add overlaybd-resize tool for userspace ext4 resize on overlaybd images

CMake/Finde2fs.cmake

@@ -4,13 +4,15 @@ if(NOT ORIGIN_EXT2FS)
     FetchContent_Declare(
         e2fsprogs
         GIT_REPOSITORY https://github.com/data-accelerator/e2fsprogs.git
-        GIT_TAG b4cf6c751196a12b1df9a269d8e0b516b99fe6a7
+        GIT_TAG 404deb95e6b0ed0ceb0148d289977e65bee7f8d0
     )
     FetchContent_GetProperties(e2fsprogs)
 
     if(NOT TARGET libext2fs_build)
         FetchContent_MakeAvailable(e2fsprogs)
         set(LIBEXT2FS_INSTALL_DIR ${e2fsprogs_SOURCE_DIR}/build/libext2fs CACHE STRING "")
+        set(E2FS_RESIZE_DIR ${e2fsprogs_SOURCE_DIR}/build/resize CACHE STRING "path to e2fsprogs resize build dir")
+        set(E2FS_INSTALL_LIB_DIR ${LIBEXT2FS_INSTALL_DIR}/lib CACHE STRING "path to e2fsprogs install-libs output")
 
         add_custom_command(
             OUTPUT ${LIBEXT2FS_INSTALL_DIR}/lib
@@ -22,7 +24,8 @@ if(NOT ORIGIN_EXT2FS)
 
     set(E2FS_FOUND yes)
     set(E2FS_LIBRARY ${LIBEXT2FS_INSTALL_DIR}/lib/libext2fs.so)
-    set(E2FS_LIBRARIES ${E2FS_LIBRARY})
+    set(E2FS_COM_ERR_LIBRARY ${e2fsprogs_SOURCE_DIR}/build/lib/libcom_err.a)
+    set(E2FS_LIBRARIES ${E2FS_LIBRARY} ${E2FS_COM_ERR_LIBRARY})
     set(E2FS_INCLUDE_DIR ${LIBEXT2FS_INSTALL_DIR}/include)
     set(E2FS_INCLUDE_DIRS ${E2FS_INCLUDE_DIR})
 

CMake/Findphoton.cmake

@@ -1,11 +1,13 @@
 include(FetchContent)
 set(FETCHCONTENT_QUIET false)
 set(PHOTON_ENABLE_EXTFS ON)
+set(PHOTON_ENABLE_RESIZE ON)
+add_definitions(-DPHOTON_ENABLE_RESIZE)
 
 FetchContent_Declare(
   photon
   GIT_REPOSITORY https://github.com/alibaba/PhotonLibOS.git
-  GIT_TAG v0.6.17
+  GIT_TAG 0178d14499d8639759a81e32ad58da5226df5e9b
 )
 
 if(BUILD_TESTING)

src/CMakeLists.txt

@@ -33,6 +33,18 @@ target_link_libraries(overlaybd_image_lib
   ${AIO_LIBRARIES}
 )
 
+# Propagate resize .o files to all consumers of overlaybd_image_lib.
+# These provide the resize_fs() symbol needed by photon's resize_extfs().
+if (NOT ORIGIN_EXT2FS)
+    target_link_libraries(overlaybd_image_lib
+        ${E2FS_RESIZE_DIR}/resize2fs.o
+        ${E2FS_RESIZE_DIR}/extent.o
+        ${E2FS_RESIZE_DIR}/resource_track.o
+        ${E2FS_LIBRARIES}
+    )
+    add_dependencies(overlaybd_image_lib libext2fs_build)
+endif()
+
 add_executable(overlaybd-tcmu
   main.cpp
 )

src/image_file.cpp

@@ -36,6 +36,9 @@
 #include "overlaybd/gzip/gz.h"
 #include "overlaybd/gzindex/gzfile.h"
 #include "overlaybd/tar/tar_file.h"
+#ifdef PHOTON_ENABLE_RESIZE
+#include <photon/fs/extfs/extfs.h>
+#endif
 
