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    Subject[PATCH 5.0 32/89] nfsd: wake blocked file lock waiters before sending callback
    Date
    From: Jeff Layton <jlayton@kernel.org>

    commit f456458e4d25a8962d0946891617c76cc3ff5fb9 upstream.

    When a blocked NFS lock is "awoken" we send a callback to the server and
    then wake any hosts waiting on it. If a client attempts to get a lock
    and then drops off the net, we could end up waiting for a long time
    until we end up waking locks blocked on that request.

    So, wake any other waiting lock requests before sending the callback.
    Do this by calling locks_delete_block in a new "prepare" phase for
    CB_NOTIFY_LOCK callbacks.

    URL: https://bugzilla.kernel.org/show_bug.cgi?id=203363
    Fixes: 16306a61d3b7 ("fs/locks: always delete_block after waiting.")
    Reported-by: Slawomir Pryczek <slawek1211@gmail.com>
    Cc: Neil Brown <neilb@suse.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: Jeff Layton <jlayton@kernel.org>
    Signed-off-by: J. Bruce Fields <bfields@redhat.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/nfsd/nfs4state.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    --- a/fs/nfsd/nfs4state.c
    +++ b/fs/nfsd/nfs4state.c
    @@ -298,6 +298,14 @@ remove_blocked_locks(struct nfs4_lockown
    }
    }

    +static void
    +nfsd4_cb_notify_lock_prepare(struct nfsd4_callback *cb)
    +{
    + struct nfsd4_blocked_lock *nbl = container_of(cb,
    + struct nfsd4_blocked_lock, nbl_cb);
    + locks_delete_block(&nbl->nbl_lock);
    +}
    +
    static int
    nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
    {
    @@ -325,6 +333,7 @@ nfsd4_cb_notify_lock_release(struct nfsd
    }

    static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops = {
    + .prepare = nfsd4_cb_notify_lock_prepare,
    .done = nfsd4_cb_notify_lock_done,
    .release = nfsd4_cb_notify_lock_release,
    };

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