/*
 * Block Translation Table library
 * Copyright (c) 2014-2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#ifndef _LINUX_BTT_H
#define _LINUX_BTT_H

#include <linux/badblocks.h>
#include <linux/types.h>

#define BTT_SIG_LEN 16
#define BTT_SIG "BTT_ARENA_INFO\0"
#define MAP_ENT_SIZE 4
#define MAP_TRIM_SHIFT 31
#define MAP_TRIM_MASK (1 << MAP_TRIM_SHIFT)
#define MAP_ERR_SHIFT 30
#define MAP_ERR_MASK (1 << MAP_ERR_SHIFT)
#define MAP_LBA_MASK (~((1 << MAP_TRIM_SHIFT) | (1 << MAP_ERR_SHIFT)))
#define MAP_ENT_NORMAL 0xC0000000
#define LOG_GRP_SIZE sizeof(struct log_group)
#define LOG_ENT_SIZE sizeof(struct log_entry)
#define ARENA_MIN_SIZE (1UL << 24)      /* 16 MB */
#define ARENA_MAX_SIZE (1ULL << 39)     /* 512 GB */
#define RTT_VALID (1UL << 31)
#define RTT_INVALID 0
#define BTT_PG_SIZE 4096
#define BTT_DEFAULT_NFREE ND_MAX_LANES
#define LOG_SEQ_INIT 1

#define IB_FLAG_ERROR 0x00000001
#define IB_FLAG_ERROR_MASK 0x00000001

#define ent_lba(ent) (ent & MAP_LBA_MASK)
#define ent_e_flag(ent) (!!(ent & MAP_ERR_MASK))
#define ent_z_flag(ent) (!!(ent & MAP_TRIM_MASK))
#define set_e_flag(ent) (ent |= MAP_ERR_MASK)

enum btt_init_state {
        INIT_UNCHECKED = 0,
        INIT_NOTFOUND,
        INIT_READY
};

/*
 * A log group represents one log 'lane', and consists of four log entries.
 * Two of the four entries are valid entries, and the remaining two are
 * padding. Due to an old bug in the padding location, we need to perform a
 * test to determine the padding scheme being used, and use that scheme
 * thereafter.
 *
 * In kernels prior to 4.15, 'log group' would have actual log entries at
 * indices (0, 2) and padding at indices (1, 3), where as the correct/updated
 * format has log entries at indices (0, 1) and padding at indices (2, 3).
 *
 * Old (pre 4.15) format:
 * +-----------------+-----------------+
 * |      ent[0]     |      ent[1]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq |       pad       |
 * +-----------------------------------+
 * |      ent[2]     |      ent[3]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq |       pad       |
 * +-----------------+-----------------+
 *
 * New format:
 * +-----------------+-----------------+
 * |      ent[0]     |      ent[1]     |
 * |       16B       |       16B       |
 * | lba/old/new/seq | lba/old/new/seq |
 * +-----------------------------------+
 * |      ent[2]     |      ent[3]     |
 * |       16B       |       16B       |
 * |       pad       |       pad       |
 * +-----------------+-----------------+
 *
 * We detect during start-up which format is in use, and set
 * arena->log_index[(0, 1)] with the detected format.
 */

struct log_entry {
        __le32 lba;
        __le32 old_map;
        __le32 new_map;
        __le32 seq;
};

struct log_group {
        struct log_entry ent[4];
};

struct btt_sb {
        u8 signature[BTT_SIG_LEN];
        u8 uuid[16];
        u8 parent_uuid[16];
        __le32 flags;
        __le16 version_major;
        __le16 version_minor;
        __le32 external_lbasize;
        __le32 external_nlba;
        __le32 internal_lbasize;
        __le32 internal_nlba;
        __le32 nfree;
        __le32 infosize;
        __le64 nextoff;
        __le64 dataoff;
        __le64 mapoff;
        __le64 logoff;
        __le64 info2off;
        u8 padding[3968];
        __le64 checksum;
};

struct free_entry {
        u32 block;
        u8 sub;
        u8 seq;
        u8 has_err;
};

struct aligned_lock {
        union {
                spinlock_t lock;
                u8 cacheline_padding[L1_CACHE_BYTES];
        };
};

