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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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