Re: [PATCH] sd: do not set changed flag on all unit attention conditions

From: Paolo Bonzini
Date: Tue Jul 17 2012 - 08:31:21 EST


Il 17/07/2012 14:21, James Bottomley ha scritto:
>> Yes, I realize failing only on specific sense codes as I did it in the
>> patch is not going to work. However, the other way round is not
>> problematic (explicitly allow some sense codes, fail on all others).
>
> Heh, I once thought that, but there's no end to the strange ideas USB
> manufacturers get.

:)

>> > Another example is "target operating conditions have changed". QEMU
>> > cannot report such changes because scsi_error prints a warning (fine)
>> > and then passes the unit attention upwards. With removable drives, this
>> > has the same problem as resizing.
> Why would a removable device ever use any of the codes under this ASC
> when the medium hasn't changed? They're all for arrays (well except
> 0x10 and 0x11 ... and they're only supposed to apply to tape changers
> with autoload support declared in the control mode page).

There are also a couple of generic ones such as "reported luns have
changed". I also considered briefly using "inquiry data has changed" to
reload the unmap parameters after live snapshot or storage migration. I
dropped the idea, please don't put me in the same bin as the USB
manufacturers.

Paolo
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