Merge commit 'c039c332f23e794deb6d6f37b9f07ff3b27fb2cf' into md

Pull in pre-requisites for adding raid10 support to dm-raid.

1 files changed, 745 insertions, 0 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
new file mode 100644
index 000000000000..2288a6399e1e
--- /dev/null
+++ b/net/ipv4/tcp_metrics.c
@@ -0,0 +1,745 @@
+#include <linux/rcupdate.h>
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/bootmem.h>
+#include <linux/module.h>
+#include <linux/cache.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/tcp.h>
+#include <linux/hash.h>
+
+#include <net/inet_connection_sock.h>
+#include <net/net_namespace.h>
+#include <net/request_sock.h>
+#include <net/inetpeer.h>
+#include <net/sock.h>
+#include <net/ipv6.h>
+#include <net/dst.h>
+#include <net/tcp.h>
+
+int sysctl_tcp_nometrics_save __read_mostly;
+
+enum tcp_metric_index {
+        TCP_METRIC_RTT,
+        TCP_METRIC_RTTVAR,
+        TCP_METRIC_SSTHRESH,
+        TCP_METRIC_CWND,
+        TCP_METRIC_REORDERING,
+
+        /* Always last.  */
+        TCP_METRIC_MAX,
+};
+
+struct tcp_fastopen_metrics {
+        u16     mss;
+        u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
+        unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
+        struct  tcp_fastopen_cookie     cookie;
+};
+
+struct tcp_metrics_block {
+        struct tcp_metrics_block __rcu  *tcpm_next;
+        struct inetpeer_addr            tcpm_addr;
+        unsigned long                   tcpm_stamp;
+        u32                             tcpm_ts;
+        u32                             tcpm_ts_stamp;
+        u32                             tcpm_lock;
+        u32                             tcpm_vals[TCP_METRIC_MAX];
+        struct tcp_fastopen_metrics     tcpm_fastopen;
+};
+
+static bool tcp_metric_locked(struct tcp_metrics_block *tm,
+                              enum tcp_metric_index idx)
+{
+        return tm->tcpm_lock & (1 << idx);
+}
+
+static u32 tcp_metric_get(struct tcp_metrics_block *tm,
+                          enum tcp_metric_index idx)
+{
+        return tm->tcpm_vals[idx];
+}
+
+static u32 tcp_metric_get_jiffies(struct tcp_metrics_block *tm,
+                                  enum tcp_metric_index idx)
+{
+        return msecs_to_jiffies(tm->tcpm_vals[idx]);
+}
+
+static void tcp_metric_set(struct tcp_metrics_block *tm,
+                           enum tcp_metric_index idx,
+                           u32 val)
+{
+        tm->tcpm_vals[idx] = val;
+}
+
+static void tcp_metric_set_msecs(struct tcp_metrics_block *tm,
+                                 enum tcp_metric_index idx,
+                                 u32 val)
+{
+        tm->tcpm_vals[idx] = jiffies_to_msecs(val);
+}
+
+static bool addr_same(const struct inetpeer_addr *a,
+                      const struct inetpeer_addr *b)
+{
+        const struct in6_addr *a6, *b6;
+
+        if (a->family != b->family)
+                return false;
+        if (a->family == AF_INET)
+                return a->addr.a4 == b->addr.a4;
+
+        a6 = (const struct in6_addr *) &a->addr.a6[0];
+        b6 = (const struct in6_addr *) &b->addr.a6[0];
+
+        return ipv6_addr_equal(a6, b6);
+}
+
+struct tcpm_hash_bucket {
+        struct tcp_metrics_block __rcu  *chain;
+};
+
+static DEFINE_SPINLOCK(tcp_metrics_lock);
+
+static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
+{
+        u32 val;
+
+        tm->tcpm_stamp = jiffies;
+
+        val = 0;
+        if (dst_metric_locked(dst, RTAX_RTT))
+                val |= 1 << TCP_METRIC_RTT;
+        if (dst_metric_locked(dst, RTAX_RTTVAR))
+                val |= 1 << TCP_METRIC_RTTVAR;
+        if (dst_metric_locked(dst, RTAX_SSTHRESH))
+                val |= 1 << TCP_METRIC_SSTHRESH;
+        if (dst_metric_locked(dst, RTAX_CWND))
+                val |= 1 << TCP_METRIC_CWND;
+        if (dst_metric_locked(dst, RTAX_REORDERING))
+                val |= 1 << TCP_METRIC_REORDERING;
+        tm->tcpm_lock = val;
+
+        tm->tcpm_vals[TCP_METRIC_RTT] = dst_metric_raw(dst, RTAX_RTT);
