/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 */

#ifndef BTRFS_DELAYED_REF_H
#define BTRFS_DELAYED_REF_H

#include <linux/refcount.h>

/* these are the possible values of struct btrfs_delayed_ref_node->action */
#define BTRFS_ADD_DELAYED_REF    1 /* add one backref to the tree */
#define BTRFS_DROP_DELAYED_REF   2 /* delete one backref from the tree */
#define BTRFS_ADD_DELAYED_EXTENT 3 /* record a full extent allocation */
#define BTRFS_UPDATE_DELAYED_HEAD 4 /* not changing ref count on head ref */

struct btrfs_delayed_ref_node {
        struct rb_node ref_node;
        /*
         * If action is BTRFS_ADD_DELAYED_REF, also link this node to
         * ref_head->ref_add_list, then we do not need to iterate the
         * whole ref_head->ref_list to find BTRFS_ADD_DELAYED_REF nodes.
         */
        struct list_head add_list;

        /* the starting bytenr of the extent */
        u64 bytenr;

        /* the size of the extent */
        u64 num_bytes;

        /* seq number to keep track of insertion order */
        u64 seq;

        /* ref count on this data structure */
        refcount_t refs;

        /*
         * how many refs is this entry adding or deleting.  For
         * head refs, this may be a negative number because it is keeping
         * track of the total mods done to the reference count.
         * For individual refs, this will always be a positive number
         *
         * It may be more than one, since it is possible for a single
         * parent to have more than one ref on an extent
         */
        int ref_mod;

        unsigned int action:8;
        unsigned int type:8;
        /* is this node still in the rbtree? */
        unsigned int is_head:1;
        unsigned int in_tree:1;
};

struct btrfs_delayed_extent_op {
        struct btrfs_disk_key key;
        u8 level;
        bool update_key;
        bool update_flags;
        bool is_data;
        u64 flags_to_set;
};

/*
 * the head refs are used to hold a lock on a given extent, which allows us
 * to make sure that only one process is running the delayed refs
 * at a time for a single extent.  They also store the sum of all the
 * reference count modifications we've queued up.
 */
struct btrfs_delayed_ref_head {
        u64 bytenr;
        u64 num_bytes;
        refcount_t refs;
        /*
         * the mutex is held while running the refs, and it is also
         * held when checking the sum of reference modifications.
         */
        struct mutex mutex;

        spinlock_t lock;
        struct rb_root_cached ref_tree;
        /* accumulate add BTRFS_ADD_DELAYED_REF nodes to this ref_add_list. */
        struct list_head ref_add_list;

        struct rb_node href_node;

        struct btrfs_delayed_extent_op *extent_op;

        /*
         * This is used to track the final ref_mod from all the refs associated
         * with this head ref, this is not adjusted as delayed refs are run,
         * this is meant to track if we need to do the csum accounting or not.
         */
        int total_ref_mod;

        /*
         * This is the current outstanding mod references for this bytenr.  This
         * is used with lookup_extent_info to get an accurate reference count
         * for a bytenr, so it is adjusted as delayed refs are run so that any
         * on disk reference count + ref_mod is accurate.
         */
        int ref_mod;

        /*
         * when a new extent is allocated, it is just reserved in memory
         * The actual extent isn't inserted into the extent allocation tree
         * until the delayed ref is processed.  must_insert_reserved is
         * used to flag a delayed ref so the accounting can be updated
         * when a full insert is done.
         *
         * It is possible the extent will be freed before it is ever
         * inserted into the extent allocation tree.  In this case
         * we need to update the in ram accounting to properly reflect
         * the free has happened.
         */
        unsigned int must_insert_reserved:1;
        unsigned int is_data:1;
        unsigned int is_system:1;
        unsigned int processing:1;
};

struct btrfs_delayed_tree_ref {
        struct btrfs_delayed_ref_node node;
        u64 root;
        u64 parent;
        int level;
};

struct btrfs_delayed_data_ref {
        struct btrfs_delayed_ref_node node;
        u64 root;
        u64 parent;
        u64 objectid;
        u64 offset;
};

struct btrfs_delayed_ref_root {
        /* head ref rbtree */
        struct rb_root_cached href_root;

