NFSv4: Fix a deadlock when recovering state on a sillyrenamed file

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: NFSv4: Fix a deadlock when recovering state on a sillyrenamed file If the file is sillyrenamed, and slated for delete on close, it is possible for a server reboot to triggeer an open reclaim, with can again race with the application call to close(). When that happens, the call to put_nfs_open_context() can trigger a synchronous delegreturn call which deadlocks because it is not marked as privileged. Instead, ensure that the call to nfs4_inode_return_delegation_on_close() catches the delegreturn, and schedules it asynchronously.

References

• https://git.kernel.org/stable/c/4fe4ae6c2e01d028856b73b6328b12b8945df871
• https://git.kernel.org/stable/c/f41a60bc43e7abbc636fee78bed0d74c31e738b0
• https://git.kernel.org/stable/c/8f8df955f078e1a023ee55161935000a67651f38