock();
198
199	return (0);
200}
201.Ed
202.Sh SEE ALSO
203.Xr geom 4 ,
204.Xr DECLARE_GEOM_CLASS 9 ,
205.Xr g_access 9 ,
206.Xr g_attach 9 ,
207.Xr g_bio 9 ,
208.Xr g_consumer 9 ,
209.Xr g_data 9 ,
210.Xr g_event 9 ,
211.Xr g_provider 9 ,
212.Xr g_provider_by_name 9 ,
213.Xr g_wither_geom 9
214.Sh AUTHORS
215.An -nosplit
216This manual page was written by
217.An Pawel Jakub Dawidek Aq Mt pjd@FreeBSD.org .
218