/* 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>
#include <linux/kobject.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_INIT_MODE   (1U << 0)
#define ZONEFS_ZONE_OPEN        (1U << 1)
#define ZONEFS_ZONE_ACTIVE      (1U << 2)
#define ZONEFS_ZONE_OFFLINE     (1U << 3)
#define ZONEFS_ZONE_READONLY    (1U << 4)
#define ZONEFS_ZONE_CNV         (1U << 31)

/*
 * In-memory per-file inode zone data.
 */
struct zonefs_zone {
        /* Zone state flags */
        unsigned int            z_flags;

        /* Zone start sector (512B unit) */
        sector_t                z_sector;

        /* Zone size (bytes) */
        loff_t                  z_size;

        /* Zone capacity (file maximum size, bytes) */
        loff_t                  z_capacity;

        /* Write pointer offset in the zone (sequential zones only, bytes) */
        loff_t                  z_wpoffset;

        /* Saved inode uid, gid and access rights */
        umode_t                 z_mode;
        kuid_t                  z_uid;
        kgid_t                  z_gid;
};

/*
 * In memory zone group information: all zones of a group are exposed
 * as files, one file per zone.
 */
struct zonefs_zone_group {
        struct inode            *g_inode;
        unsigned int            g_nr_zones;
        struct zonefs_zone      *g_zones;
};

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

        /*
         * 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;
};

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

static inline bool zonefs_zone_is_cnv(struct zonefs_zone *z)
{
        return z->z_flags & ZONEFS_ZONE_CNV;
}

static inline bool zonefs_zone_is_seq(struct zonefs_zone *z)
{
        return !zonefs_zone_is_cnv(z);
}

static inline struct zonefs_zone *zonefs_inode_zone(struct inode *inode)
{
        return inode->i_private;
}

static inline bool zonefs_inode_is_cnv(struct inode *inode)
{
        return zonefs_zone_is_cnv(zonefs_inode_zone(inode));
}

static inline bool zonefs_inode_is_seq(struct inode *inode)
{
        return zonefs_zone_is_seq(zonefs_inode_zone(inode));
}

/*
 * 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;

        struct zonefs_zone_group s_zgroup[ZONEFS_ZTYPE_MAX];

        loff_t                  s_blocks;
        loff_t                  s_used_blocks;

        unsigned int            s_max_wro_seq_files;
        atomic_t                s_wro_seq_files;

        unsigned int            s_max_active_seq_files;
        atomic_t                s_active_seq_files;

        bool                    s_sysfs_registered;
        struct kobject          s_kobj;
        struct completion       s_kobj_unregister;
};

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)

/* In super.c */
void zonefs_inode_account_active(struct inode *inode);
int zonefs_inode_zone_mgmt(struct inode *inode, enum req_op op);
void zonefs_i_size_write(struct inode *inode, loff_t isize);
void zonefs_update_stats(struct inode *inode, loff_t new_isize);
void __zonefs_io_error(struct inode *inode, bool write);

static inline void zonefs_io_error(struct inode *inode, bool write)
{
        struct zonefs_inode_info *zi = ZONEFS_I(inode);

        mutex_lock(&zi->i_truncate_mutex);
        __zonefs_io_error(inode, write);
        mutex_unlock(&zi->i_truncate_mutex);
}

/* In super.c */
extern const struct inode_operations zonefs_dir_inode_operations;
extern const struct file_operations zonefs_dir_operations;

/* In file.c */
extern const struct address_space_operations zonefs_file_aops;
extern const struct file_operations zonefs_file_operations;
int zonefs_file_truncate(struct inode *inode, loff_t isize);

/* In sysfs.c */
int zonefs_sysfs_register(struct super_block *sb);
void zonefs_sysfs_unregister(struct super_block *sb);
int zonefs_sysfs_init(void);
void zonefs_sysfs_exit(void);

#endif