2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
32 #include <sys/param.h>
34 #include <sys/kernel.h>
35 #include <sys/limits.h>
36 #include <sys/malloc.h>
37 #include <sys/queue.h>
38 #include <sys/sysctl.h>
39 #include <sys/systm.h>
41 #include <geom/geom.h>
44 #define G_ZERO_CLASS_NAME "ZERO"
46 static int g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS);
48 SYSCTL_DECL(_kern_geom);
49 static SYSCTL_NODE(_kern_geom, OID_AUTO, zero, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
51 static int g_zero_clear = 1;
52 SYSCTL_PROC(_kern_geom_zero, OID_AUTO, clear,
53 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, &g_zero_clear, 0,
54 g_zero_clear_sysctl, "I",
55 "Clear read data buffer");
56 static int g_zero_byte = 0;
57 SYSCTL_INT(_kern_geom_zero, OID_AUTO, byte, CTLFLAG_RW, &g_zero_byte, 0,
58 "Byte (octet) value to clear the buffers with");
60 static struct g_provider *gpp;
63 g_zero_clear_sysctl(SYSCTL_HANDLER_ARGS)
67 error = sysctl_handle_int(oidp, &g_zero_clear, 0, req);
68 if (error != 0 || req->newptr == NULL)
73 gpp->flags &= ~G_PF_ACCEPT_UNMAPPED;
75 gpp->flags |= G_PF_ACCEPT_UNMAPPED;
80 g_zero_start(struct bio *bp)
84 switch (bp->bio_cmd) {
86 if (g_zero_clear && (bp->bio_flags & BIO_UNMAPPED) == 0)
87 memset(bp->bio_data, g_zero_byte, bp->bio_length);
91 bp->bio_completed = bp->bio_length;
99 g_io_deliver(bp, error);
103 g_zero_init(struct g_class *mp)
106 struct g_provider *pp;
109 gp = g_new_geomf(mp, "gzero");
110 gp->start = g_zero_start;
111 gp->access = g_std_access;
112 gpp = pp = g_new_providerf(gp, "%s", gp->name);
113 pp->flags |= G_PF_DIRECT_SEND | G_PF_DIRECT_RECEIVE;
115 pp->flags |= G_PF_ACCEPT_UNMAPPED;
116 pp->mediasize = 1152921504606846976LLU;
117 pp->sectorsize = 512;
118 g_error_provider(pp, 0);
122 g_zero_destroy_geom(struct gctl_req *req __unused, struct g_class *mp __unused,
125 struct g_provider *pp;
130 pp = LIST_FIRST(&gp->provider);
133 if (pp->acr > 0 || pp->acw > 0 || pp->ace > 0)
136 g_wither_geom(gp, ENXIO);
140 static struct g_class g_zero_class = {
141 .name = G_ZERO_CLASS_NAME,
142 .version = G_VERSION,
144 .destroy_geom = g_zero_destroy_geom
147 DECLARE_GEOM_CLASS(g_zero_class, g_zero);
148 MODULE_VERSION(geom_zero, 0);