/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Simple zone file system for zoned block devices.
 *
 * Copyright (C) 2019 Western Digital Corporation or its affiliates.
 */
#ifndef __ZONEFS_H__
#define __ZONEFS_H__

#include <linux/fs.h>
#include <linux/magic.h>
#include <linux/uuid.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>

/*
 * Maximum length of file names: this only needs to be large enough to fit
 * the zone group directory names and a decimal zone number for file names.
 * 16 characters is plenty.
 */
#define ZONEFS_NAME_MAX         16

/*
 * Zone types: ZONEFS_ZTYPE_SEQ is used for all sequential zone types
 * defined in linux/blkzoned.h, that is, BLK_ZONE_TYPE_SEQWRITE_REQ and
 * BLK_ZONE_TYPE_SEQWRITE_PREF.
 */
enum zonefs_ztype {
        ZONEFS_ZTYPE_CNV,
        ZONEFS_ZTYPE_SEQ,
        ZONEFS_ZTYPE_MAX,
};

static inline enum zonefs_ztype zonefs_zone_type(struct blk_zone *zone)
{
        if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
                return ZONEFS_ZTYPE_CNV;
        return ZONEFS_ZTYPE_SEQ;
}

#define ZONEFS_ZONE_OPEN        (1 << 0)

/*
 * In-memory inode data.
 */
struct zonefs_inode_info {
        struct inode            i_vnode;

        /* File zone type */
        enum zonefs_ztype       i_ztype;

        /* File zone start sector (512B unit) */
        sector_t                i_zsector;

        /* File zone write pointer position (sequential zones only) */
        loff_t                  i_wpoffset;

        /* File maximum size */
        loff_t                  i_max_size;

        /* File zone size */
        loff_t                  i_zone_size;

        /*
         * To serialise fully against both syscall and mmap based IO and
         * sequential file truncation, two locks are used. For serializing
         * zonefs_seq_file_truncate() against zonefs_iomap_begin(), that is,
         * file truncate operations against block mapping, i_truncate_mutex is
         * used. i_truncate_mutex also protects against concurrent accesses
         * and changes to the inode private data, and in particular changes to
         * a sequential file size on completion of direct IO writes.
         * Serialization of mmap read IOs with truncate and syscall IO
         * operations is done with invalidate_lock in addition to
         * i_truncate_mutex.  Only zonefs_seq_file_truncate() takes both lock
         * (invalidate_lock first, i_truncate_mutex second).
         */
        struct mutex            i_truncate_mutex;

        /* guarded by i_truncate_mutex */
        unsigned int            i_wr_refcnt;
        unsigned int            i_flags;
};

static inline struct zonefs_inode_info *ZONEFS_I(struct inode *inode)
{
        return container_of(inode, struct zonefs_inode_info, i_vnode);
}

/*
 * On-disk super block (block 0).
 */
#define ZONEFS_LABEL_LEN        64
#define ZONEFS_UUID_SIZE        16
#define ZONEFS_SUPER_SIZE       4096

struct zonefs_super {

        /* Magic number */
        __le32          s_magic;

        /* Checksum */
        __le32          s_crc;

        /* Volume label */
        char            s_label[ZONEFS_LABEL_LEN];

        /* 128-bit uuid */
        __u8            s_uuid[ZONEFS_UUID_SIZE];

        /* Features */
        __le64          s_features;

        /* UID/GID to use for files */
        __le32          s_uid;
        __le32          s_gid;

        /* File permissions */
        __le32          s_perm;

        /* Padding to ZONEFS_SUPER_SIZE bytes */
        __u8            s_reserved[3988];

} __packed;

/*
 * Feature flags: specified in the s_features field of the on-disk super
 * block struct zonefs_super and in-memory in the s_feartures field of
 * struct zonefs_sb_info.
 */
enum zonefs_features {
        /*
         * Aggregate contiguous conventional zones into a single file.
         */
        ZONEFS_F_AGGRCNV = 1ULL << 0,
        /*
         * Use super block specified UID for files instead of default 0.
         */
        ZONEFS_F_UID = 1ULL << 1,
        /*
         * Use super block specified GID for files instead of default 0.
         */
        ZONEFS_F_GID = 1ULL << 2,
        /*
         * Use super block specified file permissions instead of default 640.
         */
        ZONEFS_F_PERM = 1ULL << 3,
};

#define ZONEFS_F_DEFINED_FEATURES \
        (ZONEFS_F_AGGRCNV | ZONEFS_F_UID | ZONEFS_F_GID | ZONEFS_F_PERM)

/*
 * Mount options for zone write pointer error handling.
 */
#define ZONEFS_MNTOPT_ERRORS_RO         (1 << 0) /* Make zone file readonly */
#define ZONEFS_MNTOPT_ERRORS_ZRO        (1 << 1) /* Make zone file offline */
#define ZONEFS_MNTOPT_ERRORS_ZOL        (1 << 2) /* Make zone file offline */
#define ZONEFS_MNTOPT_ERRORS_REPAIR     (1 << 3) /* Remount read-only */
#define ZONEFS_MNTOPT_ERRORS_MASK       \
        (ZONEFS_MNTOPT_ERRORS_RO | ZONEFS_MNTOPT_ERRORS_ZRO | \
         ZONEFS_MNTOPT_ERRORS_ZOL | ZONEFS_MNTOPT_ERRORS_REPAIR)
#define ZONEFS_MNTOPT_EXPLICIT_OPEN     (1 << 4) /* Explicit open/close of zones on open/close */

/*
 * In-memory Super block information.
 */
struct zonefs_sb_info {

        unsigned long           s_mount_opts;

        spinlock_t              s_lock;

        unsigned long long      s_features;
        kuid_t                  s_uid;
        kgid_t                  s_gid;
        umode_t                 s_perm;
        uuid_t                  s_uuid;
        unsigned int            s_zone_sectors_shift;

        unsigned int            s_nr_files[ZONEFS_ZTYPE_MAX];

        loff_t                  s_blocks;
        loff_t                  s_used_blocks;

        unsigned int            s_max_open_zones;
        atomic_t                s_open_zones;
};

static inline struct zonefs_sb_info *ZONEFS_SB(struct super_block *sb)
{
        return sb->s_fs_info;
}

#define zonefs_info(sb, format, args...)        \
        pr_info("zonefs (%s): " format, sb->s_id, ## args)
#define zonefs_err(sb, format, args...)         \
        pr_err("zonefs (%s) ERROR: " format, sb->s_id, ## args)
#define zonefs_warn(sb, format, args...)        \
        pr_warn("zonefs (%s) WARNING: " format, sb->s_id, ## args)

#endif