/* 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/types.h>
#include <linux/refcount.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <uapi/linux/btrfs_tree.h>
#include "fs.h"
#include "messages.h"

struct btrfs_trans_handle;
struct btrfs_fs_info;

/* these are the possible values of struct btrfs_delayed_ref_node->action */
enum btrfs_delayed_ref_action {
        /* Add one backref to the tree */
        BTRFS_ADD_DELAYED_REF = 1,
        /* Delete one backref from the tree */
        BTRFS_DROP_DELAYED_REF,
        /* Record a full extent allocation */
        BTRFS_ADD_DELAYED_EXTENT,
        /* Not changing ref count on head ref */
        BTRFS_UPDATE_DELAYED_HEAD,
} __packed;

struct btrfs_data_ref {
        /* For EXTENT_DATA_REF */

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

        /*
         * 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;

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

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
         * refs rbtree in the corresponding delayed ref head
         * (struct btrfs_delayed_ref_head::ref_tree).
         */
        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;

        /* The ref_root for this ref */
        u64 ref_root;

        /*
         * The parent for this ref, if this isn't set the ref_root is the
         * reference owner.
         */
        u64 parent;

        /* 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;

        union {
                struct btrfs_tree_ref tree_ref;
                struct btrfs_data_ref data_ref;
        };
};

struct btrfs_delayed_extent_op {
        struct btrfs_disk_key key;
        bool update_key;
        bool update_flags;
        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;
        /*
         * the mutex is held while running the refs, and it is also
         * held when checking the sum of reference modifications.
         */
        struct mutex mutex;

        refcount_t refs;

        /* Protects 'ref_tree' and 'ref_add_list'. */
        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 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;

        /*
         * The root that triggered the allocation when must_insert_reserved is
         * set to true.
         */
        u64 owning_root;

        /*
         * Track reserved bytes when setting must_insert_reserved.  On success
         * or cleanup, we will need to free the reservation.
         */
        u64 reserved_bytes;

        /* Tree block level, for metadata only. */
        u8 level;

        /*
         * 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.
         */
        bool must_insert_reserved;

        bool is_data;
        bool is_system;
        bool processing;
        /*
         * Indicate if it's currently in the data structure that tracks head
         * refs (struct btrfs_delayed_ref_root::head_refs).
         */
        bool tracked;
};

enum btrfs_delayed_ref_flags {
        /* Indicate that we are flushing delayed refs for the commit */
        BTRFS_DELAYED_REFS_FLUSHING,
};

struct btrfs_delayed_ref_root {
        /*
         * Track head references.
         * The keys correspond to the logical address of the extent ("bytenr")
         * right shifted by fs_info->sectorsize_bits. This is both to get a more
         * dense index space (optimizes xarray structure) and because indexes in
         * xarrays are of "unsigned long" type, meaning they are 32 bits wide on
         * 32 bits platforms, limiting the extent range to 4G which is too low
         * and makes it unusable (truncated index values) on 32 bits platforms.
         * Protected by the spinlock 'lock' defined below.
         */
        struct xarray head_refs;

        /*
         * Track dirty extent records.
         * The keys correspond to the logical address of the extent ("bytenr")
         * right shifted by fs_info->sectorsize_bits, for same reasons as above.
         */
        struct xarray dirty_extents;

        /*
         * Protects the xarray head_refs, its entries and the following fields:
         * num_heads, num_heads_ready, pending_csums and run_delayed_start.
         */
        spinlock_t lock;

        /* Total number of head refs, protected by the spinlock 'lock'. */
        unsigned long num_heads;

        /*
         * Total number of head refs ready for processing, protected by the
         * spinlock 'lock'.
         */
        unsigned long num_heads_ready;

        /*
         * Track space reserved for deleting csums of data extents.
         * Protected by the spinlock 'lock'.
         */
        u64 pending_csums;

        unsigned long flags;

        /*
         * Track from which bytenr to start searching ref heads.
         * Protected by the spinlock 'lock'.
         */
        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,
} __packed;

struct btrfs_ref {
        enum btrfs_ref_type type;
        enum btrfs_delayed_ref_action 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;

        u64 bytenr;
        u64 num_bytes;
        u64 owning_root;

        /*
         * The root that owns the reference for this reference, this will be set
         * or ->parent will be set, depending on what type of reference this is.
         */
        u64 ref_root;

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

#ifdef CONFIG_BTRFS_DEBUG
        /* Through which root is this modification. */
        u64 real_root;
#endif
};

extern struct kmem_cache *btrfs_delayed_ref_head_cachep;
extern struct kmem_cache *btrfs_delayed_ref_node_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 u64 btrfs_calc_delayed_ref_bytes(const struct btrfs_fs_info *fs_info,
                                               int num_delayed_refs)
{
        u64 num_bytes;

        num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_delayed_refs);

