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From:   Martijn Coenen <maco@android.com>
Date:   Tue, 11 Aug 2020 08:49:03 +0200
Message-ID: <CAB0TPYE-_ErKTqveFW-3Gpb8=ayoy3okyhkeScKi7r5rmLzp8A@mail.gmail.com>
Subject: Re: [PATCH v2] loop: unset GENHD_FL_NO_PART_SCAN on LOOP_CONFIGURE
To:     Lennart Poettering <mzxreary@0pointer.de>
Cc:     linux-block <linux-block@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>,
        Yang Xu <xuyang2018.jy@cn.fujitsu.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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On Mon, Aug 10, 2020 at 7:16 PM Lennart Poettering <mzxreary@0pointer.de> wrote:
>
> When LOOP_CONFIGURE is used with LO_FLAGS_PARTSCAN we need to propagate
> this into the GENHD_FL_NO_PART_SCAN. LOOP_SETSTATUS does this,
> LOOP_CONFIGURE doesn't so far. Effect is that setting up a loopback
> device with partition scanning doesn't actually work when LOOP_CONFIGURE
> is issued, though it works fine with LOOP_SETSTATUS.
>
> Let's correct that and propagate the flag in LOOP_CONFIGURE too.
>
> Fixes: 3448914e8cc5("loop: Add LOOP_CONFIGURE ioctl")
>
> Signed-off-by: Lennart Poettering <lennart@poettering.net>
> Acked-by: Martijn Coenen <maco@android.com>

Thanks, still looks good to me.

> ---
>  drivers/block/loop.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index d18160146226..2f137d6ce169 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1171,6 +1171,8 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
>         if (part_shift)
>                 lo->lo_flags |= LO_FLAGS_PARTSCAN;
>         partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
> +       if (partscan)
> +               lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
>
>         /* Grab the block_device to prevent its destruction after we
>          * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev).
> --
> 2.26.2