Re: Testing for RDMA with ib_srp: Failed to map data (-12) with max_sectors_kb=4096 and buffered I/O with 4MB writes

[Sagi Grimberg <sagi-NQWnxTmZq1alnMjI0IkVqw@public.gmane.org>]

> Hello
>
> I am still on my quest for getting 4MB buffered writes to be stable to RDMA SRP targets.
> Lots of testing has been performed here with EDR 100 back to back connections using
> mellanox ConnectX-4 with mlx5_ib, an dthe ib_srp* drivers on target server and client.
>
> In summary:
>   setting max_sectors_kb=4096 and running DIRECT_IO is solid as a rock
>   setting max_sectors_kb=2048 and running buffered 4MB writes to an FS on a multipath is rock solid
>
>   However:
>   setting max_sectors_kb=4096 and running buffered I/O sees serious mapping issues.
>
>
> I have isolated the failure and call flow to this
>
> srp_queuecommand
>      srp_map_data(scmnd, ch, req);
> 	  srp_map_idb
> 	      ret = srp_map_finish_fr(&state, req, ch, 1);	
>
>
> The -12 is returned by srp_map_finish_fr() and fed back to fail with
> ib_srp: Failed to map data (-12)

Can you print out how many FRs we used at this point?

state->nmdesc?
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