// SPDX-License-Identifier: GPL-2.0
/*
 *  fs/ext4/mballoc.h
 *
 *  Written by: Alex Tomas <alex@clusterfs.com>
 *
 */
#ifndef _EXT4_MBALLOC_H
#define _EXT4_MBALLOC_H

#include <linux/time.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/quotaops.h>
#include <linux/buffer_head.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <linux/proc_fs.h>
#include <linux/pagemap.h>
#include <linux/seq_file.h>
#include <linux/blkdev.h>
#include <linux/mutex.h>
#include "ext4_jbd2.h"
#include "ext4.h"

/*
 * mb_debug() dynamic printk msgs could be used to debug mballoc code.
 */
#ifdef CONFIG_EXT4_DEBUG
#define mb_debug(sb, fmt, ...)                                          \
        pr_debug("[%s/%d] EXT4-fs (%s): (%s, %d): %s: " fmt,            \
                current->comm, task_pid_nr(current), sb->s_id,          \
               __FILE__, __LINE__, __func__, ##__VA_ARGS__)
#else
#define mb_debug(sb, fmt, ...)  no_printk(fmt, ##__VA_ARGS__)
#endif

#define EXT4_MB_HISTORY_ALLOC           1       /* allocation */
#define EXT4_MB_HISTORY_PREALLOC        2       /* preallocated blocks used */

/*
 * How long mballoc can look for a best extent (in found extents)
 */
#define MB_DEFAULT_MAX_TO_SCAN          200

/*
 * How long mballoc must look for a best extent
 */
#define MB_DEFAULT_MIN_TO_SCAN          10

/*
 * with 'ext4_mb_stats' allocator will collect stats that will be
 * shown at umount. The collecting costs though!
 */
#define MB_DEFAULT_STATS                0

/*
 * files smaller than MB_DEFAULT_STREAM_THRESHOLD are served
 * by the stream allocator, which purpose is to pack requests
 * as close each to other as possible to produce smooth I/O traffic
 * We use locality group prealloc space for stream request.
 * We can tune the same via /proc/fs/ext4/<partition>/stream_req
 */
#define MB_DEFAULT_STREAM_THRESHOLD     16      /* 64K */

/*
 * for which requests use 2^N search using buddies
 */
#define MB_DEFAULT_ORDER2_REQS          2

/*
 * default group prealloc size 512 blocks
 */
#define MB_DEFAULT_GROUP_PREALLOC       512

/*
 * maximum length of inode prealloc list
 */
#define MB_DEFAULT_MAX_INODE_PREALLOC   512

/*
 * Number of groups to search linearly before performing group scanning
 * optimization.
 */
#define MB_DEFAULT_LINEAR_LIMIT         4

/*
 * Minimum number of groups that should be present in the file system to perform
 * group scanning optimizations.
 */
#define MB_DEFAULT_LINEAR_SCAN_THRESHOLD        16

/*
 * Number of valid buddy orders
 */
#define MB_NUM_ORDERS(sb)               ((sb)->s_blocksize_bits + 2)

struct ext4_free_data {
        /* this links the free block information from sb_info */
        struct list_head                efd_list;

        /* this links the free block information from group_info */
        struct rb_node                  efd_node;

        /* group which free block extent belongs */
        ext4_group_t                    efd_group;

        /* free block extent */
        ext4_grpblk_t                   efd_start_cluster;
        ext4_grpblk_t                   efd_count;

