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volatile-root: export original root

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This commit is contained in:
Lennart Poettering 2018-12-20 10:13:35 +01:00
parent 1de7f825d3
commit d10b92cb5e
1 changed files with 20 additions and 0 deletions
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20
src/volatile-root/volatile-root.c
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@ -3,6 +3,7 @@
#include <sys/mount.h>
#include "alloc-util.h"
#include "blockdev-util.h"
#include "escape.h"
#include "fs-util.h"
#include "main-func.h"
@ -115,6 +116,7 @@ finish:
static int run(int argc, char *argv[]) {
VolatileMode m = _VOLATILE_MODE_INVALID;
const char *path;
dev_t devt;
int r;
log_setup_service();
@ -166,6 +168,24 @@ static int run(int argc, char *argv[]) {
return 0;
}
/* We are about to replace the root directory with something else. Later code might want to know what we
* replaced here, hence let's save that information as a symlink we can later use. (This is particularly
* relevant for the overlayfs case where we'll fully obstruct the view onto the underlying device, hence
* querying the backing device node from the file system directly is no longer possible. */
r = get_block_device_harder(path, &devt);
if (r < 0)
return log_error_errno(r, "Failed to determine device major/minor of %s: %m", path);
else if (r > 0) {
_cleanup_free_ char *dn = NULL;
r = device_path_make_major_minor(S_IFBLK, devt, &dn);
if (r < 0)
return log_error_errno(r, "Failed to format device node path: %m");
if (symlink(dn, "/run/systemd/volatile-root") < 0)
log_warning_errno(errno, "Failed to create symlink /run/systemd/volatile-root: %m");
}
if (m == VOLATILE_YES)
return make_volatile(path);
else {