Implement ZERO and DISCARD operations in update_engine.
ZERO and DISCARD operations are implemented using the specific ioctl()
that allow SSD to do a faster operation when writing zeros. In case of
failure, such as when they are not supported, the operation will fall
back to write the zeros directly.
Bug: 23180264
Test: Added a unittest.
Change-Id: I0f12ab9864620b50250157c1de17b7fc58c7ea1c
diff --git a/file_descriptor.h b/file_descriptor.h
index 4d6e970..bf13611 100644
--- a/file_descriptor.h
+++ b/file_descriptor.h
@@ -78,6 +78,17 @@
// may set errno accordingly.
virtual off64_t Seek(off64_t offset, int whence) = 0;
+ // Runs a ioctl() on the file descriptor if supported. Returns whether
+ // the operation is supported. The |request| can be one of BLKDISCARD,
+ // BLKZEROOUT and BLKSECDISCARD to discard, write zeros or securely discard
+ // the blocks. These ioctls accept a range of bytes (|start| and |length|)
+ // over which they perform the operation. The return value from the ioctl is
+ // stored in |result|.
+ virtual bool BlkIoctl(int request,
+ uint64_t start,
+ uint64_t length,
+ int* result) = 0;
+
// Closes a file descriptor. The descriptor must be open prior to this call.
// Returns true on success, false otherwise. Specific implementations may set
// errno accordingly.
@@ -108,6 +119,10 @@
ssize_t Read(void* buf, size_t count) override;
ssize_t Write(const void* buf, size_t count) override;
off64_t Seek(off64_t offset, int whence) override;
+ bool BlkIoctl(int request,
+ uint64_t start,
+ uint64_t length,
+ int* result) override;
bool Close() override;
void Reset() override;
bool IsSettingErrno() override {
