From ff759cd5a3767c42bbf6db4117a2dde67f5c9727 Mon Sep 17 00:00:00 2001
From: Pascal Scholz <pascal.scholz@cyberus-technology.de>
Date: Tue, 16 Jun 2026 16:17:53 +0200
Subject: [PATCH] block: Retry locking when interrupted by EINTR

Acquiring an image lock can be interrupted with EINTR. In this case, we
returned with an error. Instead, we now retry acquiring the lock.

Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de>
On-behalf-of: SAP pascal.scholz@sap.com
---
 block/src/fcntl.rs | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/block/src/fcntl.rs b/block/src/fcntl.rs
index 98084748cf..0cb2ee552b 100644
--- a/block/src/fcntl.rs
+++ b/block/src/fcntl.rs
@@ -201,20 +201,23 @@ pub fn try_acquire_lock<Fd: AsRawFd>(
 ) -> Result<(), LockError> {
     let flock = get_flock(lock_type, granularity);
 
-    let res = fcntl(file.as_raw_fd(), FcntlArg::F_OFD_SETLK(&flock));
-    match res {
-        0 => Ok(()),
-        -1 => {
-            let io_error = io::Error::last_os_error();
-            let errno = io_error.raw_os_error().unwrap();
-            match errno {
-                // See man page for error code:
-                // <https://man7.org/linux/man-pages/man2/fcntl.2.html>
-                libc::EAGAIN | libc::EACCES => Err(LockError::AlreadyLocked),
-                _ => Err(LockError::Io(io_error)),
+    loop {
+        let res = fcntl(file.as_raw_fd(), FcntlArg::F_OFD_SETLK(&flock));
+        match res {
+            0 => return Ok(()),
+            -1 => {
+                let io_error = io::Error::last_os_error();
+                let errno = io_error.raw_os_error().unwrap();
+                match errno {
+                    // See man page for error code:
+                    // <https://man7.org/linux/man-pages/man2/fcntl.2.html>
+                    libc::EAGAIN | libc::EACCES => return Err(LockError::AlreadyLocked),
+                    libc::EINTR => continue,
+                    _ => return Err(LockError::Io(io_error)),
+                }
             }
+            val => panic!("Unexpected return value from fcntl(): {val}"),
         }
-        val => panic!("Unexpected return value from fcntl(): {val}"),
     }
 }