os/bluestore: Implemented create-bdev-label

Introduces a helper function create_bdev_label() and a new command create-bdev-label
to write essential OSD metadata (e.g., fsid, whoami) directly into the device label
at offset 0, for use on devices where support_bdev_label == false.

Usage: ./bin/ceph-bluestore-tool --path dev/osd0 --dev dev/osd0/block create-bdev-label

If a label already exists, the function throws an error to avoid overwriting.

This lays the groundwork for eventually removing duplicated metadata from
the OSD directory for devices that don’t support native bdev labels

Signed-off-by: Jaya Prakash <[email protected]>

Author: Jayaprakash-ibm

doc/man/8/ceph-bluestore-tool.rst

@@ -35,6 +35,8 @@ Synopsis
 | **ceph-bluestore-tool** trim --path *osd path*
 | **ceph-bluestore-tool** zap-device --dev *dev path*
 | **ceph-bluestore-tool** revert-wal-to-plain --path *osd path*
+| **ceph-bluestore-tool** create-bdev-labels --path *osd path* --dev *device*
+
 
 
 Description
@@ -171,6 +173,14 @@ Commands
    Changes WAL files from envelope mode to the legacy plain mode.
    Useful for downgrades, or if you might want to disable this new feature (bluefs_wal_envelope_mode).
 
+:command:`create-bdev-labels` --path *osd path* --dev *device*
+
+   Writes a bdev label to BlueStore devices that originally did not support labeling.
+   Reads metadata (e.g., fsid, ceph version) from --path and writes it to the device at --dev.
+   Only the main device (block) gets full metadata; block.db or block.wal do not.
+   The --dev path must be inside the --path directory, as its name determines the device role.
+   Use --yes-i-really-really-mean-it to recreate corrupted labels.
+
 Options
 =======
 

src/os/CMakeLists.txt

@@ -29,6 +29,7 @@ if(WITH_BLUESTORE)
     bluestore/Writer.cc
     bluestore/Compression.cc
     bluestore/BlueAdmin.cc
+    bluestore/BlueEnv.cc
   )
 endif(WITH_BLUESTORE)
 

src/os/bluestore/BlueEnv.cc

@@ -0,0 +1,113 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include <stdio.h>
+#include <string.h>
+#include <filesystem>
+#include <iostream>
+#include <fstream>
+#include <time.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include "global/global_init.h"
+#include "common/ceph_argparse.h"
+#include "include/stringify.h"
+#include "common/errno.h"
+#include "common/safe_io.h"
+
+#include "os/bluestore/BlueStore.h"
+
+using namespace std;
+
+
+int BlueStore::create_bdev_labels(CephContext *cct,
+                                 const std::string& path,
+                                 const std::vector<std::string>& devs,
+				 std::vector<uint64_t>* valid_positions,
+				 bool force)
+{
+  std::vector<std::string> metadata_files = {
+    "bfm_blocks",
+    "bfm_blocks_per_key",
+    "bfm_bytes_per_block",
+    "bfm_size",
+    "bluefs",
+    "ceph_fsid",
+    "ceph_version_when_created",
+    "created_at",
+    "elastic_shared_blobs",
+    "fsid",
+    "kv_backend",
+    "magic",
+    "osd_key",
+    "ready",
+    "require_osd_release",
+    "type",
+    "whoami"
+  };
+
+  unique_ptr<BlockDevice> bdev(BlockDevice::create(cct, devs.front(), nullptr, nullptr, nullptr, nullptr));
+  int r = bdev->open(devs.front());
+  if (r < 0) {
+    return r;
+  }
+  uint64_t size = bdev->get_size();
+
+  if (bdev->supported_bdev_label() && !force) {
+    bdev->close();
+    return -EPERM;
+  }
+
+  bdev->close();
+
+  bluestore_bdev_label_t label;
+  std::vector<uint64_t> out_positions;
+  bool is_multi = false;
+  int64_t epoch = -1;
+
+  r = BlueStore::read_bdev_label(cct, devs.front(), &label,
+    &out_positions, &is_multi, &epoch);
+
+  if (r == 0 && !force)
+    return -EEXIST;
+
+  label = bluestore_bdev_label_t();
+  label.btime = ceph_clock_now();
+
+  if (devs.front().ends_with("block")) {
+    label.description = "main";
+  } else if (devs.front().ends_with("block.db")) {
+    label.description = "bluefs db";
+  } else if (devs.front().ends_with("block.wal")) {
+    label.description = "bluefs wal";
+  }
+
+  label.size = size;
+
+  for (const auto& file : metadata_files) {
+    std::ifstream infile(path + "/" + file);
+    if (infile) {
+      std::string value((std::istreambuf_iterator<char>(infile)), std::istreambuf_iterator<char>());
+      value.erase(std::remove(value.begin(), value.end(), '\n'), value.end());
+      if (file == "fsid") {
+        label.osd_uuid.parse(value.c_str());
+      } else if (label.description == "main") {
+        label.meta[file] = value;
+      }
+    } else {
+      cerr << "Warning: unable to read metadata file: " << file << std::endl;
+    }
+  }
+
+  bool wrote_at_least_one = false;
+  for (uint64_t position : *valid_positions) {
+    r = BlueStore::write_bdev_label(cct, devs.front(), label, position);
+    if (r < 0) {
+      cerr << "unable to write label at 0x" << std::hex << position << std::dec
+           << ": " << cpp_strerror(r) << std::endl;
+    } else {
+      wrote_at_least_one = true;
+    }
+  }
+  return wrote_at_least_one ? 0 : -EIO;
+}

