Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 629 insertions, 0 deletions

diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
new file mode 100644
index 000000000..3e64a3d50
--- /dev/null
+++ b/fs/nfsd/nfscache.c
@@ -0,0 +1,629 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Request reply cache. This is currently a global cache, but this may
+ * change in the future and be a per-client cache.
+ *
+ * This code is heavily inspired by the 44BSD implementation, although
+ * it does things a bit differently.
+ *
+ * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/sunrpc/svc_xprt.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/sunrpc/addr.h>
+#include <linux/highmem.h>
+#include <linux/log2.h>
+#include <linux/hash.h>
+#include <net/checksum.h>
+
+#include "nfsd.h"
+#include "cache.h"
+#include "trace.h"
+
+/*
+ * We use this value to determine the number of hash buckets from the max
+ * cache size, the idea being that when the cache is at its maximum number
+ * of entries, then this should be the average number of entries per bucket.
+ */
+#define TARGET_BUCKET_SIZE	64
+
+struct nfsd_drc_bucket {
+	struct rb_root rb_head;
+	struct list_head lru_head;
+	spinlock_t cache_lock;
+};
+
+static struct kmem_cache	*drc_slab;
+
+static int	nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec);
+static unsigned long nfsd_reply_cache_count(struct shrinker *shrink,
+					    struct shrink_control *sc);
+static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink,
+					   struct shrink_control *sc);
+
+/*
+ * Put a cap on the size of the DRC based on the amount of available
+ * low memory in the machine.
+ *
+ *  64MB:    8192
+ * 128MB:   11585
+ * 256MB:   16384
+ * 512MB:   23170
+ *   1GB:   32768
+ *   2GB:   46340
+ *   4GB:   65536
+ *   8GB:   92681
+ *  16GB:  131072
+ *
+ * ...with a hard cap of 256k entries. In the worst case, each entry will be
+ * ~1k, so the above numbers should give a rough max of the amount of memory
+ * used in k.
+ *
+ * XXX: these limits are per-container, so memory used will increase
+ * linearly with number of containers.  Maybe that's OK.
+ */
+static unsigned int
+nfsd_cache_size_limit(void)
+{
+	unsigned int limit;
+	unsigned long low_pages = totalram_pages() - totalhigh_pages();
+
+	limit = (16 * int_sqrt(low_pages)) << (PAGE_SHIFT-10);
+	return min_t(unsigned int, limit, 256*1024);
+}
+
+/*
+ * Compute the number of hash buckets we need. Divide the max cachesize by
+ * the "target" max bucket size, and round up to next power of two.
+ */
+static unsigned int
+nfsd_hashsize(unsigned int limit)
+{
+	return roundup_pow_of_two(limit / TARGET_BUCKET_SIZE);
+}
+
+static struct svc_cacherep *
+nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum,
+			struct nfsd_net *nn)
+{
+	struct svc_cacherep	*rp;
+
+	rp = kmem_cache_alloc(drc_slab, GFP_KERNEL);
+	if (rp) {
+		rp->c_state = RC_UNUSED;
+		rp->c_type = RC_NOCACHE;
+		RB_CLEAR_NODE(&rp->c_node);
+		INIT_LIST_HEAD(&rp->c_lru);
+
+		memset(&rp->c_key, 0, sizeof(rp->c_key));
+		rp->c_key.k_xid = rqstp->rq_xid;
+		rp->c_key.k_proc = rqstp->rq_proc;
+		rpc_copy_addr((struct sockaddr *)&rp->c_key.k_addr, svc_addr(rqstp));
+		rpc_set_port((struct sockaddr *)&rp->c_key.k_addr, rpc_get_port(svc_addr(rqstp)));
+		rp->c_key.k_prot = rqstp->rq_prot;
+		rp->c_key.k_vers = rqstp->rq_vers;
+		rp->c_key.k_len = rqstp->rq_arg.len;
+		rp->c_key.k_csum = csum;
+	}
+	return rp;
+}
+
+static void
+nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
+				struct nfsd_net *nn)
+{
+	if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
+		nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
