565bc10111
It creates very huge provider (41PB) /dev/gzero. On BIO_READ request it zero-fills bio_data and on BIO_WRITE it does nothing. You can also set kern.geom.zero.clear sysctl to 0 to do nothing even for BIO_READ. I'm using it for performance testing where it is very helpful. MFC after: 3 days
114 lines
3.1 KiB
C
114 lines
3.1 KiB
C
/*-
|
|
* Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#include <sys/param.h>
|
|
#include <sys/bio.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/limits.h>
|
|
#include <sys/malloc.h>
|
|
#include <sys/queue.h>
|
|
#include <sys/sysctl.h>
|
|
#include <sys/systm.h>
|
|
|
|
#include <geom/geom.h>
|
|
|
|
|
|
#define G_ZERO_CLASS_NAME "ZERO"
|
|
|
|
SYSCTL_DECL(_kern_geom);
|
|
SYSCTL_NODE(_kern_geom, OID_AUTO, zero, CTLFLAG_RW, 0, "GEOM_ZERO stuff");
|
|
static u_int g_zero_clear = 1;
|
|
SYSCTL_UINT(_kern_geom_zero, OID_AUTO, clear, CTLFLAG_RW, &g_zero_clear, 0,
|
|
"Zero-fill bio_data.");
|
|
|
|
static void
|
|
g_zero_start(struct bio *bp)
|
|
{
|
|
int error = ENXIO;
|
|
|
|
switch (bp->bio_cmd) {
|
|
case BIO_READ:
|
|
if (g_zero_clear)
|
|
bzero(bp->bio_data, bp->bio_length);
|
|
/* FALLTHROUGH */
|
|
case BIO_DELETE:
|
|
case BIO_WRITE:
|
|
bp->bio_completed = bp->bio_length;
|
|
error = 0;
|
|
break;
|
|
case BIO_GETATTR:
|
|
default:
|
|
error = EOPNOTSUPP;
|
|
break;
|
|
}
|
|
g_io_deliver(bp, error);
|
|
}
|
|
|
|
static void
|
|
g_zero_init(struct g_class *mp)
|
|
{
|
|
struct g_geom *gp;
|
|
struct g_provider *pp;
|
|
|
|
g_topology_assert();
|
|
gp = g_new_geomf(mp, "gzero");
|
|
gp->start = g_zero_start;
|
|
gp->access = g_std_access;
|
|
pp = g_new_providerf(gp, "%s", gp->name);
|
|
pp->mediasize = 1152921504606846976LLU;
|
|
pp->sectorsize = 512;
|
|
g_error_provider(pp, 0);
|
|
}
|
|
|
|
static int
|
|
g_zero_destroy_geom(struct gctl_req *req __unused, struct g_class *mp __unused,
|
|
struct g_geom *gp)
|
|
{
|
|
struct g_provider *pp;
|
|
|
|
g_topology_assert();
|
|
if (gp == NULL)
|
|
return (0);
|
|
pp = LIST_FIRST(&gp->provider);
|
|
if (pp == NULL)
|
|
return (0);
|
|
if (pp->acr > 0 || pp->acw > 0 || pp->ace > 0)
|
|
return (EBUSY);
|
|
g_wither_geom(gp, ENXIO);
|
|
return (EBUSY);
|
|
}
|
|
|
|
static struct g_class g_zero_class = {
|
|
.name = G_ZERO_CLASS_NAME,
|
|
.version = G_VERSION,
|
|
.init = g_zero_init,
|
|
.destroy_geom = g_zero_destroy_geom
|
|
};
|
|
|
|
DECLARE_GEOM_CLASS(g_zero_class, g_zero);
|