• Jeff Layton's avatar
    nfsd: serialize layout stateid morphing operations · cc8a5532
    Jeff Layton authored
    In order to allow the client to make a sane determination of what
    happened with racing LAYOUTGET/LAYOUTRETURN/CB_LAYOUTRECALL calls, we
    must ensure that the seqids return accurately represent the order of
    operations. The simplest way to do that is to ensure that operations on
    a single stateid are serialized.
    
    This patch adds a mutex to the layout stateid, and locks it when
    checking the layout stateid's seqid. The mutex is held over the entire
    operation and released after the seqid is bumped.
    
    Note that in the case of CB_LAYOUTRECALL we must move the increment of
    the seqid and setting into a new cb "prepare" operation. The lease
    infrastructure will call the lm_break callback with a spinlock held, so
    and we can't take the mutex in that codepath.
    
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
    Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
    cc8a5532
nfs4proc.c 65.9 KB