Re: [PATCH 00/19, v5] Make ib_srp better suited for H.A. purposes

[Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org>]

On 11/12/12 23:51, Or Gerlitz wrote:
> Bart Van Assche <bvanassche-HInyCGIudOg@public.gmane.org> wrote:
>> This patch series makes the ib_srp driver better suited for use in a H.A. setup because:
>> - multipathd is notified faster about transport layer failures.
>> - Transport layer failures reliably result in SCSI host removal.
>> - Switchover can be triggered explicitly by deleting an initiator device.
>> - Disconnecting from a target without unloading ib_srp is now possible.
>
> Hi Bart,
>
> Few more questions/comments,
>
>> The individual patches are:
>> 0001-ib_srp-Enlarge-block-layer-timeout.patch
>> 0002-ib_srp-Eliminate-state-SRP_TARGET_CONNECTING.patch
>> 0003-ib_srp-Introduce-srp_handle_qp_err.patch
>> 0004-ib_srp-Suppress-superfluous-error-messages.patch
>> 0005-ib_srp-Avoid-that-SCSI-error-handling-causes-trouble.patch
>> 0006-ib_srp-Introduce-the-helper-function-srp_remove_targ.patch
>> 0007-ib_srp-Eliminate-state-SRP_TARGET_DEAD.patch
>> 0008-ib_srp-Keep-processing-commands-during-host-removal.patch
>> 0009-ib_srp-Make-srp_disconnect_target-wait-for-IB-comple.patch
>> 0010-ib_srp-Document-sysfs-attributes.patch
>> 0011-srp_transport-Fix-atttribute-registration.patch
>> 0012-srp_transport-Simplify-attribute-initialization-code.patch
>> 0013-srp_transport-Document-sysfs-attributes.patch
>> 0014-ib_srp-Allow-SRP-disconnect-through-sysfs.patch
>> 0015-ib_srp-Maintain-a-single-connection-per-I_T-nexus.patch
>> 0016-srp_transport-Add-transport-layer-error-handling.patch
>> 0017-ib_srp-Add-dev_loss_tmo-support.patch
>> 0018-ib_srp-Remove-SCSI-devices-upon-port-down-event.patch
>> 0019-scsi_transport_srp-Fail-I-O-faster.patch
>
> I understand that as a whole, this series makes SRP to function better
> in HA schemes, however, can you break this list of patches to cleanups,
> new functionality and actual HA related bug fixes and concrete
> improvements. Also, if you can spare some high level words on the
> design directions/decisions taken as the patch series evolved, as this
> effort in underway for some time now.

The goal of this patch series is to reduce path failover time in a 
multipath setup. I've done my best to indicate in the patch descriptions 
which patches are cleanup patches and which patches introduce new 
functionality. Which patches should be considered bug fixes depends on 
what is considered a bug - is it e.g. considered a bug that it can take 
more than 60s with the upstream SRP initiator before multipathd switches 
paths ? Is it considered a bug that the upstream SRP initiator does not 
remove SCSI hosts that correspond to failed paths ?

> Also for V6 -- next-time -- etc, please make sure to have Vn to appear
> in the [PATCH] brackets, as it critical when folks browse between
> different versions/postings of your to the same patch set, if you use
> git format-patch, this is easily achieved with --subject-prefix="PATCH
> Vn"

Thanks, will do.

Bart.

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