linux-kernel - Re: [PATCH 1/1] PM/Hibernate: fix "swap breaks after hibernation failures"

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Message-ID: <20090128092709.GA27210@elf.ucw.cz>
Date:	Wed, 28 Jan 2009 10:27:10 +0100
From:	Pavel Machek <pavel@...e.cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Len Brown <lenb@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>
Subject: Re: [PATCH 1/1] PM/Hibernate: fix "swap breaks after hibernation
	failures"

On Tue 2009-01-27 23:18:59, Rafael J. Wysocki wrote:
> From: Alan Jenkins <alan-jenkins@...fmail.co.uk>
> 
> http://bugzilla.kernel.org/show_bug.cgi?id=12239
> 
> The image writing code dropped a reference to the current swap device.
> This doesn't show up if the hibernation succeeds - because it doesn't
> affect the image which gets resumed.  But it means multiple _failed_
> hibernations end up freeing the swap device while it is still use!
> 
> swsusp_write() finds the block device for the swap file using swap_type_of().
> It then uses blkdev_get() / blkdev_put() to open and close the block device.
> 
> Unfortunately, blkdev_get() assumes ownership of the inode of the block_device
> passed to it.  So blkdev_put() calls iput() on the inode.  This is by design
> and other callers expect this behaviour.  The fix is for swap_type_of() to take
> a reference on the inode using bdget().
> 
> Signed-off-by: Alan Jenkins <alan-jenkins@...fmail.co.uk>
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>

Acked-by: Pavel Machek <pavel@...e.cz>

> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index f48b831..7740478 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -635,7 +635,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
>  
>  		if (!bdev) {
>  			if (bdev_p)
> -				*bdev_p = sis->bdev;
> +				*bdev_p = bdget(sis->bdev->bd_dev);
>  
>  			spin_unlock(&swap_lock);
>  			return i;
> @@ -647,7 +647,7 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p)
>  					struct swap_extent, list);
>  			if (se->start_block == offset) {
>  				if (bdev_p)
> -					*bdev_p = sis->bdev;
> +					*bdev_p = bdget(sis->bdev->bd_dev);
>  
>  				spin_unlock(&swap_lock);
>  				bdput(bdev);
> 
> 
> 
> 

-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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