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From: David Sterba <dsterba@suse.cz>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, ericvh@gmail.com,
	lucho@ionkov.net, viro@zeniv.linux.org.uk, jlayton@kernel.org,
	idryomov@gmail.com, mark@fasheh.com, jlbec@evilplan.org,
	joseph.qi@linux.alibaba.com,
	v9fs-developer@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, ceph-devel@vger.kernel.org,
	ocfs2-devel@oss.oracle.com, linux-btrfs@vger.kernel.org,
	clm@fb.com, josef@toxicpanda.com, dsterba@suse.com,
	stable@vger.kernel.org
Subject: Re: [PATCH 6/7] btrfs: Promote to unsigned long long before shifting
Date: Mon, 26 Oct 2020 17:35:46 +0100	[thread overview]
Message-ID: <20201026163546.GP6756@twin.jikos.cz> (raw)
In-Reply-To: <20201004180428.14494-7-willy@infradead.org>

On Sun, Oct 04, 2020 at 07:04:27PM +0100, Matthew Wilcox (Oracle) wrote:
> On 32-bit systems, this shift will overflow for files larger than 4GB.
> 
> Cc: stable@vger.kernel.org
> Fixes: 53b381b3abeb ("Btrfs: RAID5 and RAID6")
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  fs/btrfs/raid56.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
> index 255490f42b5d..5ee0a53301bd 100644
> --- a/fs/btrfs/raid56.c
> +++ b/fs/btrfs/raid56.c
> @@ -1089,7 +1089,7 @@ static int rbio_add_io_page(struct btrfs_raid_bio *rbio,
>  	u64 disk_start;
>  
>  	stripe = &rbio->bbio->stripes[stripe_nr];
> -	disk_start = stripe->physical + (page_index << PAGE_SHIFT);
> +	disk_start = stripe->physical + ((loff_t)page_index << PAGE_SHIFT);

It seems that this patch is mechanical replacement. If you check the
callers, the page_index is passed from an int that iterates over bits
set in an unsigned long (bitmap). The result won't overflow.

  parent reply	other threads:[~2020-10-26 16:37 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-04 18:04 [PATCH 0/7] Fix a pile of 4GB file problems on 32-bit Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 1/7] 9P: Cast to loff_t before multiplying Matthew Wilcox (Oracle)
2020-10-07  5:48   ` Christoph Hellwig
2020-10-07 18:47     ` Matthew Wilcox
2020-10-26 17:14   ` Dominique Martinet
2020-10-04 18:04 ` [PATCH 2/7] buffer: Promote to unsigned long long before shifting Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 3/7] ceph: " Matthew Wilcox (Oracle)
2020-10-06 11:29   ` Jeff Layton
2020-10-06 17:20   ` Jeff Layton
2020-10-04 18:04 ` [PATCH 4/7] ocfs2: " Matthew Wilcox (Oracle)
2020-10-04 18:04 ` [PATCH 5/7] btrfs: " Matthew Wilcox (Oracle)
2020-10-09 14:18   ` Josef Bacik
2020-10-26 17:02   ` David Sterba
2020-10-04 18:04 ` [PATCH 6/7] " Matthew Wilcox (Oracle)
2020-10-09 14:18   ` Josef Bacik
2020-10-26 16:35   ` David Sterba [this message]
2020-10-26 16:44     ` Matthew Wilcox
2020-10-26 17:03       ` David Sterba
2020-10-04 18:04 ` [PATCH 7/7] btrfs: Promote to unsigned long long before multiplying Matthew Wilcox (Oracle)
2020-10-26 16:21   ` David Sterba

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