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Subject: Re: [PATCH] floppy: reintroduce O_NDELAY fix
To:     Jiri Kosina <jikos@kernel.org>, Jens Axboe <axboe@kernel.dk>
Cc:     linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
        Wim Osterholt <wim@djo.tudelft.nl>,
        Kurt Garloff <kurt@garloff.de>
References: <20160610230255.GA27770@djo.tudelft.nl>
 <alpine.LNX.2.00.1606131414420.6874@cbobk.fhfr.pm>
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 <20160615132040.GZ14480@ZenIV.linux.org.uk>
 <alpine.LNX.2.00.1606151610420.6874@cbobk.fhfr.pm>
 <20160615224722.GA9545@djo.tudelft.nl>
 <alpine.LNX.2.00.1606160946000.6874@cbobk.fhfr.pm>
 <alpine.LNX.2.00.1606301317290.6874@cbobk.fhfr.pm>
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 <nycvar.YFH.7.76.2101211603590.5622@cbobk.fhfr.pm>
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From:   Denis Efremov <efremov@linux.com>
Message-ID: <5ef748c9-9ab9-9a7e-6ae9-6e4a292b6842@linux.com>
Date:   Tue, 26 Jan 2021 11:21:28 +0300
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On 1/22/21 2:13 PM, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@suse.cz>
> 
> This issue was originally fixed in 09954bad4 ("floppy: refactor open() 
> flags handling").
> 
> The fix as a side-effect, however, introduce issue for open(O_ACCMODE) 
> that is being used for ioctl-only open. I wrote a fix for that, but 
> instead of it being merged, full revert of 09954bad4 was performed, 
> re-introducing the O_NDELAY / O_NONBLOCK issue, and it strikes again.
> 
> This is a forward-port of the original fix to current codebase; the 
> original submission had the changelog below:
> 
> ====
> Commit 09954bad4 ("floppy: refactor open() flags handling"), as a
> side-effect, causes open(/dev/fdX, O_ACCMODE) to fail. It turns out that
> this is being used setfdprm userspace for ioctl-only open().
> 
> Reintroduce back the original behavior wrt !(FMODE_READ|FMODE_WRITE) 
> modes, while still keeping the original O_NDELAY bug fixed.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Wim Osterholt <wim@djo.tudelft.nl>
> Tested-by: Wim Osterholt <wim@djo.tudelft.nl>
> Reported-and-tested-by: Kurt Garloff <kurt@garloff.de>
> Fixes: 09954bad4 ("floppy: refactor open() flags handling")
> Fixes: f2791e7ead ("Revert "floppy: refactor open() flags handling"")
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Applied. I'll send it to Jens soon with a couple of cleanup patches.

https://github.com/evdenis/linux-floppy/commit/e32f6163c47efbdbad06258560aa00d1c7e5b699

Thanks,
Denis

> ---
>  drivers/block/floppy.c | 30 +++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
> index dfe1dfc901cc..0b71292d9d5a 100644
> --- a/drivers/block/floppy.c
> +++ b/drivers/block/floppy.c
> @@ -4121,23 +4121,23 @@ static int floppy_open(struct block_device *bdev, fmode_t mode)
>  	if (fdc_state[FDC(drive)].rawcmd == 1)
>  		fdc_state[FDC(drive)].rawcmd = 2;
>  
> -	if (!(mode & FMODE_NDELAY)) {
> -		if (mode & (FMODE_READ|FMODE_WRITE)) {
> -			drive_state[drive].last_checked = 0;
> -			clear_bit(FD_OPEN_SHOULD_FAIL_BIT,
> -				  &drive_state[drive].flags);
> -			if (bdev_check_media_change(bdev))
> -				floppy_revalidate(bdev->bd_disk);
> -			if (test_bit(FD_DISK_CHANGED_BIT, &drive_state[drive].flags))
> -				goto out;
> -			if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags))
> -				goto out;
> -		}
> -		res = -EROFS;
> -		if ((mode & FMODE_WRITE) &&
> -		    !test_bit(FD_DISK_WRITABLE_BIT, &drive_state[drive].flags))
> +	if (mode & (FMODE_READ|FMODE_WRITE)) {
> +		drive_state[drive].last_checked = 0;
> +		clear_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags);
> +		if (bdev_check_media_change(bdev))
> +			floppy_revalidate(bdev->bd_disk);
> +		if (test_bit(FD_DISK_CHANGED_BIT, &drive_state[drive].flags))
> +			goto out;
> +		if (test_bit(FD_OPEN_SHOULD_FAIL_BIT, &drive_state[drive].flags))
>  			goto out;
>  	}
> +
> +	res = -EROFS;
> +
> +	if ((mode & FMODE_WRITE) &&
> +			!test_bit(FD_DISK_WRITABLE_BIT, &drive_state[drive].flags))
> +		goto out;
> +
>  	mutex_unlock(&open_lock);
>  	mutex_unlock(&floppy_mutex);
>  	return 0;
>