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, 549 insertions, 0 deletions

diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
new file mode 100644
index 000000000..ef6bbea3f
--- /dev/null
+++ b/fs/btrfs/backref.h
@@ -0,0 +1,549 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2011 STRATO.  All rights reserved.
+ */
+
+#ifndef BTRFS_BACKREF_H
+#define BTRFS_BACKREF_H
+
+#include <linux/btrfs.h>
+#include "messages.h"
+#include "ulist.h"
+#include "disk-io.h"
+#include "extent_io.h"
+
+/*
+ * Used by implementations of iterate_extent_inodes_t (see definition below) to
+ * signal that backref iteration can stop immediately and no error happened.
+ * The value must be non-negative and must not be 0, 1 (which is a common return
+ * value from things like btrfs_search_slot() and used internally in the backref
+ * walking code) and different from BACKREF_FOUND_SHARED and
+ * BACKREF_FOUND_NOT_SHARED
+ */
+#define BTRFS_ITERATE_EXTENT_INODES_STOP 5
+
+/*
+ * Should return 0 if no errors happened and iteration of backrefs should
+ * continue. Can return BTRFS_ITERATE_EXTENT_INODES_STOP or any other non-zero
+ * value to immediately stop iteration and possibly signal an error back to
+ * the caller.
+ */
+typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 num_bytes,
+				      u64 root, void *ctx);
+
+/*
+ * Context and arguments for backref walking functions. Some of the fields are
+ * to be filled by the caller of such functions while other are filled by the
+ * functions themselves, as described below.
+ */
+struct btrfs_backref_walk_ctx {
+	/*
+	 * The address of the extent for which we are doing backref walking.
+	 * Can be either a data extent or a metadata extent.
+	 *
+	 * Must always be set by the top level caller.
+	 */
+	u64 bytenr;
+	/*
+	 * Offset relative to the target extent. This is only used for data
+	 * extents, and it's meaningful because we can have file extent items
+	 * that point only to a section of a data extent ("bookend" extents),
+	 * and we want to filter out any that don't point to a section of the
+	 * data extent containing the given offset.
+	 *
+	 * Must always be set by the top level caller.
+	 */
+	u64 extent_item_pos;
+	/*
+	 * If true and bytenr corresponds to a data extent, then references from
+	 * all file extent items that point to the data extent are considered,
+	 * @extent_item_pos is ignored.
+	 */
+	bool ignore_extent_item_pos;
+	/* A valid transaction handle or NULL. */
+	struct btrfs_trans_handle *trans;
+	/*
+	 * The file system's info object, can not be NULL.
+	 *
+	 * Must always be set by the top level caller.
+	 */
+	struct btrfs_fs_info *fs_info;
+	/*
+	 * Time sequence acquired from btrfs_get_tree_mod_seq(), in case the
+	 * caller joined the tree mod log to get a consistent view of b+trees
+	 * while we do backref walking, or BTRFS_SEQ_LAST.
+	 * When using BTRFS_SEQ_LAST, delayed refs are not checked and it uses
+	 * commit roots when searching b+trees - this is a special case for
+	 * qgroups used during a transaction commit.
+	 */
+	u64 time_seq;
+	/*
+	 * Used to collect the bytenr of metadata extents that point to the
+	 * target extent.
+	 */
+	struct ulist *refs;
+	/*
+	 * List used to collect the IDs of the roots from which the target
+	 * extent is accessible. Can be NULL in case the caller does not care
+	 * about collecting root IDs.
+	 */
+	struct ulist *roots;
+	/*
+	 * Used by iterate_extent_inodes() and the main backref walk code
+	 * (find_parent_nodes()). Lookup and store functions for an optional
+	 * cache which maps the logical address (bytenr) of leaves to an array
+	 * of root IDs.
