Disable COW for SSD checkpoint and evictlog files

Summary:
On btrfs overwriting file's blocks causes file system to allocate more
and more new blocks, eventually taking the whole disk space, while the
file is being only fraction of it.
'copy on write' is already disabled for SSD cache file to prevent the
issue. It is also needed for checkpoint files and evictlog files.

Reviewed By: xiaoxmeng

Differential Revision: D56777422

fbshipit-source-id: d8e4e7a742acad9f9ce7e87a1ffa61f04a6423fa

velox/common/caching/SsdFile.cpp

@@ -135,6 +135,7 @@ SsdFile::SsdFile(
     folly::Executor* executor)
     : fileName_(filename),
       maxRegions_(maxRegions),
+      disableFileCow_(disableFileCow),
       shardId_(shardId),
       checkpointIntervalBytes_(checkpointIntervalBytes),
       executor_(executor) {
@@ -155,7 +156,7 @@ SsdFile::SsdFile(
       filename,
       folly::errnoStr(errno));
 
-  if (disableFileCow) {
+  if (disableFileCow_) {
     disableCow(fd_);
   }
 
@@ -790,6 +791,11 @@ void SsdFile::checkpoint(bool force) {
     const auto checkpointFd = checkRc(
         ::open(checkpointPath.c_str(), O_WRONLY),
         "Open of checkpoint file for sync");
+    // TODO: add this as file open option after we migrate to use velox
+    // filesystem for ssd file access.
+    if (disableFileCow_) {
+      disableCow(checkpointFd);
+    }
     VELOX_CHECK_GE(checkpointFd, 0);
     checkRc(::fsync(checkpointFd), "Sync of checkpoint file");
     ::close(checkpointFd);
@@ -822,6 +828,9 @@ void SsdFile::initializeCheckpoint() {
   }
   const auto logPath = fileName_ + kLogExtension;
   evictLogFd_ = ::open(logPath.c_str(), O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
+  if (disableFileCow_) {
+    disableCow(evictLogFd_);
+  }
   if (evictLogFd_ < 0) {
     ++stats_.openLogErrors;
     // Failure to open the log at startup is a process terminating error.

velox/common/caching/SsdFile.h

@@ -350,6 +350,9 @@ class SsdFile {
   // Maximum size of the backing file in kRegionSize units.
   const int32_t maxRegions_;
 
+  // True if copy on write should be disabled.
+  const bool disableFileCow_;
+
   // Serializes access to all private data members.
   mutable std::shared_mutex mutex_;