#ifndef _LINUX_GENHD_H
#define _LINUX_GENHD_H

/*
 *      genhd.h Copyright (C) 1992 Drew Eckhardt
 *      Generic hard disk header file by  
 *              Drew Eckhardt
 *
 *              <drew@colorado.edu>
 */

#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/rcupdate.h>
#include <linux/slab.h>

#ifdef CONFIG_BLOCK

#define dev_to_disk(device)     container_of((device), struct gendisk, part0.__dev)
#define dev_to_part(device)     container_of((device), struct hd_struct, __dev)
#define disk_to_dev(disk)       (&(disk)->part0.__dev)
#define part_to_dev(part)       (&((part)->__dev))

extern struct device_type part_type;
extern struct kobject *block_depr;
extern struct class block_class;

enum {
/* These three have identical behaviour; use the second one if DOS FDISK gets
   confused about extended/logical partitions starting past cylinder 1023. */
        DOS_EXTENDED_PARTITION = 5,
        LINUX_EXTENDED_PARTITION = 0x85,
        WIN98_EXTENDED_PARTITION = 0x0f,

        SUN_WHOLE_DISK = DOS_EXTENDED_PARTITION,

        LINUX_SWAP_PARTITION = 0x82,
        LINUX_DATA_PARTITION = 0x83,
        LINUX_LVM_PARTITION = 0x8e,
        LINUX_RAID_PARTITION = 0xfd,    /* autodetect RAID partition */

        SOLARIS_X86_PARTITION = LINUX_SWAP_PARTITION,
        NEW_SOLARIS_X86_PARTITION = 0xbf,

        DM6_AUX1PARTITION = 0x51,       /* no DDO:  use xlated geom */
        DM6_AUX3PARTITION = 0x53,       /* no DDO:  use xlated geom */
        DM6_PARTITION = 0x54,           /* has DDO: use xlated geom & offset */
        EZD_PARTITION = 0x55,           /* EZ-DRIVE */

        FREEBSD_PARTITION = 0xa5,       /* FreeBSD Partition ID */
        OPENBSD_PARTITION = 0xa6,       /* OpenBSD Partition ID */
        NETBSD_PARTITION = 0xa9,        /* NetBSD Partition ID */
        BSDI_PARTITION = 0xb7,          /* BSDI Partition ID */
        MINIX_PARTITION = 0x81,         /* Minix Partition ID */
        UNIXWARE_PARTITION = 0x63,      /* Same as GNU_HURD and SCO Unix */
};

#define DISK_MAX_PARTS                  256
#define DISK_NAME_LEN                   32

#include <linux/major.h>
#include <linux/device.h>
#include <linux/smp.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/workqueue.h>

struct partition {
        unsigned char boot_ind;         /* 0x80 - active */
        unsigned char head;             /* starting head */
        unsigned char sector;           /* starting sector */
        unsigned char cyl;              /* starting cylinder */
        unsigned char sys_ind;          /* What partition type */
        unsigned char end_head;         /* end head */
        unsigned char end_sector;       /* end sector */
        unsigned char end_cyl;          /* end cylinder */
        __le32 start_sect;      /* starting sector counting from 0 */
        __le32 nr_sects;                /* nr of sectors in partition */
} __attribute__((packed));

struct disk_stats {
        unsigned long sectors[2];       /* READs and WRITEs */
        unsigned long ios[2];
        unsigned long merges[2];
        unsigned long ticks[2];
        unsigned long io_ticks;
        unsigned long time_in_queue;
};

