RE: [PATCH] Btrfs: fix allocation size calculations in alloc_btrfs_bio

[Zhao Lei <zhaolei@cn.fujitsu.com>]

Hi, Chris Mason

* From: Chris Mason [mailto:clm@fb.com]
> Sent: Friday, February 20, 2015 10:00 AM
> To: linux-btrfs; Zhao Lei; dsterba@suse.cz
> Subject: [PATCH] Btrfs: fix allocation size calculations in alloc_btrfs_bio
> 
> Since commit 8e5cfb55d3f (Btrfs: Make raid_map array be inlined in btrfs_bio
> structure), the raid map array is allocated along with the btrfs bio in
> alloc_btrfs_bio.  The calculation used to decide how much we need to allocate
> was using the wrong parameter passed into the allocation function.
> 
> The passed in real_stripes will be zero if a target replace operation is not
> currently running.  We want to use total_stripes instead.
> 
Sorry, my bad.

Thanks
Zhaolei

> Signed-off-by: Chris Mason <clm@fb.com>
> Reported-by: Dave Sterba <dsterba@suse.cz>
> 
> ---
>  fs/btrfs/volumes.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index cd4d131..8222f6f
> 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -4903,10 +4903,17 @@ static void sort_parity_stripes(struct btrfs_bio
> *bbio, int num_stripes)  static struct btrfs_bio *alloc_btrfs_bio(int
> total_stripes, int real_stripes)  {
>  	struct btrfs_bio *bbio = kzalloc(
> +		 /* the size of the btrfs_bio */
>  		sizeof(struct btrfs_bio) +
> +		/* plus the variable array for the stripes */
>  		sizeof(struct btrfs_bio_stripe) * (total_stripes) +
> +		/* plus the variable array for the tgt dev */
>  		sizeof(int) * (real_stripes) +
> -		sizeof(u64) * (real_stripes),
> +		/*
> +		 * plus the raid_map, which includes both the tgt dev
> +		 * and the stripes
> +		 */
> +		sizeof(u64) * (total_stripes),
>  		GFP_NOFS);
>  	if (!bbio)
>  		return NULL;
> --
> 1.8.1