repart: do not require /var/tmp if not used

If systemd-repart is running sufficiently early, /var/tmp might not be in place
yet. But if there is nothing to minimize, we won't even use it. Let's move the
check right before the first use.

systemd-repart[441]: Device '/' has no dm-crypt/dm-verity device, no need to look for…
systemd-repart[441]: Device /dev/sda opened and locked.
systemd-repart[441]: Sector size of device is 512 bytes. Using grain size of 4096.
systemd-repart[441]: Could not determine temporary directory: No such file or directory
systemd[1]: systemd-repart.service: Child 441 belongs to systemd-repart.service.
systemd[1]: systemd-repart.service: Main process exited, code=exited, status=1/FAILURE
systemd[1]: systemd-repart.service: Failed with result 'exit-code'.

1 files changed, 13 insertions, 5 deletions

diff --git a/src/partition/repart.c b/src/partition/repart.c
index d5d5e2353f..5a2f992e2d 100644
--- a/src/partition/repart.c
+++ b/src/partition/repart.c
@@ -5515,15 +5515,11 @@ static int fd_apparent_size(int fd, uint64_t *ret) {
 }
 
 static int context_minimize(Context *context) {
-        const char *vt;
+        const char *vt = NULL;
         int r;
 
         assert(context);
 
-        r = var_tmp_dir(&vt);
-        if (r < 0)
-                return log_error_errno(r, "Could not determine temporary directory: %m");
-
         LIST_FOREACH(partitions, p, context->partitions) {
                 _cleanup_(rm_rf_physical_and_freep) char *root = NULL;
                 _cleanup_(unlink_and_freep) char *temp = NULL;
@@ -5556,6 +5552,12 @@ static int context_minimize(Context *context) {
                 log_info("Pre-populating %s filesystem of partition %s twice to calculate minimal partition size",
                          p->format, strna(hint));
 
+                if (!vt) {
+                        r = var_tmp_dir(&vt);
+                        if (r < 0)
+                                return log_error_errno(r, "Could not determine temporary directory: %m");
+                }
+
                 r = tempfn_random_child(vt, "repart", &temp);
                 if (r < 0)
                         return log_error_errno(r, "Failed to generate temporary file path: %m");
@@ -5713,6 +5715,12 @@ static int context_minimize(Context *context) {
                 log_info("Pre-populating verity hash data of partition %s to calculate minimal partition size",
                          strna(hint));
 
+                if (!vt) {
+                        r = var_tmp_dir(&vt);
+                        if (r < 0)
+                                return log_error_errno(r, "Could not determine temporary directory: %m");
+                }
+
                 r = tempfn_random_child(vt, "repart", &temp);
                 if (r < 0)
                         return log_error_errno(r, "Failed to generate temporary file path: %m");