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, 533 insertions, 0 deletions

diff --git a/block/blk-flush.c b/block/blk-flush.c
new file mode 100644
index 000000000..53202eff5
--- /dev/null
+++ b/block/blk-flush.c
@@ -0,0 +1,533 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Functions to sequence PREFLUSH and FUA writes.
+ *
+ * Copyright (C) 2011		Max Planck Institute for Gravitational Physics
+ * Copyright (C) 2011		Tejun Heo <tj@kernel.org>
+ *
+ * REQ_{PREFLUSH|FUA} requests are decomposed to sequences consisted of three
+ * optional steps - PREFLUSH, DATA and POSTFLUSH - according to the request
+ * properties and hardware capability.
+ *
+ * If a request doesn't have data, only REQ_PREFLUSH makes sense, which
+ * indicates a simple flush request.  If there is data, REQ_PREFLUSH indicates
+ * that the device cache should be flushed before the data is executed, and
+ * REQ_FUA means that the data must be on non-volatile media on request
+ * completion.
+ *
+ * If the device doesn't have writeback cache, PREFLUSH and FUA don't make any
+ * difference.  The requests are either completed immediately if there's no data
+ * or executed as normal requests otherwise.
+ *
+ * If the device has writeback cache and supports FUA, REQ_PREFLUSH is
+ * translated to PREFLUSH but REQ_FUA is passed down directly with DATA.
+ *
+ * If the device has writeback cache and doesn't support FUA, REQ_PREFLUSH
+ * is translated to PREFLUSH and REQ_FUA to POSTFLUSH.
+ *
+ * The actual execution of flush is double buffered.  Whenever a request
+ * needs to execute PRE or POSTFLUSH, it queues at
+ * fq->flush_queue[fq->flush_pending_idx].  Once certain criteria are met, a
+ * REQ_OP_FLUSH is issued and the pending_idx is toggled.  When the flush
+ * completes, all the requests which were pending are proceeded to the next
+ * step.  This allows arbitrary merging of different types of PREFLUSH/FUA
+ * requests.
+ *
+ * Currently, the following conditions are used to determine when to issue
+ * flush.
+ *
+ * C1. At any given time, only one flush shall be in progress.  This makes
+ *     double buffering sufficient.
+ *
+ * C2. Flush is deferred if any request is executing DATA of its sequence.
+ *     This avoids issuing separate POSTFLUSHes for requests which shared
+ *     PREFLUSH.
+ *
+ * C3. The second condition is ignored if there is a request which has
+ *     waited longer than FLUSH_PENDING_TIMEOUT.  This is to avoid
+ *     starvation in the unlikely case where there are continuous stream of
+ *     FUA (without PREFLUSH) requests.
+ *
+ * For devices which support FUA, it isn't clear whether C2 (and thus C3)
+ * is beneficial.
+ *
+ * Note that a sequenced PREFLUSH/FUA request with DATA is completed twice.
+ * Once while executing DATA and again after the whole sequence is
+ * complete.  The first completion updates the contained bio but doesn't
+ * finish it so that the bio submitter is notified only after the whole
+ * sequence is complete.  This is implemented by testing RQF_FLUSH_SEQ in
+ * req_bio_endio().
+ *
+ * The above peculiarity requires that each PREFLUSH/FUA request has only one
+ * bio attached to it, which is guaranteed as they aren't allowed to be
+ * merged in the usual way.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/gfp.h>
+#include <linux/blk-mq.h>
+#include <linux/part_stat.h>
+
+#include "blk.h"
+#include "blk-mq.h"
+#include "blk-mq-tag.h"
+#include "blk-mq-sched.h"
+
+/* PREFLUSH/FUA sequences */
+enum {
+	REQ_FSEQ_PREFLUSH	= (1 << 0), /* pre-flushing in progress */
+	REQ_FSEQ_DATA		= (1 << 1), /* data write in progress */
+	REQ_FSEQ_POSTFLUSH	= (1 << 2), /* post-flushing in progress */
+	REQ_FSEQ_DONE		= (1 << 3),
+
+	REQ_FSEQ_ACTIONS	= REQ_FSEQ_PREFLUSH | REQ_FSEQ_DATA |
+				  REQ_FSEQ_POSTFLUSH,
+
+	/*
+	 * If flush has been pending longer than the following timeout,
+	 * it's issued even if flush_data requests are still in flight.
