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author | pjd <pjd@FreeBSD.org> | 2005-07-25 10:03:16 +0000 |
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committer | pjd <pjd@FreeBSD.org> | 2005-07-25 10:03:16 +0000 |
commit | da0fa3b3e071fca3f1287439ec8fb56f430166fd (patch) | |
tree | 928f47c30e231832f8d3eec4d2869be495ce6183 /sys | |
parent | a2d24671eab600f642f4ff91d05a29f9cc8de794 (diff) | |
download | FreeBSD-src-da0fa3b3e071fca3f1287439ec8fb56f430166fd.zip FreeBSD-src-da0fa3b3e071fca3f1287439ec8fb56f430166fd.tar.gz |
Add a very simple and small GEOM class - ZERO.
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
Diffstat (limited to 'sys')
-rw-r--r-- | sys/geom/zero/g_zero.c | 113 | ||||
-rw-r--r-- | sys/modules/geom/geom_zero/Makefile | 8 |
2 files changed, 121 insertions, 0 deletions
diff --git a/sys/geom/zero/g_zero.c b/sys/geom/zero/g_zero.c new file mode 100644 index 0000000..d458379 --- /dev/null +++ b/sys/geom/zero/g_zero.c @@ -0,0 +1,113 @@ +/*- + * 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); diff --git a/sys/modules/geom/geom_zero/Makefile b/sys/modules/geom/geom_zero/Makefile new file mode 100644 index 0000000..43dae09 --- /dev/null +++ b/sys/modules/geom/geom_zero/Makefile @@ -0,0 +1,8 @@ +# $FreeBSD$ + +.PATH: ${.CURDIR}/../../../geom/zero + +KMOD= geom_zero +SRCS= g_zero.c + +.include <bsd.kmod.mk> |