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use the switch_root function in shutdown

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removes code duplication

also move switch-root to shared
This commit is contained in:
Harald Hoyer
2014-08-28 15:25:15 +02:00
parent 667a0377fb
commit 5a4bf02ff5
5 changed files with 39 additions and 96 deletions
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src/core/main.c
+2 -2
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@@ -1853,8 +1853,8 @@ finish:
* deserializing. */
broadcast_signal(SIGTERM, false, true);
/* And switch root */
r = switch_root(switch_root_dir);
/* And switch root with MS_MOVE, because we remove the old directory afterwards and detach it. */
r = switch_root(switch_root_dir, "/mnt", true, MS_MOVE);
if (r < 0)
log_error("Failed to switch root, ignoring: %s", strerror(-r));
}
src/core/shutdown.c
+17 -73
View File
@@ -48,6 +48,7 @@
#include "killall.h"
#include "cgroup-util.h"
#include "def.h"
#include "switch-root.h"
#define FINALIZE_ATTEMPTS 50
@@ -131,16 +132,7 @@ static int parse_argv(int argc, char *argv[]) {
return 0;
}
static int prepare_new_root(void) {
static const char dirs[] =
"/run/initramfs/oldroot\0"
"/run/initramfs/proc\0"
"/run/initramfs/sys\0"
"/run/initramfs/dev\0"
"/run/initramfs/run\0";
const char *dir;
static int switch_root_initramfs(void) {
if (mount("/run/initramfs", "/run/initramfs", NULL, MS_BIND, NULL) < 0) {
log_error("Failed to mount bind /run/initramfs on /run/initramfs: %m");
return -errno;
@@ -151,66 +143,13 @@ static int prepare_new_root(void) {
return -errno;
}
NULSTR_FOREACH(dir, dirs)
if (mkdir_p_label(dir, 0755) < 0 && errno != EEXIST) {
log_error("Failed to mkdir %s: %m", dir);
return -errno;
}
if (mount("/sys", "/run/initramfs/sys", NULL, MS_BIND, NULL) < 0) {
log_error("Failed to mount bind /sys on /run/initramfs/sys: %m");
return -errno;
}
if (mount("/proc", "/run/initramfs/proc", NULL, MS_BIND, NULL) < 0) {
log_error("Failed to mount bind /proc on /run/initramfs/proc: %m");
return -errno;
}
if (mount("/dev", "/run/initramfs/dev", NULL, MS_BIND, NULL) < 0) {
log_error("Failed to mount bind /dev on /run/initramfs/dev: %m");
return -errno;
}
if (mount("/run", "/run/initramfs/run", NULL, MS_BIND, NULL) < 0) {
log_error("Failed to mount bind /run on /run/initramfs/run: %m");
return -errno;
}
return 0;
/* switch_root with MS_BIND, because there might still be processes lurking around, which have open file desriptors.
* /run/initramfs/shutdown will take care of these.
* Also do not detach the old root, because /run/initramfs/shutdown needs to access it.
*/
return switch_root("/run/initramfs", "/oldroot", false, MS_BIND);
}
static int pivot_to_new_root(void) {
if (chdir("/run/initramfs") < 0) {
log_error("Failed to change directory to /run/initramfs: %m");
return -errno;
}
/* Work-around for a kernel bug: for some reason the kernel
* refuses switching root if any file systems are mounted
* MS_SHARED. Hence remount them MS_PRIVATE here as a
* work-around.