+		kfree(rp->c_replvec.iov_base);
+	}
+	if (rp->c_state != RC_UNUSED) {
+		rb_erase(&rp->c_node, &b->rb_head);
+		list_del(&rp->c_lru);
+		atomic_dec(&nn->num_drc_entries);
+		nfsd_stats_drc_mem_usage_sub(nn, sizeof(*rp));
+	}
+	kmem_cache_free(drc_slab, rp);
+}
+
+static void
+nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
+			struct nfsd_net *nn)
+{
+	spin_lock(&b->cache_lock);
+	nfsd_reply_cache_free_locked(b, rp, nn);
+	spin_unlock(&b->cache_lock);
+}
+
+int nfsd_drc_slab_create(void)
+{
+	drc_slab = kmem_cache_create("nfsd_drc",
+				sizeof(struct svc_cacherep), 0, 0, NULL);
+	return drc_slab ? 0: -ENOMEM;
+}
+
+void nfsd_drc_slab_free(void)
+{
+	kmem_cache_destroy(drc_slab);
+}
+
+static int nfsd_reply_cache_stats_init(struct nfsd_net *nn)
+{
+	return nfsd_percpu_counters_init(nn->counter, NFSD_NET_COUNTERS_NUM);
+}
+
+static void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn)
+{
+	nfsd_percpu_counters_destroy(nn->counter, NFSD_NET_COUNTERS_NUM);
+}
+
+int nfsd_reply_cache_init(struct nfsd_net *nn)
+{
+	unsigned int hashsize;
+	unsigned int i;
+	int status = 0;
+
+	nn->max_drc_entries = nfsd_cache_size_limit();
+	atomic_set(&nn->num_drc_entries, 0);
+	hashsize = nfsd_hashsize(nn->max_drc_entries);
+	nn->maskbits = ilog2(hashsize);
+
+	status = nfsd_reply_cache_stats_init(nn);
+	if (status)
+		goto out_nomem;
+
+	nn->nfsd_reply_cache_shrinker.scan_objects = nfsd_reply_cache_scan;
+	nn->nfsd_reply_cache_shrinker.count_objects = nfsd_reply_cache_count;
+	nn->nfsd_reply_cache_shrinker.seeks = 1;
+	status = register_shrinker(&nn->nfsd_reply_cache_shrinker,
+				   "nfsd-reply:%s", nn->nfsd_name);
+	if (status)
+		goto out_stats_destroy;
+
+	nn->drc_hashtbl = kvzalloc(array_size(hashsize,
+				sizeof(*nn->drc_hashtbl)), GFP_KERNEL);
+	if (!nn->drc_hashtbl)
+		goto out_shrinker;
+
+	for (i = 0; i < hashsize; i++) {
+		INIT_LIST_HEAD(&nn->drc_hashtbl[i].lru_head);
+		spin_lock_init(&nn->drc_hashtbl[i].cache_lock);
+	}
+	nn->drc_hashsize = hashsize;
+
+	return 0;
+out_shrinker:
+	unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
+out_stats_destroy:
+	nfsd_reply_cache_stats_destroy(nn);
+out_nomem:
+	printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
+	return -ENOMEM;
+}
+
+void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
+{
+	struct svc_cacherep	*rp;
+	unsigned int i;
+
+	unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
+
+	for (i = 0; i < nn->drc_hashsize; i++) {
+		struct list_head *head = &nn->drc_hashtbl[i].lru_head;
+		while (!list_empty(head)) {
+			rp = list_first_entry(head, struct svc_cacherep, c_lru);
+			nfsd_reply_cache_free_locked(&nn->drc_hashtbl[i],
+									rp, nn);
+		}
+	}
+	nfsd_reply_cache_stats_destroy(nn);
+
+	kvfree(nn->drc_hashtbl);
+	nn->drc_hashtbl = NULL;
+	nn->drc_hashsize = 0;
+
+}
+
+/*
+ * Move cache entry to end of LRU list, and queue the cleaner to run if it's
+ * not already scheduled.
+ */
+static void
+lru_put_end(struct nfsd_drc_bucket *b, struct svc_cacherep *rp)
+{
+	rp->c_timestamp = jiffies;
+	list_move_tail(&rp->c_lru, &b->lru_head);
+}
+
+static noinline struct nfsd_drc_bucket *
+nfsd_cache_bucket_find(__be32 xid, struct nfsd_net *nn)
+{
+	unsigned int hash = hash_32((__force u32)xid, nn->maskbits);
+
+	return &nn->drc_hashtbl[hash];
+}
+
+static long prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn,
+			 unsigned int max)
+{
+	struct svc_cacherep *rp, *tmp;
+	long freed = 0;
+
+	list_for_each_entry_safe(rp, tmp, &b->lru_head, c_lru) {
+		/*
+		 * Don't free entries attached to calls that are still
+		 * in-progress, but do keep scanning the list.