+        tm->tcpm_vals[TCP_METRIC_RTTVAR] = dst_metric_raw(dst, RTAX_RTTVAR);
+        tm->tcpm_vals[TCP_METRIC_SSTHRESH] = dst_metric_raw(dst, RTAX_SSTHRESH);
+        tm->tcpm_vals[TCP_METRIC_CWND] = dst_metric_raw(dst, RTAX_CWND);
+        tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
+        tm->tcpm_ts = 0;
+        tm->tcpm_ts_stamp = 0;
+        tm->tcpm_fastopen.mss = 0;
+        tm->tcpm_fastopen.syn_loss = 0;
+        tm->tcpm_fastopen.cookie.len = 0;
+}
+
+static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
+                                          struct inetpeer_addr *addr,
+                                          unsigned int hash,
+                                          bool reclaim)
+{
+        struct tcp_metrics_block *tm;
+        struct net *net;
+
+        spin_lock_bh(&tcp_metrics_lock);
+        net = dev_net(dst->dev);
+        if (unlikely(reclaim)) {
+                struct tcp_metrics_block *oldest;
+
+                oldest = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain);
+                for (tm = rcu_dereference(oldest->tcpm_next); tm;
+                     tm = rcu_dereference(tm->tcpm_next)) {
+                        if (time_before(tm->tcpm_stamp, oldest->tcpm_stamp))
+                                oldest = tm;
+                }
+                tm = oldest;
+        } else {
+                tm = kmalloc(sizeof(*tm), GFP_ATOMIC);
+                if (!tm)
+                        goto out_unlock;
+        }
+        tm->tcpm_addr = *addr;
+
+        tcpm_suck_dst(tm, dst);
+
+        if (likely(!reclaim)) {
+                tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
+                rcu_assign_pointer(net->ipv4.tcp_metrics_hash[hash].chain, tm);
+        }
+
+out_unlock:
+        spin_unlock_bh(&tcp_metrics_lock);
+        return tm;
+}
+
+#define TCP_METRICS_TIMEOUT             (60 * 60 * HZ)
+
+static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
+{
+        if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
+                tcpm_suck_dst(tm, dst);
+}
+
+#define TCP_METRICS_RECLAIM_DEPTH       5
+#define TCP_METRICS_RECLAIM_PTR         (struct tcp_metrics_block *) 0x1UL
+
+static struct tcp_metrics_block *tcp_get_encode(struct tcp_metrics_block *tm, int depth)
+{
+        if (tm)
+                return tm;
+        if (depth > TCP_METRICS_RECLAIM_DEPTH)
+                return TCP_METRICS_RECLAIM_PTR;
+        return NULL;
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *addr,
+                                                   struct net *net, unsigned int hash)
+{
+        struct tcp_metrics_block *tm;
+        int depth = 0;
+
+        for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+             tm = rcu_dereference(tm->tcpm_next)) {
+                if (addr_same(&tm->tcpm_addr, addr))
+                        break;
+                depth++;
+        }
+        return tcp_get_encode(tm, depth);
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics_req(struct request_sock *req,
+                                                       struct dst_entry *dst)
+{
+        struct tcp_metrics_block *tm;
+        struct inetpeer_addr addr;
+        unsigned int hash;
+        struct net *net;
+
+        addr.family = req->rsk_ops->family;
+        switch (addr.family) {
+        case AF_INET:
+                addr.addr.a4 = inet_rsk(req)->rmt_addr;
+                hash = (__force unsigned int) addr.addr.a4;
+                break;
+        case AF_INET6:
+                *(struct in6_addr *)addr.addr.a6 = inet6_rsk(req)->rmt_addr;
+                hash = ipv6_addr_hash(&inet6_rsk(req)->rmt_addr);
+                break;
+        default:
+                return NULL;
+        }
+
+        net = dev_net(dst->dev);
+        hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+        for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+             tm = rcu_dereference(tm->tcpm_next)) {
+                if (addr_same(&tm->tcpm_addr, &addr))
