MDEV-27901 Windows : expensive system calls used to calculate file system block size

The result is not used anywhere but in the output of Innodb information
schema, but this can take as much as 7%CPU (only) on a benchmark.

Fix to move fs blocksize calculate to where it is used.

storage/innobase/handler/i_s.cc

@@ -6745,6 +6745,9 @@ static ST_FIELD_INFO innodb_sys_tablespaces_fields_info[]=
   END_OF_ST_FIELD_INFO
 };
 
+
+extern size_t os_file_get_fs_block_size(const char *path);
+
 /**********************************************************************//**
 Function to fill INFORMATION_SCHEMA.INNODB_SYS_TABLESPACES with information
 collected by scanning SYS_TABLESPACESS table.
@@ -6814,11 +6817,10 @@ i_s_dict_fill_sys_tablespaces(
 	OK(fields[SYS_TABLESPACES_ZIP_PAGE_SIZE]->store(
 		   page_size.physical(), true));
 
-	os_file_stat_t	stat;
+	size_t fs_block_size = 0;
 	os_file_size_t	file;
 
 	memset(&file, 0xff, sizeof(file));
-	memset(&stat, 0x0, sizeof(stat));
 
 	if (fil_space_t* s = fil_space_acquire_silent(space)) {
 		const char *filepath = s->chain.start
@@ -6828,36 +6830,19 @@ i_s_dict_fill_sys_tablespaces(
 		}
 
 		file = os_file_get_size(filepath);
-
-		/* Get the file system (or Volume) block size. */
-		switch (dberr_t err = os_file_get_status(filepath, &stat,
-							 false, false)) {
-		case DB_FAIL:
-			ib::warn()
-				<< "File '" << filepath << "', failed to get "
-				<< "stats";
-			break;
-
-		case DB_SUCCESS:
-		case DB_NOT_FOUND:
-			break;
-
-		default:
-			ib::error() << "File '" << filepath << "' " << err;
-			break;
-		}
+		fs_block_size= os_file_get_fs_block_size(filepath);
 
 file_done:
 		fil_space_release(s);
 	}
 
 	if (file.m_total_size == static_cast<os_offset_t>(~0)) {
-		stat.block_size = 0;
+		fs_block_size = 0;
 		file.m_total_size = 0;
 		file.m_alloc_size = 0;
 	}
 
-	OK(fields[SYS_TABLESPACES_FS_BLOCK_SIZE]->store(stat.block_size, true));
+	OK(fields[SYS_TABLESPACES_FS_BLOCK_SIZE]->store(fs_block_size, true));
 
 	OK(fields[SYS_TABLESPACES_FILE_SIZE]->store(file.m_total_size, true));
 

storage/innobase/os/os0file.cc

@@ -4795,48 +4795,6 @@ os_file_get_status_win32(
 				CloseHandle(fh);
 			}
 		}
-		stat_info->block_size = 0;
-
-		/* What follows, is calculation of FS block size, which is not important
-		(it is just shown in I_S innodb tables). The error to calculate it will be ignored.*/
-		char	volname[MAX_PATH];
-		BOOL	result = GetVolumePathName(path, volname, MAX_PATH);
-		static	bool warned_once = false;
-		if (!result) {
-			if (!warned_once) {
-				ib::warn()
-					<< "os_file_get_status_win32: "
-					<< "Failed to get the volume path name for: "
-					<< path
-					<< "- OS error number " << GetLastError();
-				warned_once = true;
-			}
-			return(DB_SUCCESS);
-		}
-
-		DWORD	sectorsPerCluster;
-		DWORD	bytesPerSector;
-		DWORD	numberOfFreeClusters;
-		DWORD	totalNumberOfClusters;
-
-		result = GetDiskFreeSpace(
-			(LPCSTR) volname,
-			&sectorsPerCluster,
-			&bytesPerSector,
-			&numberOfFreeClusters,
-			&totalNumberOfClusters);
-
-		if (!result) {
-			if (!warned_once) {
-				ib::warn()
-					<< "GetDiskFreeSpace(" << volname << ",...) "
-					<< "failed "
-					<< "- OS error number " << GetLastError();
-				warned_once = true;
-			}
-			return(DB_SUCCESS);
-		}
-		stat_info->block_size = bytesPerSector * sectorsPerCluster;
 	} else {
 		stat_info->type = OS_FILE_TYPE_UNKNOWN;
 	}
@@ -5736,6 +5694,36 @@ os_is_sparse_file_supported(os_file_t fh)
 #endif /* _WIN32 */
 }
 
+/*
+  Get file system block size, by path.
+
+  This is expensive on Windows, and not very useful in general,
+  (only shown in some I_S table), so we keep that out of usual
+  stat.
+*/
+size_t os_file_get_fs_block_size(const char *path)
+{
+#ifdef _WIN32
+  char volname[MAX_PATH];
+  if (!GetVolumePathName(path, volname, MAX_PATH))
+    return 0;
+  DWORD sectorsPerCluster;
+  DWORD bytesPerSector;
+  DWORD numberOfFreeClusters;
+  DWORD totalNumberOfClusters;
+
+  if (GetDiskFreeSpace(volname, &sectorsPerCluster, &bytesPerSector,
+                       &numberOfFreeClusters, &totalNumberOfClusters))
+    return ((size_t) bytesPerSector) * sectorsPerCluster;
+#else
+  os_file_stat_t info;
+  if (os_file_get_status(path, &info, false, false) == DB_SUCCESS)
+    return info.block_size;
+#endif
+  return 0;
+}
+
+
 /** This function returns information about the specified file
 @param[in]	path		pathname of the file
 @param[out]	stat_info	information of a file in a directory