#define PARTITION_META_INFO_VOLNAMELTH  64
/*
 * Enough for the string representation of any kind of UUID plus NULL.
 * EFI UUID is 36 characters. MSDOS UUID is 11 characters.
 */
#define PARTITION_META_INFO_UUIDLTH     37

struct partition_meta_info {
        char uuid[PARTITION_META_INFO_UUIDLTH];
        u8 volname[PARTITION_META_INFO_VOLNAMELTH];
};

struct hd_struct {
        sector_t start_sect;
        /*
         * nr_sects is protected by sequence counter. One might extend a
         * partition while IO is happening to it and update of nr_sects
         * can be non-atomic on 32bit machines with 64bit sector_t.
         */
        sector_t nr_sects;
        seqcount_t nr_sects_seq;
        sector_t alignment_offset;
        unsigned int discard_alignment;
        struct device __dev;
        struct kobject *holder_dir;
        int policy, partno;
        struct partition_meta_info *info;
#ifdef CONFIG_FAIL_MAKE_REQUEST
        int make_it_fail;
#endif
        unsigned long stamp;
        atomic_t in_flight[2];
#ifdef  CONFIG_SMP
        struct disk_stats __percpu *dkstats;
#else
        struct disk_stats dkstats;
#endif
        atomic_t ref;
        struct rcu_head rcu_head;
};

#define GENHD_FL_REMOVABLE                      1
/* 2 is unused */
#define GENHD_FL_MEDIA_CHANGE_NOTIFY            4
#define GENHD_FL_CD                             8
#define GENHD_FL_UP                             16
#define GENHD_FL_SUPPRESS_PARTITION_INFO        32
#define GENHD_FL_EXT_DEVT                       64 /* allow extended devt */
#define GENHD_FL_NATIVE_CAPACITY                128
#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE     256
#define GENHD_FL_NO_PART_SCAN                   512

enum {
        DISK_EVENT_MEDIA_CHANGE                 = 1 << 0, /* media changed */
        DISK_EVENT_EJECT_REQUEST                = 1 << 1, /* eject requested */
};

#define BLK_SCSI_MAX_CMDS       (256)
#define BLK_SCSI_CMD_PER_LONG   (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))

struct blk_scsi_cmd_filter {
        unsigned long read_ok[BLK_SCSI_CMD_PER_LONG];
        unsigned long write_ok[BLK_SCSI_CMD_PER_LONG];
        struct kobject kobj;
};

struct disk_part_tbl {
        struct rcu_head rcu_head;
        int len;
        struct hd_struct __rcu *last_lookup;
        struct hd_struct __rcu *part[];
};

struct disk_events;
struct badblocks;

struct gendisk {
        /* major, first_minor and minors are input parameters only,
         * don't use directly.  Use disk_devt() and disk_max_parts().
         */
        int major;                      /* major number of driver */
        int first_minor;
        int minors;                     /* maximum number of minors, =1 for
                                         * disks that can't be partitioned. */

        char disk_name[DISK_NAME_LEN];  /* name of major driver */
        char *(*devnode)(struct gendisk *gd, umode_t *mode);

        unsigned int events;            /* supported events */
        unsigned int async_events;      /* async events, subset of all */

        /* Array of pointers to partitions indexed by partno.
         * Protected with matching bdev lock but stat and other
         * non-critical accesses use RCU.  Always access through
         * helpers.
         */
        struct disk_part_tbl __rcu *part_tbl;
        struct hd_struct part0;

        const struct block_device_operations *fops;
        struct request_queue *queue;
        void *private_data;

        int flags;
        struct device *driverfs_dev;  // FIXME: remove
        struct kobject *slave_dir;

        struct timer_rand_state *random;
        atomic_t sync_io;               /* RAID */
        struct disk_events *ev;
#ifdef  CONFIG_BLK_DEV_INTEGRITY
        struct blk_integrity *integrity;
#endif
        int node_id;
        RH_KABI_EXTEND(struct badblocks *bb)
};

static inline struct gendisk *part_to_disk(struct hd_struct *part)
{
        if (likely(part)) {
                if (part->partno)
                        return dev_to_disk(part_to_dev(part)->parent);
                else
                        return dev_to_disk(part_to_dev(part));
        }
        return NULL;
}

