On 08/10/2016 06:30 PM, Steffen Maier wrote:
> 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")
> Cc: <stable@xxxxxxxxxxxxxxx> # 3.2+
> Reviewed-by: Benjamin Block <bblock@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/s390/scsi/zfcp_fsf.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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