nsresourced: fix build without libbpf

```
In file included from ../src/nsresourced/nsresourced-manager.c:9:
../src/shared/bpf-link.h:5:10: fatal error: bpf/libbpf.h: No such file or directory
    5 | #include <bpf/libbpf.h>
      |          ^~~~~~~~~~~~~~
```

Follow-up for 46718d344f

src/nsresourced/nsresourced-manager.c

@@ -6,7 +6,9 @@
 #include "sd-daemon.h"
 
 #include "bpf-dlopen.h"
+#if HAVE_VMLINUX_H
 #include "bpf-link.h"
+#endif
 #include "build-path.h"
 #include "common-signal.h"
 #include "env-util.h"

src/partition/repart.c

@@ -304,19 +304,6 @@ static SubvolumeFlags subvolume_flags_from_string(const char *s) {
         return flags;
 }
 
-static char* subvolume_flags_to_string(SubvolumeFlags flags) {
-        const char *l[CONST_LOG2U(_SUBVOLUME_FLAGS_MASK + 1) + 1]; /* one string per known flag at most */
-        size_t m = 0;
-
-        if (FLAGS_SET(flags, SUBVOLUME_RO))
-                l[m++] = "ro";
-
-        assert(m < ELEMENTSOF(l));
-        l[m] = NULL;
-
-        return strv_join((char**) l, ",");
-}
-
 typedef struct Subvolume {
         char *path;
         SubvolumeFlags flags;
@@ -2438,6 +2425,14 @@ static int partition_read_definition(Partition *p, const char *path, const char
                                   "SizeMinBytes=/SizeMaxBytes= cannot be used with Verity=%s.",
                                   verity_mode_to_string(p->verity));
 
+        if (!ordered_hashmap_isempty(p->subvolumes) && arg_offline > 0)
+                return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EOPNOTSUPP),
+                                  "Subvolumes= cannot be used with --offline=yes.");
+
+        if (p->default_subvolume && arg_offline > 0)
+                return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EOPNOTSUPP),
+                                  "DefaultSubvolume= cannot be used with --offline=yes.");
+
         if (p->default_subvolume && !ordered_hashmap_contains(p->subvolumes, p->default_subvolume))
                 return log_syntax(NULL, LOG_ERR, path, 1, SYNTHETIC_ERRNO(EINVAL),
                                   "DefaultSubvolume= must be one of the paths in Subvolumes=.");
@@ -4286,7 +4281,7 @@ static int prepare_temporary_file(Context *context, PartitionTarget *t, uint64_t
 
 static bool loop_device_error_is_fatal(const Partition *p, int r) {
         assert(p);
-        return arg_offline == 0 || (r != -ENOENT && !ERRNO_IS_PRIVILEGE(r));
+        return arg_offline == 0 || (r != -ENOENT && !ERRNO_IS_PRIVILEGE(r)) || !ordered_hashmap_isempty(p->subvolumes) || p->default_subvolume;
 }
 
 static int partition_target_prepare(
@@ -5793,38 +5788,6 @@ static int partition_populate_filesystem(Context *context, Partition *p, const c
         return 0;
 }
 
-static int append_btrfs_subvols(char ***l, OrderedHashmap *subvolumes, const char *default_subvolume) {
-        Subvolume *subvolume;
-        int r;
-
-        assert(l);
-
-        ORDERED_HASHMAP_FOREACH(subvolume, subvolumes) {
-                _cleanup_free_ char *s = NULL, *f = NULL;
-
-                s = strdup(subvolume->path);
-                if (!s)
-                        return log_oom();
-
-                f = subvolume_flags_to_string(subvolume->flags);
-                if (!f)
-                        return log_oom();
-
-                if (streq_ptr(subvolume->path, default_subvolume) &&
-                    !strextend_with_separator(&f, ",", "default"))
-                        return log_oom();
-
-                if (!isempty(f) && !strextend_with_separator(&s, ":", f))
-                        return log_oom();
-
-                r = strv_extend_many(l, "--subvol", s);
-                if (r < 0)
-                        return log_oom();
-        }
-
-        return 0;
-}
-
 static int finalize_extra_mkfs_options(const Partition *p, const char *root, char ***ret) {
         _cleanup_strv_free_ char **sv = NULL;
         int r;
@@ -5838,18 +5801,6 @@ static int finalize_extra_mkfs_options(const Partition *p, const char *root, cha
                                        "Failed to determine mkfs command line options for '%s': %m",
                                        p->format);
 
-        if (partition_needs_populate(p) && root && streq(p->format, "btrfs")) {
-                r = append_btrfs_subvols(&sv, p->subvolumes, p->default_subvolume);
-                if (r < 0)
-                        return r;
-
-                if (p->suppressing) {
-                        r = append_btrfs_subvols(&sv, p->suppressing->subvolumes, NULL);
-                        if (r < 0)
-                                return r;
-                }
-        }
-
         *ret = TAKE_PTR(sv);
         return 0;
 }