+	 */
+	FLUSH_PENDING_TIMEOUT	= 5 * HZ,
+};
+
+static void blk_kick_flush(struct request_queue *q,
+			   struct blk_flush_queue *fq, blk_opf_t flags);
+
+static inline struct blk_flush_queue *
+blk_get_flush_queue(struct request_queue *q, struct blk_mq_ctx *ctx)
+{
+	return blk_mq_map_queue(q, REQ_OP_FLUSH, ctx)->fq;
+}
+
+static unsigned int blk_flush_policy(unsigned long fflags, struct request *rq)
+{
+	unsigned int policy = 0;
+
+	if (blk_rq_sectors(rq))
+		policy |= REQ_FSEQ_DATA;
+
+	if (fflags & (1UL << QUEUE_FLAG_WC)) {
+		if (rq->cmd_flags & REQ_PREFLUSH)
+			policy |= REQ_FSEQ_PREFLUSH;
+		if (!(fflags & (1UL << QUEUE_FLAG_FUA)) &&
+		    (rq->cmd_flags & REQ_FUA))
+			policy |= REQ_FSEQ_POSTFLUSH;
+	}
+	return policy;
+}
+
+static unsigned int blk_flush_cur_seq(struct request *rq)
+{
+	return 1 << ffz(rq->flush.seq);
+}
+
+static void blk_flush_restore_request(struct request *rq)
+{
+	/*
+	 * After flush data completion, @rq->bio is %NULL but we need to
+	 * complete the bio again.  @rq->biotail is guaranteed to equal the
+	 * original @rq->bio.  Restore it.
+	 */
+	rq->bio = rq->biotail;
+
+	/* make @rq a normal request */
+	rq->rq_flags &= ~RQF_FLUSH_SEQ;
+	rq->end_io = rq->flush.saved_end_io;
+}
+
+static void blk_flush_queue_rq(struct request *rq, bool add_front)
+{
+	blk_mq_add_to_requeue_list(rq, add_front, true);
+}
+
+static void blk_account_io_flush(struct request *rq)
+{
+	struct block_device *part = rq->q->disk->part0;
+
+	part_stat_lock();
+	part_stat_inc(part, ios[STAT_FLUSH]);
+	part_stat_add(part, nsecs[STAT_FLUSH],
+		      ktime_get_ns() - rq->start_time_ns);
+	part_stat_unlock();
+}
+
+/**
+ * blk_flush_complete_seq - complete flush sequence
+ * @rq: PREFLUSH/FUA request being sequenced
+ * @fq: flush queue
+ * @seq: sequences to complete (mask of %REQ_FSEQ_*, can be zero)
+ * @error: whether an error occurred
+ *
+ * @rq just completed @seq part of its flush sequence, record the
+ * completion and trigger the next step.
+ *
+ * CONTEXT:
+ * spin_lock_irq(fq->mq_flush_lock)
+ */
+static void blk_flush_complete_seq(struct request *rq,
+				   struct blk_flush_queue *fq,
+				   unsigned int seq, blk_status_t error)
+{
+	struct request_queue *q = rq->q;
+	struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
+	blk_opf_t cmd_flags;
+
+	BUG_ON(rq->flush.seq & seq);
+	rq->flush.seq |= seq;
+	cmd_flags = rq->cmd_flags;
+
+	if (likely(!error))
+		seq = blk_flush_cur_seq(rq);
+	else
+		seq = REQ_FSEQ_DONE;
+
+	switch (seq) {
+	case REQ_FSEQ_PREFLUSH:
+	case REQ_FSEQ_POSTFLUSH:
+		/* queue for flush */
+		if (list_empty(pending))
+			fq->flush_pending_since = jiffies;
+		list_move_tail(&rq->flush.list, pending);
+		break;
+
+	case REQ_FSEQ_DATA:
+		list_move_tail(&rq->flush.list, &fq->flush_data_in_flight);
+		blk_flush_queue_rq(rq, true);
+		break;
+
+	case REQ_FSEQ_DONE:
+		/*
+		 * @rq was previously adjusted by blk_insert_flush() for
+		 * flush sequencing and may already have gone through the
+		 * flush data request completion path.  Restore @rq for
+		 * normal completion and end it.