+                        break;
+        }
+        tcpm_check_stamp(tm, dst);
+        return tm;
+}
+
+static struct tcp_metrics_block *__tcp_get_metrics_tw(struct inet_timewait_sock *tw)
+{
+        struct inet6_timewait_sock *tw6;
+        struct tcp_metrics_block *tm;
+        struct inetpeer_addr addr;
+        unsigned int hash;
+        struct net *net;
+
+        addr.family = tw->tw_family;
+        switch (addr.family) {
+        case AF_INET:
+                addr.addr.a4 = tw->tw_daddr;
+                hash = (__force unsigned int) addr.addr.a4;
+                break;
+        case AF_INET6:
+                tw6 = inet6_twsk((struct sock *)tw);
+                *(struct in6_addr *)addr.addr.a6 = tw6->tw_v6_daddr;
+                hash = ipv6_addr_hash(&tw6->tw_v6_daddr);
+                break;
+        default:
+                return NULL;
+        }
+
+        net = twsk_net(tw);
+        hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+        for (tm = rcu_dereference(net->ipv4.tcp_metrics_hash[hash].chain); tm;
+             tm = rcu_dereference(tm->tcpm_next)) {
+                if (addr_same(&tm->tcpm_addr, &addr))
+                        break;
+        }
+        return tm;
+}
+
+static struct tcp_metrics_block *tcp_get_metrics(struct sock *sk,
+                                                 struct dst_entry *dst,
+                                                 bool create)
+{
+        struct tcp_metrics_block *tm;
+        struct inetpeer_addr addr;
+        unsigned int hash;
+        struct net *net;
+        bool reclaim;
+
+        addr.family = sk->sk_family;
+        switch (addr.family) {
+        case AF_INET:
+                addr.addr.a4 = inet_sk(sk)->inet_daddr;
+                hash = (__force unsigned int) addr.addr.a4;
+                break;
+        case AF_INET6:
+                *(struct in6_addr *)addr.addr.a6 = inet6_sk(sk)->daddr;
+                hash = ipv6_addr_hash(&inet6_sk(sk)->daddr);
+                break;
+        default:
+                return NULL;
+        }
+
+        net = dev_net(dst->dev);
+        hash = hash_32(hash, net->ipv4.tcp_metrics_hash_log);
+
+        tm = __tcp_get_metrics(&addr, net, hash);
+        reclaim = false;
+        if (tm == TCP_METRICS_RECLAIM_PTR) {
+                reclaim = true;
+                tm = NULL;
+        }
+        if (!tm && create)
+                tm = tcpm_new(dst, &addr, hash, reclaim);
+        else
+                tcpm_check_stamp(tm, dst);
+
+        return tm;
+}
+
+/* Save metrics learned by this TCP session.  This function is called
+ * only, when TCP finishes successfully i.e. when it enters TIME-WAIT
+ * or goes from LAST-ACK to CLOSE.
+ */
+void tcp_update_metrics(struct sock *sk)
+{
+        const struct inet_connection_sock *icsk = inet_csk(sk);
+        struct dst_entry *dst = __sk_dst_get(sk);
+        struct tcp_sock *tp = tcp_sk(sk);
+        struct tcp_metrics_block *tm;
+        unsigned long rtt;
+        u32 val;
+        int m;
+
+        if (sysctl_tcp_nometrics_save || !dst)
+                return;
+
+        if (dst->flags & DST_HOST)
+                dst_confirm(dst);
+
+        rcu_read_lock();
+        if (icsk->icsk_backoff || !tp->srtt) {
+                /* This session failed to estimate rtt. Why?
+                 * Probably, no packets returned in time.  Reset our
+                 * results.
+                 */
+                tm = tcp_get_metrics(sk, dst, false);
+                if (tm && !tcp_metric_locked(tm, TCP_METRIC_RTT))
+                        tcp_metric_set(tm, TCP_METRIC_RTT, 0);
+                goto out_unlock;
+        } else
+                tm = tcp_get_metrics(sk, dst, true);
+
+        if (!tm)
+                goto out_unlock;
+
+        rtt = tcp_metric_get_jiffies(tm, TCP_METRIC_RTT);
+        m = rtt - tp->srtt;
+
+        /* If newly calculated rtt larger than stored one, store new
+         * one. Otherwise, use EWMA. Remember, rtt overestimation is
+         * always better than underestimation.
