sbin/dump/snapshot.c

   1 /*      $NetBSD: snapshot.c,v 1.3 2006/10/26 20:02:30 hannken Exp $     */
   2
   3 /*-
   4  * Copyright (c) 2005 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Juergen Hannken-Illjes.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/param.h>
  33 #include <sys/ioctl.h>
  34 #include <sys/mount.h>
  35 #include <sys/stat.h>
  36
  37 #include <dev/fssvar.h>
  38
  39 #include <errno.h>
  40 #include <fcntl.h>
  41 #include <stdio.h>
  42 #include <stdlib.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45
  46 #include "snapshot.h"
  47
  48 /*
  49  * Create a snapshot of the file system currently mounted on the first argument
  50  * using the second argument as backing store and return an open file
  51  * descriptor for the snapshot.  If the second argument is NULL, use the first
  52  * as backing store.  If the third argument is not NULL, it gets the time the
  53  * snapshot was created.  If the fourth argument is not NULL, it gets the
  54  * snapshot device path.
  55  */
  56 int
  57 snap_open(char *mountpoint, char *backup, time_t *snap_date, char **snap_dev)
  58 {
  59         int i, fd, israw, fsinternal, dounlink, flags;
  60         char path[MAXPATHLEN], fss_dev[14];
  61         dev_t mountdev;
  62         struct fss_set fss;
  63         struct fss_get fsg;
  64         struct stat sb;
  65         struct statvfs fsb;
  66
  67         dounlink = 0;
  68         fd = -1;
  69
  70         fss.fss_mount = mountpoint;
  71         fss.fss_bstore = backup ? backup : fss.fss_mount;
  72         fss.fss_csize = 0;
  73
  74         if (stat(fss.fss_mount, &sb) < 0)
  75                 goto fail;
  76         mountdev = sb.st_dev;
  77
  78         /*
  79          * Prepare the backing store. `backup' is either a raw device,
  80          * a file or a directory.  If it is a file, it must not exist.
  81          */
  82         israw = 0;
  83         if (stat(fss.fss_bstore, &sb) == 0) {
  84                 if (S_ISDIR(sb.st_mode)) {
  85                         snprintf(path, sizeof(path),
  86                             "%s/XXXXXXXXXX", fss.fss_bstore);
  87                         fd = mkstemp(path);
  88                         fss.fss_bstore = path;
  89                         dounlink = 1;
  90                 } else if (S_ISCHR(sb.st_mode)) {
  91                         fd = open(fss.fss_bstore, O_RDWR);
  92                         israw = 1;
  93                 } else
  94                         goto fail;
  95         } else {
  96                 fd = open(fss.fss_bstore, O_CREAT|O_EXCL|O_WRONLY, 0600);
  97                 dounlink = 1;
  98         }
  99         if (fd < 0)
 100                 goto fail;
 101
 102         if (fstat(fd, &sb) < 0)
 103                 goto fail;
 104         fsinternal = (!israw && sb.st_dev == mountdev);
 105
 106         /*
 107          * If the backing store is a plain file and the snapshot
 108          * is not file system internal, truncate to file system
 109          * free space.
 110          */
 111         if (!israw && !fsinternal) {
 112                 if (statvfs(fss.fss_bstore, &fsb) < 0)
 113                         goto fail;
 114                 if (ftruncate(fd, (off_t)fsb.f_frsize*fsb.f_bavail) < 0)
 115                         goto fail;
 116         }
 117
 118         if (close(fd) < 0)
 119                 goto fail;
 120
 121         /*
 122          * Create the snapshot on the first free snapshot device.
 123          */
 124         for (i = 0; ; i++) {
 125                 snprintf(fss_dev, sizeof(fss_dev), "/dev/rfss%d", i);
 126                 if ((fd = open(fss_dev, O_RDWR, 0)) < 0)
 127                         goto fail;
 128
 129                 if (ioctl(fd, FSSIOFGET, &flags) < 0)
 130                         goto fail;
 131
 132                 if (ioctl(fd, FSSIOCSET, &fss) < 0) {
 133                         if (errno != EBUSY)
 134                                 goto fail;
 135                         close(fd);
 136                         fd = -1;
 137                         continue;
 138                 }
 139
 140                 if (snap_dev != NULL) {
 141                         *snap_dev = strdup(fss_dev);
 142                         if (*snap_dev == NULL) {
 143                                 ioctl(fd, FSSIOCCLR);
 144                                 goto fail;
 145                         }
 146                 }
 147
 148                 flags |= FSS_UNCONFIG_ON_CLOSE;
 149                 if (ioctl(fd, FSSIOCGET, &fsg) < 0 ||
 150                     ioctl(fd, FSSIOFSET, &flags) < 0 ||
 151                     (!israw && unlink(fss.fss_bstore) < 0)) {
 152                         ioctl(fd, FSSIOCCLR);
 153                         goto fail;
 154                 }
 155
 156                 if (snap_date != NULL)
 157                         *snap_date = fsg.fsg_time.tv_sec;
 158                 return fd;
 159         }
 160
 161 fail:
 162         if (dounlink)
 163                 unlink(fss.fss_bstore);
 164         if (fd >= 0)
 165                 close(fd);
 166
 167         return -1;
 168 }