linux-kernel - Re: [PATCH v7 0/5] Introduce provisioning primitives

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Message-ID: <yq1sfb21zsa.fsf@ca-mkp.ca.oracle.com>
Date:   Wed, 07 Jun 2023 22:03:40 -0400
From:   "Martin K. Petersen" <martin.petersen@...cle.com>
To:     Dave Chinner <david@...morbit.com>
Cc:     Sarthak Kukreti <sarthakkukreti@...omium.org>,
        Mike Snitzer <snitzer@...nel.org>,
        Joe Thornber <thornber@...hat.com>,
        Jens Axboe <axboe@...nel.dk>,
        Christoph Hellwig <hch@...radead.org>,
        Theodore Ts'o <tytso@....edu>, dm-devel@...hat.com,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Darrick J. Wong" <djwong@...nel.org>,
        Brian Foster <bfoster@...hat.com>,
        Bart Van Assche <bvanassche@...gle.com>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Joe Thornber <ejt@...hat.com>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        Jason Wang <jasowang@...hat.com>,
        Alasdair Kergon <agk@...hat.com>
Subject: Re: [PATCH v7 0/5] Introduce provisioning primitives


Dave,

> Possibly unintentionally, I didn't call it REQ_OP_PROVISION but that's
> what I intended - the operation does not contain data at all. It's an
> operation like REQ_OP_DISCARD or REQ_OP_WRITE_ZEROS - it contains a
> range of sectors that need to be provisioned (or discarded), and
> nothing else.

Yep. That's also how SCSI defines it. The act of provisioning a block
range is done through an UNMAP command using a special flag. All it does
is pin down those LBAs so future writes to them won't result in ENOSPC.

-- 
Martin K. Petersen	Oracle Linux Engineering