Re: [PATCH 1/1] mpt3sas: Ignore unaligned completion length for ZBC_IN

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Bart,

On 2/14/17 12:59, Bart Van Assche wrote:
>>> What software generated a ZBC_IN request with type REQ_TYPE_FS? Shouldn't
>>> all ZBC_IN requests be assigned type REQ_TYPE_BLOCK_PC?
>>
>> Any application that issues a BLKREPORTZONE ioctl (e.g. mkfs.f2fs or
>> libzbc tools) or kernel component calling blkdev_report_zones (e.g.
>> f2fs) will generate one or more REQ_OP_ZONE_REPORT BIO which translate
>> into a REQ_TYPE_FS requests for the command ZBC_IN. That command does
>> not operate on LBAs. The transfer length of the request can be any
>> length larger than 64B and the reply length will be at least 64B and
>> aligned on a multiple of 64.
>>
>> The patch "mpt3sas: Force request partial completion alignment" applied
>> last week forgot this case, and frankly, I did too despite having looked
>> at it.
> 
> Hello Damien,
> 
> How about modifying the block layer core such that it sets REQ_TYPE_BLOCK_PC
> for REQ_OP_ZONE_REPORT requests? Would that be a valid alternative to the
> above patch?

I think so. But my understanding of REQ_TYPE_BLOCK_PC is that it is the
type for requests issued internally (scsi_execute) of from things like
the SG driver, so in essence, all requests not derived from a BIO... Is
this correct ? If yes, then setting the BLOCK_TYPE_PC for
REQ_OP_ZONE_REPORT (and REQ_OP_ZONE_RESET while at it) would break this
model, wouldn't it ?

Best regards.

-- 
Damien Le Moal, Ph.D.
Sr. Manager, System Software Research Group,
Western Digital Corporation
Damien.LeMoal@xxxxxxx
(+81) 0466-98-3593 (ext. 513593)
1 kirihara-cho, Fujisawa,
Kanagawa, 252-0888 Japan
www.wdc.com, www.hgst.com



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