Dynamic hot-plug udev rules for policies

[thirdparty/mdadm.git] / policy.c

diff --git a/policy.c b/policy.c
index ba976db1a7c0fc8374916b2a37a9641672592505..38b0072b5d111ab6f76168185c575efc0a5d4d8c 100644 (file)
--- a/policy.c
+++ b/policy.c
@@ -764,3 +764,136 @@ int policy_check_path(struct mdinfo *disk, struct map_ent *array)
        fclose(f);
        return rv == 5;
 }
+
+/* invocation of udev rule file */
+char udev_template_start[] =
+"# do not edit this file, it is automatically generated by mdadm\n"
+"\n";
+
+/* find rule named rule_type and return its value */
+char *find_rule(struct rule *rule, char *rule_type)
+{
+       while (rule) {
+               if (rule->name == rule_type)
+                       return rule->value;
+
+               rule = rule->next;
+       }
+       return NULL;
+}
+
+#define UDEV_RULE_FORMAT \
+"ACTION==\"add\", SUBSYSTEM=\"block\", " \
+"ENV{DEVTYPE}==\"%s\", ENV{ID_PATH}==\"%s\", " \
+"RUN+=\"/sbin/mdadm --incremental $env{DEVNAME}\", "
+
+#define UDEV_RULE_FORMAT_NOTYPE \
+"ACTION==\"add\", SUBSYSTEM=\"block\", " \
+"ENV{ID_PATH}==\"%s\", " \
+"RUN+=\"/sbin/mdadm --incremental $env{DEVNAME}\", "
+
+/* Write rule in the rule file. Use format from UDEV_RULE_FORMAT */
+int write_rule(struct rule *rule, int fd, int force_part)
+{
+       char line[1024];
+       char *pth = find_rule(rule, rule_path);
+       char *typ = find_rule(rule, rule_type);
+       if (!pth)
+               return -1;
+
+       if (force_part)
+               typ = type_part;
+       if (typ)
+               snprintf(line, sizeof(line) - 1, UDEV_RULE_FORMAT, typ, pth);
+       else
+               snprintf(line, sizeof(line) - 1, UDEV_RULE_FORMAT_NOTYPE, pth);
+       return write(fd, line, strlen(line)) == (int)strlen(line);
+}
+
+/* Generate single entry in udev rule basing on POLICY line found in config
+ * file. Take only those with paths, only first occurrence if paths are equal
+ * and if actions supports handling of spares (>=act_spare_same_slot)
+ */
+int generate_entries(int fd)
+{
+       struct pol_rule *loop, *dup;
+       char *loop_value, *dup_value;
+       int duplicate;
+
+       for (loop = config_rules; loop; loop = loop->next) {
+               if (loop->type != rule_policy && loop->type != rule_part)
+                       continue;
+               duplicate = 0;
+
+               /* only policies with paths and with actions supporting
+                * bare disks are considered */
+               loop_value = find_rule(loop->rule, pol_act);
+               if (!loop_value || map_act(loop_value) < act_spare_same_slot)
+                       continue;
+               loop_value = find_rule(loop->rule, rule_path);
+               if (!loop_value)
+                       continue;
+               for (dup = config_rules; dup != loop; dup = dup->next) {
+                       if (dup->type != rule_policy && loop->type != rule_part)
+                               continue;
+                       dup_value = find_rule(dup->rule, pol_act);
+                       if (!dup_value || map_act(dup_value) < act_spare_same_slot)
+                               continue;
+                       dup_value = find_rule(dup->rule, rule_path);
+                       if (!dup_value)
+                               continue;
+                       if (strcmp(loop_value, dup_value) == 0) {
+                               duplicate = 1;
+                               break;
+                       }
+               }
+
+               /* not a dup or first occurrence */
+               if (!duplicate)
+                       if (!write_rule(loop->rule, fd, loop->type == rule_part) )
+                               return 0;
+       }
+       return 1;
+}
+
+/* Write_rules routine creates dynamic udev rules used to handle
+ * hot-plug events for bare devices (and making them spares)
+ */
+int Write_rules(char *rule_name)
+{
+       int fd;
+       char udev_rule_file[PATH_MAX];
+
+       if (rule_name) {
+              strcpy(udev_rule_file, rule_name);
+              strcat(udev_rule_file, ".temp");
+               fd = creat(udev_rule_file,
+                          S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+              if (fd == -1)
+                      return 1;
+       } else
+               fd = 1;
+
+       /* write static invocation */
+       if (write(fd, udev_template_start,
+                sizeof(udev_template_start) - 1)
+          != (int)sizeof(udev_template_start)-1)
+              goto abort;
+
+       /* iterate, if none created or error occurred, remove file */
+       if (generate_entries(fd) < 0)
+              goto abort;
+
+       fsync(fd);
+       if (rule_name) {
+              close(fd);
+              rename(udev_rule_file, rule_name);
+       }
+       return 0;
+abort:
+       if (rule_name) {
+              close(fd);
+              unlink(udev_rule_file);
+       }
+       return 1;
+}