3.16.40-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Steffen Maier <maier@xxxxxxxxxxxxxxxxxx> commit 70369f8e15b220f50a16348c79a61d3f7054813c upstream. In the hardware data router case, introduced with kernel 3.2 commit 86a9668a8d29 ("[SCSI] zfcp: support for hardware data router") the ELS/GS request&response length needs to be initialized as in the chained SBAL case. Otherwise, the FCP channel rejects ELS requests with FSF_REQUEST_SIZE_TOO_LARGE. Such ELS requests can be issued by user space through BSG / HBA API, or zfcp itself uses ADISC ELS for remote port link test on RSCN. The latter can cause a short path outage due to unnecessary remote target port recovery because the always failing ADISC cannot detect extremely short path interruptions beyond the local FCP channel. Below example is decoded with zfcpdbf from s390-tools: Timestamp : ... Area : SAN Subarea : 00 Level : 1 Exception : - CPU id : .. Caller : zfcp_dbf_san_req+0408 Record id : 1 Tag : fssels1 Request id : 0x<reqid> Destination ID : 0x00<target d_id> Payload info : 52000000 00000000 <our wwpn > [ADISC] <our wwnn > 00<s_id> 00000000 00000000 00000000 00000000 00000000 Timestamp : ... Area : HBA Subarea : 00 Level : 1 Exception : - CPU id : .. Caller : zfcp_dbf_hba_fsf_res+0740 Record id : 1 Tag : fs_ferr Request id : 0x<reqid> Request status : 0x00000010 FSF cmnd : 0x0000000b [FSF_QTCB_SEND_ELS] FSF sequence no: 0x... FSF issued : ... FSF stat : 0x00000061 [FSF_REQUEST_SIZE_TOO_LARGE] FSF stat qual : 00000000 00000000 00000000 00000000 Prot stat : 0x00000100 Prot stat qual : 00000000 00000000 00000000 00000000 Signed-off-by: Steffen Maier <maier@xxxxxxxxxxxxxxxxxx> Fixes: 86a9668a8d29 ("[SCSI] zfcp: support for hardware data router") Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxxxxxxx> Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/s390/scsi/zfcp_fsf.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/drivers/s390/scsi/zfcp_fsf.c +++ b/drivers/s390/scsi/zfcp_fsf.c @@ -984,8 +984,12 @@ static int zfcp_fsf_setup_ct_els_sbals(s if (zfcp_adapter_multi_buffer_active(adapter)) { if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_req)) return -EIO; + qtcb->bottom.support.req_buf_length = + zfcp_qdio_real_bytes(sg_req); if (zfcp_qdio_sbals_from_sg(qdio, &req->qdio_req, sg_resp)) return -EIO; + qtcb->bottom.support.resp_buf_length = + zfcp_qdio_real_bytes(sg_resp); zfcp_qdio_set_data_div(qdio, &req->qdio_req, zfcp_qdio_sbale_count(sg_req));