On Fri, May 24, 2019 at 09:07:42AM -0400, Josef Bacik wrote: > On Fri, May 24, 2019 at 05:43:54PM +0800, Yao Liu wrote: > > Some I/O requests that have been sent succussfully but have not yet been > > replied won't be resubmitted after reconnecting because of server restart, > > so we add a list to track them. > > > > Signed-off-by: Yao Liu <yotta.liu@xxxxxxxxx> > > Nack, this is what the timeout stuff is supposed to handle. The commands will > timeout and we'll resubmit them if we have alive sockets. Thanks, > > Josef > On the one hand, if num_connections == 1 and the only sock has dead, then we do nbd_genl_reconfigure to reconnect within dead_conn_timeout, nbd_xmit_timeout will not resubmit commands that have been sent succussfully but have not yet been replied. The log is as follows: [270551.108746] block nbd0: Receive control failed (result -104) [270551.108747] block nbd0: Send control failed (result -32) [270551.108750] block nbd0: Request send failed, requeueing [270551.116207] block nbd0: Attempted send on invalid socket [270556.119584] block nbd0: reconnected socket [270581.161751] block nbd0: Connection timed out [270581.165038] block nbd0: shutting down sockets [270581.165041] print_req_error: I/O error, dev nbd0, sector 5123224 flags 8801 [270581.165149] print_req_error: I/O error, dev nbd0, sector 5123232 flags 8801 [270581.165580] block nbd0: Connection timed out [270581.165587] print_req_error: I/O error, dev nbd0, sector 844680 flags 8801 [270581.166184] print_req_error: I/O error, dev nbd0, sector 5123240 flags 8801 [270581.166554] block nbd0: Connection timed out [270581.166576] print_req_error: I/O error, dev nbd0, sector 844688 flags 8801 [270581.167124] print_req_error: I/O error, dev nbd0, sector 5123248 flags 8801 [270581.167590] block nbd0: Connection timed out [270581.167597] print_req_error: I/O error, dev nbd0, sector 844696 flags 8801 [270581.168021] print_req_error: I/O error, dev nbd0, sector 5123256 flags 8801 [270581.168487] block nbd0: Connection timed out [270581.168493] print_req_error: I/O error, dev nbd0, sector 844704 flags 8801 [270581.170183] print_req_error: I/O error, dev nbd0, sector 5123264 flags 8801 [270581.170540] block nbd0: Connection timed out [270581.173333] block nbd0: Connection timed out [270581.173728] block nbd0: Connection timed out [270581.174135] block nbd0: Connection timed out On the other hand, if we wait nbd_xmit_timeout to handle resubmission, the I/O requests will have a big delay. For example, if timeout time is 30s, and from sock dead to nbd_genl_reconfigure returned OK we only spend 2s, the I/O requests will still be handled by nbd_xmit_timeout after 30s.
