Re: [PATCH 7/7] btrfs: don't BUG_ON allocation errors in btrfs_drop_snapshot

[Tsutomu Itoh <t-itoh@jp.fujitsu.com>]

Hi, Mark,

(2011/07/22 4:48), Mark Fasheh wrote:
> In addition to properly handling allocation failure from btrfs_alloc_path, I
> also fixed up the kzalloc error handling code immediately below it.
> 
> Signed-off-by: Mark Fasheh <mfasheh@suse.com>
> ---
>  fs/btrfs/extent-tree.c |    8 ++++++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index ff339b2..4cf5257 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -6271,10 +6271,14 @@ int btrfs_drop_snapshot(struct btrfs_root *root,
>  	int level;
>  
>  	path = btrfs_alloc_path();
> -	BUG_ON(!path);
> +	if (!path)
> +		return -ENOMEM;
>  
>  	wc = kzalloc(sizeof(*wc), GFP_NOFS);
> -	BUG_ON(!wc);
> +	if (!wc) {
> +		btrfs_free_path(path);
> +		return -ENOMEM;
> +	}
>  
>  	trans = btrfs_start_transaction(tree_root, 0);
>  	BUG_ON(IS_ERR(trans));

Currently, callers of btrfs_drop_snapshot() ignore the return code.
But btrfs_drop_snapshot() detects the error by BUG_ON.

The caller still ignore the return code though your modification returns
the error code to the caller. 
So, we can not detect error. I don't think that it is good.

Thanks,
Tsutomu