On 01/13/2011 10:37 AM, Tejun Heo wrote:
Hey, Jeff.
On Wed, Jan 12, 2011 at 01:35:07PM -0500, Jeff Garzik wrote:
The previous patch breaks READ VERIFY translation for all cases
-except- this one.
Ooh, right; then, can we just fix that?
The bottom line is that this patch simply wants to trigger an ATA
command, and return immediately, discarding the command results.
I'm not even sure a "run this command in background, and discard
results" facility requires the EH.
It doens't necessarily require EH but the dependency is rather
delicate because we still ride on SCSI EH. For example, we don't have
any provision for running qc's without the associated scmd. If the
command fails, libata EH rides on SCSI EH and the interaction relies
on the association between qc's and scmd's. We may be able to add
privison for this case but we already have working mechanism in EH for
internal commands so it's just easiser that way.
In this case we -do- have an associated scmd, otherwise he would not be
able to trigger the READ VERIFY translation code.
So it seems a question of (a) who generates READ VERIFY, and (b) can we
have them issue the command without waiting for the results?
Which is something I would have thought SG_IO/bsg already provided...
It remains unclear to me why EH must be updated, simply to execute a
non-data ATA command without waiting.
Jeff
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