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Diffstat (limited to 'include/linux/device-mapper.h')
| -rw-r--r-- | include/linux/device-mapper.h | 608 |
1 files changed, 608 insertions, 0 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h new file mode 100644 index 000000000..51cc1deb7 --- /dev/null +++ b/include/linux/device-mapper.h @@ -0,0 +1,608 @@ +/* + * 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> +#include <linux/math64.h> +#include <linux/ratelimit.h> + +struct dm_dev; +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; +}; + +/* + * 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); +typedef int (*dm_map_request_fn) (struct dm_target *ti, struct request *clone, + union map_info *map_context); +typedef int (*dm_clone_and_map_request_fn) (struct dm_target *ti, + struct request *rq, + union map_info *map_context, + struct request **clone); +typedef void (*dm_release_clone_request_fn) (struct request *clone); + +/* + * 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); +typedef int (*dm_request_endio_fn) (struct dm_target *ti, + struct request *clone, int error, + union map_info *map_context); + +typedef void (*dm_presuspend_fn) (struct dm_target *ti); +typedef void (*dm_presuspend_undo_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 void (*dm_status_fn) (struct dm_target *ti, status_type_t status_type, + unsigned status_flags, char *result, unsigned maxlen); + +typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv); + +typedef int (*dm_ioctl_fn) (struct dm_target *ti, 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); + +/* + * These iteration functions are typically used to check (and combine) + * properties of underlying devices. + * E.g. Does at least one underlying device support flush? + * Does any underlying device not support WRITE_SAME? + * + * The callout function is called once for each contiguous section of + * an underlying device. State can be maintained in *data. + * Return non-zero to stop iterating through any further devices. + */ +typedef int (*iterate_devices_callout_fn) (struct dm_target *ti, + struct dm_dev *dev, + sector_t start, sector_t len, + void *data); + +/* + * This function must iterate through each section of device used by the + * target until it encounters a non-zero return code, which it then returns. + * Returns zero if no callout returned non-zero. + */ +typedef int (*dm_iterate_devices_fn) (struct dm_target *ti, + iterate_devices_callout_fn fn, + void *data); + +typedef void (*dm_io_hints_fn) (struct dm_target *ti, + struct queue_limits *limits); + +/* + * Returns: + * 0: The target can handle the next I/O immediately. + * 1: The target can't handle the next I/O immediately. + */ +typedef int (*dm_busy_fn) (struct dm_target *ti); + +void dm_error(const char *message); + +struct dm_dev { + struct block_device *bdev; + fmode_t mode; + char name[16]; +}; + +/* + * Constructors should call these functions to ensure destination devices + * are opened/closed correctly. + */ +int dm_get_device(struct dm_target *ti, const char *path, fmode_t 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 { + uint64_t features; + const char *name; + struct module *module; + unsigned version[3]; + dm_ctr_fn ctr; + dm_dtr_fn dtr; + dm_map_fn map; + dm_map_request_fn map_rq; + dm_clone_and_map_request_fn clone_and_map_rq; + dm_release_clone_request_fn release_clone_rq; + dm_endio_fn end_io; + dm_request_endio_fn rq_end_io; + dm_presuspend_fn presuspend; + dm_presuspend_undo_fn presuspend_undo; + 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; + dm_busy_fn busy; + dm_iterate_devices_fn iterate_devices; + dm_io_hints_fn io_hints; + + /* For internal device-mapper use. */ + struct list_head list; +}; + +/* + * Target features + */ + +/* + * Any table that contains an instance of this target must have only one. + */ +#define DM_TARGET_SINGLETON 0x00000001 +#define dm_target_needs_singleton(type) ((type)->features & DM_TARGET_SINGLETON) + +/* + * Indicates that a target does not support read-only devices. + */ +#define DM_TARGET_ALWAYS_WRITEABLE 0x00000002 +#define dm_target_always_writeable(type) \ + ((type)->features & DM_TARGET_ALWAYS_WRITEABLE) + +/* + * Any device that contains a table with an instance of this target may never + * have tables containing any different target type. + */ +#define DM_TARGET_IMMUTABLE 0x00000004 +#define dm_target_is_immutable(type) ((type)->features & DM_TARGET_IMMUTABLE) + +/* + * Some targets need to be sent the same WRITE bio severals times so + * that they can send copies of it to different devices. This function + * examines any supplied bio and returns the number of copies of it the + * target requires. + */ +typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio); + +struct dm_target { + struct dm_table *table; + struct target_type *type; + + /* target limits */ + sector_t begin; + sector_t len; + + /* If non-zero, maximum size of I/O submitted to a target. */ + uint32_t max_io_len; + + /* + * A number of zero-length barrier bios that will be submitted + * to the target for the purpose of flushing cache. + * + * The bio number can be accessed with dm_bio_get_target_bio_nr. + * It is a responsibility of the target driver to remap these bios + * to the real underlying devices. + */ + unsigned num_flush_bios; + + /* + * The number of discard bios that will