feat(gdr): GPU Direct RDMA (GDR) support for direct storage-to-GPU transfers.

.github/workflows/build.yml

@@ -2,7 +2,9 @@ name: Build
 
 on:
   push:
-    branches: [ "main", "dev" ]
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
 
 jobs:
   build:
@@ -26,3 +28,26 @@ jobs:
         cargo build --release
         cmake -S . -B build -DCMAKE_CXX_COMPILER=clang++-14 -DCMAKE_C_COMPILER=clang-14 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DSHUFFLE_METHOD=g++11
         cmake --build build -j 32
+  build-gdr:
+    runs-on: self-hosted  # or `ubuntu-22.04`
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Prepare
+      run: |
+        sudo apt install -y cmake libuv1-dev liblz4-dev liblzma-dev libdouble-conversion-dev libdwarf-dev libunwind-dev
+        sudo apt install -y libaio-dev libgflags-dev libgoogle-glog-dev libgtest-dev libgmock-dev clang-format-14 clang-14 clang-tidy-14 lld-14
+        sudo apt install -y libgoogle-perftools-dev google-perftools libssl-dev gcc-12 g++-12 libboost-all-dev meson rustc cargo
+        sudo apt install -y nvidia-cuda-toolkit
+        wget https://github.com/apple/foundationdb/releases/download/7.1.61/foundationdb-clients_7.1.61-1_amd64.deb && sudo dpkg -i foundationdb-clients_7.1.61-1_amd64.deb
+        git clone https://github.com/libfuse/libfuse.git libfuse -b fuse-3.16.2 --depth 1 && mkdir libfuse/build && cd libfuse/build && meson setup .. && ninja && sudo ninja install && cd ../.. && rm -rf libfuse
+        git submodule update --init --recursive
+        ./patches/apply.sh
+
+    - name: Build
+      run: |
+        cargo build --release
+        cmake -S . -B build -DCMAKE_CXX_COMPILER=clang++-14 -DCMAKE_C_COMPILER=clang-14 -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_EXPORT_COMPILE_COMMANDS=ON -DSHUFFLE_METHOD=g++11 -DHF3FS_ENABLE_GDR=ON
+        cmake --build build -j 32
+        ctest --test-dir build -R test_gdr --output-on-failure

CMakeLists.txt

@@ -201,6 +201,7 @@ include(cmake/DumpConfig.cmake)
 include(cmake/Jemalloc.cmake)
 include(cmake/ApacheArrow.cmake)
 include(cmake/AddCrate.cmake)
+include(cmake/Cuda.cmake)
 configure_file(cmake/CTestCustom.cmake ${CMAKE_BINARY_DIR} @ONLY)
 
 add_subdirectory(src)

cmake/CLangFormat.cmake

@@ -1,5 +1,5 @@
-set(CLANG_FORMAT "/usr/bin/clang-format-14")
-if(EXISTS ${CLANG_FORMAT})
+find_program(CLANG_FORMAT NAMES clang-format-14 clang-format)
+if(CLANG_FORMAT)
     message(STATUS "Found clang-format at ${CLANG_FORMAT}")
 
