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

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Message-ID: <yq161bpgkl5.fsf@sermon.lab.mkp.net>
Date:	Thu, 29 Jan 2015 19:48:06 -0500
From:	"Martin K. Petersen" <martin.petersen@...cle.com>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	Jens Axboe <axboe@...nel.dk>,
	Christoph Hellwig <hch@...radead.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-api@...r.kernel.org, Jeff Layton <jlayton@...chiereds.net>,
	"J. Bruce Fields" <bfields@...ldses.org>
Subject: Re: [RESEND] [PATCH] block: create ioctl to discard-or-zeroout a range of blocks

>>>>> "Darrick" == Darrick J Wong <darrick.wong@...cle.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.

Looks good to me, Darrick.

Reviewed-by: Martin K. Petersen <martin.petersen@...cle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering
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