cloud-hypervisor/vhost_user_fs/src/fs_cache_req_handler.rs

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use crate::fuse;
use std::io;
use std::os::unix::io::RawFd;
use vhost_rs::vhost_user::message::{
VhostUserFSSlaveMsg, VhostUserFSSlaveMsgFlags, VHOST_USER_FS_SLAVE_ENTRIES,
};
use vhost_rs::vhost_user::{SlaveFsCacheReq, VhostUserMasterReqHandler};
/// Trait for virtio-fs cache requests operations. This is mainly used to hide
/// vhost-user details from virtio-fs's fuse part.
pub trait FsCacheReqHandler: Send + Sync + 'static {
/// Setup a dedicated mapping so that guest can access file data in DAX style.
fn map(
&mut self,
foffset: u64,
moffset: u64,
len: u64,
flags: u64,
fd: RawFd,
) -> io::Result<()>;
/// Remove those mappings that provide the access to file data.
fn unmap(&mut self, requests: Vec<fuse::RemovemappingOne>) -> io::Result<()>;
}
impl FsCacheReqHandler for SlaveFsCacheReq {
fn map(
&mut self,
foffset: u64,
moffset: u64,
len: u64,
flags: u64,
fd: RawFd,
) -> io::Result<()> {
let mut msg: VhostUserFSSlaveMsg = Default::default();
msg.fd_offset[0] = foffset;
msg.cache_offset[0] = moffset;
msg.len[0] = len;
msg.flags[0] = if (flags & fuse::SetupmappingFlags::WRITE.bits()) != 0 {
VhostUserFSSlaveMsgFlags::MAP_W | VhostUserFSSlaveMsgFlags::MAP_R
} else {
VhostUserFSSlaveMsgFlags::MAP_R
};
self.fs_slave_map(&msg, fd)
}
fn unmap(&mut self, requests: Vec<fuse::RemovemappingOne>) -> io::Result<()> {
for chunk in requests.chunks(VHOST_USER_FS_SLAVE_ENTRIES) {
let mut msg: VhostUserFSSlaveMsg = Default::default();
for (ind, req) in chunk.iter().enumerate() {
msg.len[ind] = req.len;
msg.cache_offset[ind] = req.moffset;
}
self.fs_slave_unmap(&msg)?;
}
Ok(())
}
}