vhost_user_block: Refactor vhost_user_block backend code into a new crate

Extract the majority of the code that provides the vhost-user-block
backend into its own crate and port the binary to use it.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vhost_user_block/src/lib.rs

@@ -0,0 +1,276 @@
+// Copyright 2019 Red Hat, Inc. All Rights Reserved.
+//
+// Portions Copyright 2019 Intel Corporation. All Rights Reserved.
+//
+// Portions Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+//
+// Portions Copyright 2017 The Chromium OS Authors. All rights reserved.
+//
+// SPDX-License-Identifier: (Apache-2.0 AND BSD-3-Clause)
+
+extern crate log;
+extern crate vhost_rs;
+extern crate vhost_user_backend;
+extern crate vm_virtio;
+
+use epoll;
+use log::*;
+use qcow::{self, ImageType, QcowFile};
+use std::fs::File;
+use std::fs::OpenOptions;
+use std::io::Read;
+use std::io::{Seek, SeekFrom, Write};
+use std::mem;
+use std::os::unix::fs::OpenOptionsExt;
+use std::path::PathBuf;
+use std::slice;
+use std::sync::{Arc, RwLock};
+use std::vec::Vec;
+use vhost_rs::vhost_user::message::*;
+use vhost_user_backend::{VhostUserBackend, Vring, VringWorker};
+use virtio_bindings::bindings::virtio_blk::*;
+use vm_memory::{Bytes, GuestMemoryError, GuestMemoryMmap};
+use vm_virtio::block::{build_disk_image_id, Request};
+
+const QUEUE_SIZE: usize = 1024;
+const NUM_QUEUES: usize = 1;
+const SECTOR_SHIFT: u8 = 9;
+const SECTOR_SIZE: u64 = (0x01 as u64) << SECTOR_SHIFT;
+const BLK_SIZE: u32 = 512;
+
+trait DiskFile: Read + Seek + Write + Send + Sync {}
+impl<D: Read + Seek + Write + Send + Sync> DiskFile for D {}
+
+pub type Result<T> = std::result::Result<T, Error>;
+pub type VhostUserBackendResult<T> = std::result::Result<T, std::io::Error>;
+
+#[derive(Debug)]
+pub enum Error {
+    /// Failed to detect image type.
+    DetectImageType,
+    /// Bad memory address.
+    GuestMemory(GuestMemoryError),
+    /// Can't open image file.
+    OpenImage,
+    /// Failed to parse direct parameter.
+    ParseDirectParam,
+    /// Failed to parse image parameter.
+    ParseImageParam,
+    /// Failed to parse sock parameter.
+    ParseSockParam,
+    /// Failed to parse readonly parameter.
+    ParseReadOnlyParam,
+}
+
+pub struct VhostUserBlkBackend {
+    mem: Option<GuestMemoryMmap>,
+    vring_worker: Option<Arc<VringWorker>>,
+    disk_image: Box<dyn DiskFile>,
+    disk_image_id: Vec<u8>,
+    disk_nsectors: u64,
+    config: virtio_blk_config,
+    rdonly: bool,
+}
+
+impl VhostUserBlkBackend {
+    pub fn new(image_path: String, rdonly: bool, direct: bool) -> Result<Self> {
+        let mut options = OpenOptions::new();
+        options.read(true);
+        options.write(!rdonly);
+        if direct {
+            options.custom_flags(libc::O_DIRECT);
+        }
+        let image: File = options.open(&image_path).unwrap();
+        let mut raw_img: vm_virtio::RawFile = vm_virtio::RawFile::new(image, direct);
+
+        let image_id = build_disk_image_id(&PathBuf::from(&image_path));
+        let image_type = qcow::detect_image_type(&mut raw_img).unwrap();
+        let mut image = match image_type {
+            ImageType::Raw => Box::new(raw_img) as Box<dyn DiskFile>,
+            ImageType::Qcow2 => Box::new(QcowFile::from(raw_img).unwrap()) as Box<dyn DiskFile>,
+        };
+
+        let nsectors = (image.seek(SeekFrom::End(0)).unwrap() as u64) / SECTOR_SIZE;
+        let mut config = virtio_blk_config::default();
+
+        config.capacity = nsectors;
+        config.blk_size = BLK_SIZE;
+        config.size_max = 65535;
+        config.seg_max = 128 - 2;
+        config.min_io_size = 1;
+        config.opt_io_size = 1;
+        config.num_queues = 1;
+        config.wce = 1;
+
+        Ok(VhostUserBlkBackend {
+            mem: None,
+            vring_worker: None,
+            disk_image: image,
+            disk_image_id: image_id,
+            disk_nsectors: nsectors,
+            config,
+            rdonly,
+        })
+    }
+
+    pub fn process_queue(&mut self, vring: &mut Vring) -> bool {
+        let mut used_any = false;
+        let mem = match self.mem.as_ref() {
+            Some(m) => m,
+            None => return false,
+        };
+
+        while let Some(head) = vring.mut_queue().iter(mem).next() {
+            debug!("got an element in the queue");
+            let len;
+            match Request::parse(&head, mem) {
+                Ok(request) => {
