SDSTOR-20656: clear wbc chunk selector

README.md

@@ -320,6 +320,7 @@ sudo build/Debug/src/test/legacy_ublk/homeblk_ublk \
 | `--vol_size_mb` / `--page_size` | Volume size and logical block size (default 4096) when creating. |
 | `--num_threads` | HomeBlocks iomgr reactor count. |
 | `--data_chunk_size_mb` / `--index_chunk_size_mb` | HomeStore chunk sizing (see the note below). |
+| `--dynamic_chunk_allocation=<true\|false>` | Lazy (thin) data chunk allocation for new volumes: `true` starts a volume with a few chunks and grows on demand, `false` pre-allocates all of its chunks at create. Overrides the `dynamic_chunk_allocation` dynamic config (default `true`). |
 | `--device_id <n>` | ublk device id: `-1` to assign one, `>=0` to recover a kernel-preserved device. |
 
 In another terminal, drive I/O at the printed device. All raw I/O is `O_DIRECT` with the volume's page size as

conanfile.py

@@ -10,7 +10,7 @@
 
 class HomeBlocksConan(ConanFile):
     name = "homeblocks"
-    version = "6.0.10"
+    version = "6.0.11"
 
     homepage = "https://github.com/eBay/HomeBlocks"
     description = "Block Store built on HomeStore"

src/lib/home_blks_config.fbs

@@ -22,6 +22,9 @@ table HomeBlksSettings{
     // homestore dataservice chunk size;
     hs_data_chunk_size_mb: uint32 = 2048;
 
+    // lazy chunk allocator on/off
+    dynamic_chunk_allocation: bool = true;
+
     // how often (in appended LSNs) the leader auto-proposes a SyncRSCommitLSN entry; also gates how
     // often a commit_lsn advance triggers a HomeStore checkpoint (SDSTOR-22888, CraftReplDev::
     // checkpoint_lsn_interval_), tying checkpoint cadence to this same periodic cadence;

src/lib/homeblks_impl.cpp

@@ -275,6 +275,16 @@ hs_chunk_size_cfg_t HomeBlocksImpl::get_chunk_size() const {
     return hs_chunk_sz;
 }
 
+bool HomeBlocksImpl::dynamic_chunk_allocation() const {
+    if (SISL_OPTIONS.count("dynamic_chunk_allocation")) {
+        auto const on = SISL_OPTIONS["dynamic_chunk_allocation"].as< bool >();
+        LOGI("Using dynamic_chunk_allocation option value: {}", on);
+        return on;
+    }
+
+    return HB_DYNAMIC_CONFIG(dynamic_chunk_allocation);
+}
+
 void HomeBlocksImpl::init_homestore() {
     LOGI("Starting iomgr with {} threads", config_.threads);
     ioenvironment.with_iomgr(iomgr::iomgr_params{.num_threads = config_.threads}).with_http_server();

src/lib/homeblks_impl.hpp

@@ -153,6 +153,7 @@ class HomeBlocksImpl : public home_blocks, public std::enable_shared_from_this<
     bool is_restricted() const { return is_restricted_.load(); }
     bool is_shutting_down() const { return shutdown_started_.test(); }
     hs_chunk_size_cfg_t get_chunk_size() const;
+    bool dynamic_chunk_allocation() const;
     bool is_graceful_shutdown() const { return gracefully_shutdown_; }
 
 public:

src/lib/volume/tests/test_common.hpp

@@ -59,6 +59,8 @@ SISL_OPTION_GROUP(
      "number"),
     (index_chunk_size_mb, "", "index_chunk_size_mb", "index_chunk_size_mb",
      ::cxxopts::value< uint32_t >()->default_value("128"), "number"),
+    (dynamic_chunk_allocation, "", "dynamic_chunk_allocation", "lazy chunk allocation on/off",
+     ::cxxopts::value< bool >()->default_value("true"), "true or false"),
     (data_chunk_size_mb, "", "data_chunk_size_mb", "data_chunk_size_mb",
      ::cxxopts::value< uint32_t >()->default_value("128"), "number"));