        /* dirty extent records */
        struct rb_root dirty_extent_root;

        /* this spin lock protects the rbtree and the entries inside */
        spinlock_t lock;

        /* how many delayed ref updates we've queued, used by the
         * throttling code
         */
        atomic_t num_entries;

        /* total number of head nodes in tree */
        unsigned long num_heads;

        /* total number of head nodes ready for processing */
        unsigned long num_heads_ready;

        u64 pending_csums;

        /*
         * set when the tree is flushing before a transaction commit,
         * used by the throttling code to decide if new updates need
         * to be run right away
         */
        int flushing;

        u64 run_delayed_start;

        /*
         * To make qgroup to skip given root.
         * This is for snapshot, as btrfs_qgroup_inherit() will manually
         * modify counters for snapshot and its source, so we should skip
         * the snapshot in new_root/old_roots or it will get calculated twice
         */
        u64 qgroup_to_skip;
};

enum btrfs_ref_type {
        BTRFS_REF_NOT_SET,
        BTRFS_REF_DATA,
        BTRFS_REF_METADATA,
        BTRFS_REF_LAST,
};

struct btrfs_data_ref {
        /* For EXTENT_DATA_REF */

        /* Root which refers to this data extent */
        u64 ref_root;

        /* Inode which refers to this data extent */
        u64 ino;

        /*
         * file_offset - extent_offset
         *
         * file_offset is the key.offset of the EXTENT_DATA key.
         * extent_offset is btrfs_file_extent_offset() of the EXTENT_DATA data.
         */
        u64 offset;
};

struct btrfs_tree_ref {
        /*
         * Level of this tree block
         *
         * Shared for skinny (TREE_BLOCK_REF) and normal tree ref.
         */
        int level;

        /*
         * Root which refers to this tree block.
         *
         * For TREE_BLOCK_REF (skinny metadata, either inline or keyed)
         */
        u64 root;

        /* For non-skinny metadata, no special member needed */
};

struct btrfs_ref {
        enum btrfs_ref_type type;
        int action;

        /*
         * Whether this extent should go through qgroup record.
         *
         * Normally false, but for certain cases like delayed subtree scan,
         * setting this flag can hugely reduce qgroup overhead.
         */
        bool skip_qgroup;

        /*
         * Optional. For which root is this modification.
         * Mostly used for qgroup optimization.
         *
         * When unset, data/tree ref init code will populate it.
         * In certain cases, we're modifying reference for a different root.
         * E.g. COW fs tree blocks for balance.
         * In that case, tree_ref::root will be fs tree, but we're doing this
         * for reloc tree, then we should set @real_root to reloc tree.
         */
        u64 real_root;
        u64 bytenr;
        u64 len;

        /* Bytenr of the parent tree block */
        u64 parent;
        union {
                struct btrfs_data_ref data_ref;
                struct btrfs_tree_ref tree_ref;
        };
};

extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
extern struct kmem_cache *btrfs_delayed_tree_ref_cachep;
extern struct kmem_cache *btrfs_delayed_data_ref_cachep;
extern struct kmem_cache *btrfs_delayed_extent_op_cachep;

int __init btrfs_delayed_ref_init(void);
void __cold btrfs_delayed_ref_exit(void);

static inline void btrfs_init_generic_ref(struct btrfs_ref *generic_ref,
                                int action, u64 bytenr, u64 len, u64 parent)
{
        generic_ref->action = action;
        generic_ref->bytenr = bytenr;
        generic_ref->len = len;
        generic_ref->parent = parent;
}

static inline void btrfs_init_tree_ref(struct btrfs_ref *generic_ref,
                                int level, u64 root)
{
        /* If @real_root not set, use @root as fallback */
        if (!generic_ref->real_root)
                generic_ref->real_root = root;
        generic_ref->tree_ref.level = level;
        generic_ref->tree_ref.root = root;
        generic_ref->type = BTRFS_REF_METADATA;
}

