On Mon, 2019-11-11 at 06:51 -0500, xiubli@xxxxxxxxxx wrote:
> From: Xiubo Li <xiubli@xxxxxxxxxx>
>
> For example, if we have 5 mds in the mdsmap and the states are:
> m_info[5] --> [-1, 1, -1, 1, 1]
>
> If we get a ramdon number 1, then we should get the mds index 3 as
> expected, but actually we will get index 2, which the state is -1.
>
> Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> ---
> fs/ceph/mdsmap.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c
> index ce2d00da5096..2011147f76bf 100644
> --- a/fs/ceph/mdsmap.c
> +++ b/fs/ceph/mdsmap.c
> @@ -20,7 +20,7 @@
> int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
> {
> int n = 0;
> - int i;
> + int i, j;
>
> /* special case for one mds */
> if (1 == m->m_num_mds && m->m_info[0].state > 0)
> @@ -35,9 +35,12 @@ int ceph_mdsmap_get_random_mds(struct ceph_mdsmap *m)
>
> /* pick */
> n = prandom_u32() % n;
> - for (i = 0; n > 0; i++, n--)
> - while (m->m_info[i].state <= 0)
> - i++;
> + for (j = 0, i = 0; i < m->m_num_mds; i++) {
> + if (m->m_info[0].state > 0)
> + j++;
> + if (j > n)
> + break;
> + }
>
> return i;
> }
Looks good. I'll merge after some testing.
Took me a minute but the crux of the issue is that the for loop
increment gets done regardless of the outcome of the while loop test.
This looks nicer too. I don't think it's actually possible, but the
while loop _looks_ like it could walk off the end of the array.
Thanks,
--
Jeff Layton <jlayton@xxxxxxxxxx>