src/os/bluestore/BlueStore.h

@@ -4175,6 +4175,13 @@ class BlueStore : public ObjectStore,
 
   void _fsck_check_objects(FSCKDepth depth,
     FSCK_ObjectCtx& ctx);
+
+public:
+  static int create_bdev_labels(CephContext *cct,
+                          const std::string& path,
+                          const std::vector<std::string>& devs,
+			  std::vector<uint64_t>* valid_positions,
+			  bool force);
 };
 
 inline std::ostream& operator<<(std::ostream& out, const BlueStore::volatile_statfs& s) {

src/os/bluestore/bluestore_tool.cc

@@ -357,6 +357,7 @@ int main(int argc, char **argv)
         "show-label, "
         "show-label-at, "
         "set-label-key, "
+	"create-bdev-labels, "
         "rm-label-key, "
         "prime-osd-dir, "
         "bluefs-super-dump, "
@@ -520,6 +521,16 @@ int main(int argc, char **argv)
       exit(EXIT_FAILURE);
     }
   }
+  if (action == "create-bdev-labels") {
+    if (path.empty()) {
+      cerr << "must specify bluestore path" << std::endl;
+      exit(EXIT_FAILURE);
+    }
+    if (devs.size() != 1) {
+      cerr << "must specify the main bluestore device" << std::endl;
+      exit(EXIT_FAILURE);
+    }
+  }
   if (action == "show-label") {
     if (devs.empty() && path.empty()) {
       cerr << "must specify bluestore path *or* raw device(s)" << std::endl;
@@ -837,6 +848,32 @@ int main(int argc, char **argv)
     jf.close_section();
     jf.flush(cout);
   }
+  else if (action == "create-bdev-labels") {
+
+    std::vector<uint64_t> valid_positions = {0};
+
+    bool force = vm.count("yes-i-really-really-mean-it");
+    int r = BlueStore::create_bdev_labels(cct.get(), path, devs, &valid_positions, force);
+    if (r == -EPERM && !force) {
+      cerr << "device " << devs.front()
+           << " already supports bdev label refusing to create a new label without --yes-i-really-really-mean-it"
+           << std::endl;
+      exit(EXIT_FAILURE);
+    }
+
+    if (r == -EEXIST && !force) {
+      cerr << "device " << devs.front() << " already has a label" << std::endl;
+      cerr << "Creating a new label on top of an existing one is a dangerous operation "
+	   << "which could cause data loss.\n"
+	   << "Please confirm with --yes-i-really-really-mean-it option" << std::endl;
+      exit(EXIT_FAILURE);
+    }
+
+    if (r < 0) {
+      cerr << "Failed to create bdev label: " << cpp_strerror(r) << std::endl;
+      exit(EXIT_FAILURE);
+    }
+  }
   else if (action == "set-label-key") {
     bluestore_bdev_label_t label;
     std::vector<uint64_t> valid_positions;