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NFSv4 client live hangs after live data migration recovery

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After a live data migration event at the NFS server, the client may send
I/O requests to the wrong server, causing a live hang due to repeated
recovery events.  On the wire, this will appear as an I/O request failing
with NFS4ERR_BADSESSION, followed by successful CREATE_SESSION, repeatedly.
NFS4ERR_BADSSESSION is returned because the session ID being used was
issued by the other server and is not valid at the old server.

The failure is caused by async worker threads having cached the transport
(xprt) in the rpc_task structure.  After the migration recovery completes,
the task is redispatched and the task resends the request to the wrong
server based on the old value still present in tk_xprt.

The solution is to recompute the tk_xprt field of the rpc_task structure
so that the request goes to the correct server.

Signed-off-by: Bill Baker <bill.baker@oracle.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Tested-by: Helen Chao <helen.chao@oracle.com>
Fixes: fb43d17210 ("SUNRPC: Use the multipath iterator to assign a ...")
Cc: stable@vger.kernel.org # v4.9+
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
This commit is contained in:
Bill Baker
2018-06-19 16:24:58 -05:00
committed by Anna Schumaker
parent 32cd3ee511
commit 0f90be132c
3 changed files with 29 additions and 9 deletions
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9
fs/nfs/nfs4proc.c
View File

@@ -581,8 +581,15 @@ nfs4_async_handle_exception(struct rpc_task *task, struct nfs_server *server,
ret = -EIO;
return ret;
out_retry:
if (ret == 0)
if (ret == 0) {
exception->retry = 1;
/*
* For NFS4ERR_MOVED, the client transport will need to
* be recomputed after migration recovery has completed.
*/
if (errorcode == -NFS4ERR_MOVED)
rpc_task_release_transport(task);
}
return ret;
}