 #define PARALLEL_LOAD_INDEX 32
 using namespace photon::fs;
@@ -614,3 +617,59 @@ int ImageFile::create_snapshot(const char *new_config_path) {
 
     return 0;
 }
+
+int ImageFile::resize(uint64_t target_size, bool resize_fs) {
+    if (read_only) {
+        LOG_ERROR_RETURN(EROFS, -1, "cannot resize a read-only image (no upper layer)");
+    }
+
+    auto rw = (LSMT::IFileRW *)m_file;
+    struct stat st;
+    if (m_file->fstat(&st) != 0) {
+         LOG_ERRNO_RETURN(0, -1, "fstat failed");
+    }
+    uint64_t current = (uint64_t)st.st_size;
+
+    if (target_size == current && !resize_fs) {
+        LOG_INFO("vsize already equals target (` bytes), nothing to do", target_size);
+        return 0;
+    }
+
+    if (target_size > current) {
+        // Expand: grow block device first, then filesystem
+        if (rw->update_vsize(target_size) != 0) {
+            LOG_ERROR_RETURN(0, -1, "failed to update vsize for expand");
+        }
+    }
+
+    if (resize_fs) {
+#ifdef PHOTON_ENABLE_RESIZE
+        if (photon::fs::resize_extfs(m_file, target_size, 0) != 0) {
+            if (target_size >= current) {
+                LOG_ERROR("resize_extfs failed. "
+                          "Re-run to retry or use e2fsck to recover.");
+            } else {
+                LOG_ERROR("resize_extfs failed during shrink.");
+            }
+            return -1;
+        }
+#else
+        LOG_ERROR_RETURN(ENOSYS, -1, "resize_fs not supported (built without PHOTON_ENABLE_RESIZE)");
+#endif
+    }
+
+    if (target_size < current) {
+        // Shrink: shrinking without resizing the filesystem is unsafe.
+         if (!resize_fs) {
+             LOG_ERROR_RETURN(EINVAL, -1, "cannot shrink without resizing filesystem");
+         }
+        // Shrink: update vsize after filesystem is shrunk
+        if (rw->update_vsize(target_size) != 0) {
+            LOG_ERROR("filesystem resized but failed to update vsize. Re-run to retry.");
+            return -1;
+        }
+    }
+
+    LOG_INFO("resize done: ` -> ` bytes", current, target_size);
+    return 0;
+}

src/image_file.h

@@ -121,6 +121,11 @@ class ImageFile : public photon::fs::ForwardFile {
 
     int create_snapshot(const char *new_config_path);
 
+    // Resize the block device (and optionally the ext4 filesystem).
+    // target_size: new block device size in bytes.
+    // resize_fs: if true, also resize the ext4 filesystem to match.
+    int resize(uint64_t target_size, bool resize_fs = false);
+
 private:
     Prefetcher *m_prefetcher = nullptr;
     ImageConfigNS::ImageConfig conf;

src/test/CMakeLists.txt

@@ -49,3 +49,28 @@ add_test(
     NAME trace_test
     COMMAND ${EXECUTABLE_OUTPUT_PATH}/trace_test
 )
+
+if (NOT ORIGIN_EXT2FS)
+    set_source_files_properties(
+        ${E2FS_RESIZE_DIR}/resize2fs.o
+        ${E2FS_RESIZE_DIR}/extent.o
+        ${E2FS_RESIZE_DIR}/resource_track.o
+        PROPERTIES GENERATED TRUE EXTERNAL_OBJECT TRUE)
+    add_executable(resize_test
+        resize_test.cpp
+        ${E2FS_RESIZE_DIR}/resize2fs.o
+        ${E2FS_RESIZE_DIR}/extent.o
+        ${E2FS_RESIZE_DIR}/resource_track.o
+    )
+    target_include_directories(resize_test PUBLIC
+        ${PHOTON_INCLUDE_DIR}
+        ${E2FS_INCLUDE_DIRS}
+        ${E2FS_RESIZE_DIR}
+    )
+    target_link_libraries(resize_test gtest pthread photon_static ${E2FS_LIBRARIES})
+    add_dependencies(resize_test libext2fs_build)
+    add_test(
+        NAME resize_test
+        COMMAND ${EXECUTABLE_OUTPUT_PATH}/resize_test
+    )
+endif()