Messages in this thread | | | Date | Tue, 3 Jul 2012 14:35:12 -0600 | From | Matthew Wilcox <> | Subject | Re: [ 38/48] SCSI & usb-storage: add try_rc_10_first flag |
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On Wed, Jul 04, 2012 at 12:07:52AM +0400, James Bottomley wrote: > > The reason for the try_rc_10_first flag is that some devices return > > bogus data in response to RC16. Like, an 800 GB device claiming to > > have 3 exabytes. > > So we could easily send both and only believe RC10 if the device is > under 2TB. However, what about all the extra flags we read out of RC16, > like trim, large sector size and DIF capability? If the device lies > about its capacity, won't we get bogus values for those as well, which > is going to cause other screw ups?
I think the necessary algorithm is simpler than that:
Send RC10 (unless the device supports PI, in which case it's probably enterprisey and well-tested) Send RC16 If RC10 capacity agrees with RC16 capacity, use extra RC16 data. (for values of "agrees with" that include the "-1 to use RC16" indicator)
Sure, it's one extra command, but really, who cares?
-- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step."
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