+         */
+        if (!tcp_metric_locked(tm, TCP_METRIC_RTT)) {
+                if (m <= 0)
+                        rtt = tp->srtt;
+                else
+                        rtt -= (m >> 3);
+                tcp_metric_set_msecs(tm, TCP_METRIC_RTT, rtt);
+        }
+
+        if (!tcp_metric_locked(tm, TCP_METRIC_RTTVAR)) {
+                unsigned long var;
+
+                if (m < 0)
+                        m = -m;
+
+                /* Scale deviation to rttvar fixed point */
+                m >>= 1;
+                if (m < tp->mdev)
+                        m = tp->mdev;
+
+                var = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
+                if (m >= var)
+                        var = m;
+                else
+                        var -= (var - m) >> 2;
+
+                tcp_metric_set_msecs(tm, TCP_METRIC_RTTVAR, var);
+        }
+
+        if (tcp_in_initial_slowstart(tp)) {
+                /* Slow start still did not finish. */
+                if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+                        if (val && (tp->snd_cwnd >> 1) > val)
+                                tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+                                               tp->snd_cwnd >> 1);
+                }
+                if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_CWND);
+                        if (tp->snd_cwnd > val)
+                                tcp_metric_set(tm, TCP_METRIC_CWND,
+                                               tp->snd_cwnd);
+                }
+        } else if (tp->snd_cwnd > tp->snd_ssthresh &&
+                   icsk->icsk_ca_state == TCP_CA_Open) {
+                /* Cong. avoidance phase, cwnd is reliable. */
+                if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
+                        tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+                                       max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
+                if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_CWND);
+                        tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_cwnd) >> 1);
+                }
+        } else {
+                /* Else slow start did not finish, cwnd is non-sense,
+                 * ssthresh may be also invalid.
+                 */
+                if (!tcp_metric_locked(tm, TCP_METRIC_CWND)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_CWND);
+                        tcp_metric_set(tm, TCP_METRIC_CWND,
+                                       (val + tp->snd_ssthresh) >> 1);
+                }
+                if (!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+                        if (val && tp->snd_ssthresh > val)
+                                tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
+                                               tp->snd_ssthresh);
+                }
+                if (!tcp_metric_locked(tm, TCP_METRIC_REORDERING)) {
+                        val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+                        if (val < tp->reordering &&
+                            tp->reordering != sysctl_tcp_reordering)
+                                tcp_metric_set(tm, TCP_METRIC_REORDERING,
+                                               tp->reordering);
+                }
+        }
+        tm->tcpm_stamp = jiffies;
+out_unlock:
+        rcu_read_unlock();
+}
+
+/* Initialize metrics on socket. */
+
+void tcp_init_metrics(struct sock *sk)
+{
+        struct dst_entry *dst = __sk_dst_get(sk);
+        struct tcp_sock *tp = tcp_sk(sk);
+        struct tcp_metrics_block *tm;
+        u32 val;
+
+        if (dst == NULL)
+                goto reset;
+
+        dst_confirm(dst);
+
+        rcu_read_lock();
+        tm = tcp_get_metrics(sk, dst, true);
+        if (!tm) {
+                rcu_read_unlock();
+                goto reset;
+        }
+
+        if (tcp_metric_locked(tm, TCP_METRIC_CWND))
+                tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
+
+        val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
+        if (val) {
+                tp->snd_ssthresh = val;
+                if (tp->snd_ssthresh > tp->snd_cwnd_clamp)
+                        tp->snd_ssthresh = tp->snd_cwnd_clamp;
+        } else {
+                /* ssthresh may have been reduced unnecessarily during.
+                 * 3WHS. Restore it back to its initial default.
+                 */
+                tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
+        }
+        val = tcp_metric_get(tm, TCP_METRIC_REORDERING);
+        if (val && tp->reordering != val) {
+                tcp_disable_fack(tp);
+                tcp_disable_early_retrans(tp);
+                tp->reordering = val;
+        }
+
+        val = tcp_metric_get(tm, TCP_METRIC_RTT);
+        if (val == 0 || tp->srtt == 0) {
+                rcu_read_unlock();
+                goto reset;
+        }
+        /* Initial rtt is determined from SYN,SYN-ACK.
+         * The segment is small and rtt may appear much
+         * less than real one. Use per-dst memory
+         * to make it more realistic.
