os/bluestore: Add unittest for BlueFS::truncate()

Add unittest for some truncate scenarios.

Fixes: https://tracker.ceph.com/issues/68385 (addendum)

Signed-off-by: Adam Kupczyk <[email protected]>

Author: aclamk

src/test/objectstore/test_bluefs.cc

@@ -1419,6 +1419,87 @@ TEST(BlueFS, test_concurrent_dir_link_and_compact_log_56210) {
   }
 }
 
+TEST(BlueFS, truncate_drops_allocations) {
+  constexpr uint64_t K = 1024;
+  constexpr uint64_t M = 1024 * K;
+  uuid_d fsid;
+  const char* DIR_NAME="dir";
+  const char* FILE_NAME="file1";
+  struct {
+    uint64_t preallocated_size;
+    uint64_t write_size;
+    uint64_t truncate_to;
+    uint64_t allocated_after_truncate;
+    uint64_t slow_size = 0;
+    uint64_t slow_alloc_size = 64*K;
+    uint64_t db_size = 128*M;
+    uint64_t db_alloc_size = 1*M;
+  } scenarios [] = {
+    // on DB(which is SLOW) : 1 => 1, 64K remains
+    { 1*M, 1, 1, 64*K },
+    // on DB(which is SLOW), alloc 4K : 1 => 1, 4K remains
+    { 1*M, 1, 1, 4*K, 0, 4*K },
+    // on DB(which is SLOW), truncation on AU boundary : 128K => 128K, 128K remains
+    { 1*M, 128*K, 128*K, 128*K },
+    // on DB(which is SLOW), no prealloc, truncation to 0 : 1666K => 0, 0 remains
+    { 0, 1666*K, 0, 0 },
+    // on DB, truncate to 123K, expect 1M occupied
+    { 1234*K, 123*K, 123*K, 1*M, 128*M, 64*K, 10*M, 1*M },
+    // on DB, truncate to 0, expect 0 occupied
+    { 1234*K, 345*K, 0, 0, 128*M, 64*K, 10*M, 1*M },
+    // on DB, truncate to AU boundary, expect exactly 1M occupied
+    { 1234*K, 1123*K, 1*M, 1*M, 128*M, 64*K, 10*M, 1*M },
+    // on DB and SLOW, truncate only data on SLOW
+    { 0, 10*M+1, 10*M+1, 10*M+64*K, 128*M, 64*K, 10*M, 1*M },
+    // on DB and SLOW, preallocate and truncate only data on SLOW
+    { 6*M, 12*M, 10*M+1, 10*M+64*K, 128*M, 64*K, 10*M, 1*M },
+    // on DB and SLOW, preallocate and truncate all in SLOW and some on DB
+    // note! prealloc 6M is important, one allocation for 12M will fallback to SLOW
+    // in 6M + 6M we can be sure that 6M is on DB and 6M is on SLOW
+    { 6*M, 12*M, 3*M+1, 4*M, 128*M, 64*K, 11*M, 1*M },
+  };
+  for (auto& s : scenarios) {
+    ConfSaver conf(g_ceph_context->_conf);
+    conf.SetVal("bluefs_shared_alloc_size", stringify(s.slow_alloc_size).c_str());
+    conf.SetVal("bluefs_alloc_size", stringify(s.db_alloc_size).c_str());
+
+    g_ceph_context->_conf.set_val("bluefs_shared_alloc_size", stringify(s.slow_alloc_size));
+    g_ceph_context->_conf.set_val("bluefs_alloc_size", stringify(s.db_alloc_size));
+    TempBdev bdev_db{s.db_size};
+    TempBdev bdev_slow{s.slow_size};
+
+    BlueFS fs(g_ceph_context);
+    if (s.db_size != 0) {
+      ASSERT_EQ(0, fs.add_block_device(BlueFS::BDEV_DB, bdev_db.path, false, 0));
+    }
+    if (s.slow_size != 0) {
+      ASSERT_EQ(0, fs.add_block_device(BlueFS::BDEV_SLOW, bdev_slow.path, false, 0));
+    }
+
+    ASSERT_EQ(0, fs.mkfs(fsid, {BlueFS::BDEV_DB, false, false}));
+    ASSERT_EQ(0, fs.mount());
+    ASSERT_EQ(0, fs.maybe_verify_layout({BlueFS::BDEV_DB, false, false}));
+    BlueFS::FileWriter *h;
+    ASSERT_EQ(0, fs.mkdir("dir"));
+    ASSERT_EQ(0, fs.open_for_write(DIR_NAME, FILE_NAME, &h, false));
+    uint64_t pre = fs.get_used();
+    ASSERT_EQ(0, fs.preallocate(h->file, 0, s.preallocated_size));
+    const std::string content(s.write_size, 'x');
+    h->append(content.c_str(), content.length());
+    fs.fsync(h);
+    ASSERT_EQ(0, fs.truncate(h, s.truncate_to));
+    fs.fsync(h);
+    uint64_t post = fs.get_used();
+    fs.close_writer(h);
+    EXPECT_EQ(pre, post - s.allocated_after_truncate);
+
+    fs.umount();
+  }
+}
+
+
+
+
 TEST(BlueFS, test_log_runway) {
   uint64_t max_log_runway = 65536;
   ConfSaver conf(g_ceph_context->_conf);