+		 */
+		list_del_init(&rq->flush.list);
+		blk_flush_restore_request(rq);
+		blk_mq_end_request(rq, error);
+		break;
+
+	default:
+		BUG();
+	}
+
+	blk_kick_flush(q, fq, cmd_flags);
+}
+
+static enum rq_end_io_ret flush_end_io(struct request *flush_rq,
+				       blk_status_t error)
+{
+	struct request_queue *q = flush_rq->q;
+	struct list_head *running;
+	struct request *rq, *n;
+	unsigned long flags = 0;
+	struct blk_flush_queue *fq = blk_get_flush_queue(q, flush_rq->mq_ctx);
+
+	/* release the tag's ownership to the req cloned from */
+	spin_lock_irqsave(&fq->mq_flush_lock, flags);
+
+	if (!req_ref_put_and_test(flush_rq)) {
+		fq->rq_status = error;
+		spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
+		return RQ_END_IO_NONE;
+	}
+
+	blk_account_io_flush(flush_rq);
+	/*
+	 * Flush request has to be marked as IDLE when it is really ended
+	 * because its .end_io() is called from timeout code path too for
+	 * avoiding use-after-free.
+	 */
+	WRITE_ONCE(flush_rq->state, MQ_RQ_IDLE);
+	if (fq->rq_status != BLK_STS_OK) {
+		error = fq->rq_status;
+		fq->rq_status = BLK_STS_OK;
+	}
+
+	if (!q->elevator) {
+		flush_rq->tag = BLK_MQ_NO_TAG;
+	} else {
+		blk_mq_put_driver_tag(flush_rq);
+		flush_rq->internal_tag = BLK_MQ_NO_TAG;
+	}
+
+	running = &fq->flush_queue[fq->flush_running_idx];
+	BUG_ON(fq->flush_pending_idx == fq->flush_running_idx);
+
+	/* account completion of the flush request */
+	fq->flush_running_idx ^= 1;
+
+	/* and push the waiting requests to the next stage */
+	list_for_each_entry_safe(rq, n, running, flush.list) {
+		unsigned int seq = blk_flush_cur_seq(rq);
+
+		BUG_ON(seq != REQ_FSEQ_PREFLUSH && seq != REQ_FSEQ_POSTFLUSH);
+		blk_flush_complete_seq(rq, fq, seq, error);
+	}
+
+	spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
+	return RQ_END_IO_NONE;
+}
+
+bool is_flush_rq(struct request *rq)
+{
+	return rq->end_io == flush_end_io;
+}
+
+/**
+ * blk_kick_flush - consider issuing flush request
+ * @q: request_queue being kicked
+ * @fq: flush queue
+ * @flags: cmd_flags of the original request
+ *
+ * Flush related states of @q have changed, consider issuing flush request.
+ * Please read the comment at the top of this file for more info.
+ *
+ * CONTEXT:
+ * spin_lock_irq(fq->mq_flush_lock)
+ *
+ */
+static void blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq,
+			   blk_opf_t flags)
+{
+	struct list_head *pending = &fq->flush_queue[fq->flush_pending_idx];
+	struct request *first_rq =
+		list_first_entry(pending, struct request, flush.list);
+	struct request *flush_rq = fq->flush_rq;
+
+	/* C1 described at the top of this file */
+	if (fq->flush_pending_idx != fq->flush_running_idx || list_empty(pending))
+		return;
+
+	/* C2 and C3 */
+	if (!list_empty(&fq->flush_data_in_flight) &&
+	    time_before(jiffies,
+			fq->flush_pending_since + FLUSH_PENDING_TIMEOUT))
+		return;
+
+	/*
+	 * Issue flush and toggle pending_idx.  This makes pending_idx
+	 * different from running_idx, which means flush is in flight.
+	 */
+	fq->flush_pending_idx ^= 1;
+
+	blk_rq_init(q, flush_rq);
+
+	/*
+	 * In case of none scheduler, borrow tag from the first request
+	 * since they can't be in flight at the same time. And acquire
+	 * the tag's ownership for flush req.