+                    debug!("element is a valid request");
+                    let status = match request.execute(
+                        &mut self.disk_image,
+                        self.disk_nsectors,
+                        mem,
+                        &self.disk_image_id,
+                    ) {
+                        Ok(l) => {
+                            len = l;
+                            VIRTIO_BLK_S_OK
+                        }
+                        Err(e) => {
+                            len = 1;
+                            e.status()
+                        }
+                    };
+                    mem.write_obj(status, request.status_addr).unwrap();
+                }
+                Err(err) => {
+                    error!("failed to parse available descriptor chain: {:?}", err);
+                    len = 0;
+                }
+            }
+            vring.mut_queue().add_used(mem, head.index, len);
+            used_any = true;
+        }
+
+        used_any
+    }
+
+    pub fn set_vring_worker(&mut self, vring_worker: Option<Arc<VringWorker>>) {
+        self.vring_worker = vring_worker;
+    }
+}
+
+impl VhostUserBackend for VhostUserBlkBackend {
+    fn num_queues(&self) -> usize {
+        NUM_QUEUES
+    }
+
+    fn max_queue_size(&self) -> usize {
+        QUEUE_SIZE
+    }
+
+    fn features(&self) -> u64 {
+        let mut avail_features = 1 << VIRTIO_BLK_F_MQ
+            | 1 << VIRTIO_BLK_F_CONFIG_WCE
+            | 1 << VIRTIO_F_VERSION_1
+            | VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits();
+
+        if self.rdonly {
+            avail_features |= 1 << VIRTIO_BLK_F_RO;
+        }
+        avail_features
+    }
+
+    fn protocol_features(&self) -> VhostUserProtocolFeatures {
+        VhostUserProtocolFeatures::CONFIG
+    }
+
+    fn update_memory(&mut self, mem: GuestMemoryMmap) -> VhostUserBackendResult<()> {
+        self.mem = Some(mem);
+        Ok(())
+    }
+
+    fn handle_event(
+        &mut self,
+        device_event: u16,
+        evset: epoll::Events,
+        vrings: &[Arc<RwLock<Vring>>],
+    ) -> VhostUserBackendResult<bool> {
+        if evset != epoll::Events::EPOLLIN {
+            warn!("invalid events operation");
+            return Ok(false);
+        }
+
+        debug!("event received: {:?}", device_event);
+
+        let mut vring = vrings[0].write().unwrap();
+        if self.process_queue(&mut vring) {
+            debug!("signalling queue");
+            vring.signal_used_queue().unwrap();
+        }
+
+        Ok(false)
+    }
+
+    fn get_config(&self, _offset: u32, _size: u32) -> Vec<u8> {
+        // self.config is a statically allocated virtio_blk_config
+        let buf = unsafe {
+            slice::from_raw_parts(
+                &self.config as *const virtio_blk_config as *const _,
+                mem::size_of::<virtio_blk_config>(),
+            )
+        };
+
+        buf.to_vec()
+    }
+}
+
+pub struct VhostUserBlkBackendConfig<'a> {
+    pub image: &'a str,
+    pub sock: &'a str,
+    pub readonly: bool,
+    pub direct: bool,
+}
+
+impl<'a> VhostUserBlkBackendConfig<'a> {
+    pub fn parse(backend: &'a str) -> Result<Self> {
+        let params_list: Vec<&str> = backend.split(',').collect();
+
+        let mut image: &str = "";
+        let mut sock: &str = "";
+        let mut readonly: bool = false;
+        let mut direct: bool = false;
+
+        for param in params_list.iter() {
+            if param.starts_with("image=") {
+                image = &param[6..];
+            } else if param.starts_with("sock=") {
+                sock = &param[5..];
+            } else if param.starts_with("readonly=") {
+                readonly = match param[9..].parse::<bool>() {
+                    Ok(b) => b,
+                    Err(_) => return Err(Error::ParseReadOnlyParam),
+                }
+            } else if param.starts_with("direct=") {
+                direct = match param[7..].parse::<bool>() {
+                    Ok(b) => b,
+                    Err(_) => return Err(Error::ParseDirectParam),
+                }
+            }
+        }
+
+        if image.is_empty() {
+            return Err(Error::ParseImageParam);
+        }
+        if sock.is_empty() {
+            return Err(Error::ParseSockParam);
+        }
+
+        Ok(VhostUserBlkBackendConfig {
+            image,
+            sock,
+            readonly,
+            direct,
+        })
+    }
+}