fs: implement cache invalidation

Implement cache invalidation - we do support non-direct reads so tell the page cache to drop all data that the extents map to. Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
westerndigitalcorporation · Jan 25, 2023 · b04ca0c · b04ca0c
1 parent 604a3a9
commit b04ca0c
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Showing 8 changed files with 65 additions and 4 deletions.
diff --git a/fs/io_zenfs.cc b/fs/io_zenfs.cc
@@ -325,6 +325,38 @@ ZoneExtent* ZoneFile::GetExtent(uint64_t file_offset, uint64_t* dev_offset) {
   return NULL;
 }
 
+IOStatus ZoneFile::InvalidateCache(uint64_t pos, uint64_t size) {
+  ReadLock lck(this);
+  uint64_t offset = pos;
+  uint64_t left = size;
+  IOStatus s = IOStatus::OK();
+
+  if (left == 0) {
+    left = GetFileSize();
+  }
+
+  while (left) {
+    uint64_t dev_offset;
+    ZoneExtent* extent = GetExtent(offset, &dev_offset);
+
+    if (!extent) {
+      s = IOStatus::IOError("Extent not found while invalidating cache");
+      break;
+    }
+
+    uint64_t extent_end = extent->start_ + extent->length_;
+    uint64_t invalidate_size = std::min(left, extent_end - dev_offset);
+
+    s = zbd_->InvalidateCache(dev_offset, invalidate_size);
+    if (!s.ok()) break;
+
+    left -= invalidate_size;
+    offset += invalidate_size;
+  }
+
+  return s;
+}
+
 IOStatus ZoneFile::PositionedRead(uint64_t offset, size_t n, Slice* result,
                                   char* scratch, bool direct) {
   ZenFSMetricsLatencyGuard guard(zbd_->GetMetrics(), ZENFS_READ_LATENCY,

diff --git a/fs/io_zenfs.h b/fs/io_zenfs.h
@@ -150,6 +150,8 @@ class ZoneFile {
   uint32_t GetNrLinks() { return linkfiles_.size(); }
   const std::vector<std::string>& GetLinkFiles() const { return linkfiles_; }
 
+  IOStatus InvalidateCache(uint64_t pos, uint64_t size);
+
  private:
   void ReleaseActiveZone();
   void SetActiveZone(Zone* zone);
@@ -282,8 +284,8 @@ class ZonedSequentialFile : public FSSequentialFile {
     return zoneFile_->GetBlockSize();
   }
 
-  IOStatus InvalidateCache(size_t /*offset*/, size_t /*length*/) override {
-    return IOStatus::OK();
+  IOStatus InvalidateCache(size_t offset, size_t length) override {
+    return zoneFile_->InvalidateCache(offset, length);
   }
 };
 
@@ -314,8 +316,8 @@ class ZonedRandomAccessFile : public FSRandomAccessFile {
     return zoneFile_->GetBlockSize();
   }
 
-  IOStatus InvalidateCache(size_t /*offset*/, size_t /*length*/) override {
-    return IOStatus::OK();
+  IOStatus InvalidateCache(size_t offset, size_t length) override {
+    return zoneFile_->InvalidateCache(offset, length);
   }
 };
 

diff --git a/fs/zbd_zenfs.cc b/fs/zbd_zenfs.cc
@@ -647,6 +647,15 @@ IOStatus ZonedBlockDevice::AllocateEmptyZone(Zone **zone_out) {
   return IOStatus::OK();
 }
 
