From: Chuck Lever <chuck.lever@xxxxxxxxxx> The reverted commit attempted to enable NFSD to retransmit pending callback operations if an NFS client disconnects, but unintentionally introduces a hazardous behavior regression if the client becomes permanently unreachable while callback operations are still pending. A disconnect can occur due to network partition or if the NFS server needs to force the NFS client to retransmit (for example, if a GSS window under-run occurs). Reverting the commit will make NFSD behave the same as it did in v6.8 and before. Pending callback operations are permanently lost if the client connection is terminated before the client receives them. For some callback operations, this loss is not harmful. However, for CB_RECALL, the loss means a delegation might be revoked unnecessarily. For CB_OFFLOAD, pending COPY operations will never complete unless the NFS client subsequently sends an OFFLOAD_STATUS operation, which the Linux NFS client does not currently implement. These issues still need to be addressed somehow. Reported-by: Dai Ngo <dai.ngo@xxxxxxxxxx> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218735 Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- fs/nfsd/nfs4callback.c | 20 ++------------------ 1 file changed, 2 insertions(+), 18 deletions(-) diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index e440f72b9d4e..d153af81f406 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -986,14 +986,6 @@ static bool nfsd4_queue_cb(struct nfsd4_callback *cb) return queue_delayed_work(callback_wq, &cb->cb_work, 0); } -static void nfsd4_queue_cb_delayed(struct nfsd4_callback *cb, - unsigned long msecs) -{ - trace_nfsd_cb_queue(cb->cb_clp, cb); - queue_delayed_work(callback_wq, &cb->cb_work, - msecs_to_jiffies(msecs)); -} - static void nfsd41_cb_inflight_begin(struct nfs4_client *clp) { atomic_inc(&clp->cl_cb_inflight); @@ -1502,16 +1494,8 @@ nfsd4_run_cb_work(struct work_struct *work) clnt = clp->cl_cb_client; if (!clnt) { - if (test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags)) - nfsd41_destroy_cb(cb); - else { - /* - * XXX: Ideally, we could wait for the client to - * reconnect, but I haven't figured out how - * to do that yet. - */ - nfsd4_queue_cb_delayed(cb, 25); - } + /* Callback channel broken, or client killed; give up: */ + nfsd41_destroy_cb(cb); return; }
