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Date:   Wed, 22 Apr 2020 10:07:52 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Martijn Coenen <maco@android.com>
Cc:     Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
        Ming Lei <ming.lei@redhat.com>,
        Narayan Kamath <narayan@google.com>,
        Zimuzo Ezeozue <zezeozue@google.com>, kernel-team@android.com,
        linux-block <linux-block@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Martijn Coenen <maco@google.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Subject: Re: [PATCH 4/4] loop: Add LOOP_SET_FD_AND_STATUS ioctl.
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References: <20200420080409.111693-1-maco@android.com> <20200420080409.111693-5-maco@android.com> <20200422061919.GA22819@lst.de> <CAB0TPYHCHytLouWSpwKvi3qpZCzAYhuEot9y+ssnE8vDGgtQpg@mail.gmail.com>
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On Wed, Apr 22, 2020 at 10:06:17AM +0200, Martijn Coenen wrote:
> > line at the top of lo_compat_ioctl, and switches the LOOP_SET_STATUS
> > and LOOP_GET_STATUS case to it?
> 
> Did you mean in regular lo_ioctl()?

Yes, sorry.

> eg something like this:
> 
> @@ -1671,6 +1671,7 @@ static int lo_ioctl(struct block_device *bdev,
> fmode_t mode,
>         unsigned int cmd, unsigned long arg)
>  {
>         struct loop_device *lo = bdev->bd_disk->private_data;
> +       void __user *argp = (void __user *) arg;
>         int err;
> 
>         switch (cmd) {
> @@ -1694,21 +1695,19 @@ static int lo_ioctl(struct block_device *bdev,
> fmode_t mode,
>         case LOOP_SET_STATUS:
>                 err = -EPERM;
>                 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
> -                       err = loop_set_status_old(lo,
> -                                       (struct loop_info __user *)arg);
> +                       err = loop_set_status_old(lo, argp);
>                 }
>                 break;
>         case LOOP_GET_STATUS:
> -               return loop_get_status_old(lo, (struct loop_info __user *) arg);
> +               return loop_get_status_old(lo, argp);
>         case LOOP_SET_STATUS64:
>                 err = -EPERM;
>                 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
> -                       err = loop_set_status64(lo,
> -                                       (struct loop_info64 __user *) arg);
> +                       err = loop_set_status64(lo, argp);
>                 }
>                 break;
>         case LOOP_GET_STATUS64:
> -               return loop_get_status64(lo, (struct loop_info64 __user *) arg);
> +               return loop_get_status64(lo, argp);

Exactly!