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Date:   Sun, 23 Feb 2020 20:03:11 +0100
From:   Domenico Andreoli <domenico.andreoli@linux.com>
To:     "Darrick J. Wong" <darrick.wong@oracle.com>
Cc:     Christoph Hellwig <hch@lst.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-pm@vger.kernel.org
Subject: Re: Regression: hibernation is broken since
 e6bc9de714972cac34daa1dc1567ee48a47a9342
Message-ID: <20200223190311.GA26811@dumbo>
Mail-Followup-To: "Darrick J. Wong" <darrick.wong@oracle.com>,
        Christoph Hellwig <hch@lst.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-pm@vger.kernel.org
References: <20200213172351.GA6747@dumbo>
 <20200213175753.GS6874@magnolia>
 <20200213183515.GA8798@dumbo>
 <20200213193410.GB6868@magnolia>
 <20200213194135.GF6870@magnolia>
 <20200214211523.GA32637@dumbo>
 <20200222002319.GK9504@magnolia>
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On Fri, Feb 21, 2020 at 04:23:19PM -0800, Darrick J. Wong wrote:
> 
> Ok, third try.  Does the following work?  This is a little more
> selective in that it only disables the write protection on the swap
> device/file that uswusp is going to write to.

Yes it works but also verified that once the S_SWAPFILE bit is cleared
it's never restored, therefore the protecton is gone after the first
hibernation.

> 
> --D
> 
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 77438954cc2b..a3ae9cbbfcf0 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -372,10 +372,17 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
>  			 */
>  			swdev = new_decode_dev(swap_area.dev);
>  			if (swdev) {
> +				struct block_device *bd;
> +
>  				offset = swap_area.offset;
> -				data->swap = swap_type_of(swdev, offset, NULL);
> +				data->swap = swap_type_of(swdev, offset, &bd);
>  				if (data->swap < 0)
>  					error = -ENODEV;
> +
> +				inode_lock(bd->bd_inode);
> +				bd->bd_inode->i_flags &= ~S_SWAPFILE;
> +				inode_unlock(bd->bd_inode);
> +				bdput(bd);
>  			} else {
>  				data->swap = -1;
>  				error = -EINVAL;

-- 
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