NetBSD/sbin/dump/snapshot.c

176 lines
4.9 KiB
C

/* $NetBSD: snapshot.c,v 1.3 2006/10/26 20:02:30 hannken Exp $ */
/*-
* Copyright (c) 2005 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Juergen Hannken-Illjes.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <dev/fssvar.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "snapshot.h"
/*
* Create a snapshot of the file system currently mounted on the first argument
* using the second argument as backing store and return an open file
* descriptor for the snapshot. If the second argument is NULL, use the first
* as backing store. If the third argument is not NULL, it gets the time the
* snapshot was created. If the fourth argument is not NULL, it gets the
* snapshot device path.
*/
int
snap_open(char *mountpoint, char *backup, time_t *snap_date, char **snap_dev)
{
int i, fd, israw, fsinternal, dounlink, flags;
char path[MAXPATHLEN], fss_dev[14];
dev_t mountdev;
struct fss_set fss;
struct fss_get fsg;
struct stat sb;
struct statvfs fsb;
dounlink = 0;
fd = -1;
fss.fss_mount = mountpoint;
fss.fss_bstore = backup ? backup : fss.fss_mount;
fss.fss_csize = 0;
if (stat(fss.fss_mount, &sb) < 0)
goto fail;
mountdev = sb.st_dev;
/*
* Prepare the backing store. `backup' is either a raw device,
* a file or a directory. If it is a file, it must not exist.
*/
israw = 0;
if (stat(fss.fss_bstore, &sb) == 0) {
if (S_ISDIR(sb.st_mode)) {
snprintf(path, sizeof(path),
"%s/XXXXXXXXXX", fss.fss_bstore);
fd = mkstemp(path);
fss.fss_bstore = path;
dounlink = 1;
} else if (S_ISCHR(sb.st_mode)) {
fd = open(fss.fss_bstore, O_RDWR);
israw = 1;
} else
goto fail;
} else {
fd = open(fss.fss_bstore, O_CREAT|O_EXCL|O_WRONLY, 0600);
dounlink = 1;
}
if (fd < 0)
goto fail;
if (fstat(fd, &sb) < 0)
goto fail;
fsinternal = (!israw && sb.st_dev == mountdev);
/*
* If the backing store is a plain file and the snapshot
* is not file system internal, truncate to file system
* free space.
*/
if (!israw && !fsinternal) {
if (statvfs(fss.fss_bstore, &fsb) < 0)
goto fail;
if (ftruncate(fd, (off_t)fsb.f_frsize*fsb.f_bavail) < 0)
goto fail;
}
if (close(fd) < 0)
goto fail;
/*
* Create the snapshot on the first free snapshot device.
*/
for (i = 0; ; i++) {
snprintf(fss_dev, sizeof(fss_dev), "/dev/rfss%d", i);
if ((fd = open(fss_dev, O_RDWR, 0)) < 0)
goto fail;
if (ioctl(fd, FSSIOFGET, &flags) < 0)
goto fail;
if (ioctl(fd, FSSIOCSET, &fss) < 0) {
if (errno != EBUSY)
goto fail;
close(fd);
fd = -1;
continue;
}
if (snap_dev != NULL) {
*snap_dev = strdup(fss_dev);
if (*snap_dev == NULL) {
ioctl(fd, FSSIOCCLR);
goto fail;
}
}
flags |= FSS_UNCONFIG_ON_CLOSE;
if (ioctl(fd, FSSIOCGET, &fsg) < 0 ||
ioctl(fd, FSSIOFSET, &flags) < 0 ||
(!israw && unlink(fss.fss_bstore) < 0)) {
ioctl(fd, FSSIOCCLR);
goto fail;
}
if (snap_date != NULL)
*snap_date = fsg.fsg_time.tv_sec;
return fd;
}
fail:
if (dounlink)
unlink(fss.fss_bstore);
if (fd >= 0)
close(fd);
return -1;
}