Re: [PATCH v4] block: create ioctl to discard-or-zeroout a range of blocks

["Martin K. Petersen" <martin.petersen@oracle.com>]

>>>>> "Darrick" == Darrick J Wong <darrick.wong@oracle.com> 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.

Jens? Christoph?

-- 
Martin K. Petersen	Oracle Linux Engineering