Re: [PATCH] ext2/ext3:useless code for return value

["æåå(Peter Pan)"]

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(æåå)<wppan@xxxxxxxxxxxxxxxxx>
> >
> > ---
> >   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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