/* SPDX-License-Identifier: GPL-2.0 */

#ifndef BTRFS_EXTENT_MAP_H
#define BTRFS_EXTENT_MAP_H

#include <linux/compiler_types.h>
#include <linux/spinlock_types.h>
#include <linux/rbtree.h>
#include <linux/list.h>
#include <linux/refcount.h>
#include "fs.h"

struct btrfs_inode;
struct btrfs_fs_info;

#define EXTENT_MAP_LAST_BYTE ((u64)-4)
#define EXTENT_MAP_HOLE ((u64)-3)
#define EXTENT_MAP_INLINE ((u64)-2)

/* bits for the extent_map::flags field */
enum {
        /* this entry not yet on disk, don't free it */
        ENUM_BIT(EXTENT_FLAG_PINNED),
        ENUM_BIT(EXTENT_FLAG_COMPRESS_ZLIB),
        ENUM_BIT(EXTENT_FLAG_COMPRESS_LZO),
        ENUM_BIT(EXTENT_FLAG_COMPRESS_ZSTD),
        /* pre-allocated extent */
        ENUM_BIT(EXTENT_FLAG_PREALLOC),
        /* Logging this extent */
        ENUM_BIT(EXTENT_FLAG_LOGGING),
        /* This em is merged from two or more physically adjacent ems */
        ENUM_BIT(EXTENT_FLAG_MERGED),
};

/*
 * This structure represents file extents and holes.
 *
 * Unlike on-disk file extent items, extent maps can be merged to save memory.
 * This means members only match file extent items before any merging.
 *
 * Keep this structure as compact as possible, as we can have really large
 * amounts of allocated extent maps at any time.
 */
struct extent_map {
        struct rb_node rb_node;

        /* All of these are in bytes. */

        /* File offset matching the offset of a BTRFS_EXTENT_ITEM_KEY key. */
        u64 start;

        /*
         * Length of the file extent.
         *
         * For non-inlined file extents it's btrfs_file_extent_item::num_bytes.
         * For inline extents it's sectorsize, since inline data starts at
         * offsetof(struct btrfs_file_extent_item, disk_bytenr) thus
         * btrfs_file_extent_item::num_bytes is not valid.
         */
        u64 len;

        /*
         * The bytenr of the full on-disk extent.
         *
         * For regular extents it's btrfs_file_extent_item::disk_bytenr.
         * For holes it's EXTENT_MAP_HOLE and for inline extents it's
         * EXTENT_MAP_INLINE.
         */
        u64 disk_bytenr;

        /*
         * The full on-disk extent length, matching
         * btrfs_file_extent_item::disk_num_bytes.
         */
        u64 disk_num_bytes;

        /*
         * Offset inside the decompressed extent.
         *
         * For regular extents it's btrfs_file_extent_item::offset.
         * For holes and inline extents it's 0.
         */
        u64 offset;

        /*
         * The decompressed size of the whole on-disk extent, matching
         * btrfs_file_extent_item::ram_bytes.
         */
        u64 ram_bytes;

        /*
         * Generation of the extent map, for merged em it's the highest
         * generation of all merged ems.
         * For non-merged extents, it's from btrfs_file_extent_item::generation.
         */
        u64 generation;
        u32 flags;
        refcount_t refs;
        struct list_head list;
};

struct extent_map_tree {
        struct rb_root root;
        struct list_head modified_extents;
        rwlock_t lock;
};

struct btrfs_inode;

static inline void btrfs_extent_map_set_compression(struct extent_map *em,
                                                    enum btrfs_compression_type type)
{
        if (type == BTRFS_COMPRESS_ZLIB)
                em->flags |= EXTENT_FLAG_COMPRESS_ZLIB;
        else if (type == BTRFS_COMPRESS_LZO)
                em->flags |= EXTENT_FLAG_COMPRESS_LZO;
        else if (type == BTRFS_COMPRESS_ZSTD)
                em->flags |= EXTENT_FLAG_COMPRESS_ZSTD;
}

static inline enum btrfs_compression_type btrfs_extent_map_compression(
                                                       const struct extent_map *em)
{
        if (em->flags & EXTENT_FLAG_COMPRESS_ZLIB)
                return BTRFS_COMPRESS_ZLIB;

        if (em->flags & EXTENT_FLAG_COMPRESS_LZO)
                return BTRFS_COMPRESS_LZO;

        if (em->flags & EXTENT_FLAG_COMPRESS_ZSTD)
                return BTRFS_COMPRESS_ZSTD;

        return BTRFS_COMPRESS_NONE;
}

/*
 * More efficient way to determine if extent is compressed, instead of using
 * 'extent_map_compression() != BTRFS_COMPRESS_NONE'.
 */
static inline bool btrfs_extent_map_is_compressed(const struct extent_map *em)
{
        return (em->flags & (EXTENT_FLAG_COMPRESS_ZLIB |
                             EXTENT_FLAG_COMPRESS_LZO |
                             EXTENT_FLAG_COMPRESS_ZSTD)) != 0;
}

static inline int btrfs_extent_map_in_tree(const struct extent_map *em)
{
        return !RB_EMPTY_NODE(&em->rb_node);
}

static inline u64 btrfs_extent_map_block_start(const struct extent_map *em)
{
        if (em->disk_bytenr < EXTENT_MAP_LAST_BYTE) {
                if (btrfs_extent_map_is_compressed(em))
                        return em->disk_bytenr;
                return em->disk_bytenr + em->offset;
        }
        return em->disk_bytenr;
}

static inline u64 btrfs_extent_map_end(const struct extent_map *em)
{
        if (em->start + em->len < em->start)
                return (u64)-1;
        return em->start + em->len;
}

void btrfs_extent_map_tree_init(struct extent_map_tree *tree);
struct extent_map *btrfs_lookup_extent_mapping(struct extent_map_tree *tree,
                                               u64 start, u64 len);
void btrfs_remove_extent_mapping(struct btrfs_inode *inode, struct extent_map *em);
int btrfs_split_extent_map(struct btrfs_inode *inode, u64 start, u64 len, u64 pre,
                           u64 new_logical);

struct extent_map *btrfs_alloc_extent_map(void);
void btrfs_free_extent_map(struct extent_map *em);
int __init btrfs_extent_map_init(void);
void __cold btrfs_extent_map_exit(void);
int btrfs_unpin_extent_cache(struct btrfs_inode *inode, u64 start, u64 len, u64 gen);
void btrfs_clear_em_logging(struct btrfs_inode *inode, struct extent_map *em);
struct extent_map *btrfs_search_extent_mapping(struct extent_map_tree *tree,
                                               u64 start, u64 len);
int btrfs_add_extent_mapping(struct btrfs_inode *inode,
                             struct extent_map **em_in, u64 start, u64 len);
void btrfs_drop_extent_map_range(struct btrfs_inode *inode,
                                 u64 start, u64 end,
                                 bool skip_pinned);
int btrfs_replace_extent_map_range(struct btrfs_inode *inode,
                                   struct extent_map *new_em,
                                   bool modified);
void btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan);
void btrfs_init_extent_map_shrinker_work(struct btrfs_fs_info *fs_info);

#endif