[Drbd-dev] always use REQ_OP_WRITE_ZEROES for zeroing offload

[Martin K. Petersen]

Christoph Hellwig <hch at lst.de> writes:

Christoph,

> This series makes REQ_OP_WRITE_ZEROES the only zeroing offload
> supported by the block layer, and switches existing implementations
> of REQ_OP_DISCARD that correctly set discard_zeroes_data to it,
> removes incorrect discard_zeroes_data, and also switches WRITE SAME
> based zeroing in SCSI to this new method.

Very, very nice. I think this is the correct approach.

I'm going to send two follow-up patches that allow us to use UNMAP for
discards and WRITE SAME w/ UNMAP for zeroout. That appears to be the
preferred configuration for most storage devices.

-- 
Martin K. Petersen	Oracle Linux Engineering