+		 */
+		if (rp->c_state == RC_INPROG)
+			continue;
+		if (atomic_read(&nn->num_drc_entries) <= nn->max_drc_entries &&
+		    time_before(jiffies, rp->c_timestamp + RC_EXPIRE))
+			break;
+		nfsd_reply_cache_free_locked(b, rp, nn);
+		if (max && freed++ > max)
+			break;
+	}
+	return freed;
+}
+
+static long nfsd_prune_bucket(struct nfsd_drc_bucket *b, struct nfsd_net *nn)
+{
+	return prune_bucket(b, nn, 3);
+}
+
+/*
+ * Walk the LRU list and prune off entries that are older than RC_EXPIRE.
+ * Also prune the oldest ones when the total exceeds the max number of entries.
+ */
+static long
+prune_cache_entries(struct nfsd_net *nn)
+{
+	unsigned int i;
+	long freed = 0;
+
+	for (i = 0; i < nn->drc_hashsize; i++) {
+		struct nfsd_drc_bucket *b = &nn->drc_hashtbl[i];
+
+		if (list_empty(&b->lru_head))
+			continue;
+		spin_lock(&b->cache_lock);
+		freed += prune_bucket(b, nn, 0);
+		spin_unlock(&b->cache_lock);
+	}
+	return freed;
+}
+
+static unsigned long
+nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+	struct nfsd_net *nn = container_of(shrink,
+				struct nfsd_net, nfsd_reply_cache_shrinker);
+
+	return atomic_read(&nn->num_drc_entries);
+}
+
+static unsigned long
+nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+	struct nfsd_net *nn = container_of(shrink,
+				struct nfsd_net, nfsd_reply_cache_shrinker);
+
+	return prune_cache_entries(nn);
+}
+/*
+ * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes
+ */
+static __wsum
+nfsd_cache_csum(struct svc_rqst *rqstp)
+{
+	int idx;
+	unsigned int base;
+	__wsum csum;
+	struct xdr_buf *buf = &rqstp->rq_arg;
+	const unsigned char *p = buf->head[0].iov_base;
+	size_t csum_len = min_t(size_t, buf->head[0].iov_len + buf->page_len,
+				RC_CSUMLEN);
+	size_t len = min(buf->head[0].iov_len, csum_len);
+
+	/* rq_arg.head first */
+	csum = csum_partial(p, len, 0);
+	csum_len -= len;
+
+	/* Continue into page array */
+	idx = buf->page_base / PAGE_SIZE;
+	base = buf->page_base & ~PAGE_MASK;
+	while (csum_len) {
+		p = page_address(buf->pages[idx]) + base;
+		len = min_t(size_t, PAGE_SIZE - base, csum_len);
+		csum = csum_partial(p, len, csum);
+		csum_len -= len;
+		base = 0;
+		++idx;
+	}
+	return csum;
+}
+
+static int
+nfsd_cache_key_cmp(const struct svc_cacherep *key,
+			const struct svc_cacherep *rp, struct nfsd_net *nn)
+{
+	if (key->c_key.k_xid == rp->c_key.k_xid &&
+	    key->c_key.k_csum != rp->c_key.k_csum) {
+		nfsd_stats_payload_misses_inc(nn);
+		trace_nfsd_drc_mismatch(nn, key, rp);
+	}
+
+	return memcmp(&key->c_key, &rp->c_key, sizeof(key->c_key));
+}
+
+/*
+ * Search the request hash for an entry that matches the given rqstp.
+ * Must be called with cache_lock held. Returns the found entry or
+ * inserts an empty key on failure.
+ */
+static struct svc_cacherep *
+nfsd_cache_insert(struct nfsd_drc_bucket *b, struct svc_cacherep *key,
+			struct nfsd_net *nn)
+{
+	struct svc_cacherep	*rp, *ret = key;
+	struct rb_node		**p = &b->rb_head.rb_node,
+				*parent = NULL;
+	unsigned int		entries = 0;
+	int cmp;
+
+	while (*p != NULL) {
+		++entries;
+		parent = *p;
+		rp = rb_entry(parent, struct svc_cacherep, c_node);
+
+		cmp = nfsd_cache_key_cmp(key, rp, nn);
+		if (cmp < 0)
+			p = &parent->rb_left;
+		else if (cmp > 0)
+			p = &parent->rb_right;
+		else {
+			ret = rp;
+			goto out;
+		}
+	}
+	rb_link_node(&key->c_node, parent, p);
+	rb_insert_color(&key->c_node, &b->rb_head);
+out:
+	/* tally hash chain length stats */
+	if (entries > nn->longest_chain) {
+		nn->longest_chain = entries;
+		nn->longest_chain_cachesize = atomic_read(&nn->num_drc_entries);
+	} else if (entries == nn->longest_chain) {
+		/* prefer to keep the smallest cachesize possible here */
+		nn->longest_chain_cachesize = min_t(unsigned int,
+				nn->longest_chain_cachesize,
+				atomic_read(&nn->num_drc_entries));
+	}
+
+	lru_put_end(b, ret);
+	return ret;
+}
+
+/**
+ * nfsd_cache_lookup - Find an entry in the duplicate reply cache
+ * @rqstp: Incoming Call to find
+ *
+ * Try to find an entry matching the current call in the cache. When none
+ * is found, we try to grab the oldest expired entry off the LRU list. If
+ * a suitable one isn't there, then drop the cache_lock and allocate a
+ * new one, then search again in case one got inserted while this thread
+ * didn't hold the lock.
