> On Aug 24, 2016, at 2:23 PM, Trond Myklebust <trondmy@xxxxxxxxxxxxxxx> wrote: > >> >> On Aug 24, 2016, at 14:10, Chuck Lever <chuck.lever@xxxxxxxxxx> wrote: >> >> Hi- >> >> I have a wire capture that shows this race while a simple I/O workload is >> running: >> >> 0. The client reconnects after a network partition >> 1. The client sends a couple of READ requests >> 2. The client independently discovers its lease has expired >> 3. The client establishes a fresh lease >> 4. The client destroys open, lock, and delegation stateids for the file >> that was open under the previous lease >> 5. The client issues a new OPEN to recover state for that file >> 6. The server replies to the READs in step 1. with NFS4ERR_EXPIRED >> 7. The client turns the READs around immediately using the current open >> stateid for that file, which is the zero stateid >> 8. The server replies NFS4_OK to the OPEN from step 5 >> >> If I understand the code correctly, if the server happened to send those >> READ replies after its OPEN reply (rather than before), the client would >> have used the recovered open stateid instead of the zero stateid when >> resending the READ requests. >> >> Would it be better if the client recognized there is state recovery in >> progress, and then waited for recovery to complete, before retrying the >> READs? >> > > Why isn’t the session draining taking care of ensuring the READs don’t happen until after recovery is done? This is NFSv4.0. (Apologies, I recalled NFS4ERR_EXPIRED had been removed from NFSv4.1, but I see that I was mistaken). Here's step 1 and 2, exactly. After the partition heals, the client sends: C READ C GETATTR C READ C RENEW The server responds to the RENEW first with GSS_CTXPROBLEM. The client's gssd connects and establishes a fresh GSS context. The client sends the RENEW again with the fresh context, and the server responds NFS4ERR_EXPIRED. This triggers step 3. The replies for those READ calls are in step 6., after state recovery has started. -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
