Look for sudden changes in the first and second derivatives in order
to eliminate outlier changes to target_highest_slotid (which are
due to out-of-order RPC requests).
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 91 +++++++++++++++++++++++++++++++++++++++++++----------
fs/nfsd/state.h | 3 ++
2 files changed, 77 insertions(+), 17 deletions(-)
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index ed937c8..0eb563d 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2064,6 +2064,57 @@ out:
return status;
}
+static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
+{
+ s1 -= s2;
+ if (s1 == 0)
+ return 0;
+ if (s1 < 0)
+ return (s1 - 1) >> 1;
+ return (s1 + 1) >> 1;
+}
+
+static int nfs41_sign_s32(s32 s1)
+{
+ if (s1 > 0)
+ return 1;
+ if (s1 < 0)
+ return -1;
+ return 0;
+}
+
+static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
+{
+ if (!s1 || !s2)
+ return true;
+ return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
+}
+
+/* Try to eliminate outliers by checking for sharp changes in the
+ * derivatives and second derivatives
+ */
+static bool nfsd4_is_outlier_target_slotid(struct nfsd4_slot_table *tbl,
+ u32 new_highest)
+{
+ s32 d_highest, d2_highest;
+ bool ret = true;
+
+ d_highest = nfs41_derivative_target_slotid(new_highest,
+ tbl->slt_client_highest_slotid);
+ d2_highest = nfs41_derivative_target_slotid(d_highest,
+ tbl->slt_d_client_highest_slotid);
+ /* Is first derivative same sign? */
+ if (nfs41_same_sign_or_zero_s32(d_highest, tbl->slt_d_client_highest_slotid))
+ ret = false;
+ /* Is second derivative same sign? */
+ if (nfs41_same_sign_or_zero_s32(d2_highest, tbl->slt_d2_client_highest_slotid))
+ ret = false;
+ tbl->slt_client_highest_slotid = new_highest;
+ tbl->slt_d_client_highest_slotid = d_highest;
+ tbl->slt_d2_client_highest_slotid = d2_highest;
+ return ret;
+}
+
static void nfsd4_sequence_adjust_slot_table(struct nfsd4_session *session,
struct nfsd4_slot *slot, u32 sa_highest_slotid,
struct nfsd4_sequence *res)
@@ -2074,26 +2125,32 @@ static void nfsd4_sequence_adjust_slot_table(struct nfsd4_session *session,
spin_lock(&tbl->slt_lock);
+ if (nfsd4_is_outlier_target_slotid(tbl, sa_highest_slotid))
+ goto out;
+ if (slot->sl_generation != tbl->slt_generation)
+ goto out;
+
+ /* Deal with slot table truncation... */
+ nfsd4_truncate_slot_table_locked(tbl,
+ max(sa_highest_slotid, tbl->slt_highest_slotid));
+
next_target = tbl->slt_target_highest_slotid;
+ next_highest = tbl->slt_highest_slotid;
/* Is the client bumping against our current window limits? */
- if (sa_highest_slotid >= tbl->slt_target_highest_slotid) {
- /* Yes! Grow the window size by 1/4 */
- next_target += 1 + (tbl->slt_target_highest_slotid >> 2);
- next_highest = next_target;
- } else {
- /*
- * If this slot hasn't seen our previous values, then don't
- * trust that the client has seen them. Don't adjust the
- * slot table yet.
- */
- if (slot->sl_generation != tbl->slt_generation)
- goto out;
- /* No! Try to shrink the window size by 1/2 */
- next_target >>= 1;
- if (sa_highest_slotid + 1 > next_target)
- next_target = sa_highest_slotid + 1;
- next_highest = tbl->slt_target_highest_slotid;
+ if (tbl->slt_d_client_highest_slotid > 0) {
+ if (sa_highest_slotid >= tbl->slt_target_highest_slotid) {
+ /* Yes! Grow the window size by 1/4 */
+ next_target += 1 + (tbl->slt_target_highest_slotid >> 2);
+ next_highest = next_target;
+ }
+ } else /* (tbl->slt_d_client_highest_slotid <= 0) */ {
+ if (next_target > sa_highest_slotid + 1) {
+ /* Try to shrink the window size by 1/2 */
+ next_target >>= 1;
+ next_target = max(next_target, sa_highest_slotid + 1);
+ }
+ next_highest = max(tbl->slt_target_highest_slotid, next_target);
}
nfsd4_fc_set_highest_slotid_locked(session, tbl,
next_target, next_highest);
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index c2f897f..94a72e5 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -150,6 +150,9 @@ struct nfsd4_slot_table {
unsigned long slt_generation;
u32 slt_target_highest_slotid;
u32 slt_highest_slotid;
+ u32 slt_client_highest_slotid;
+ s32 slt_d_client_highest_slotid;
+ s32 slt_d2_client_highest_slotid;
};
struct nfsd4_channel_attrs {
--
1.7.11.7
--
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