Re: libata error handling

[Luben Tuikov <luben_tuikov@adaptec.com>]

On 08/18/05 23:49, Jeff Garzik wrote:
> 1) The fine-grained hooks of the SCSI layer are somewhat standard for 
> block devices.  The events they signify -- timeout, abort cmd, dev 
> reset, bus reset, and host reset -- map precisely to the events that we 
> must deal with at the ATA level.

"dev reset, bus reset" -- non existant, as I'm sure you're aware of,
depending on what _transport_ you use. ;-)

> 2) When libata SAT translation layer becomes optional, and libata drives 
> a "true" block device,

Yes, this will be very cool! (when (S)ATA(PI) devices become true block
devices.

> use of ->eh_strategy_handler() will actually be 
> an obstacle due to false sharing of code paths.  ->eh_strategy_handler() 

I fully agree.

> is indeed a single "do it all" EH entrypoint, but within that entrypoint 
> you must perform several SCSI-specific tasks.
> 
> 3) ->eh_strategy_handler() has continually proven to be a method of 
> error handling poorly supported by the SCSI layer.  There are many 
> assumption coded into the SCSI layer that this is -not- the path taken 
> by LLD EH code, and libata must constantly work around these assumptions.

I agree.

> 
> 4) libata is the -only- user of ->eh_strategy_handler(), and oddballs 

Not any more ;-)

Using the command time out hook and the strategy routine, gives _complete_
control over host recovery, and I really do mean _complete_.

	Luben


> must be stomped out.  It creates a maintenance burden on the SCSI layer 
> that should be eliminated.
> 
> 
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