+ *
+ * Return values:
+ *   %RC_DOIT: Process the request normally
+ *   %RC_REPLY: Reply from cache
+ *   %RC_DROPIT: Do not process the request further
+ */
+int nfsd_cache_lookup(struct svc_rqst *rqstp)
+{
+	struct nfsd_net		*nn;
+	struct svc_cacherep	*rp, *found;
+	__wsum			csum;
+	struct nfsd_drc_bucket	*b;
+	int type = rqstp->rq_cachetype;
+	int rtn = RC_DOIT;
+
+	rqstp->rq_cacherep = NULL;
+	if (type == RC_NOCACHE) {
+		nfsd_stats_rc_nocache_inc();
+		goto out;
+	}
+
+	csum = nfsd_cache_csum(rqstp);
+
+	/*
+	 * Since the common case is a cache miss followed by an insert,
+	 * preallocate an entry.
+	 */
+	nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	rp = nfsd_reply_cache_alloc(rqstp, csum, nn);
+	if (!rp)
+		goto out;
+
+	b = nfsd_cache_bucket_find(rqstp->rq_xid, nn);
+	spin_lock(&b->cache_lock);
+	found = nfsd_cache_insert(b, rp, nn);
+	if (found != rp)
+		goto found_entry;
+
+	nfsd_stats_rc_misses_inc();
+	rqstp->rq_cacherep = rp;
+	rp->c_state = RC_INPROG;
+
+	atomic_inc(&nn->num_drc_entries);
+	nfsd_stats_drc_mem_usage_add(nn, sizeof(*rp));
+
+	nfsd_prune_bucket(b, nn);
+
+out_unlock:
+	spin_unlock(&b->cache_lock);
+out:
+	return rtn;
+
+found_entry:
+	/* We found a matching entry which is either in progress or done. */
+	nfsd_reply_cache_free_locked(NULL, rp, nn);
+	nfsd_stats_rc_hits_inc();
+	rtn = RC_DROPIT;
+	rp = found;
+
+	/* Request being processed */
+	if (rp->c_state == RC_INPROG)
+		goto out_trace;
+
+	/* From the hall of fame of impractical attacks:
+	 * Is this a user who tries to snoop on the cache? */
+	rtn = RC_DOIT;
+	if (!test_bit(RQ_SECURE, &rqstp->rq_flags) && rp->c_secure)
+		goto out_trace;
+
+	/* Compose RPC reply header */
+	switch (rp->c_type) {
+	case RC_NOCACHE:
+		break;
+	case RC_REPLSTAT:
+		svc_putu32(&rqstp->rq_res.head[0], rp->c_replstat);
+		rtn = RC_REPLY;
+		break;
+	case RC_REPLBUFF:
+		if (!nfsd_cache_append(rqstp, &rp->c_replvec))
+			goto out_unlock; /* should not happen */
+		rtn = RC_REPLY;
+		break;
+	default:
+		WARN_ONCE(1, "nfsd: bad repcache type %d\n", rp->c_type);
+	}
+
+out_trace:
+	trace_nfsd_drc_found(nn, rqstp, rtn);
+	goto out_unlock;
+}
+
+/**
+ * nfsd_cache_update - Update an entry in the duplicate reply cache.
+ * @rqstp: svc_rqst with a finished Reply
+ * @cachetype: which cache to update
+ * @statp: Reply's status code
+ *
+ * This is called from nfsd_dispatch when the procedure has been
+ * executed and the complete reply is in rqstp->rq_res.
+ *
+ * We're copying around data here rather than swapping buffers because
+ * the toplevel loop requires max-sized buffers, which would be a waste
+ * of memory for a cache with a max reply size of 100 bytes (diropokres).
