Thread (22 messages) 22 messages, 7 authors, 2005-08-19

Re: libata error handling

From: Luben Tuikov <hidden>
Date: 2005-08-19 18:46:39
Also in: linux-scsi, lkml

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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