Messages in this thread | | | Date | Thu, 6 Sep 2012 12:09:23 +0200 | From | David Sterba <> | Subject | Re: [PATCH 1/3] btrfs: remove unnecessary -ENOMEM BUG_ON check in extent-tree.c/exclude_super_stripes |
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On Thu, Sep 06, 2012 at 02:40:41PM +0800, Wang Sheng-Hui wrote: > The memory allocation failure is BUG_ON in add_excluded_extent (following > the code path) and btrfs_rmap_block. No need to BUG_ON -ENOMEM inside > exclude_super_stripes itself.
No please.
> Its return value is always 0, and useless for its callers. Set it as void > instead 0-returned.
btrfs_rmap_block itself contains a BUG_ON:
3980 int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree, 3981 u64 chunk_start, u64 physical, u64 devid, 3982 u64 **logical, int *naddrs, int *stripe_len) 3983 { 3984 struct extent_map_tree *em_tree = &map_tree->map_tree; 3985 struct extent_map *em; 3986 struct map_lookup *map; 3987 u64 *buf; 3988 u64 bytenr; 3989 u64 length; 3990 u64 stripe_nr; 3991 int i, j, nr = 0; 3992 3993 read_lock(&em_tree->lock); 3994 em = lookup_extent_mapping(em_tree, chunk_start, 1); 3995 read_unlock(&em_tree->lock); 3996 3997 BUG_ON(!em || em->start != chunk_start);
And this should be turned into an 'return error', thus giving a non-zero return code that should be handled in the callers.
Eg. this patch attempts to do that http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg15470.html
but has not been merged due to incorrect fix inside exclude_super_stripes (introduced in the patch).
The same objection for return code cleanups will hold for any function that returns 0 but is full of BUG_ONs.
david
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