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"Darrick" == Darrick J Wong [off-list ref] writes:
Darrick> Create a new ioctl to expose the block layer's newfound ability
Darrick> to issue either a zeroing discard, a WRITE SAME with a zero
Darrick> page, or a regular write with the zero page. This BLKZEROOUT2
Darrick> ioctl takes {start, length, flags} as parameters. So far, the
Darrick> only flag available is to enable the zeroing discard part --
Darrick> without it, the call invokes the old BLKZEROOUT behavior.
Darrick> start and length have the same meaning as in BLKZEROOUT.
Darrick> Furthermore, because BLKZEROOUT2 issues commands directly to
Darrick> the storage device, we must invalidate the page cache (as a
Darrick> regular O_DIRECT write would do) to avoid returning stale cache
Darrick> contents at a later time.
Looks good to me, Darrick.
Reviewed-by: Martin K. Petersen <redacted>
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Martin K. Petersen Oracle Linux Engineering