static inline void part_pack_uuid(const u8 *uuid_str, u8 *to)
{
        int i;
        for (i = 0; i < 16; ++i) {
                *to++ = (hex_to_bin(*uuid_str) << 4) |
                        (hex_to_bin(*(uuid_str + 1)));
                uuid_str += 2;
                switch (i) {
                case 3:
                case 5:
                case 7:
                case 9:
                        uuid_str++;
                        continue;
                }
        }
}

static inline int blk_part_pack_uuid(const u8 *uuid_str, u8 *to)
{
        part_pack_uuid(uuid_str, to);
        return 0;
}

static inline int disk_max_parts(struct gendisk *disk)
{
        if (disk->flags & GENHD_FL_EXT_DEVT)
                return DISK_MAX_PARTS;
        return disk->minors;
}

static inline bool disk_part_scan_enabled(struct gendisk *disk)
{
        return disk_max_parts(disk) > 1 &&
                !(disk->flags & GENHD_FL_NO_PART_SCAN);
}

static inline dev_t disk_devt(struct gendisk *disk)
{
        return disk_to_dev(disk)->devt;
}

static inline dev_t part_devt(struct hd_struct *part)
{
        return part_to_dev(part)->devt;
}

extern struct hd_struct *disk_get_part(struct gendisk *disk, int partno);

static inline void disk_put_part(struct hd_struct *part)
{
        if (likely(part))
                put_device(part_to_dev(part));
}

/*
 * Smarter partition iterator without context limits.
 */
#define DISK_PITER_REVERSE      (1 << 0) /* iterate in the reverse direction */
#define DISK_PITER_INCL_EMPTY   (1 << 1) /* include 0-sized parts */
#define DISK_PITER_INCL_PART0   (1 << 2) /* include partition 0 */
#define DISK_PITER_INCL_EMPTY_PART0 (1 << 3) /* include empty partition 0 */

struct disk_part_iter {
        struct gendisk          *disk;
        struct hd_struct        *part;
        int                     idx;
        unsigned int            flags;
};

extern void disk_part_iter_init(struct disk_part_iter *piter,
                                 struct gendisk *disk, unsigned int flags);
extern struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter);
extern void disk_part_iter_exit(struct disk_part_iter *piter);

extern struct hd_struct *disk_map_sector_rcu(struct gendisk *disk,
                                             sector_t sector);

/*
 * Macros to operate on percpu disk statistics:
 *
 * {disk|part|all}_stat_{add|sub|inc|dec}() modify the stat counters
 * and should be called between disk_stat_lock() and
 * disk_stat_unlock().
 *
 * part_stat_read() can be called at any time.
 *
 * part_stat_{add|set_all}() and {init|free}_part_stats are for
 * internal use only.
 */
#ifdef  CONFIG_SMP
#define part_stat_lock()        ({ rcu_read_lock(); get_cpu(); })
#define part_stat_unlock()      do { put_cpu(); rcu_read_unlock(); } while (0)

#define __part_stat_add(cpu, part, field, addnd)                        \
        (per_cpu_ptr((part)->dkstats, (cpu))->field += (addnd))

#define part_stat_read(part, field)                                     \
({                                                                      \
        typeof((part)->dkstats->field) res = 0;                         \
        unsigned int _cpu;                                              \
        for_each_possible_cpu(_cpu)                                     \
                res += per_cpu_ptr((part)->dkstats, _cpu)->field;       \
        res;                                                            \
})

static inline void part_stat_set_all(struct hd_struct *part, int value)
{
        int i;

        for_each_possible_cpu(i)
                memset(per_cpu_ptr(part->dkstats, i), value,
                                sizeof(struct disk_stats));
}

static inline int init_part_stats(struct hd_struct *part)
{
        part->dkstats = alloc_percpu(struct disk_stats);
        if (!part->dkstats)
                return 0;
        return 1;
}

static inline void free_part_stats(struct hd_struct *part)
{
        free_percpu(part->dkstats);
}