/**
 * struct arena_info - handle for an arena
 * @size:               Size in bytes this arena occupies on the raw device.
 *                      This includes arena metadata.
 * @external_lba_start: The first external LBA in this arena.
 * @internal_nlba:      Number of internal blocks available in the arena
 *                      including nfree reserved blocks
 * @internal_lbasize:   Internal and external lba sizes may be different as
 *                      we can round up 'odd' external lbasizes such as 520B
 *                      to be aligned.
 * @external_nlba:      Number of blocks contributed by the arena to the number
 *                      reported to upper layers. (internal_nlba - nfree)
 * @external_lbasize:   LBA size as exposed to upper layers.
 * @nfree:              A reserve number of 'free' blocks that is used to
 *                      handle incoming writes.
 * @version_major:      Metadata layout version major.
 * @version_minor:      Metadata layout version minor.
 * @sector_size:        The Linux sector size - 512 or 4096
 * @nextoff:            Offset in bytes to the start of the next arena.
 * @infooff:            Offset in bytes to the info block of this arena.
 * @dataoff:            Offset in bytes to the data area of this arena.
 * @mapoff:             Offset in bytes to the map area of this arena.
 * @logoff:             Offset in bytes to the log area of this arena.
 * @info2off:           Offset in bytes to the backup info block of this arena.
 * @freelist:           Pointer to in-memory list of free blocks
 * @rtt:                Pointer to in-memory "Read Tracking Table"
 * @map_locks:          Spinlocks protecting concurrent map writes
 * @nd_btt:             Pointer to parent nd_btt structure.
 * @list:               List head for list of arenas
 * @debugfs_dir:        Debugfs dentry
 * @flags:              Arena flags - may signify error states.
 * @err_lock:           Mutex for synchronizing error clearing.
 * @log_index:          Indices of the valid log entries in a log_group
 *
 * arena_info is a per-arena handle. Once an arena is narrowed down for an
 * IO, this struct is passed around for the duration of the IO.
 */
struct arena_info {
        u64 size;                       /* Total bytes for this arena */
        u64 external_lba_start;
        u32 internal_nlba;
        u32 internal_lbasize;
        u32 external_nlba;
        u32 external_lbasize;
        u32 nfree;
        u16 version_major;
        u16 version_minor;
        u32 sector_size;
        /* Byte offsets to the different on-media structures */
        u64 nextoff;
        u64 infooff;
        u64 dataoff;
        u64 mapoff;
        u64 logoff;
        u64 info2off;
        /* Pointers to other in-memory structures for this arena */
        struct free_entry *freelist;
        u32 *rtt;
        struct aligned_lock *map_locks;
        struct nd_btt *nd_btt;
        struct list_head list;
        struct dentry *debugfs_dir;
        /* Arena flags */
        u32 flags;
        struct mutex err_lock;
        int log_index[2];
};

/**
 * struct btt - handle for a BTT instance
 * @btt_disk:           Pointer to the gendisk for BTT device
 * @btt_queue:          Pointer to the request queue for the BTT device
 * @arena_list:         Head of the list of arenas
 * @debugfs_dir:        Debugfs dentry
 * @nd_btt:             Parent nd_btt struct
 * @nlba:               Number of logical blocks exposed to the upper layers
 *                      after removing the amount of space needed by metadata
 * @rawsize:            Total size in bytes of the available backing device
 * @lbasize:            LBA size as requested and presented to upper layers.
 *                      This is sector_size + size of any metadata.
 * @sector_size:        The Linux sector size - 512 or 4096
 * @lanes:              Per-lane spinlocks
 * @init_lock:          Mutex used for the BTT initialization
 * @init_state:         Flag describing the initialization state for the BTT
 * @num_arenas:         Number of arenas in the BTT instance
 * @phys_bb:            Pointer to the namespace's badblocks structure
 */
struct btt {
        struct gendisk *btt_disk;
        struct request_queue *btt_queue;
        struct list_head arena_list;
        struct dentry *debugfs_dir;
        struct nd_btt *nd_btt;
        u64 nlba;
        unsigned long long rawsize;
        u32 lbasize;
        u32 sector_size;
        struct nd_region *nd_region;
        struct mutex init_lock;
        int init_state;
        int num_arenas;
        struct badblocks *phys_bb;
};

bool nd_btt_arena_is_valid(struct nd_btt *nd_btt, struct btt_sb *super);
int nd_btt_version(struct nd_btt *nd_btt, struct nd_namespace_common *ndns,
                struct btt_sb *btt_sb);

#endif