static inline void btrfs_init_data_ref(struct btrfs_ref *generic_ref,
                                u64 ref_root, u64 ino, u64 offset)
{
        /* If @real_root not set, use @root as fallback */
        if (!generic_ref->real_root)
                generic_ref->real_root = ref_root;
        generic_ref->data_ref.ref_root = ref_root;
        generic_ref->data_ref.ino = ino;
        generic_ref->data_ref.offset = offset;
        generic_ref->type = BTRFS_REF_DATA;
}

static inline struct btrfs_delayed_extent_op *
btrfs_alloc_delayed_extent_op(void)
{
        return kmem_cache_alloc(btrfs_delayed_extent_op_cachep, GFP_NOFS);
}

static inline void
btrfs_free_delayed_extent_op(struct btrfs_delayed_extent_op *op)
{
        if (op)
                kmem_cache_free(btrfs_delayed_extent_op_cachep, op);
}

static inline void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref)
{
        WARN_ON(refcount_read(&ref->refs) == 0);
        if (refcount_dec_and_test(&ref->refs)) {
                WARN_ON(ref->in_tree);
                switch (ref->type) {
                case BTRFS_TREE_BLOCK_REF_KEY:
                case BTRFS_SHARED_BLOCK_REF_KEY:
                        kmem_cache_free(btrfs_delayed_tree_ref_cachep, ref);
                        break;
                case BTRFS_EXTENT_DATA_REF_KEY:
                case BTRFS_SHARED_DATA_REF_KEY:
                        kmem_cache_free(btrfs_delayed_data_ref_cachep, ref);
                        break;
                default:
                        BUG();
                }
        }
}

static inline void btrfs_put_delayed_ref_head(struct btrfs_delayed_ref_head *head)
{
        if (refcount_dec_and_test(&head->refs))
                kmem_cache_free(btrfs_delayed_ref_head_cachep, head);
}

int btrfs_add_delayed_tree_ref(struct btrfs_trans_handle *trans,
                               struct btrfs_ref *generic_ref,
                               struct btrfs_delayed_extent_op *extent_op,
                               int *old_ref_mod, int *new_ref_mod);
int btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
                               struct btrfs_ref *generic_ref,
                               u64 reserved, int *old_ref_mod,
                               int *new_ref_mod);
int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes,
                                struct btrfs_delayed_extent_op *extent_op);
void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
                              struct btrfs_delayed_ref_root *delayed_refs,
                              struct btrfs_delayed_ref_head *head);

struct btrfs_delayed_ref_head *
btrfs_find_delayed_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
                            u64 bytenr);
int btrfs_delayed_ref_lock(struct btrfs_delayed_ref_root *delayed_refs,
                           struct btrfs_delayed_ref_head *head);
static inline void btrfs_delayed_ref_unlock(struct btrfs_delayed_ref_head *head)
{
        mutex_unlock(&head->mutex);
}
void btrfs_delete_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
                           struct btrfs_delayed_ref_head *head);

struct btrfs_delayed_ref_head *btrfs_select_ref_head(
                struct btrfs_delayed_ref_root *delayed_refs);

int btrfs_check_delayed_seq(struct btrfs_fs_info *fs_info, u64 seq);

void btrfs_delayed_refs_rsv_release(struct btrfs_fs_info *fs_info, int nr);
void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
                                  enum btrfs_reserve_flush_enum flush);
void btrfs_migrate_to_delayed_refs_rsv(struct btrfs_fs_info *fs_info,
                                       struct btrfs_block_rsv *src,
                                       u64 num_bytes);
int btrfs_should_throttle_delayed_refs(struct btrfs_trans_handle *trans);
bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);

/*
 * helper functions to cast a node into its container
 */
static inline struct btrfs_delayed_tree_ref *
btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node)
{
        return container_of(node, struct btrfs_delayed_tree_ref, node);
}

static inline struct btrfs_delayed_data_ref *
btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node)
{
        return container_of(node, struct btrfs_delayed_data_ref, node);
}

#endif