block: aligned: Add seeking cursor and drop RawFile

RawFile wrapped AlignedFile only to add a seek position and the file
trait impls that the qcow and vhost_user_block code expects. Fold that
position and every impl onto AlignedFile so the wrapper layer goes away
and callers work with a single O_DIRECT aware file type.

AlignedFile now tracks a cursor and implements Read, Write, Seek,
WriteZeroesAt, PunchHole, FileSync, SeekHole, BlockBackend, Clone,
AsRawFd and AsFd in addition to the positional FileExt path. The
direct_io flag is dropped because alignment already encodes it, where
a zero alignment means the file was not opened with O_DIRECT.

All RawFile uses in the qcow internals and vhost_user_block move to
AlignedFile, and raw_file.rs is removed.

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

vhost_user_block/src/lib.rs

@@ -19,8 +19,7 @@ use std::sync::{Arc, Mutex, RwLock, RwLockWriteGuard};
 use std::time::Instant;
 use std::{convert, io, process, result};
 
-use block::formats::qcow::internal::RawFile;
-use block::{Request, RequestType, VirtioBlockConfig, build_serial};
+use block::{AlignedFile, Request, RequestType, VirtioBlockConfig, build_serial};
 use libc::EFD_NONBLOCK;
 use log::{debug, error, info, warn};
 use option_parser::{OptionParser, OptionParserError, Toggle};
@@ -85,7 +84,7 @@ impl convert::From<Error> for io::Error {
 }
 
 struct VhostUserBlkThread {
-    disk_image: Arc<Mutex<RawFile>>,
+    disk_image: Arc<Mutex<AlignedFile>>,
     serial: Vec<u8>,
     disk_nsectors: u64,
     event_idx: bool,
@@ -96,7 +95,7 @@ struct VhostUserBlkThread {
 
 impl VhostUserBlkThread {
     fn new(
-        disk_image: Arc<Mutex<RawFile>>,
+        disk_image: Arc<Mutex<AlignedFile>>,
         serial: Vec<u8>,
         disk_nsectors: u64,
         writeback: Arc<AtomicBool>,
@@ -230,7 +229,7 @@ impl VhostUserBlkBackend {
             options.custom_flags(libc::O_DIRECT);
         }
         let image: File = options.open(image_path).unwrap();
-        let raw_img = RawFile::new(image, direct);
+        let raw_img = AlignedFile::new(image, direct);
 
         let serial = build_serial(&PathBuf::from(&image_path));
         let image = Arc::new(Mutex::new(raw_img));