        /* transaction which freed this extent */
        tid_t                           efd_tid;
};

struct ext4_prealloc_space {
        struct list_head        pa_inode_list;
        struct list_head        pa_group_list;
        union {
                struct list_head pa_tmp_list;
                struct rcu_head pa_rcu;
        } u;
        spinlock_t              pa_lock;
        atomic_t                pa_count;
        unsigned                pa_deleted;
        ext4_fsblk_t            pa_pstart;      /* phys. block */
        ext4_lblk_t             pa_lstart;      /* log. block */
        ext4_grpblk_t           pa_len;         /* len of preallocated chunk */
        ext4_grpblk_t           pa_free;        /* how many blocks are free */
        unsigned short          pa_type;        /* pa type. inode or group */
        spinlock_t              *pa_obj_lock;
        struct inode            *pa_inode;      /* hack, for history only */
};

enum {
        MB_INODE_PA = 0,
        MB_GROUP_PA = 1
};

struct ext4_free_extent {
        ext4_lblk_t fe_logical;
        ext4_grpblk_t fe_start; /* In cluster units */
        ext4_group_t fe_group;
        ext4_grpblk_t fe_len;   /* In cluster units */
};

/*
 * Locality group:
 *   we try to group all related changes together
 *   so that writeback can flush/allocate them together as well
 *   Size of lg_prealloc_list hash is determined by MB_DEFAULT_GROUP_PREALLOC
 *   (512). We store prealloc space into the hash based on the pa_free blocks
 *   order value.ie, fls(pa_free)-1;
 */
#define PREALLOC_TB_SIZE 10
struct ext4_locality_group {
        /* for allocator */
        /* to serialize allocates */
        struct mutex            lg_mutex;
        /* list of preallocations */
        struct list_head        lg_prealloc_list[PREALLOC_TB_SIZE];
        spinlock_t              lg_prealloc_lock;
};

struct ext4_allocation_context {
        struct inode *ac_inode;
        struct super_block *ac_sb;

        /* original request */
        struct ext4_free_extent ac_o_ex;

        /* goal request (normalized ac_o_ex) */
        struct ext4_free_extent ac_g_ex;

        /* the best found extent */
        struct ext4_free_extent ac_b_ex;

        /* copy of the best found extent taken before preallocation efforts */
        struct ext4_free_extent ac_f_ex;

        ext4_group_t ac_last_optimal_group;
        __u32 ac_groups_considered;
        __u32 ac_flags;         /* allocation hints */
        __u16 ac_groups_scanned;
        __u16 ac_groups_linear_remaining;
        __u16 ac_found;
        __u16 ac_tail;
        __u16 ac_buddy;
        __u8 ac_status;
        __u8 ac_criteria;
        __u8 ac_2order;         /* if request is to allocate 2^N blocks and
                                 * N > 0, the field stores N, otherwise 0 */
        __u8 ac_op;             /* operation, for history only */
        struct page *ac_bitmap_page;
        struct page *ac_buddy_page;
        struct ext4_prealloc_space *ac_pa;
        struct ext4_locality_group *ac_lg;
};

#define AC_STATUS_CONTINUE      1
#define AC_STATUS_FOUND         2
#define AC_STATUS_BREAK         3

struct ext4_buddy {
        struct page *bd_buddy_page;
        void *bd_buddy;
        struct page *bd_bitmap_page;
        void *bd_bitmap;
        struct ext4_group_info *bd_info;
        struct super_block *bd_sb;
        __u16 bd_blkbits;
        ext4_group_t bd_group;
};

static inline ext4_fsblk_t ext4_grp_offs_to_block(struct super_block *sb,
                                        struct ext4_free_extent *fex)
{
        return ext4_group_first_block_no(sb, fex->fe_group) +
                (fex->fe_start << EXT4_SB(sb)->s_cluster_bits);
}

typedef int (*ext4_mballoc_query_range_fn)(
        struct super_block              *sb,
        ext4_group_t                    agno,
        ext4_grpblk_t                   start,
        ext4_grpblk_t                   len,
        void                            *priv);

int
ext4_mballoc_query_range(
        struct super_block              *sb,
        ext4_group_t                    agno,
        ext4_grpblk_t                   start,
        ext4_grpblk_t                   end,
        ext4_mballoc_query_range_fn     formatter,
        void                            *priv);

#endif