#else /* !CONFIG_SMP */
#define part_stat_lock()        ({ rcu_read_lock(); 0; })
#define part_stat_unlock()      rcu_read_unlock()

#define __part_stat_add(cpu, part, field, addnd)                                \
        ((part)->dkstats.field += addnd)

#define part_stat_read(part, field)     ((part)->dkstats.field)

static inline void part_stat_set_all(struct hd_struct *part, int value)
{
        memset(&part->dkstats, value, sizeof(struct disk_stats));
}

static inline int init_part_stats(struct hd_struct *part)
{
        return 1;
}

static inline void free_part_stats(struct hd_struct *part)
{
}

#endif /* CONFIG_SMP */

#define part_stat_add(cpu, part, field, addnd)  do {                    \
        __part_stat_add((cpu), (part), field, addnd);                   \
        if ((part)->partno)                                             \
                __part_stat_add((cpu), &part_to_disk((part))->part0,    \
                                field, addnd);                          \
} while (0)

#define part_stat_dec(cpu, gendiskp, field)                             \
        part_stat_add(cpu, gendiskp, field, -1)
#define part_stat_inc(cpu, gendiskp, field)                             \
        part_stat_add(cpu, gendiskp, field, 1)
#define part_stat_sub(cpu, gendiskp, field, subnd)                      \
        part_stat_add(cpu, gendiskp, field, -subnd)

static inline void part_inc_in_flight(struct hd_struct *part, int rw)
{
        atomic_inc(&part->in_flight[rw]);
        if (part->partno)
                atomic_inc(&part_to_disk(part)->part0.in_flight[rw]);
}

static inline void part_dec_in_flight(struct hd_struct *part, int rw)
{
        atomic_dec(&part->in_flight[rw]);
        if (part->partno)
                atomic_dec(&part_to_disk(part)->part0.in_flight[rw]);
}

static inline int part_in_flight(struct hd_struct *part)
{
        return atomic_read(&part->in_flight[0]) + atomic_read(&part->in_flight[1]);
}

static inline struct partition_meta_info *alloc_part_info(struct gendisk *disk)
{
        if (disk)
                return kzalloc_node(sizeof(struct partition_meta_info),
                                    GFP_KERNEL, disk->node_id);
        return kzalloc(sizeof(struct partition_meta_info), GFP_KERNEL);
}

static inline void free_part_info(struct hd_struct *part)
{
        kfree(part->info);
}

/* block/blk-core.c */
extern void part_round_stats(int cpu, struct hd_struct *part);

/* block/genhd.c */
extern void add_disk(struct gendisk *disk);
extern void del_gendisk(struct gendisk *gp);
extern struct gendisk *get_gendisk(dev_t dev, int *partno);
extern struct block_device *bdget_disk(struct gendisk *disk, int partno);

extern void set_device_ro(struct block_device *bdev, int flag);
extern void set_disk_ro(struct gendisk *disk, int flag);

static inline int get_disk_ro(struct gendisk *disk)
{
        return disk->part0.policy;
}

extern void disk_block_events(struct gendisk *disk);
extern void disk_unblock_events(struct gendisk *disk);
extern void disk_flush_events(struct gendisk *disk, unsigned int mask);
extern unsigned int disk_clear_events(struct gendisk *disk, unsigned int mask);

/* drivers/char/random.c */
extern void add_disk_randomness(struct gendisk *disk);
extern void rand_initialize_disk(struct gendisk *disk);

static inline sector_t get_start_sect(struct block_device *bdev)
{
        return bdev->bd_part->start_sect;
}
static inline sector_t get_capacity(struct gendisk *disk)
{
        return disk->part0.nr_sects;
}
static inline void set_capacity(struct gendisk *disk, sector_t size)
{
        disk->part0.nr_sects = size;
}

