• Benjamin Coddington's avatar
    NFS: Always wait for I/O completion before unlock · f30cb757
    Benjamin Coddington authored
    NFS attempts to wait for read and write completion before unlocking in
    order to ensure that the data returned was protected by the lock.  When
    this waiting is interrupted by a signal, the unlock may be skipped, and
    messages similar to the following are seen in the kernel ring buffer:
    
    [20.167876] Leaked locks on dev=0x0:0x2b ino=0x8dd4c3:
    [20.168286] POSIX: fl_owner=ffff880078b06940 fl_flags=0x1 fl_type=0x0 fl_pid=20183
    [20.168727] POSIX: fl_owner=ffff880078b06680 fl_flags=0x1 fl_type=0x0 fl_pid=20185
    
    For NFSv3, the missing unlock will cause the server to refuse conflicting
    locks indefinitely.  For NFSv4, the leftover lock will be removed by the
    server after the lease timeout.
    
    This patch fixes this issue by skipping the usual wait in
    nfs_iocounter_wait if the FL_CLOSE flag is set when signaled.  Instead, the
    wait happens in the unlock RPC task on the NFS UOC rpc_waitqueue.
    
    For NFSv3, use lockd's new nlmclnt_operations along with
    nfs_async_iocounter_wait to defer NLM's unlock task until the lock
    context's iocounter reaches zero.
    
    For NFSv4, call nfs_async_iocounter_wait() directly from unlock's
    current rpc_call_prepare.
    Signed-off-by: default avatarBenjamin Coddington <bcodding@redhat.com>
    Reviewed-by: default avatarJeff Layton <jlayton@redhat.com>
    Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
    f30cb757
nfs4proc.c 251 KB