fuse_loop: wait for instance to close after killing

On unmap, only report success if the instance we are killing actually
terminates. This is especially important so that cleanup routines can be
assured that /run files are actually cleaned up after calling
cleanup_unused_run_files.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>

src/tools/fuse_loop.rs

@@ -16,6 +16,7 @@ use futures::stream::{StreamExt, TryStreamExt};
 use futures::channel::mpsc::{Sender, Receiver};
 
 use proxmox::const_regex;
+use proxmox::tools::time;
 use proxmox_fuse::{*, requests::FuseRequest};
 use super::loopdev;
 use super::fs;
@@ -288,8 +289,28 @@ fn unmap_from_backing(backing_file: &Path) -> Result<(), Error> {
     let pid = pid_str.parse::<i32>().map_err(|err|
         format_err!("malformed PID ({}) in pidfile - {}", pid_str, err))?;
 
+    let pid = Pid::from_raw(pid);
+
     // send SIGINT to trigger cleanup and exit in target process
-    signal::kill(Pid::from_raw(pid), Signal::SIGINT)?;
+    signal::kill(pid, Signal::SIGINT)?;
+
+    // block until unmap is complete or timeout
+    let start = time::epoch_i64();
+    loop {
+        match signal::kill(pid, None) {
+            Ok(_) => {
+                // 10 second timeout, then assume failure
+                if (time::epoch_i64() - start) > 10 {
+                    return Err(format_err!("timed out waiting for PID '{}' to exit", &pid));
+                }
+                std::thread::sleep(std::time::Duration::from_millis(100));
+            },
+            Err(nix::Error::Sys(nix::errno::Errno::ESRCH)) => {
+                break;
+            },
+            Err(e) => return Err(e.into()),
+        }
+    }
 
     Ok(())
 }