+	 */
+	bool (*cache_lookup)(u64 leaf_bytenr, void *user_ctx,
+			     const u64 **root_ids_ret, int *root_count_ret);
+	void (*cache_store)(u64 leaf_bytenr, const struct ulist *root_ids,
+			    void *user_ctx);
+	/*
+	 * If this is not NULL, then the backref walking code will call this
+	 * for each indirect data extent reference as soon as it finds one,
+	 * before collecting all the remaining backrefs and before resolving
+	 * indirect backrefs. This allows for the caller to terminate backref
+	 * walking as soon as it finds one backref that matches some specific
+	 * criteria. The @cache_lookup and @cache_store callbacks should not
+	 * be NULL in order to use this callback.
+	 */
+	iterate_extent_inodes_t *indirect_ref_iterator;
+	/*
+	 * If this is not NULL, then the backref walking code will call this for
+	 * each extent item it's meant to process before it actually starts
+	 * processing it. If this returns anything other than 0, then it stops
+	 * the backref walking code immediately.
+	 */
+	int (*check_extent_item)(u64 bytenr, const struct btrfs_extent_item *ei,
+				 const struct extent_buffer *leaf, void *user_ctx);
+	/*
+	 * If this is not NULL, then the backref walking code will call this for
+	 * each extent data ref it finds (BTRFS_EXTENT_DATA_REF_KEY keys) before
+	 * processing that data ref. If this callback return false, then it will
+	 * ignore this data ref and it will never resolve the indirect data ref,
+	 * saving time searching for leaves in a fs tree with file extent items
+	 * matching the data ref.
+	 */
+	bool (*skip_data_ref)(u64 root, u64 ino, u64 offset, void *user_ctx);
+	/* Context object to pass to the callbacks defined above. */
+	void *user_ctx;
+};
+
+struct inode_fs_paths {
+	struct btrfs_path		*btrfs_path;
+	struct btrfs_root		*fs_root;
+	struct btrfs_data_container	*fspath;
+};
+
+struct btrfs_backref_shared_cache_entry {
+	u64 bytenr;
+	u64 gen;
+	bool is_shared;
+};
+
+#define BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE 8
+
+struct btrfs_backref_share_check_ctx {
+	/* Ulists used during backref walking. */
+	struct ulist refs;
+	/*
+	 * The current leaf the caller of btrfs_is_data_extent_shared() is at.
+	 * Typically the caller (at the moment only fiemap) tries to determine
+	 * the sharedness of data extents point by file extent items from entire
+	 * leaves.
+	 */
+	u64 curr_leaf_bytenr;
+	/*
+	 * The previous leaf the caller was at in the previous call to
+	 * btrfs_is_data_extent_shared(). This may be the same as the current
+	 * leaf. On the first call it must be 0.
+	 */
+	u64 prev_leaf_bytenr;
+	/*
+	 * A path from a root to a leaf that has a file extent item pointing to
+	 * a given data extent should never exceed the maximum b+tree height.
+	 */
+	struct btrfs_backref_shared_cache_entry path_cache_entries[BTRFS_MAX_LEVEL];
+	bool use_path_cache;
+	/*
+	 * Cache the sharedness result for the last few extents we have found,
+	 * but only for extents for which we have multiple file extent items
+	 * that point to them.
+	 * It's very common to have several file extent items that point to the
+	 * same extent (bytenr) but with different offsets and lengths. This
+	 * typically happens for COW writes, partial writes into prealloc
+	 * extents, NOCOW writes after snapshoting a root, hole punching or
+	 * reflinking within the same file (less common perhaps).
+	 * So keep a small cache with the lookup results for the extent pointed
+	 * by the last few file extent items. This cache is checked, with a
+	 * linear scan, whenever btrfs_is_data_extent_shared() is called, so
+	 * it must be small so that it does not negatively affect performance in
+	 * case we don't have multiple file extent items that point to the same
+	 * data extent.
+	 */
+	struct {
+		u64 bytenr;
+		bool is_shared;
+	} prev_extents_cache[BTRFS_BACKREF_CTX_PREV_EXTENTS_SIZE];
+	/*
+	 * The slot in the prev_extents_cache array that will be used for
+	 * storing the sharedness result of a new data extent.
