IoUringProvidedBufferRing: use folly::align_ceil

Summary:
Use folly::align_ceil instead of calculating it by hand, which was buggy when huge_pages = false.

Add a very basic test to validate both huge_pages = true and false.

Reviewed By: yfeldblum

Differential Revision: D72349393

fbshipit-source-id: 97b35e5f81e8975add5932440ddeef956562d1fd

Author: spikeh

folly/io/async/IoUringProvidedBufferRing.cpp

@@ -19,6 +19,7 @@
 #include <folly/Conv.h>
 #include <folly/ExceptionString.h>
 #include <folly/String.h>
+#include <folly/lang/Align.h>
 
 #if FOLLY_HAS_LIBURING
 
@@ -32,7 +33,7 @@ IoUringProvidedBufferRing::ProvidedBuffersBuffer::ProvidedBuffersBuffer(
   ringMask_ = ringCount - 1;
   ringMemSize_ = sizeof(struct io_uring_buf) * ringCount;
 
-  ringMemSize_ = (ringMemSize_ + kBufferAlignMask) & (~kBufferAlignMask);
+  ringMemSize_ = align_ceil(ringMemSize_, kBufferAlignBytes);
 
   if (bufferShift_ < 5) {
     bufferShift_ = 5; // for alignment
@@ -44,11 +45,11 @@ IoUringProvidedBufferRing::ProvidedBuffersBuffer::ProvidedBuffersBuffer(
 
   int pages;
   if (huge_pages) {
-    allSize_ = (allSize_ + kHugePageMask) & (~kHugePageMask);
-    pages = allSize_ / (1 + kHugePageMask);
+    allSize_ = align_ceil(allSize_, kHugePageSizeBytes);
+    pages = allSize_ / kHugePageSizeBytes;
   } else {
-    allSize_ = (kPageMask + kPageMask) & ~kPageMask;
-    pages = allSize_ / (1 + kPageMask);
+    allSize_ = align_ceil(allSize_, kPageSizeBytes);
+    pages = allSize_ / kPageSizeBytes;
   }
 
   buffer_ = ::mmap(

folly/io/async/IoUringProvidedBufferRing.h

@@ -106,10 +106,9 @@ class IoUringProvidedBufferRing : public IoUringBufferProviderBase {
     char* bufferBuffer_;
     uint32_t bufferCount_;
 
-    // static constexpr
-    static constexpr size_t kHugePageMask = (1LLU << 21) - 1; // 2MB
-    static constexpr size_t kPageMask = (1LLU << 12) - 1; // 4095
-    static constexpr size_t kBufferAlignMask{31LLU};
+    static constexpr size_t kHugePageSizeBytes = 1024 * 1024 * 2;
+    static constexpr size_t kPageSizeBytes = 4096;
+    static constexpr size_t kBufferAlignBytes = 32;
   };
 
   io_uring* ioRingPtr_;

folly/io/async/test/IoUringProvidedBufferRingTest.cpp

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <folly/io/async/IoUringProvidedBufferRing.h>
+
+#include <gtest/gtest.h>
+
+#if FOLLY_HAS_LIBURING
+
+using namespace ::testing;
+using namespace ::std;
+using namespace ::folly;
+
+int get_shift(int x) {
+  int shift = findLastSet(x) - 1;
+  if (x != (1 << shift)) {
+    shift++;
+  }
+  return shift;
+}
+
+struct IoUringProvidedBufferRingTest : testing::Test {};
+
+TEST_F(IoUringProvidedBufferRingTest, Create) {
+  io_uring ring{};
+  io_uring_queue_init(512, &ring, 0);
+  int sizeShift = std::max<int>(get_shift(4096), 5);
+  int ringShift = std::max<int>(get_shift(1000), 1);
+  IoUringProvidedBufferRing bufRing{&ring, 1, 1000, sizeShift, ringShift};
+  EXPECT_EQ(bufRing.count(), 1000);
+}
+
+#endif