block: Add punch_hole and write_zeroes to AsyncIo trait

Add punch_hole() and write_zeroes() methods to the AsyncIo trait
with stub implementations for all backends. These will be used to
support DISCARD and WRITE_ZEROES operations.

Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>

block/src/async_io.rs

@@ -96,6 +96,12 @@ pub enum AsyncIoError {
     /// Failed synchronizing file.
     #[error("Failed synchronizing file")]
     Fsync(#[source] std::io::Error),
+    /// Failed punching hole.
+    #[error("Failed punching hole")]
+    PunchHole(#[source] std::io::Error),
+    /// Failed writing zeroes.
+    #[error("Failed writing zeroes")]
+    WriteZeroes(#[source] std::io::Error),
     /// Failed submitting batch requests.
     #[error("Failed submitting batch requests")]
     SubmitBatchRequests(#[source] std::io::Error),
@@ -118,6 +124,8 @@ pub trait AsyncIo: Send {
         user_data: u64,
     ) -> AsyncIoResult<()>;
     fn fsync(&mut self, user_data: Option<u64>) -> AsyncIoResult<()>;
+    fn punch_hole(&mut self, offset: u64, length: u64, user_data: u64) -> AsyncIoResult<()>;
+    fn write_zeroes(&mut self, offset: u64, length: u64, user_data: u64) -> AsyncIoResult<()>;
     fn next_completed_request(&mut self) -> Option<(u64, i32)>;
     fn batch_requests_enabled(&self) -> bool {
         false

block/src/fixed_vhd_async.rs

@@ -115,6 +115,18 @@ impl AsyncIo for FixedVhdAsync {
         self.raw_file_async.next_completed_request()
     }
 
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for fixed VHD",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for fixed VHD",
+        )))
+    }
+
     fn batch_requests_enabled(&self) -> bool {
         true
     }

block/src/fixed_vhd_sync.rs

@@ -113,4 +113,16 @@ impl AsyncIo for FixedVhdSync {
     fn next_completed_request(&mut self) -> Option<(u64, i32)> {
         self.raw_file_sync.next_completed_request()
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for fixed VHD",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for fixed VHD",
+        )))
+    }
 }

block/src/qcow_sync.rs

@@ -11,7 +11,7 @@ use std::sync::{Arc, Mutex};
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::async_io::{
-    AsyncIo, AsyncIoResult, BorrowedDiskFd, DiskFile, DiskFileError, DiskFileResult,
+    AsyncIo, AsyncIoError, AsyncIoResult, BorrowedDiskFd, DiskFile, DiskFileError, DiskFileResult,
 };
 use crate::qcow::{QcowFile, RawFile, Result as QcowResult};
 use crate::{AsyncAdaptor, BlockBackend};
@@ -146,4 +146,16 @@ impl AsyncIo for QcowSync {
     fn next_completed_request(&mut self) -> Option<(u64, i32)> {
         self.completion_list.pop_front()
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for QCOW sync backend",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for QCOW sync backend",
+        )))
+    }
 }

block/src/raw_async.rs

@@ -253,4 +253,16 @@ impl AsyncIo for RawFileAsync {
 
         Ok(())
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for raw async backend",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for raw async backend",
+        )))
+    }
 }

block/src/raw_async_aio.rs

@@ -161,4 +161,16 @@ impl AsyncIo for RawFileAsyncAio {
             Some((events[0].data, events[0].res as i32))
         }
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported with AIO backend",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported with AIO backend",
+        )))
+    }
 }

block/src/raw_sync.rs

@@ -146,4 +146,16 @@ impl AsyncIo for RawFileSync {
     fn next_completed_request(&mut self) -> Option<(u64, i32)> {
         self.completion_list.pop_front()
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for raw sync backend",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for raw sync backend",
+        )))
+    }
 }

block/src/vhdx_sync.rs

@@ -9,7 +9,7 @@ use std::os::fd::AsRawFd;
 use vmm_sys_util::eventfd::EventFd;
 
 use crate::async_io::{
-    AsyncIo, AsyncIoResult, BorrowedDiskFd, DiskFile, DiskFileError, DiskFileResult,
+    AsyncIo, AsyncIoError, AsyncIoResult, BorrowedDiskFd, DiskFile, DiskFileError, DiskFileResult,
 };
 use crate::vhdx::{Result as VhdxResult, Vhdx};
 use crate::{AsyncAdaptor, BlockBackend, Error};
@@ -114,4 +114,16 @@ impl AsyncIo for VhdxSync {
     fn next_completed_request(&mut self) -> Option<(u64, i32)> {
         self.completion_list.pop_front()
     }
+
+    fn punch_hole(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::PunchHole(std::io::Error::other(
+            "punch_hole not supported for VHDX",
+        )))
+    }
+
+    fn write_zeroes(&mut self, _offset: u64, _length: u64, _user_data: u64) -> AsyncIoResult<()> {
+        Err(AsyncIoError::WriteZeroes(std::io::Error::other(
+            "write_zeroes not supported for VHDX",
+        )))
+    }
 }