linux-kernel - Re: [PATCH-v2] target/iblock: Convert WRITE_SAME to blkdev_issue

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Message-ID: <yq1vaodhpl8.fsf@oracle.com>
Date:   Fri, 02 Jun 2017 20:39:15 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     "Nicholas A. Bellinger" <nab@...ux-iscsi.org>
Cc:     target-devel <target-devel@...r.kernel.org>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Mike Christie <mchristi@...hat.com>,
        Hannes Reinecke <hare@...e.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Jens Axboe <axboe@...com>
Subject: Re: [PATCH-v2] target/iblock: Convert WRITE_SAME to blkdev_issue_zeroout


Nicholas,

> The people who are actively using iblock_execute_write_same_direct()
> are doing so in the context of ESX VAAI BlockZero, together with
> EXTENDED_COPY and COMPARE_AND_WRITE primitives.
>
> In practice though I've not seen any users of IBLOCK WRITE_SAME for
> anything other than VAAI BlockZero, so just using
> blkdev_issue_zeroout() when available, and falling back to
> iblock_execute_write_same() if the WRITE_SAME buffer contains anything
> other than zeros should be OK.
>
> (Hook up max_write_zeroes_sectors to signal LBPRZ feature bit in
>  target_configure_unmap_from_queue - nab)

Looks reasonable.

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

-- 
Martin K. Petersen	Oracle Linux Engineering