linux-ext4 - Re: [dm-devel] [PATCH 01/27] target: remove an incorrect unmap zeroes data deduction

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Message-ID: <yq1r169k2xu.fsf@ca-mkp.ca.oracle.com>
Date:   Wed, 06 Apr 2022 23:06:16 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Jens Axboe <axboe@...nel.dk>, jfs-discussion@...ts.sourceforge.net,
        linux-nvme@...ts.infradead.org,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        dm-devel@...hat.com, target-devel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, drbd-dev@...ts.linbit.com,
        linux-s390@...r.kernel.org, linux-nilfs@...r.kernel.org,
        linux-scsi@...r.kernel.org, cluster-devel@...hat.com,
        xen-devel@...ts.xenproject.org, linux-ext4@...r.kernel.org,
        linux-um@...ts.infradead.org, nbd@...er.debian.org,
        linux-block@...r.kernel.org, linux-bcache@...r.kernel.org,
        ceph-devel@...r.kernel.org, linux-raid@...r.kernel.org,
        linux-mmc@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-xfs@...r.kernel.org, ocfs2-devel@....oracle.com,
        linux-fsdevel@...r.kernel.org, ntfs3@...ts.linux.dev,
        linux-btrfs@...r.kernel.org
Subject: Re: [dm-devel] [PATCH 01/27] target: remove an incorrect unmap
 zeroes data deduction


Christoph,

> For block devices the target code implements UNMAP as calls to
> blkdev_issue_discard, which does not guarantee zeroing just because
> Write Zeroes is supported.
>
> Note that this does not affect the file backed path which uses
> fallocate to punch holes.

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

-- 
Martin K. Petersen	Oracle Linux Engineering