+	 */
+	int prev_extents_cache_slot;
+};
+
+struct btrfs_backref_share_check_ctx *btrfs_alloc_backref_share_check_ctx(void);
+void btrfs_free_backref_share_ctx(struct btrfs_backref_share_check_ctx *ctx);
+
+int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
+			struct btrfs_path *path, struct btrfs_key *found_key,
+			u64 *flags);
+
+int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
+			    struct btrfs_key *key, struct btrfs_extent_item *ei,
+			    u32 item_size, u64 *out_root, u8 *out_level);
+
+int iterate_extent_inodes(struct btrfs_backref_walk_ctx *ctx,
+			  bool search_commit_root,
+			  iterate_extent_inodes_t *iterate, void *user_ctx);
+
+int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
+				struct btrfs_path *path, void *ctx,
+				bool ignore_offset);
+
+int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
+
+int btrfs_find_all_leafs(struct btrfs_backref_walk_ctx *ctx);
+int btrfs_find_all_roots(struct btrfs_backref_walk_ctx *ctx,
+			 bool skip_commit_root_sem);
+char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
+			u32 name_len, unsigned long name_off,
+			struct extent_buffer *eb_in, u64 parent,
+			char *dest, u32 size);
+
+struct btrfs_data_container *init_data_container(u32 total_bytes);
+struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
+					struct btrfs_path *path);
+void free_ipath(struct inode_fs_paths *ipath);
+
+int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
+			  u64 start_off, struct btrfs_path *path,
+			  struct btrfs_inode_extref **ret_extref,
+			  u64 *found_off);
+int btrfs_is_data_extent_shared(struct btrfs_inode *inode, u64 bytenr,
+				u64 extent_gen,
+				struct btrfs_backref_share_check_ctx *ctx);
+
+int __init btrfs_prelim_ref_init(void);
+void __cold btrfs_prelim_ref_exit(void);
+
+struct prelim_ref {
+	struct rb_node rbnode;
+	u64 root_id;
+	struct btrfs_key key_for_search;
+	int level;
+	int count;
+	struct extent_inode_elem *inode_list;
+	u64 parent;
+	u64 wanted_disk_byte;
+};
+
+/*
+ * Iterate backrefs of one extent.
+ *
+ * Now it only supports iteration of tree block in commit root.
+ */
+struct btrfs_backref_iter {
+	u64 bytenr;
+	struct btrfs_path *path;
+	struct btrfs_fs_info *fs_info;
+	struct btrfs_key cur_key;
+	u32 item_ptr;
+	u32 cur_ptr;
+	u32 end_ptr;
+};
+
+struct btrfs_backref_iter *btrfs_backref_iter_alloc(struct btrfs_fs_info *fs_info);
+
+static inline void btrfs_backref_iter_free(struct btrfs_backref_iter *iter)
+{
+	if (!iter)
+		return;
+	btrfs_free_path(iter->path);
+	kfree(iter);
+}
+
+static inline struct extent_buffer *btrfs_backref_get_eb(
+		struct btrfs_backref_iter *iter)
+{
+	if (!iter)
+		return NULL;
+	return iter->path->nodes[0];
+}
+
+/*
+ * For metadata with EXTENT_ITEM key (non-skinny) case, the first inline data
+ * is btrfs_tree_block_info, without a btrfs_extent_inline_ref header.
+ *
+ * This helper determines if that's the case.
+ */
+static inline bool btrfs_backref_has_tree_block_info(
+		struct btrfs_backref_iter *iter)
+{
+	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY &&
+	    iter->cur_ptr - iter->item_ptr == sizeof(struct btrfs_extent_item))
+		return true;
+	return false;
+}
+
+int btrfs_backref_iter_start(struct btrfs_backref_iter *iter, u64 bytenr);
+
+int btrfs_backref_iter_next(struct btrfs_backref_iter *iter);
+
+static inline bool btrfs_backref_iter_is_inline_ref(
+		struct btrfs_backref_iter *iter)
+{
+	if (iter->cur_key.type == BTRFS_EXTENT_ITEM_KEY ||
+	    iter->cur_key.type == BTRFS_METADATA_ITEM_KEY)
+		return true;
+	return false;
+}
+
+static inline void btrfs_backref_iter_release(struct btrfs_backref_iter *iter)
+{
+	iter->bytenr = 0;
+	iter->item_ptr = 0;
+	iter->cur_ptr = 0;
+	iter->end_ptr = 0;
+	btrfs_release_path(iter->path);
+	memset(&iter->cur_key, 0, sizeof(iter->cur_key));
+}
+
+/*
+ * Backref cache related structures
+ *
+ * The whole objective of backref_cache is to build a bi-directional map
+ * of tree blocks (represented by backref_node) and all their parents.