+         *
+         * A bit of theory. RTT is time passed after "normal" sized packet
+         * is sent until it is ACKed. In normal circumstances sending small
+         * packets force peer to delay ACKs and calculation is correct too.
+         * The algorithm is adaptive and, provided we follow specs, it
+         * NEVER underestimate RTT. BUT! If peer tries to make some clever
+         * tricks sort of "quick acks" for time long enough to decrease RTT
+         * to low value, and then abruptly stops to do it and starts to delay
+         * ACKs, wait for troubles.
+         */
+        val = msecs_to_jiffies(val);
+        if (val > tp->srtt) {
+                tp->srtt = val;
+                tp->rtt_seq = tp->snd_nxt;
+        }
+        val = tcp_metric_get_jiffies(tm, TCP_METRIC_RTTVAR);
+        if (val > tp->mdev) {
+                tp->mdev = val;
+                tp->mdev_max = tp->rttvar = max(tp->mdev, tcp_rto_min(sk));
+        }
+        rcu_read_unlock();
+
+        tcp_set_rto(sk);
+reset:
+        if (tp->srtt == 0) {
+                /* RFC6298: 5.7 We've failed to get a valid RTT sample from
+                 * 3WHS. This is most likely due to retransmission,
+                 * including spurious one. Reset the RTO back to 3secs
+                 * from the more aggressive 1sec to avoid more spurious
+                 * retransmission.
+                 */
+                tp->mdev = tp->mdev_max = tp->rttvar = TCP_TIMEOUT_FALLBACK;
+                inet_csk(sk)->icsk_rto = TCP_TIMEOUT_FALLBACK;
+        }
+        /* Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
+         * retransmitted. In light of RFC6298 more aggressive 1sec
+         * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
+         * retransmission has occurred.
+         */
+        if (tp->total_retrans > 1)
+                tp->snd_cwnd = 1;
+        else
+                tp->snd_cwnd = tcp_init_cwnd(tp, dst);
+        tp->snd_cwnd_stamp = tcp_time_stamp;
+}
+
+bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check)
+{
+        struct tcp_metrics_block *tm;
+        bool ret;
+
+        if (!dst)
+                return false;
+
+        rcu_read_lock();
+        tm = __tcp_get_metrics_req(req, dst);
+        if (paws_check) {
+                if (tm &&
+                    (u32)get_seconds() - tm->tcpm_ts_stamp < TCP_PAWS_MSL &&
+                    (s32)(tm->tcpm_ts - req->ts_recent) > TCP_PAWS_WINDOW)
+                        ret = false;
+                else
+                        ret = true;
+        } else {
+                if (tm && tcp_metric_get(tm, TCP_METRIC_RTT) && tm->tcpm_ts_stamp)
+                        ret = true;
+                else
+                        ret = false;
+        }
+        rcu_read_unlock();
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(tcp_peer_is_proven);
+
+void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst)
+{
+        struct tcp_metrics_block *tm;
+
+        rcu_read_lock();
+        tm = tcp_get_metrics(sk, dst, true);
+        if (tm) {
+                struct tcp_sock *tp = tcp_sk(sk);
+
+                if ((u32)get_seconds() - tm->tcpm_ts_stamp <= TCP_PAWS_MSL) {
+                        tp->rx_opt.ts_recent_stamp = tm->tcpm_ts_stamp;
+                        tp->rx_opt.ts_recent = tm->tcpm_ts;
+                }
+        }
+        rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(tcp_fetch_timewait_stamp);
+
+/* VJ's idea. Save last timestamp seen from this destination and hold
+ * it at least for normal timewait interval to use for duplicate
+ * segment detection in subsequent connections, before they enter
+ * synchronized state.
