linux-kernel - Re: [PATCH/RFC -nxt] mtd_blkdevs: Set GENHD_FL_NO

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Message-ID: <20211201072328.GA31765@lst.de>
Date:   Wed, 1 Dec 2021 08:23:28 +0100
From:   Christoph Hellwig <hch@....de>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Michael Walle <michael@...le.cc>,
        Pratyush Yadav <p.yadav@...com>, linux-mtd@...ts.infradead.org,
        linux-block@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH/RFC -nxt] mtd_blkdevs: Set GENHD_FL_NO_PART

On Tue, Nov 30, 2021 at 05:23:46PM +0100, Geert Uytterhoeven wrote:
> When DT declares the partitions of an spi-nor device using
> "fixed-partitions", the individual mtdblockN partitions are now scanned
> for partitition tables, which should not happen.
> 
> Fix this by setting the GENHD_FL_NO_PART flag in the MTD block layer
> interface.
> 
> Fixes: 1ebe2e5f9d68e94c ("block: remove GENHD_FL_EXT_DEVT")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> Seen with e.g. arch/arm/boot/dts/r8a7791-koelsch.dts.
> I only noticed because I have debug code to measure QSPI performance,
> which informed me about 8 x 512 bytes being read from each partition
> detected.
> 
> RFC as I'm not sure this is correct in all cases.
> I did verify that in the absence of "fixed-partitions", the spi-nor
> device is not scanned for partitions before and after commit
> 1ebe2e5f9d68e94c.

As far as I can tell mtd fixed partitions have nothing to do with
the block layer concept of partitions.  What kind of behavior change
did you see?