+	 *
+	 * In case of IO scheduler, flush rq need to borrow scheduler tag
+	 * just for cheating put/get driver tag.
+	 */
+	flush_rq->mq_ctx = first_rq->mq_ctx;
+	flush_rq->mq_hctx = first_rq->mq_hctx;
+
+	if (!q->elevator) {
+		flush_rq->tag = first_rq->tag;
+
+		/*
+		 * We borrow data request's driver tag, so have to mark
+		 * this flush request as INFLIGHT for avoiding double
+		 * account of this driver tag
+		 */
+		flush_rq->rq_flags |= RQF_MQ_INFLIGHT;
+	} else
+		flush_rq->internal_tag = first_rq->internal_tag;
+
+	flush_rq->cmd_flags = REQ_OP_FLUSH | REQ_PREFLUSH;
+	flush_rq->cmd_flags |= (flags & REQ_DRV) | (flags & REQ_FAILFAST_MASK);
+	flush_rq->rq_flags |= RQF_FLUSH_SEQ;
+	flush_rq->end_io = flush_end_io;
+	/*
+	 * Order WRITE ->end_io and WRITE rq->ref, and its pair is the one
+	 * implied in refcount_inc_not_zero() called from
+	 * blk_mq_find_and_get_req(), which orders WRITE/READ flush_rq->ref
+	 * and READ flush_rq->end_io
+	 */
+	smp_wmb();
+	req_ref_set(flush_rq, 1);
+
+	blk_flush_queue_rq(flush_rq, false);
+}
+
+static enum rq_end_io_ret mq_flush_data_end_io(struct request *rq,
+					       blk_status_t error)
+{
+	struct request_queue *q = rq->q;
+	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
+	struct blk_mq_ctx *ctx = rq->mq_ctx;
+	unsigned long flags;
+	struct blk_flush_queue *fq = blk_get_flush_queue(q, ctx);
+
+	if (q->elevator) {
+		WARN_ON(rq->tag < 0);
+		blk_mq_put_driver_tag(rq);
+	}
+
+	/*
+	 * After populating an empty queue, kick it to avoid stall.  Read
+	 * the comment in flush_end_io().
+	 */
+	spin_lock_irqsave(&fq->mq_flush_lock, flags);
+	blk_flush_complete_seq(rq, fq, REQ_FSEQ_DATA, error);
+	spin_unlock_irqrestore(&fq->mq_flush_lock, flags);
+
+	blk_mq_sched_restart(hctx);
+	return RQ_END_IO_NONE;
+}
+
+/**
+ * blk_insert_flush - insert a new PREFLUSH/FUA request
+ * @rq: request to insert
+ *
+ * To be called from __elv_add_request() for %ELEVATOR_INSERT_FLUSH insertions.
+ * or __blk_mq_run_hw_queue() to dispatch request.
+ * @rq is being submitted.  Analyze what needs to be done and put it on the
+ * right queue.
+ */
+void blk_insert_flush(struct request *rq)
+{
+	struct request_queue *q = rq->q;
+	unsigned long fflags = q->queue_flags;	/* may change, cache */
+	unsigned int policy = blk_flush_policy(fflags, rq);
+	struct blk_flush_queue *fq = blk_get_flush_queue(q, rq->mq_ctx);
+
+	/*
+	 * @policy now records what operations need to be done.  Adjust
+	 * REQ_PREFLUSH and FUA for the driver.
+	 */
+	rq->cmd_flags &= ~REQ_PREFLUSH;
+	if (!(fflags & (1UL << QUEUE_FLAG_FUA)))
+		rq->cmd_flags &= ~REQ_FUA;
+
+	/*
+	 * REQ_PREFLUSH|REQ_FUA implies REQ_SYNC, so if we clear any
+	 * of those flags, we have to set REQ_SYNC to avoid skewing
+	 * the request accounting.
+	 */
+	rq->cmd_flags |= REQ_SYNC;
+
+	/*
+	 * An empty flush handed down from a stacking driver may
+	 * translate into nothing if the underlying device does not
+	 * advertise a write-back cache.  In this case, simply
+	 * complete the request.