+ */
+
+/*
+ * Represent a tree block in the backref cache
+ */
+struct btrfs_backref_node {
+	struct {
+		struct rb_node rb_node;
+		u64 bytenr;
+	}; /* Use rb_simple_node for search/insert */
+
+	u64 new_bytenr;
+	/* Objectid of tree block owner, can be not uptodate */
+	u64 owner;
+	/* Link to pending, changed or detached list */
+	struct list_head list;
+
+	/* List of upper level edges, which link this node to its parents */
+	struct list_head upper;
+	/* List of lower level edges, which link this node to its children */
+	struct list_head lower;
+
+	/* NULL if this node is not tree root */
+	struct btrfs_root *root;
+	/* Extent buffer got by COWing the block */
+	struct extent_buffer *eb;
+	/* Level of the tree block */
+	unsigned int level:8;
+	/* Is the block in a non-shareable tree */
+	unsigned int cowonly:1;
+	/* 1 if no child node is in the cache */
+	unsigned int lowest:1;
+	/* Is the extent buffer locked */
+	unsigned int locked:1;
+	/* Has the block been processed */
+	unsigned int processed:1;
+	/* Have backrefs of this block been checked */
+	unsigned int checked:1;
+	/*
+	 * 1 if corresponding block has been COWed but some upper level block
+	 * pointers may not point to the new location
+	 */
+	unsigned int pending:1;
+	/* 1 if the backref node isn't connected to any other backref node */
+	unsigned int detached:1;
+
+	/*
+	 * For generic purpose backref cache, where we only care if it's a reloc
+	 * root, doesn't care the source subvolid.
+	 */
+	unsigned int is_reloc_root:1;
+};
+
+#define LOWER	0
+#define UPPER	1
+
+/*
+ * Represent an edge connecting upper and lower backref nodes.
+ */
+struct btrfs_backref_edge {
+	/*
+	 * list[LOWER] is linked to btrfs_backref_node::upper of lower level
+	 * node, and list[UPPER] is linked to btrfs_backref_node::lower of
+	 * upper level node.
+	 *
+	 * Also, build_backref_tree() uses list[UPPER] for pending edges, before
+	 * linking list[UPPER] to its upper level nodes.
+	 */
+	struct list_head list[2];
+
+	/* Two related nodes */
+	struct btrfs_backref_node *node[2];
+};
+
+struct btrfs_backref_cache {
+	/* Red black tree of all backref nodes in the cache */
+	struct rb_root rb_root;
+	/* For passing backref nodes to btrfs_reloc_cow_block */
+	struct btrfs_backref_node *path[BTRFS_MAX_LEVEL];
+	/*
+	 * List of blocks that have been COWed but some block pointers in upper
+	 * level blocks may not reflect the new location
+	 */
+	struct list_head pending[BTRFS_MAX_LEVEL];
+	/* List of backref nodes with no child node */
+	struct list_head leaves;
+	/* List of blocks that have been COWed in current transaction */
+	struct list_head changed;
+	/* List of detached backref node. */
+	struct list_head detached;
+
+	u64 last_trans;
+
+	int nr_nodes;
+	int nr_edges;
+
+	/* List of unchecked backref edges during backref cache build */
+	struct list_head pending_edge;
+
+	/* List of useless backref nodes during backref cache build */
+	struct list_head useless_node;
+
+	struct btrfs_fs_info *fs_info;
+
+	/*
+	 * Whether this cache is for relocation
+	 *
+	 * Reloction backref cache require more info for reloc root compared
+	 * to generic backref cache.
