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root/include/linux/device-mapper.h

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INCLUDED FROM


DEFINITIONS

This source file includes following definitions.
  1. to_sector
  2. to_bytes

/*
 * Copyright (C) 2001 Sistina Software (UK) Limited.
 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the LGPL.
 */

#ifndef _LINUX_DEVICE_MAPPER_H
#define _LINUX_DEVICE_MAPPER_H

#include <linux/bio.h>
#include <linux/blkdev.h>

struct dm_target;
struct dm_table;
struct mapped_device;
struct bio_vec;

typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;

union map_info {
        void *ptr;
        unsigned long long ll;
};

/*
 * In the constructor the target parameter will already have the
 * table, type, begin and len fields filled in.
 */
typedef int (*dm_ctr_fn) (struct dm_target *target,
                          unsigned int argc, char **argv);

/*
 * The destructor doesn't need to free the dm_target, just
 * anything hidden ti->private.
 */
typedef void (*dm_dtr_fn) (struct dm_target *ti);

/*
 * The map function must return:
 * < 0: error
 * = 0: The target will handle the io by resubmitting it later
 * = 1: simple remap complete
 * = 2: The target wants to push back the io
 */
typedef int (*dm_map_fn) (struct dm_target *ti, struct bio *bio,
                          union map_info *map_context);

/*
 * Returns:
 * < 0 : error (currently ignored)
 * 0   : ended successfully
 * 1   : for some reason the io has still not completed (eg,
 *       multipath target might want to requeue a failed io).
 * 2   : The target wants to push back the io
 */
typedef int (*dm_endio_fn) (struct dm_target *ti,
                            struct bio *bio, int error,
                            union map_info *map_context);

typedef void (*dm_flush_fn) (struct dm_target *ti);
typedef void (*dm_presuspend_fn) (struct dm_target *ti);
typedef void (*dm_postsuspend_fn) (struct dm_target *ti);
typedef int (*dm_preresume_fn) (struct dm_target *ti);
typedef void (*dm_resume_fn) (struct dm_target *ti);

typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
                             char *result, unsigned int maxlen);

typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);

typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
                            struct file *filp, unsigned int cmd,
                            unsigned long arg);

typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
                            struct bio_vec *biovec, int max_size);

void dm_error(const char *message);

/*
 * Combine device limits.
 */
void dm_set_device_limits(struct dm_target *ti, struct block_device *bdev);

struct dm_dev {
        struct block_device *bdev;
        int mode;
        char name[16];
};

/*
 * Constructors should call these functions to ensure destination devices
 * are opened/closed correctly.
 * FIXME: too many arguments.
 */
int dm_get_device(struct dm_target *ti, const char *path, sector_t start,
                  sector_t len, int mode, struct dm_dev **result);
void dm_put_device(struct dm_target *ti, struct dm_dev *d);

/*
 * Information about a target type
 */
struct target_type {
        const char *name;
        struct module *module;
        unsigned version[3];
        dm_ctr_fn ctr;
        dm_dtr_fn dtr;
        dm_map_fn map;
        dm_endio_fn end_io;
        dm_flush_fn flush;
        dm_presuspend_fn presuspend;
        dm_postsuspend_fn postsuspend;
        dm_preresume_fn preresume;
        dm_resume_fn resume;
        dm_status_fn status;
        dm_message_fn message;
        dm_ioctl_fn ioctl;
        dm_merge_fn merge;
};

struct io_restrictions {
        unsigned long bounce_pfn;
        unsigned long seg_boundary_mask;
        unsigned max_hw_sectors;
        unsigned max_sectors;
        unsigned max_segment_size;
        unsigned short hardsect_size;
        unsigned short max_hw_segments;
        unsigned short max_phys_segments;
        unsigned char no_cluster; /* inverted so that 0 is default */
};

struct dm_target {
        struct dm_table *table;
        struct target_type *type;

        /* target limits */
        sector_t begin;
        sector_t len;

        /* FIXME: turn this into a mask, and merge with io_restrictions */
        /* Always a power of 2 */
        sector_t split_io;

        /*
         * These are automatically filled in by
         * dm_table_get_device.
         */
        struct io_restrictions limits;

        /* target specific data */
        void *private;

        /* Used to provide an error string from the ctr */
        char *error;
};

int dm_register_target(struct target_type *t);
int dm_unregister_target(struct target_type *t);


/*-----------------------------------------------------------------
 * Functions for creating and manipulating mapped devices.
 * Drop the reference with dm_put when you finish with the object.
 *---------------------------------------------------------------*/

/*
 * DM_ANY_MINOR chooses the next available minor number.
 */
#define DM_ANY_MINOR (-1)
int dm_create(int minor, struct mapped_device **md);

/*
 * Reference counting for md.
 */
struct mapped_device *dm_get_md(dev_t dev);
void dm_get(struct mapped_device *md);
void dm_put(struct mapped_device *md);