+	 */
+	if (!policy) {
+		blk_mq_end_request(rq, 0);
+		return;
+	}
+
+	BUG_ON(rq->bio != rq->biotail); /*assumes zero or single bio rq */
+
+	/*
+	 * If there's data but flush is not necessary, the request can be
+	 * processed directly without going through flush machinery.  Queue
+	 * for normal execution.
+	 */
+	if ((policy & REQ_FSEQ_DATA) &&
+	    !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
+		blk_mq_request_bypass_insert(rq, false, true);
+		return;
+	}
+
+	/*
+	 * @rq should go through flush machinery.  Mark it part of flush
+	 * sequence and submit for further processing.
+	 */
+	memset(&rq->flush, 0, sizeof(rq->flush));
+	INIT_LIST_HEAD(&rq->flush.list);
+	rq->rq_flags |= RQF_FLUSH_SEQ;
+	rq->flush.saved_end_io = rq->end_io; /* Usually NULL */
+
+	rq->end_io = mq_flush_data_end_io;
+
+	spin_lock_irq(&fq->mq_flush_lock);
+	blk_flush_complete_seq(rq, fq, REQ_FSEQ_ACTIONS & ~policy, 0);
+	spin_unlock_irq(&fq->mq_flush_lock);
+}
+
+/**
+ * blkdev_issue_flush - queue a flush
+ * @bdev:	blockdev to issue flush for
+ *
+ * Description:
+ *    Issue a flush for the block device in question.
+ */
+int blkdev_issue_flush(struct block_device *bdev)
+{
+	struct bio bio;
+
+	bio_init(&bio, bdev, NULL, 0, REQ_OP_WRITE | REQ_PREFLUSH);
+	return submit_bio_wait(&bio);
+}
+EXPORT_SYMBOL(blkdev_issue_flush);
+
+struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size,
+					      gfp_t flags)
+{
+	struct blk_flush_queue *fq;
+	int rq_sz = sizeof(struct request);
+
+	fq = kzalloc_node(sizeof(*fq), flags, node);
+	if (!fq)
+		goto fail;
+
+	spin_lock_init(&fq->mq_flush_lock);
+
+	rq_sz = round_up(rq_sz + cmd_size, cache_line_size());
+	fq->flush_rq = kzalloc_node(rq_sz, flags, node);
+	if (!fq->flush_rq)
+		goto fail_rq;
+
+	INIT_LIST_HEAD(&fq->flush_queue[0]);
+	INIT_LIST_HEAD(&fq->flush_queue[1]);
+	INIT_LIST_HEAD(&fq->flush_data_in_flight);
+
+	return fq;
+
+ fail_rq:
+	kfree(fq);
+ fail:
+	return NULL;
+}
+
+void blk_free_flush_queue(struct blk_flush_queue *fq)
+{
+	/* bio based request queue hasn't flush queue */
+	if (!fq)
+		return;
+
+	kfree(fq->flush_rq);
+	kfree(fq);
+}
+
+/*
+ * Allow driver to set its own lock class to fq->mq_flush_lock for
+ * avoiding lockdep complaint.
+ *
+ * flush_end_io() may be called recursively from some driver, such as
+ * nvme-loop, so lockdep may complain 'possible recursive locking' because
+ * all 'struct blk_flush_queue' instance share same mq_flush_lock lock class
+ * key. We need to assign different lock class for these driver's
+ * fq->mq_flush_lock for avoiding the lockdep warning.
+ *
+ * Use dynamically allocated lock class key for each 'blk_flush_queue'
+ * instance is over-kill, and more worse it introduces horrible boot delay
+ * issue because synchronize_rcu() is implied in lockdep_unregister_key which
+ * is called for each hctx release. SCSI probing may synchronously create and
+ * destroy lots of MQ request_queues for non-existent devices, and some robot
+ * test kernel always enable lockdep option. It is observed that more than half
+ * an hour is taken during SCSI MQ probe with per-fq lock class.
+ */
+void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
+		struct lock_class_key *key)
+{
+	lockdep_set_class(&hctx->fq->mq_flush_lock, key);
+}
+EXPORT_SYMBOL_GPL(blk_mq_hctx_set_fq_lock_class);