+	 */
+	unsigned int is_reloc;
+};
+
+void btrfs_backref_init_cache(struct btrfs_fs_info *fs_info,
+			      struct btrfs_backref_cache *cache, int is_reloc);
+struct btrfs_backref_node *btrfs_backref_alloc_node(
+		struct btrfs_backref_cache *cache, u64 bytenr, int level);
+struct btrfs_backref_edge *btrfs_backref_alloc_edge(
+		struct btrfs_backref_cache *cache);
+
+#define		LINK_LOWER	(1 << 0)
+#define		LINK_UPPER	(1 << 1)
+static inline void btrfs_backref_link_edge(struct btrfs_backref_edge *edge,
+					   struct btrfs_backref_node *lower,
+					   struct btrfs_backref_node *upper,
+					   int link_which)
+{
+	ASSERT(upper && lower && upper->level == lower->level + 1);
+	edge->node[LOWER] = lower;
+	edge->node[UPPER] = upper;
+	if (link_which & LINK_LOWER)
+		list_add_tail(&edge->list[LOWER], &lower->upper);
+	if (link_which & LINK_UPPER)
+		list_add_tail(&edge->list[UPPER], &upper->lower);
+}
+
+static inline void btrfs_backref_free_node(struct btrfs_backref_cache *cache,
+					   struct btrfs_backref_node *node)
+{
+	if (node) {
+		ASSERT(list_empty(&node->list));
+		ASSERT(list_empty(&node->lower));
+		ASSERT(node->eb == NULL);
+		cache->nr_nodes--;
+		btrfs_put_root(node->root);
+		kfree(node);
+	}
+}
+
+static inline void btrfs_backref_free_edge(struct btrfs_backref_cache *cache,
+					   struct btrfs_backref_edge *edge)
+{
+	if (edge) {
+		cache->nr_edges--;
+		kfree(edge);
+	}
+}
+
+static inline void btrfs_backref_unlock_node_buffer(
+		struct btrfs_backref_node *node)
+{
+	if (node->locked) {
+		btrfs_tree_unlock(node->eb);
+		node->locked = 0;
+	}
+}
+
+static inline void btrfs_backref_drop_node_buffer(
+		struct btrfs_backref_node *node)
+{
+	if (node->eb) {
+		btrfs_backref_unlock_node_buffer(node);
+		free_extent_buffer(node->eb);
+		node->eb = NULL;
+	}
+}
+
+/*
+ * Drop the backref node from cache without cleaning up its children
+ * edges.
+ *
+ * This can only be called on node without parent edges.
+ * The children edges are still kept as is.
+ */
+static inline void btrfs_backref_drop_node(struct btrfs_backref_cache *tree,
+					   struct btrfs_backref_node *node)
+{
+	ASSERT(list_empty(&node->upper));
+
+	btrfs_backref_drop_node_buffer(node);
+	list_del_init(&node->list);
+	list_del_init(&node->lower);
+	if (!RB_EMPTY_NODE(&node->rb_node))
+		rb_erase(&node->rb_node, &tree->rb_root);
+	btrfs_backref_free_node(tree, node);
+}
+
+void btrfs_backref_cleanup_node(struct btrfs_backref_cache *cache,
+				struct btrfs_backref_node *node);
+
+void btrfs_backref_release_cache(struct btrfs_backref_cache *cache);
+
+static inline void btrfs_backref_panic(struct btrfs_fs_info *fs_info,
+				       u64 bytenr, int errno)
+{
+	btrfs_panic(fs_info, errno,
+		    "Inconsistency in backref cache found at offset %llu",
+		    bytenr);
+}
+
+int btrfs_backref_add_tree_node(struct btrfs_backref_cache *cache,
+				struct btrfs_path *path,
+				struct btrfs_backref_iter *iter,
+				struct btrfs_key *node_key,
+				struct btrfs_backref_node *cur);
+
+int btrfs_backref_finish_upper_links(struct btrfs_backref_cache *cache,
+				     struct btrfs_backref_node *start);
+
+void btrfs_backref_error_cleanup(struct btrfs_backref_cache *cache,
+				 struct btrfs_backref_node *node);
+
+#endif