+IOStatus ZonedBlockDevice::InvalidateCache(uint64_t pos, uint64_t size) {
+  int ret = zbd_be_->InvalidateCache(pos, size);
+
+  if (ret) {
+    return IOStatus::IOError("Failed to invalidate cache");
+  }
+  return IOStatus::OK();
+}
+
 int ZonedBlockDevice::Read(char *buf, uint64_t offset, int n, bool direct) {
   int ret = 0;
   int left = n;

diff --git a/fs/zbd_zenfs.h b/fs/zbd_zenfs.h
@@ -110,6 +110,7 @@ class ZonedBlockDeviceBackend {
   virtual IOStatus Close(uint64_t start) = 0;
   virtual int Read(char *buf, int size, uint64_t pos, bool direct) = 0;
   virtual int Write(char *data, uint32_t size, uint64_t pos) = 0;
+  virtual int InvalidateCache(uint64_t pos, uint64_t size) = 0;
   virtual bool ZoneIsSwr(std::unique_ptr<ZoneList> &zones,
                          unsigned int idx) = 0;
   virtual bool ZoneIsOffline(std::unique_ptr<ZoneList> &zones,
@@ -215,6 +216,7 @@ class ZonedBlockDevice {
   void GetZoneSnapshot(std::vector<ZoneSnapshot> &snapshot);
 
   int Read(char *buf, uint64_t offset, int n, bool direct);
+  IOStatus InvalidateCache(uint64_t pos, uint64_t size);
 
   IOStatus ReleaseMigrateZone(Zone *zone);
 

diff --git a/fs/zbdlib_zenfs.cc b/fs/zbdlib_zenfs.cc
@@ -167,6 +167,10 @@ IOStatus ZbdlibBackend::Close(uint64_t start) {
   return IOStatus::OK();
 }
 
+int ZbdlibBackend::InvalidateCache(uint64_t pos, uint64_t size) {
+  return posix_fadvise(read_f_, pos, size, POSIX_FADV_DONTNEED);
+}
+
 int ZbdlibBackend::Read(char *buf, int size, uint64_t pos, bool direct) {
   return pread(direct ? read_direct_f_ : read_f_, buf, size, pos);
 }

diff --git a/fs/zbdlib_zenfs.h b/fs/zbdlib_zenfs.h
@@ -40,6 +40,7 @@ class ZbdlibBackend : public ZonedBlockDeviceBackend {
   IOStatus Close(uint64_t start);
   int Read(char *buf, int size, uint64_t pos, bool direct);
   int Write(char *data, uint32_t size, uint64_t pos);
+  int InvalidateCache(uint64_t pos, uint64_t size);
 
   bool ZoneIsSwr(std::unique_ptr<ZoneList> &zones, unsigned int idx) {
     struct zbd_zone *z = &((struct zbd_zone *)zones->GetData())[idx];

diff --git a/fs/zonefs_zenfs.cc b/fs/zonefs_zenfs.cc
@@ -301,6 +301,15 @@ IOStatus ZoneFsBackend::Close(uint64_t start) {
   return IOStatus::OK();
 }
 
+int ZoneFsBackend::InvalidateCache(uint64_t pos, uint64_t size) {
+  uint64_t offset = LBAToZoneOffset(pos);
+
+  std::shared_ptr<ZoneFsFile> file = GetZoneFile(pos, O_RDONLY);
+  if (file == nullptr) return -EINVAL;
+
+  return posix_fadvise(file->GetFd(), offset, size, POSIX_FADV_DONTNEED);
+}
+
 int ZoneFsBackend::Read(char *buf, int size, uint64_t pos, bool direct) {
   int flags = direct ? O_RDONLY | O_DIRECT : O_RDONLY;
   uint64_t offset = LBAToZoneOffset(pos);

diff --git a/fs/zonefs_zenfs.h b/fs/zonefs_zenfs.h
@@ -77,6 +77,8 @@ class ZoneFsBackend : public ZonedBlockDeviceBackend {
   IOStatus Close(uint64_t start);
   int Read(char *buf, int size, uint64_t pos, bool direct);
   int Write(char *data, uint32_t size, uint64_t pos);
+  int InvalidateCache(uint64_t pos, uint64_t size);
+
   bool ZoneIsSwr(std::unique_ptr<ZoneList> &zones, unsigned int idx);
   bool ZoneIsOffline(std::unique_ptr<ZoneList> &zones, unsigned int idx);
   bool ZoneIsWritable(std::unique_ptr<ZoneList> &zones, unsigned int idx);