#ifdef CONFIG_SOLARIS_X86_PARTITION

#define SOLARIS_X86_NUMSLICE    16
#define SOLARIS_X86_VTOC_SANE   (0x600DDEEEUL)

struct solaris_x86_slice {
        __le16 s_tag;           /* ID tag of partition */
        __le16 s_flag;          /* permission flags */
        __le32 s_start;         /* start sector no of partition */
        __le32 s_size;          /* # of blocks in partition */
};

struct solaris_x86_vtoc {
        unsigned int v_bootinfo[3];     /* info needed by mboot (unsupported) */
        __le32 v_sanity;                /* to verify vtoc sanity */
        __le32 v_version;               /* layout version */
        char    v_volume[8];            /* volume name */
        __le16  v_sectorsz;             /* sector size in bytes */
        __le16  v_nparts;               /* number of partitions */
        unsigned int v_reserved[10];    /* free space */
        struct solaris_x86_slice
                v_slice[SOLARIS_X86_NUMSLICE]; /* slice headers */
        unsigned int timestamp[SOLARIS_X86_NUMSLICE]; /* timestamp (unsupported) */
        char    v_asciilabel[128];      /* for compatibility */
};

#endif /* CONFIG_SOLARIS_X86_PARTITION */

#ifdef CONFIG_BSD_DISKLABEL
/*
 * BSD disklabel support by Yossi Gottlieb <yogo@math.tau.ac.il>
 * updated by Marc Espie <Marc.Espie@openbsd.org>
 */

/* check against BSD src/sys/sys/disklabel.h for consistency */

#define BSD_DISKMAGIC   (0x82564557UL)  /* The disk magic number */
#define BSD_MAXPARTITIONS       16
#define OPENBSD_MAXPARTITIONS   16
#define BSD_FS_UNUSED           0       /* disklabel unused partition entry ID */
struct bsd_disklabel {
        __le32  d_magic;                /* the magic number */
        __s16   d_type;                 /* drive type */
        __s16   d_subtype;              /* controller/d_type specific */
        char    d_typename[16];         /* type name, e.g. "eagle" */
        char    d_packname[16];                 /* pack identifier */ 
        __u32   d_secsize;              /* # of bytes per sector */
        __u32   d_nsectors;             /* # of data sectors per track */
        __u32   d_ntracks;              /* # of tracks per cylinder */
        __u32   d_ncylinders;           /* # of data cylinders per unit */
        __u32   d_secpercyl;            /* # of data sectors per cylinder */
        __u32   d_secperunit;           /* # of data sectors per unit */
        __u16   d_sparespertrack;       /* # of spare sectors per track */
        __u16   d_sparespercyl;         /* # of spare sectors per cylinder */
        __u32   d_acylinders;           /* # of alt. cylinders per unit */
        __u16   d_rpm;                  /* rotational speed */
        __u16   d_interleave;           /* hardware sector interleave */
        __u16   d_trackskew;            /* sector 0 skew, per track */
        __u16   d_cylskew;              /* sector 0 skew, per cylinder */
        __u32   d_headswitch;           /* head switch time, usec */
        __u32   d_trkseek;              /* track-to-track seek, usec */
        __u32   d_flags;                /* generic flags */
#define NDDATA 5
        __u32   d_drivedata[NDDATA];    /* drive-type specific information */
#define NSPARE 5
        __u32   d_spare[NSPARE];        /* reserved for future use */
        __le32  d_magic2;               /* the magic number (again) */
        __le16  d_checksum;             /* xor of data incl. partitions */

                        /* filesystem and partition information: */
        __le16  d_npartitions;          /* number of partitions in following */
        __le32  d_bbsize;               /* size of boot area at sn0, bytes */
        __le32  d_sbsize;               /* max size of fs superblock, bytes */
        struct  bsd_partition {         /* the partition table */
                __le32  p_size;         /* number of sectors in partition */
                __le32  p_offset;       /* starting sector */
                __le32  p_fsize;        /* filesystem basic fragment size */
                __u8    p_fstype;       /* filesystem type, see below */
                __u8    p_frag;         /* filesystem fragments per block */
                __le16  p_cpg;          /* filesystem cylinders per group */
        } d_partitions[BSD_MAXPARTITIONS];      /* actually may be more */
};

