g_zero.c

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    1 /*-
    2  * Copyright (c) 2005 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 AUTHORS AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/8.3/sys/geom/zero/g_zero.c 211064 2010-08-08 09:06:59Z jh $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/bio.h>
   32 #include <sys/kernel.h>
   33 #include <sys/limits.h>
   34 #include <sys/malloc.h>
   35 #include <sys/queue.h>
   36 #include <sys/sysctl.h>
   37 #include <sys/systm.h>
   38 
   39 #include <geom/geom.h>
   40 
   41 
   42 #define G_ZERO_CLASS_NAME       "ZERO"
   43 
   44 SYSCTL_DECL(_kern_geom);
   45 SYSCTL_NODE(_kern_geom, OID_AUTO, zero, CTLFLAG_RW, 0, "GEOM_ZERO stuff");
   46 static int g_zero_clear = 1;
   47 SYSCTL_INT(_kern_geom_zero, OID_AUTO, clear, CTLFLAG_RW, &g_zero_clear, 0,
   48     "Clear read data buffer");
   49 static int g_zero_byte = 0;
   50 SYSCTL_INT(_kern_geom_zero, OID_AUTO, byte, CTLFLAG_RW, &g_zero_byte, 0,
   51     "Byte (octet) value to clear the buffers with");
   52 
   53 static void
   54 g_zero_start(struct bio *bp)
   55 {
   56         int error = ENXIO;
   57 
   58         switch (bp->bio_cmd) {
   59         case BIO_READ:
   60                 if (g_zero_clear)
   61                         memset(bp->bio_data, g_zero_byte, bp->bio_length);
   62                 /* FALLTHROUGH */
   63         case BIO_DELETE:
   64         case BIO_WRITE:
   65                 bp->bio_completed = bp->bio_length;
   66                 error = 0;
   67                 break;
   68         case BIO_GETATTR:
   69         default:
   70                 error = EOPNOTSUPP;
   71                 break;
   72         }
   73         g_io_deliver(bp, error);
   74 }
   75 
   76 static void
   77 g_zero_init(struct g_class *mp)
   78 {
   79         struct g_geom *gp;
   80         struct g_provider *pp;
   81 
   82         g_topology_assert();
   83         gp = g_new_geomf(mp, "gzero");
   84         gp->start = g_zero_start;
   85         gp->access = g_std_access;
   86         pp = g_new_providerf(gp, "%s", gp->name);
   87         pp->mediasize = 1152921504606846976LLU;
   88         pp->sectorsize = 512;
   89         g_error_provider(pp, 0);
   90 }
   91 
   92 static int
   93 g_zero_destroy_geom(struct gctl_req *req __unused, struct g_class *mp __unused,
   94     struct g_geom *gp)
   95 {
   96         struct g_provider *pp;
   97 
   98         g_topology_assert();
   99         if (gp == NULL)
  100                 return (0);
  101         pp = LIST_FIRST(&gp->provider);
  102         if (pp == NULL)
  103                 return (0);
  104         if (pp->acr > 0 || pp->acw > 0 || pp->ace > 0)
  105                 return (EBUSY);
  106         g_wither_geom(gp, ENXIO);
  107         return (0);
  108 }
  109 
  110 static struct g_class g_zero_class = {
  111         .name = G_ZERO_CLASS_NAME,
  112         .version = G_VERSION,
  113         .init = g_zero_init,
  114         .destroy_geom = g_zero_destroy_geom
  115 };
  116 
  117 DECLARE_GEOM_CLASS(g_zero_class, g_zero);

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FreeBSD/Linux Kernel Cross Reference sys/geom/zero/g_zero.c

FreeBSD/Linux Kernel Cross Reference
sys/geom/zero/g_zero.c