Re: LibPATA code issues / 2.6.15.4

[Mark Lord <lkml@rtr.ca>]

Mark Lord wrote:
>> Mark Lord wrote:
>>
>>>> sdb: Current: sense key: Medium Error
>>>>     Additional sense: Unrecovered read error - auto reallocate failed
>>>> end_request: I/O error, dev sdb, sector 398283329
>>>> raid1: Disk failure on sdb2, disabling device.
>>>>         Operation continuing on 1 devices
> ..
>>> The command failing above is SCSI WRITE_10, which is being
>>> translated into ATA_CMD_WRITE_FUA_EXT by libata.
>>>
>>> This command fails -- unrecognized by the drive in question.
>>> But libata reports it (most incorrectly) as a "medium error",
>>> and the drive is taken out of service from its RAID.
>>>
>>> Bad, bad, and worse.

.. hold off on 2.6.16 because of this or not?

> 
> Well, no doubt whatsoever about it being a "regression",
> since the FUA code is *new* in 2.6.16 (not present in 2.6.15).
> 
> The FUA code should either get fixed, or removed from 2.6.16.

Actually, now that I've done a little more digging, this FUA stuff
is inherently dangerous as implemented.  A least a few SATA controllers
including pipelines and whatnot that rely upon recognizing the (S)ATA
opcodes being using.  And I sincerely doubt that any of those will
recognize the very newish (and aptly named..) FUA opcodes.

These may be unsafe in general, unless we tag controllers as
FUA-capable and NON-FUA-capable, in addition to tagging the drives.

:/