#endif  /* CONFIG_BSD_DISKLABEL */

#ifdef CONFIG_UNIXWARE_DISKLABEL
/*
 * Unixware slices support by Andrzej Krzysztofowicz <ankry@mif.pg.gda.pl>
 * and Krzysztof G. Baranowski <kgb@knm.org.pl>
 */

#define UNIXWARE_DISKMAGIC     (0xCA5E600DUL)   /* The disk magic number */
#define UNIXWARE_DISKMAGIC2    (0x600DDEEEUL)   /* The slice table magic nr */
#define UNIXWARE_NUMSLICE      16
#define UNIXWARE_FS_UNUSED     0                /* Unused slice entry ID */

struct unixware_slice {
        __le16   s_label;       /* label */
        __le16   s_flags;       /* permission flags */
        __le32   start_sect;    /* starting sector */
        __le32   nr_sects;      /* number of sectors in slice */
};

struct unixware_disklabel {
        __le32   d_type;                /* drive type */
        __le32   d_magic;                /* the magic number */
        __le32   d_version;              /* version number */
        char    d_serial[12];           /* serial number of the device */
        __le32   d_ncylinders;           /* # of data cylinders per device */
        __le32   d_ntracks;              /* # of tracks per cylinder */
        __le32   d_nsectors;             /* # of data sectors per track */
        __le32   d_secsize;              /* # of bytes per sector */
        __le32   d_part_start;           /* # of first sector of this partition */
        __le32   d_unknown1[12];         /* ? */
        __le32  d_alt_tbl;              /* byte offset of alternate table */
        __le32  d_alt_len;              /* byte length of alternate table */
        __le32  d_phys_cyl;             /* # of physical cylinders per device */
        __le32  d_phys_trk;             /* # of physical tracks per cylinder */
        __le32  d_phys_sec;             /* # of physical sectors per track */
        __le32  d_phys_bytes;           /* # of physical bytes per sector */
        __le32  d_unknown2;             /* ? */
        __le32   d_unknown3;             /* ? */
        __le32  d_pad[8];               /* pad */

        struct unixware_vtoc {
                __le32  v_magic;                /* the magic number */
                __le32  v_version;              /* version number */
                char    v_name[8];              /* volume name */
                __le16  v_nslices;              /* # of slices */
                __le16  v_unknown1;             /* ? */
                __le32  v_reserved[10];         /* reserved */
                struct unixware_slice
                        v_slice[UNIXWARE_NUMSLICE];     /* slice headers */
        } vtoc;

};  /* 408 */

#endif /* CONFIG_UNIXWARE_DISKLABEL */

#ifdef CONFIG_MINIX_SUBPARTITION
#   define MINIX_NR_SUBPARTITIONS  4
#endif /* CONFIG_MINIX_SUBPARTITION */

#define ADDPART_FLAG_NONE       0
#define ADDPART_FLAG_RAID       1
#define ADDPART_FLAG_WHOLEDISK  2

extern int blk_alloc_devt(struct hd_struct *part, dev_t *devt);
extern void blk_free_devt(dev_t devt);
extern dev_t blk_lookup_devt(const char *name, int partno);
extern char *disk_name (struct gendisk *hd, int partno, char *buf);

extern int disk_expand_part_tbl(struct gendisk *disk, int target);
extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
extern int invalidate_partitions(struct gendisk *disk, struct block_device *bdev);
extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
                                                     int partno, sector_t start,
                                                     sector_t len, int flags,
                                                     struct partition_meta_info
                                                       *info);
extern void __delete_partition(struct hd_struct *);
extern void delete_partition(struct gendisk *, int);
extern void printk_all_partitions(void);

