#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) {
"/sys\0"
"/run\0";
- int r, old_root_fd = -1;
+ _cleanup_close_ int old_root_fd = -1;
struct stat new_root_stat;
bool old_root_remove;
- const char *i;
+ 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) {
- r = -errno;
log_error("Failed to stat directory %s: %m", new_root);
- goto fail;
+ return -errno;
}
/* Work-around for a kernel bug: for some reason the kernel
snprintf(new_mount, sizeof(new_mount), "%s%s", new_root, i);
char_array_0(new_mount);
+ mkdir_parents(new_mount, 0755);
+
if ((stat(new_mount, &sb) < 0) ||
sb.st_dev != new_root_stat.st_dev) {
}
}
+ 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) {
- r = -errno;
log_error("Failed to change directory to %s: %m", new_root);
- goto fail;
+ return -errno;
}
if (old_root_remove) {
log_warning("Failed to open root directory: %m");
}
- if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
- r = -errno;
+ /* 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);
- goto fail;
+ return -errno;
}
if (chroot(".") < 0) {
- r = -errno;
log_error("Failed to change root: %m");
- goto fail;
+ return -errno;
+ }
+
+ if (chdir("/") < 0) {
+ log_error("Failed to change directory: %m");
+ return -errno;
}
if (old_root_fd >= 0) {
}
}
- r = 0;
-
-fail:
- if (old_root_fd >= 0)
- close_nointr_nofail(old_root_fd);
-
- return r;
+ return 0;
}