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SubjectRe: [PATCH] ext2/ext3:useless code for return value
On 05/08/2010 12:23 AM, Jan Kara wrote:
>> When rsv is the right hand side of goal, we should return NULL,
>> because now rsv's prev is NULL, or we return rsv.
>>
>> Signed-off-by: Peter Pan(潘卫平)<wppan@redflag-linux.com>
>>
>> ---
>> fs/ext2/balloc.c | 6 +-----
>> fs/ext3/balloc.c | 6 +-----
>> 2 files changed, 2 insertions(+), 10 deletions(-)
>>
>> diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
>> index 3cf038c..023990f 100644
>> --- a/fs/ext2/balloc.c
>> +++ b/fs/ext2/balloc.c
>> @@ -323,11 +323,7 @@ search_reserve_window(struct rb_root *root,
>> ext2_fsblk_t goal)
>> * side of the interval containing the goal. If it's the RHS,
>> * we need to back up one.
>> */
>> - if (rsv->rsv_start> goal) {
>> - n = rb_prev(&rsv->rsv_node);
>> - rsv = rb_entry(n, struct ext2_reserve_window_node, rsv_node);
>> - }
>> - return rsv;
>> + return (rsv->rsv_start< goal) ? rsv : NULL;
> Hmm, I'm not sure I understand your reasoning. Suppose we have an RB-tree
> with two intervals 0-10, 20-30. Interval 0-10 is in the root. Now we search
> for goal 15. In the root we go to right because 10<15, in the next node we go
> to left because 15< 20. Then the loop terminates. Now your code would return
> NULL but previous code would return rb_prev of interval 20-30 which is 0-10.
> And that is what we want as far as I understand what we expect from the
> function...
>
> Honza
You got the point!
Many thanks.

Regards
--
Peter Pan
Red Flag Software Co.,Ltd
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