/*
 * An arbitrary pointer may be stored alongside a mapped device.
 */
void dm_set_mdptr(struct mapped_device *md, void *ptr);
void *dm_get_mdptr(struct mapped_device *md);

/*
 * A device can still be used while suspended, but I/O is deferred.
 */
int dm_suspend(struct mapped_device *md, unsigned suspend_flags);
int dm_resume(struct mapped_device *md);

/*
 * Event functions.
 */
uint32_t dm_get_event_nr(struct mapped_device *md);
int dm_wait_event(struct mapped_device *md, int event_nr);
uint32_t dm_next_uevent_seq(struct mapped_device *md);
void dm_uevent_add(struct mapped_device *md, struct list_head *elist);

/*
 * Info functions.
 */
const char *dm_device_name(struct mapped_device *md);
int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid);
struct gendisk *dm_disk(struct mapped_device *md);
int dm_suspended(struct mapped_device *md);
int dm_noflush_suspending(struct dm_target *ti);
union map_info *dm_get_mapinfo(struct bio *bio);

/*
 * Geometry functions.
 */
int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo);
int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo);


/*-----------------------------------------------------------------
 * Functions for manipulating device-mapper tables.
 *---------------------------------------------------------------*/

/*
 * First create an empty table.
 */
int dm_table_create(struct dm_table **result, int mode,
                    unsigned num_targets, struct mapped_device *md);

/*
 * Then call this once for each target.
 */
int dm_table_add_target(struct dm_table *t, const char *type,
                        sector_t start, sector_t len, char *params);

/*
 * Finally call this to make the table ready for use.
 */
int dm_table_complete(struct dm_table *t);

/*
 * Unplug all devices in a table.
 */
void dm_table_unplug_all(struct dm_table *t);

/*
 * Table reference counting.
 */
struct dm_table *dm_get_table(struct mapped_device *md);
void dm_table_get(struct dm_table *t);
void dm_table_put(struct dm_table *t);

/*
 * Queries
 */
sector_t dm_table_get_size(struct dm_table *t);
unsigned int dm_table_get_num_targets(struct dm_table *t);
int dm_table_get_mode(struct dm_table *t);
struct mapped_device *dm_table_get_md(struct dm_table *t);

/*
 * Trigger an event.
 */
void dm_table_event(struct dm_table *t);

/*
 * The device must be suspended before calling this method.
 */
int dm_swap_table(struct mapped_device *md, struct dm_table *t);

/*
 * A wrapper around vmalloc.
 */
void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);

/*-----------------------------------------------------------------
 * Macros.
 *---------------------------------------------------------------*/
#define DM_NAME "device-mapper"

#define DMERR(f, arg...) \
        printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
#define DMERR_LIMIT(f, arg...) \
        do { \
                if (printk_ratelimit()) \
                        printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
                               f "\n", ## arg); \
        } while (0)

#define DMWARN(f, arg...) \
        printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
#define DMWARN_LIMIT(f, arg...) \
        do { \
                if (printk_ratelimit()) \
                        printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
                               f "\n", ## arg); \
        } while (0)

#define DMINFO(f, arg...) \
        printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
#define DMINFO_LIMIT(f, arg...) \
        do { \
                if (printk_ratelimit()) \
                        printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
                               "\n", ## arg); \
        } while (0)

#ifdef CONFIG_DM_DEBUG
#  define DMDEBUG(f, arg...) \
        printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
#  define DMDEBUG_LIMIT(f, arg...) \
        do { \
                if (printk_ratelimit()) \
                        printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
                               "\n", ## arg); \
        } while (0)
#else
#  define DMDEBUG(f, arg...) do {} while (0)
#  define DMDEBUG_LIMIT(f, arg...) do {} while (0)
#endif

#define DMEMIT(x...) sz += ((sz >= maxlen) ? \
                          0 : scnprintf(result + sz, maxlen - sz, x))

#define SECTOR_SHIFT 9

/*
 * Definitions of return values from target end_io function.
 */
#define DM_ENDIO_INCOMPLETE     1
#define DM_ENDIO_REQUEUE        2

/*
 * Definitions of return values from target map function.
 */
#define DM_MAPIO_SUBMITTED      0
#define DM_MAPIO_REMAPPED       1
#define DM_MAPIO_REQUEUE        DM_ENDIO_REQUEUE

/*
 * Ceiling(n / sz)
 */
#define dm_div_up(n, sz) (((n) + (sz) - 1) / (sz))

#define dm_sector_div_up(n, sz) ( \
{ \
        sector_t _r = ((n) + (sz) - 1); \
        sector_div(_r, (sz)); \
        _r; \
} \
)

/*
 * ceiling(n / size) * size
 */
#define dm_round_up(n, sz) (dm_div_up((n), (sz)) * (sz))

static inline sector_t to_sector(unsigned long n)
{
        return (n >> SECTOR_SHIFT);
}

static inline unsigned long to_bytes(sector_t n)
{
        return (n << SECTOR_SHIFT);
}

#endif  /* _LINUX_DEVICE_MAPPER_H */

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