extern struct gendisk *alloc_disk_node(int minors, int node_id);
extern struct gendisk *alloc_disk(int minors);
extern struct kobject *get_disk(struct gendisk *disk);
extern void put_disk(struct gendisk *disk);
extern void blk_register_region(dev_t devt, unsigned long range,
                        struct module *module,
                        struct kobject *(*probe)(dev_t, int *, void *),
                        int (*lock)(dev_t, void *),
                        void *data);
extern void blk_unregister_region(dev_t devt, unsigned long range);

extern ssize_t part_size_show(struct device *dev,
                              struct device_attribute *attr, char *buf);
extern ssize_t part_stat_show(struct device *dev,
                              struct device_attribute *attr, char *buf);
extern ssize_t part_inflight_show(struct device *dev,
                              struct device_attribute *attr, char *buf);
#ifdef CONFIG_FAIL_MAKE_REQUEST
extern ssize_t part_fail_show(struct device *dev,
                              struct device_attribute *attr, char *buf);
extern ssize_t part_fail_store(struct device *dev,
                               struct device_attribute *attr,
                               const char *buf, size_t count);
#endif /* CONFIG_FAIL_MAKE_REQUEST */

static inline void hd_ref_init(struct hd_struct *part)
{
        atomic_set(&part->ref, 1);
        smp_mb();
}

static inline void hd_struct_get(struct hd_struct *part)
{
        atomic_inc(&part->ref);
        smp_mb__after_atomic_inc();
}

static inline int hd_struct_try_get(struct hd_struct *part)
{
        return atomic_inc_not_zero(&part->ref);
}

static inline void hd_struct_put(struct hd_struct *part)
{
        if (atomic_dec_and_test(&part->ref))
                __delete_partition(part);
}

/*
 * Any access of part->nr_sects which is not protected by partition
 * bd_mutex or gendisk bdev bd_mutex, should be done using this
 * accessor function.
 *
 * Code written along the lines of i_size_read() and i_size_write().
 * CONFIG_PREEMPT case optimizes the case of UP kernel with preemption
 * on.
 */
static inline sector_t part_nr_sects_read(struct hd_struct *part)
{
#if BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_SMP)
        sector_t nr_sects;
        unsigned seq;
        do {
                seq = read_seqcount_begin(&part->nr_sects_seq);
                nr_sects = part->nr_sects;
        } while (read_seqcount_retry(&part->nr_sects_seq, seq));
        return nr_sects;
#elif BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_PREEMPT)
        sector_t nr_sects;

        preempt_disable();
        nr_sects = part->nr_sects;
        preempt_enable();
        return nr_sects;
#else
        return part->nr_sects;
#endif
}

/*
 * Should be called with mutex lock held (typically bd_mutex) of partition
 * to provide mutual exlusion among writers otherwise seqcount might be
 * left in wrong state leaving the readers spinning infinitely.
 */
static inline void part_nr_sects_write(struct hd_struct *part, sector_t size)
{
#if BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_SMP)
        write_seqcount_begin(&part->nr_sects_seq);
        part->nr_sects = size;
        write_seqcount_end(&part->nr_sects_seq);
#elif BITS_PER_LONG==32 && defined(CONFIG_LBDAF) && defined(CONFIG_PREEMPT)
        preempt_disable();
        part->nr_sects = size;
        preempt_enable();
#else
        part->nr_sects = size;
#endif
}

#else /* CONFIG_BLOCK */

static inline void printk_all_partitions(void) { }

static inline dev_t blk_lookup_devt(const char *name, int partno)
{
        dev_t devt = MKDEV(0, 0);
        return devt;
}

static inline int blk_part_pack_uuid(const u8 *uuid_str, u8 *to)
{
        return -EINVAL;
}
#endif /* CONFIG_BLOCK */

#endif /* _LINUX_GENHD_H */