*
* https://bugzilla.redhat.com/show_bug.cgi?id=847418 */
if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
log_warning("Failed to make \"/\" private mount: %m");
if (pivot_root(".", "oldroot") < 0) {
log_error("pivot failed: %m");
/* only chroot if pivot root succeeded */
return -errno;
}
chroot(".");
setsid();
make_console_stdio();
log_info("Successfully changed into root pivot.");
return 0;
}
int main(int argc, char *argv[]) {
bool need_umount, need_swapoff, need_loop_detach, need_dm_detach;
@@ -372,16 +311,21 @@ int main(int argc, char *argv[]) {
if (!in_container && !in_initrd() &&
access("/run/initramfs/shutdown", X_OK) == 0) {
if (prepare_new_root() >= 0 &&
pivot_to_new_root() >= 0) {
r = switch_root_initramfs();
if (r >= 0) {
arguments[0] = (char*) "/shutdown";
log_info("Returning to initrd...");
setsid();
make_console_stdio();
log_info("Successfully changed into root pivot.\n"
"Returning to initrd...");
execv("/shutdown", arguments);
log_error("Failed to execute shutdown binary: %m");
}
} else
log_error("Failed to switch root to \"/run/initramfs\": %s", strerror(-r));
}
if (need_umount || need_swapoff || need_loop_detach || need_dm_detach)
src/core/switch-root.c
-164
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@@ -1,164 +0,0 @@
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2012 Harald Hoyer, Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <sys/stat.h>
#include <stdbool.h>
#include <errno.h>
#include <string.h>
#include <sys/mount.h>
#include <unistd.h>
#include <fcntl.h>
#include "util.h"
#include "path-util.h"
#include "switch-root.h"
#include "mkdir.h"
#include "base-filesystem.h"
#include "missing.h"
int switch_root(const char *new_root) {
/* Don't try to unmount/move the old "/", there's no way to do it. */
static const char move_mounts[] =
"/dev\0"
"/proc\0"
"/sys\0"
"/run\0";
_cleanup_close_ int old_root_fd = -1;
struct stat new_root_stat;
bool old_root_remove;
const char *i, *temporary_old_root;
int r;
if (path_equal(new_root, "/"))
return 0;
/* When using pivot_root() we assume that /mnt exists as place
* we can temporarily move the old root to. As we immediately
* unmount it from there it doesn't matter much which
* directory we choose for this, but it should be more likely
* than not that /mnt exists and is suitable as mount point
* and is on the same fs as the old root dir */
temporary_old_root = strappenda(new_root, "/mnt");
mkdir_p(temporary_old_root, 0755);
old_root_remove = in_initrd();
if (stat(new_root, &new_root_stat) < 0) {
log_error("Failed to stat directory %s: %m", new_root);
return -errno;
}
/* Work-around for a kernel bug: for some reason the kernel
* refuses switching root if any file systems are mounted
* MS_SHARED. Hence remount them MS_PRIVATE here as a
* work-around.
*
* https://bugzilla.redhat.com/show_bug.cgi?id=847418 */
if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
log_warning("Failed to make \"/\" private mount: %m");
NULSTR_FOREACH(i, move_mounts) {
char new_mount[PATH_MAX];
struct stat sb;
snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
char_array_0(new_mount);
mkdir_p(new_mount, 0755);
if ((stat(new_mount, &sb) < 0) ||
sb.st_dev != new_root_stat.st_dev) {
/* Mount point seems to be mounted already or
* stat failed. Unmount the old mount
* point. */
if (umount2(i, MNT_DETACH) < 0)
log_warning("Failed to unmount %s: %m", i);
continue;
}
if (mount(i, new_mount, NULL, MS_MOVE, NULL) < 0) {
log_error("Failed to move mount %s to %s, forcing unmount: %m", i, new_mount);
if (umount2(i, MNT_FORCE) < 0)
log_warning("Failed to unmount %s: %m", i);
}
}
r = base_filesystem_create(new_root);
if (r < 0) {
log_error("Failed to create the base filesystem: %s", strerror(-r));
return r;
}
if (chdir(new_root) < 0) {
log_error("Failed to change directory to %s: %m", new_root);
return -errno;
}
if (old_root_remove) {
old_root_fd = open("/", O_RDONLY|O_NONBLOCK|O_CLOEXEC|O_NOCTTY|O_DIRECTORY);
if (old_root_fd < 0)
log_warning("Failed to open root directory: %m");
}
/* We first try a pivot_root() so that we can umount the old
* root dir. In many cases (i.e. where rootfs is /), that's
* not possible however, and hence we simply overmount root */
if (pivot_root(new_root, temporary_old_root) >= 0) {
/* Immediately get rid of the old root. Since we are
* running off it we need to do this lazily. */
if (umount2("/mnt", MNT_DETACH) < 0) {
log_error("Failed to umount old root dir /mnt: %m");
return -errno;
}
} else if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
log_error("Failed to mount moving %s to /: %m", new_root);
return -errno;
}
if (chroot(".") < 0) {
log_error("Failed to change root: %m");
return -errno;
}
if (chdir("/") < 0) {
log_error("Failed to change directory: %m");
return -errno;
}
if (old_root_fd >= 0) {
struct stat rb;
if (fstat(old_root_fd, &rb) < 0)
log_warning("Failed to stat old root directory, leaving: %m");
else {
rm_rf_children(old_root_fd, false, false, &rb);
old_root_fd = -1;
}
}
return 0;
}
src/core/switch-root.h
-24
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@@ -1,24 +0,0 @@
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
#pragma once
/***
This file is part of systemd.
Copyright 2012 Harald Hoyer, Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
int switch_root(const char *switch_root);