+ */
+bool tcp_remember_stamp(struct sock *sk)
+{
+        struct dst_entry *dst = __sk_dst_get(sk);
+        bool ret = false;
+
+        if (dst) {
+                struct tcp_metrics_block *tm;
+
+                rcu_read_lock();
+                tm = tcp_get_metrics(sk, dst, true);
+                if (tm) {
+                        struct tcp_sock *tp = tcp_sk(sk);
+
+                        if ((s32)(tm->tcpm_ts - tp->rx_opt.ts_recent) <= 0 ||
+                            ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
+                             tm->tcpm_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) {
+                                tm->tcpm_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp;
+                                tm->tcpm_ts = tp->rx_opt.ts_recent;
+                        }
+                        ret = true;
+                }
+                rcu_read_unlock();
+        }
+        return ret;
+}
+
+bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw)
+{
+        struct tcp_metrics_block *tm;
+        bool ret = false;
+
+        rcu_read_lock();
+        tm = __tcp_get_metrics_tw(tw);
+        if (tm) {
+                const struct tcp_timewait_sock *tcptw;
+                struct sock *sk = (struct sock *) tw;
+
+                tcptw = tcp_twsk(sk);
+                if ((s32)(tm->tcpm_ts - tcptw->tw_ts_recent) <= 0 ||
+                    ((u32)get_seconds() - tm->tcpm_ts_stamp > TCP_PAWS_MSL &&
+                     tm->tcpm_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) {
+                        tm->tcpm_ts_stamp = (u32)tcptw->tw_ts_recent_stamp;
+                        tm->tcpm_ts        = tcptw->tw_ts_recent;
+                }
+                ret = true;
+        }
+        rcu_read_unlock();
+
+        return ret;
+}
+
+static DEFINE_SEQLOCK(fastopen_seqlock);
+
+void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
+                            struct tcp_fastopen_cookie *cookie,
+                            int *syn_loss, unsigned long *last_syn_loss)
+{
+        struct tcp_metrics_block *tm;
+
+        rcu_read_lock();
+        tm = tcp_get_metrics(sk, __sk_dst_get(sk), false);
+        if (tm) {
+                struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+                unsigned int seq;
+
+                do {
+                        seq = read_seqbegin(&fastopen_seqlock);
+                        if (tfom->mss)
+                                *mss = tfom->mss;
+                        *cookie = tfom->cookie;
+                        *syn_loss = tfom->syn_loss;
+                        *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
+                } while (read_seqretry(&fastopen_seqlock, seq));
+        }
+        rcu_read_unlock();
+}
+
+void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
+                            struct tcp_fastopen_cookie *cookie, bool syn_lost)
+{
+        struct tcp_metrics_block *tm;
+
+        rcu_read_lock();
+        tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);
+        if (tm) {
+                struct tcp_fastopen_metrics *tfom = &tm->tcpm_fastopen;
+
+                write_seqlock_bh(&fastopen_seqlock);
+                tfom->mss = mss;
+                if (cookie->len > 0)
+                        tfom->cookie = *cookie;
+                if (syn_lost) {
+                        ++tfom->syn_loss;
+                        tfom->last_syn_loss = jiffies;
+                } else
+                        tfom->syn_loss = 0;
+                write_sequnlock_bh(&fastopen_seqlock);
+        }
+        rcu_read_unlock();
+}
+
+static unsigned int tcpmhash_entries;
+static int __init set_tcpmhash_entries(char *str)
+{
+        ssize_t ret;
+
+        if (!str)
+                return 0;
+
+        ret = kstrtouint(str, 0, &tcpmhash_entries);
+        if (ret)
+                return 0;
+
+        return 1;
+}
+__setup("tcpmhash_entries=", set_tcpmhash_entries);
+
+static int __net_init tcp_net_metrics_init(struct net *net)
+{
+        size_t size;
+        unsigned int slots;
+
+        slots = tcpmhash_entries;
+        if (!slots) {
+                if (totalram_pages >= 128 * 1024)
+                        slots = 16 * 1024;
+                else
+                        slots = 8 * 1024;
+        }
+
+        net->ipv4.tcp_metrics_hash_log = order_base_2(slots);
+        size = sizeof(struct tcpm_hash_bucket) << net->ipv4.tcp_metrics_hash_log;
+
+        net->ipv4.tcp_metrics_hash = kzalloc(size, GFP_KERNEL);
+        if (!net->ipv4.tcp_metrics_hash)
+                return -ENOMEM;
+
+        return 0;
+}
+
+static void __net_exit tcp_net_metrics_exit(struct net *net)
+{
+        kfree(net->ipv4.tcp_metrics_hash);
+}
+
+static __net_initdata struct pernet_operations tcp_net_metrics_ops = {
+        .init   =       tcp_net_metrics_init,
+        .exit   =       tcp_net_metrics_exit,
+};
+
+void __init tcp_metrics_init(void)
+{
+        register_pernet_subsys(&tcp_net_metrics_ops);
+}