     set(SOURCE_DIRS

cmake/Cuda.cmake

@@ -0,0 +1,89 @@
+# CUDA/GDR Support for 3FS
+#
+# This module provides optional CUDA support for GPU Direct RDMA (GDR).
+# GDR enables direct data transfers between storage and GPU memory.
+#
+# Options:
+#   HF3FS_ENABLE_GDR - Enable GPU Direct RDMA support (default: OFF)
+#
+# When HF3FS_ENABLE_GDR is ON:
+#   - CUDA Toolkit will be searched
+#   - HF3FS_ENABLE_GDR=1 will be defined for opted-in targets
+#   - CUDA libraries will be linked to relevant targets
+#
+# Usage in CMakeLists.txt:
+#   include(cmake/Cuda.cmake)
+#   target_add_gdr_support(mytarget SCOPE PRIVATE)
+
+option(HF3FS_ENABLE_GDR "Enable GPU Direct RDMA (GDR) support" OFF)
+
+set(HF3FS_CUDA_LIBRARIES "")
+set(HF3FS_CUDA_INCLUDE_DIRS "")
+
+if(HF3FS_ENABLE_GDR)
+    message(STATUS "GDR support requested, searching for CUDA...")
+
+    # Try to find CUDA Toolkit
+    # CMake 3.17+ has FindCUDAToolkit which is preferred
+    if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.17")
+        find_package(CUDAToolkit QUIET)
+        if(CUDAToolkit_FOUND)
+            if(NOT TARGET CUDA::cudart OR NOT TARGET CUDA::cuda_driver)
+                message(FATAL_ERROR
+                    "CUDAToolkit was found, but required CUDA::cudart and CUDA::cuda_driver targets are unavailable")
+            endif()
+            set(HF3FS_CUDA_LIBRARIES CUDA::cudart CUDA::cuda_driver)
+            set(HF3FS_CUDA_INCLUDE_DIRS ${CUDAToolkit_INCLUDE_DIRS})
+            message(STATUS "Found CUDA Toolkit ${CUDAToolkit_VERSION}")
+            message(STATUS "  CUDA include: ${CUDAToolkit_INCLUDE_DIRS}")
+            message(STATUS "  CUDA libraries: CUDA::cudart;CUDA::cuda_driver")
+        endif()
+    else()
+        # Fallback for older CMake
+        find_package(CUDA QUIET)
+        if(CUDA_FOUND AND CUDA_CUDA_LIBRARY)
+            set(HF3FS_CUDA_LIBRARIES ${CUDA_LIBRARIES} ${CUDA_CUDA_LIBRARY})
+            list(REMOVE_DUPLICATES HF3FS_CUDA_LIBRARIES)
+            set(HF3FS_CUDA_INCLUDE_DIRS ${CUDA_INCLUDE_DIRS})
+            message(STATUS "Found CUDA ${CUDA_VERSION}")
+            message(STATUS "  CUDA include: ${CUDA_INCLUDE_DIRS}")
+            message(STATUS "  CUDA libraries: ${HF3FS_CUDA_LIBRARIES}")
+        elseif(CUDA_FOUND)
+            message(STATUS "Legacy CUDA discovery did not provide the required driver library")
+        endif()
+    endif()
+
+    if(NOT HF3FS_CUDA_LIBRARIES)
+        message(FATAL_ERROR
+            "HF3FS_ENABLE_GDR=ON requires CUDA runtime and driver libraries, but required CUDA components were not found")
+    endif()
+
+    message(STATUS "GDR support enabled")
+
+    # Check for nvidia_peermem (informational only)
+    if(EXISTS "/sys/module/nvidia_peermem")
+        message(STATUS "nvidia_peermem module detected")
+    else()
+        message(STATUS "nvidia_peermem module not detected (required at runtime for GDR)")
+    endif()
+else()
+    message(STATUS "GDR support disabled (use -DHF3FS_ENABLE_GDR=ON to enable)")
+endif()
+
+# Helper function to add GDR support to a target
+function(target_add_gdr_support TARGET)
+    cmake_parse_arguments(GDR "" "SCOPE" "" ${ARGN})
+    if(NOT GDR_SCOPE)
+        set(GDR_SCOPE PRIVATE)
+    endif()
+
+    if(HF3FS_ENABLE_GDR)
+        target_compile_definitions(${TARGET} ${GDR_SCOPE} HF3FS_ENABLE_GDR=1)
+        target_include_directories(${TARGET} PRIVATE ${HF3FS_CUDA_INCLUDE_DIRS})
+        # Project targets use the plain target_link_libraries signature. Keeping
+        # that signature also propagates CUDA link requirements from static
+        # libraries to their final consumers.
+        target_link_libraries(${TARGET} ${HF3FS_CUDA_LIBRARIES})
+        message(STATUS "Added GDR support to target: ${TARGET} (${GDR_SCOPE})")
+    endif()
+endfunction()