        /*
         * We have to check the mount option here because we could be enabling
         * the free space tree for the first time and don't have the compat_ro
         * option set yet.
         *
         * We need extra reservations if we have the free space tree because
         * we'll have to modify that tree as well.
         */
        if (btrfs_test_opt(fs_info, FREE_SPACE_TREE))
                num_bytes *= 2;

        return num_bytes;
}

static inline u64 btrfs_calc_delayed_ref_csum_bytes(const struct btrfs_fs_info *fs_info,
                                                    int num_csum_items)
{
        /*
         * Deleting csum items does not result in new nodes/leaves and does not
         * require changing the free space tree, only the csum tree, so this is
         * all we need.
         */
        return btrfs_calc_metadata_size(fs_info, num_csum_items);
}

void btrfs_init_tree_ref(struct btrfs_ref *generic_ref, int level, u64 mod_root,
                         bool skip_qgroup);
void btrfs_init_data_ref(struct btrfs_ref *generic_ref, u64 ino, u64 offset,
                         u64 mod_root, bool skip_qgroup);

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);
}

void btrfs_put_delayed_ref(struct btrfs_delayed_ref_node *ref);

static inline u64 btrfs_ref_head_to_space_flags(
                                struct btrfs_delayed_ref_head *head_ref)
{
        if (head_ref->is_data)
                return BTRFS_BLOCK_GROUP_DATA;
        else if (head_ref->is_system)
                return BTRFS_BLOCK_GROUP_SYSTEM;
        return BTRFS_BLOCK_GROUP_METADATA;
}

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 btrfs_add_delayed_data_ref(struct btrfs_trans_handle *trans,
                               struct btrfs_ref *generic_ref,
                               u64 reserved);
int btrfs_add_delayed_extent_op(struct btrfs_trans_handle *trans,
                                u64 bytenr, u64 num_bytes, u8 level,
                                struct btrfs_delayed_extent_op *extent_op);
void btrfs_merge_delayed_refs(struct btrfs_fs_info *fs_info,
                              struct btrfs_delayed_ref_root *delayed_refs,
                              struct btrfs_delayed_ref_head *head);

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

struct btrfs_delayed_ref_head *btrfs_select_ref_head(
                const struct btrfs_fs_info *fs_info,
                struct btrfs_delayed_ref_root *delayed_refs);
void btrfs_unselect_ref_head(struct btrfs_delayed_ref_root *delayed_refs,
                             struct btrfs_delayed_ref_head *head);
struct btrfs_delayed_ref_node *btrfs_select_delayed_ref(struct btrfs_delayed_ref_head *head);

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_refs, int nr_csums);
void btrfs_update_delayed_refs_rsv(struct btrfs_trans_handle *trans);
void btrfs_inc_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
void btrfs_dec_delayed_refs_rsv_bg_inserts(struct btrfs_fs_info *fs_info);
void btrfs_inc_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
void btrfs_dec_delayed_refs_rsv_bg_updates(struct btrfs_fs_info *fs_info);
int btrfs_delayed_refs_rsv_refill(struct btrfs_fs_info *fs_info,
                                  enum btrfs_reserve_flush_enum flush);
bool btrfs_check_space_for_delayed_refs(struct btrfs_fs_info *fs_info);
bool btrfs_find_delayed_tree_ref(struct btrfs_delayed_ref_head *head,
                                 u64 root, u64 parent);
void btrfs_destroy_delayed_refs(struct btrfs_transaction *trans);

static inline u64 btrfs_delayed_ref_owner(const struct btrfs_delayed_ref_node *node)
{
        if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
            node->type == BTRFS_SHARED_DATA_REF_KEY)
                return node->data_ref.objectid;
        return node->tree_ref.level;
}

static inline u64 btrfs_delayed_ref_offset(const struct btrfs_delayed_ref_node *node)
{
        if (node->type == BTRFS_EXTENT_DATA_REF_KEY ||
            node->type == BTRFS_SHARED_DATA_REF_KEY)
                return node->data_ref.offset;
        return 0;
}

static inline u8 btrfs_ref_type(const struct btrfs_ref *ref)
{
        ASSERT(ref->type == BTRFS_REF_DATA || ref->type == BTRFS_REF_METADATA);

        if (ref->type == BTRFS_REF_DATA) {
                if (ref->parent)
                        return BTRFS_SHARED_DATA_REF_KEY;
                else
                        return BTRFS_EXTENT_DATA_REF_KEY;
        } else {
                if (ref->parent)
                        return BTRFS_SHARED_BLOCK_REF_KEY;
                else
                        return BTRFS_TREE_BLOCK_REF_KEY;
        }

        return 0;
}

#endif