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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 2014-08-21 16:21:26 +02:00
parent 667a0377fb
commit 5a4bf02ff5
5 changed files with 39 additions and 96 deletions
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4
Makefile.am
View file

@ -868,6 +868,8 @@ libsystemd_shared_la_SOURCES = \
src/shared/memfd.h \
src/shared/uid-range.c \
src/shared/uid-range.h \
src/shared/switch-root.h \
src/shared/switch-root.c \
src/shared/nss-util.h
nodist_libsystemd_shared_la_SOURCES = \
@ -1109,8 +1111,6 @@ libsystemd_core_la_SOURCES = \
src/core/namespace.h \
src/core/build.h \
src/core/sysfs-show.h \
src/core/switch-root.h \
src/core/switch-root.c \
src/core/killall.h \
src/core/killall.c \
src/core/audit-fd.c \

4
src/core/main.c
View file

@ -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));
}

90
src/core/shutdown.c
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)

35
src/core/switch-root.c → src/shared/switch-root.c
View file

@ -34,7 +34,7 @@
#include "base-filesystem.h"
#include "missing.h"
int switch_root(const char *new_root) {
int switch_root(const char *new_root, const char *oldroot, bool detach_oldroot, unsigned long mountflags) {
/* Don't try to unmount/move the old "/", there's no way to do it. */
static const char move_mounts[] =
@ -52,14 +52,8 @@ int switch_root(const char *new_root) {
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);
temporary_old_root = strappenda(new_root, oldroot);
mkdir_p_label(temporary_old_root, 0755);
old_root_remove = in_initrd();
@ -84,7 +78,7 @@ int switch_root(const char *new_root) {
snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
char_array_0(new_mount);
mkdir_p(new_mount, 0755);
mkdir_p_label(new_mount, 0755);
if ((stat(new_mount, &sb) < 0) ||
sb.st_dev != new_root_stat.st_dev) {
@ -97,11 +91,16 @@ int switch_root(const char *new_root) {
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 (mount(i, new_mount, NULL, mountflags, NULL) < 0) {
if (mountflags & MS_MOVE) {
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);
}
if (mountflags & MS_BIND)
log_error("Failed to bind mount %s to %s: %m", i, new_mount);
if (umount2(i, MNT_FORCE) < 0)
log_warning("Failed to unmount %s: %m", i);
}
}
@ -127,10 +126,10 @@ int switch_root(const char *new_root) {
* 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");
/* Immediately get rid of the old root, if detach_oldroot is set.
* Since we are running off it we need to do this lazily. */
if (detach_oldroot && umount2(oldroot, MNT_DETACH) < 0) {
log_error("Failed to umount old root dir %s: %m", oldroot);
return -errno;
}

2
src/core/switch-root.h → src/shared/switch-root.h
View file

@ -21,4 +21,4 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
int switch_root(const char *switch_root);
int switch_root(const char *new_root, const char *oldroot, bool detach_oldroot, unsigned long mountflags);