+ *
+ * If we should start to use different types of cache entries tailored
+ * specifically for attrstat and fh's, we may save even more space.
+ *
+ * Also note that a cachetype of RC_NOCACHE can legally be passed when
+ * nfsd failed to encode a reply that otherwise would have been cached.
+ * In this case, nfsd_cache_update is called with statp == NULL.
+ */
+void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
+{
+	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
+	struct svc_cacherep *rp = rqstp->rq_cacherep;
+	struct kvec	*resv = &rqstp->rq_res.head[0], *cachv;
+	struct nfsd_drc_bucket *b;
+	int		len;
+	size_t		bufsize = 0;
+
+	if (!rp)
+		return;
+
+	b = nfsd_cache_bucket_find(rp->c_key.k_xid, nn);
+
+	len = resv->iov_len - ((char*)statp - (char*)resv->iov_base);
+	len >>= 2;
+
+	/* Don't cache excessive amounts of data and XDR failures */
+	if (!statp || len > (256 >> 2)) {
+		nfsd_reply_cache_free(b, rp, nn);
+		return;
+	}
+
+	switch (cachetype) {
+	case RC_REPLSTAT:
+		if (len != 1)
+			printk("nfsd: RC_REPLSTAT/reply len %d!\n",len);
+		rp->c_replstat = *statp;
+		break;
+	case RC_REPLBUFF:
+		cachv = &rp->c_replvec;
+		bufsize = len << 2;
+		cachv->iov_base = kmalloc(bufsize, GFP_KERNEL);
+		if (!cachv->iov_base) {
+			nfsd_reply_cache_free(b, rp, nn);
+			return;
+		}
+		cachv->iov_len = bufsize;
+		memcpy(cachv->iov_base, statp, bufsize);
+		break;
+	case RC_NOCACHE:
+		nfsd_reply_cache_free(b, rp, nn);
+		return;
+	}
+	spin_lock(&b->cache_lock);
+	nfsd_stats_drc_mem_usage_add(nn, bufsize);
+	lru_put_end(b, rp);
+	rp->c_secure = test_bit(RQ_SECURE, &rqstp->rq_flags);
+	rp->c_type = cachetype;
+	rp->c_state = RC_DONE;
+	spin_unlock(&b->cache_lock);
+	return;
+}
+
+/*
+ * Copy cached reply to current reply buffer. Should always fit.
+ * FIXME as reply is in a page, we should just attach the page, and
+ * keep a refcount....
+ */
+static int
+nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data)
+{
+	struct kvec	*vec = &rqstp->rq_res.head[0];
+
+	if (vec->iov_len + data->iov_len > PAGE_SIZE) {
+		printk(KERN_WARNING "nfsd: cached reply too large (%zd).\n",
+				data->iov_len);
+		return 0;
+	}
+	memcpy((char*)vec->iov_base + vec->iov_len, data->iov_base, data->iov_len);
+	vec->iov_len += data->iov_len;
+	return 1;
+}
+
+/*
+ * Note that fields may be added, removed or reordered in the future. Programs
+ * scraping this file for info should test the labels to ensure they're
+ * getting the correct field.
+ */
+int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
+{
+	struct nfsd_net *nn = net_generic(file_inode(m->file)->i_sb->s_fs_info,
+					  nfsd_net_id);
+
+	seq_printf(m, "max entries:           %u\n", nn->max_drc_entries);
+	seq_printf(m, "num entries:           %u\n",
+		   atomic_read(&nn->num_drc_entries));
+	seq_printf(m, "hash buckets:          %u\n", 1 << nn->maskbits);
+	seq_printf(m, "mem usage:             %lld\n",
+		   percpu_counter_sum_positive(&nn->counter[NFSD_NET_DRC_MEM_USAGE]));
+	seq_printf(m, "cache hits:            %lld\n",
+		   percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_HITS]));
+	seq_printf(m, "cache misses:          %lld\n",
+		   percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_MISSES]));
+	seq_printf(m, "not cached:            %lld\n",
+		   percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_NOCACHE]));
+	seq_printf(m, "payload misses:        %lld\n",
+		   percpu_counter_sum_positive(&nn->counter[NFSD_NET_PAYLOAD_MISSES]));
+	seq_printf(m, "longest chain len:     %u\n", nn->longest_chain);
+	seq_printf(m, "cachesize at longest:  %u\n", nn->longest_chain_cachesize);
+	return 0;
+}