sys/dev/virtual/disk/vdisk.c

   1 /*
   2  * Copyright (c) 2006 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/dev/virtual/disk/vdisk.c,v 1.6 2007/05/25 02:21:14 dillon Exp $
  35  */
  36
  37 /*
  38  * Virtual disk driver
  39  */
  40 #include <sys/types.h>
  41 #include <sys/param.h>
  42 #include <sys/systm.h>
  43 #include <sys/kernel.h>
  44 #include <sys/malloc.h>
  45 #include <sys/conf.h>
  46 #include <sys/buf.h>
  47 #include <sys/devicestat.h>
  48 #include <sys/disk.h>
  49 #include <machine/md_var.h>
  50
  51 #include <sys/buf2.h>
  52
  53 #include <sys/stat.h>
  54 #include <unistd.h>
  55
  56 struct vkd_softc {
  57         struct bio_queue_head bio_queue;
  58         struct devstat stats;
  59         struct disk disk;
  60         cdev_t dev;
  61         int unit;
  62         int fd;
  63 };
  64
  65 #define CDEV_MAJOR      97
  66
  67 static d_strategy_t     vkdstrategy;
  68 static d_open_t         vkdopen;
  69
  70 static struct dev_ops vkd_ops = {
  71         { "vkd", CDEV_MAJOR, D_DISK },
  72         .d_open =       vkdopen,
  73         .d_close =      nullclose,
  74         .d_read =       physread,
  75         .d_write =      physwrite,
  76         .d_strategy =   vkdstrategy,
  77 };
  78
  79 static void
  80 vkdinit(void *dummy __unused)
  81 {
  82         struct vkdisk_info *dsk;
  83         struct vkd_softc *sc;
  84         struct stat st;
  85         int i;
  86
  87         for (i = 0; i < DiskNum; i++) {
  88                 /* check that the 'bus device' has been initialized */
  89                 dsk = &DiskInfo[i];
  90                 if (dsk == NULL || dsk->type != VKD_DISK)
  91                         continue;
  92                 if (dsk->fd < 0 || fstat(dsk->fd, &st) < 0)
  93                         continue;
  94
  95                 /* and create a new device */
  96                 sc = kmalloc(sizeof(*sc), M_DEVBUF, M_WAITOK | M_ZERO);
  97                 sc->unit = dsk->unit;
  98                 sc->fd = dsk->fd;
  99                 bioq_init(&sc->bio_queue);
 100                 devstat_add_entry(&sc->stats, "vkd", sc->unit, DEV_BSIZE,
 101                                   DEVSTAT_NO_ORDERED_TAGS,
 102                                   DEVSTAT_TYPE_DIRECT | DEVSTAT_TYPE_IF_OTHER,
 103                                   DEVSTAT_PRIORITY_DISK);
 104                 sc->dev = disk_create(sc->unit, &sc->disk, &vkd_ops);
 105                 sc->dev->si_drv1 = sc;
 106                 sc->dev->si_iosize_max = 256 * 1024;
 107         }
 108 }
 109
 110 SYSINIT(vkdisk, SI_SUB_DRIVERS, SI_ORDER_FIRST, vkdinit, NULL);
 111
 112 static int
 113 vkdopen(struct dev_open_args *ap)
 114 {
 115         struct vkd_softc *sc;
 116         struct disk_info info;
 117         struct stat st;
 118         cdev_t dev;
 119
 120         dev = ap->a_head.a_dev;
 121         sc = dev->si_drv1;
 122         if (fstat(sc->fd, &st) < 0 || st.st_size == 0)
 123                 return(ENXIO);
 124
 125         bzero(&info, sizeof(info));
 126         info.d_media_blksize = DEV_BSIZE;
 127         info.d_media_blocks = st.st_size / info.d_media_blksize;
 128
 129         info.d_nheads = 1;
 130         info.d_ncylinders = 1;
 131         info.d_secpertrack = info.d_media_blocks;
 132         info.d_secpercyl = info.d_secpertrack * info.d_nheads;
 133
 134         disk_setdiskinfo(&sc->disk, &info);
 135         return(0);
 136 }
 137
 138 static int
 139 vkdstrategy(struct dev_strategy_args *ap)
 140 {
 141         struct bio *bio = ap->a_bio;
 142         struct buf *bp;
 143         struct vkd_softc *sc;
 144         cdev_t dev;
 145         int n;
 146
 147         dev = ap->a_head.a_dev;
 148         sc = dev->si_drv1;
 149
 150         bioqdisksort(&sc->bio_queue, bio);
 151         while ((bio = bioq_first(&sc->bio_queue)) != NULL) {
 152                 bioq_remove(&sc->bio_queue, bio);
 153                 bp = bio->bio_buf;
 154
 155                 devstat_start_transaction(&sc->stats);
 156
 157                 switch(bp->b_cmd) {
 158                 case BUF_CMD_READ:
 159                         lseek(sc->fd, bio->bio_offset, 0);
 160                         n = read(sc->fd, bp->b_data, bp->b_bcount);
 161                         break;
 162                 case BUF_CMD_WRITE:
 163                         /* XXX HANDLE SHORT WRITE XXX */
 164                         lseek(sc->fd, bio->bio_offset, 0);
 165                         n = write(sc->fd, bp->b_data, bp->b_bcount);
 166                         break;
 167                 default:
 168                         panic("vkd: bad b_cmd %d", bp->b_cmd);
 169                         break; /* not reached */
 170                 }
 171                 if (n != bp->b_bcount) {
 172                         bp->b_error = EIO;
 173                         bp->b_flags |= B_ERROR;
 174                 }
 175
 176                 bp->b_resid = bp->b_bcount - n;
 177                 devstat_end_transaction_buf(&sc->stats, bp);
 178                 biodone(bio);
 179         }
 180         return(0);
 181 }
 182