diff options
| author | Andreas Gruenbacher <agruenba@redhat.com> | 2019-05-17 19:18:43 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-31 06:48:12 -0700 |
| commit | f22537fe00c1bd7d42214a86ac433f67567da96e (patch) | |
| tree | 4ffc6a618ec290ef8a537ae793d18ed4f6a3623c /fs/gfs2 | |
| parent | 235aeafb93e96b7540338952dc62d893a00dc7f6 (diff) | |
gfs2: Fix sign extension bug in gfs2_update_stats
commit 5a5ec83d6ac974b12085cd99b196795f14079037 upstream.
Commit 4d207133e9c3 changed the types of the statistic values in struct
gfs2_lkstats from s64 to u64. Because of that, what should be a signed
value in gfs2_update_stats turned into an unsigned value. When shifted
right, we end up with a large positive value instead of a small negative
value, which results in an incorrect variance estimate.
Fixes: 4d207133e9c3 ("gfs2: Make statistics unsigned, suitable for use with do_div()")
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Cc: stable@vger.kernel.org # v4.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs/gfs2')
| -rw-r--r-- | fs/gfs2/lock_dlm.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/fs/gfs2/lock_dlm.c b/fs/gfs2/lock_dlm.c index 8b907c5cc913..3c3d037df824 100644 --- a/fs/gfs2/lock_dlm.c +++ b/fs/gfs2/lock_dlm.c @@ -32,9 +32,10 @@ extern struct workqueue_struct *gfs2_control_wq; * @delta is the difference between the current rtt sample and the * running average srtt. We add 1/8 of that to the srtt in order to * update the current srtt estimate. The variance estimate is a bit - * more complicated. We subtract the abs value of the @delta from - * the current variance estimate and add 1/4 of that to the running - * total. + * more complicated. We subtract the current variance estimate from + * the abs value of the @delta and add 1/4 of that to the running + * total. That's equivalent to 3/4 of the current variance + * estimate plus 1/4 of the abs of @delta. * * Note that the index points at the array entry containing the smoothed * mean value, and the variance is always in the following entry @@ -50,7 +51,7 @@ static inline void gfs2_update_stats(struct gfs2_lkstats *s, unsigned index, s64 delta = sample - s->stats[index]; s->stats[index] += (delta >> 3); index++; - s->stats[index] += ((abs(delta) - s->stats[index]) >> 2); + s->stats[index] += (s64)(abs(delta) - s->stats[index]) >> 2; } /** |