Add vitastor-disk update-sb command

docs/usage/disk.en.md

@@ -17,6 +17,7 @@ It supports the following commands:
 - [purge](#purge)
 - [read-sb](#read-sb)
 - [write-sb](#write-sb)
+- [update-sb](#update-sb)
 - [udev](#udev)
 - [exec-osd](#exec-osd)
 - [pre-exec](#pre-exec)
@@ -182,6 +183,14 @@ Try to read Vitastor OSD superblock from `<device>` and print it in JSON format.
 
 Read JSON from STDIN and write it into Vitastor OSD superblock on `<device>`.
 
+## update-sb
+
+`vitastor-disk update-sb <device> [--force] [--<parameter> <value>] [...]`
+
+Read Vitastor OSD superblock from <device>, update parameters in it and write it back.
+
+`--force` allows to ignore validation errors.
+
 ## udev
 
 `vitastor-disk udev <device>`

docs/usage/disk.ru.md

@@ -17,6 +17,7 @@ vitastor-disk - инструмент командной строки для уп
 - [purge](#purge)
 - [read-sb](#read-sb)
 - [write-sb](#write-sb)
+- [update-sb](#update-sb)
 - [udev](#udev)
 - [exec-osd](#exec-osd)
 - [pre-exec](#pre-exec)
@@ -187,6 +188,15 @@ throttle_target_mbs, throttle_target_parallelism, throttle_threshold_us.
 
 Прочитать JSON со стандартного ввода и записать его в суперблок OSD на диск `<device>`.
 
+## update-sb
+
+`vitastor-disk update-sb <device> [--force] [--<параметр> <значение>] [...]`
+
+Прочитать суперблок OSD с диска `<device>`, изменить в нём заданные параметры и записать обратно.
+
+Опция `--force` позволяет читать суперблок, даже если он считается некорректным
+из-за ошибок валидации.
+
 ## udev
 
 `vitastor-disk udev <device>`

src/disk_tool.cpp

@@ -127,6 +127,10 @@ static const char *help_text =
     "vitastor-disk write-sb <device>\n"
     "  Read JSON from STDIN and write it into Vitastor OSD superblock on <device>.\n"
     "\n"
+    "vitastor-disk update-sb <device> [--force] [--<parameter> <value>] [...]\n"
+    "  Read Vitastor OSD superblock from <device>, update parameters in it and write it back.\n"
+    "  --force allows to ignore validation errors.\n"
+    "\n"
     "vitastor-disk udev <device>\n"
     "  Try to read Vitastor OSD superblock from <device> and print variables for udev.\n"
     "\n"
@@ -363,6 +367,15 @@ int main(int argc, char *argv[])
         }
         return self.write_sb(cmd[1]);
     }
+    else if (!strcmp(cmd[0], "update-sb"))
+    {
+        if (cmd.size() != 2)
+        {
+            fprintf(stderr, "Exactly 1 device path argument is required\n");
+            return 1;
+        }
+        return self.update_sb(cmd[1]);
+    }
     else if (!strcmp(cmd[0], "start") || !strcmp(cmd[0], "stop") ||
         !strcmp(cmd[0], "restart") || !strcmp(cmd[0], "enable") || !strcmp(cmd[0], "disable"))
     {

src/disk_tool.h

@@ -109,6 +109,7 @@ struct disk_tool_t
     int udev_import(std::string device);
     int read_sb(std::string device);
     int write_sb(std::string device);
+    int update_sb(std::string device);
     int exec_osd(std::string device);
     int systemd_start_stop_osds(const std::vector<std::string> & cmd, const std::vector<std::string> & devices);
     int pre_exec_osd(std::string device);

src/disk_tool_udev.cpp

@@ -86,6 +86,24 @@ int disk_tool_t::write_sb(std::string device)
     return !write_osd_superblock(device, params);
 }
 
+int disk_tool_t::update_sb(std::string device)
+{
+    json11::Json sb = read_osd_superblock(device, true, options.find("force") != options.end());
+    if (sb.is_null())
+    {
+        return 1;
+    }
+    auto sb_obj = sb["params"].object_items();
+    for (auto & kv: options)
+    {
+        if (kv.first != "force")
+        {
+            sb_obj[kv.first] = kv.second;
+        }
+    }
+    return !write_osd_superblock(device, sb_obj);
+}
+
 uint32_t disk_tool_t::write_osd_superblock(std::string device, json11::Json params)
 {
     std::string json_data = params.dump();