be submitted to the target. + * The bio number can be accessed with dm_bio_get_target_bio_nr. + */ + unsigned num_discard_bios; + + /* + * The number of WRITE SAME bios that will be submitted to the target. + * The bio number can be accessed with dm_bio_get_target_bio_nr. + */ + unsigned num_write_same_bios; + + /* + * The minimum number of extra bytes allocated in each bio for the + * target to use. dm_per_bio_data returns the data location. + */ + unsigned per_bio_data_size; + + /* + * If defined, this function is called to find out how many + * duplicate bios should be sent to the target when writing + * data. + */ + dm_num_write_bios_fn num_write_bios; + + /* target specific data */ + void *private; + + /* Used to provide an error string from the ctr */ + char *error; + + /* + * Set if this target needs to receive flushes regardless of + * whether or not its underlying devices have support. + */ + bool flush_supported:1; + + /* + * Set if this target needs to receive discards regardless of + * whether or not its underlying devices have support. + */ + bool discards_supported:1; + + /* + * Set if the target required discard bios to be split + * on max_io_len boundary. + */ + bool split_discard_bios:1; + + /* + * Set if this target does not return zeroes on discarded blocks. + */ + bool discard_zeroes_data_unsupported:1; +}; + +/* Each target can link one of these into the table */ +struct dm_target_callbacks { + struct list_head list; + int (*congested_fn) (struct dm_target_callbacks *, int); +}; + +/* + * For bio-based dm. + * One of these is allocated for each bio. + * This structure shouldn't be touched directly by target drivers. + * It is here so that we can inline dm_per_bio_data and + * dm_bio_from_per_bio_data + */ +struct dm_target_io { + struct dm_io *io; + struct dm_target *ti; + unsigned target_bio_nr; + unsigned *len_ptr; + struct bio clone; +}; + +static inline void *dm_per_bio_data(struct bio *bio, size_t data_size) +{ + return (char *)bio - offsetof(struct dm_target_io, clone) - data_size; +} + +static inline struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size) +{ + return (struct bio *)((char *)data + data_size + offsetof(struct dm_target_io, clone)); +} + +static inline unsigned dm_bio_get_target_bio_nr(const struct bio *bio) +{ + return container_of(bio, struct dm_target_io, clone)->target_bio_nr; +} + +int dm_register_target(struct target_type *t); +void dm_unregister_target(struct target_type *t); + +/* + * Target argument parsing. + */ +struct dm_arg_set { + unsigned argc; + char **argv; +}; + +/* + * The minimum and maximum value of a numeric argument, together with + * the error message to use if the number is found to be outside that range. + */ +struct dm_arg { + unsigned min; + unsigned max; + char *error; +}; + +/* + * Validate the next argument, either returning it as *value or, if invalid, + * returning -EINVAL and setting *error. + */ +int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set, + unsigned *value, char **error); + +/* + * Process the next argument as the start of a group containing between + * arg->min and arg->max further arguments. Either return the size as + * *num_args or, if invalid, return -EINVAL and set *error. + */ +int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set, + unsigned *num_args, char **error); + +/* + * Return the current argument and shift to the next. + */ +const char *dm_shift_arg(struct dm_arg_set *as); + +/* + * Move through num_args arguments. + */ +void dm_consume_args(struct dm_arg_set *as, unsigned num_args); + +/*----------------------------------------------------------------- + * 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); +int dm_hold(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 dm_target *ti); +int dm_noflush_suspending(struct dm_target *ti); +void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors); +union map_info *dm_get_rq_mapinfo(struct request *rq); + +struct queue_limits *dm_get_queue_limits(struct mapped_device *md); + +/* + * 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, fmode_t 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); + +/* + * Target_ctr should call this if it needs to add any callbacks. + */ +void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb); + +/* + * Finally call this to make the table ready for use. + */ +int dm_table_complete(struct dm_table *t); + +/* + * Target may require that it is never sent I/O larger than len. + */ +int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len); + +/* + * Table reference counting. + */ +struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx); +void dm_put_live_table(struct mapped_device *md, int srcu_idx); +void dm_sync_table(struct mapped_device *md); + +/* + * Queries + */ +sector_t dm_table_get_size(struct dm_table *t); +unsigned int dm_table_get_num_targets(struct dm_table *t); +fmode_t 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); + +/* + * Run the queue for request-based targets. + */ +void dm_table_run_md_queue_async(struct dm_table *t); + +/* + * The device must be suspended before calling this method. + * Returns the previous table, which the caller must destroy. + */ +struct dm_table *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" + +#ifdef CONFIG_PRINTK +extern struct ratelimit_state dm_ratelimit_state; + +#define dm_ratelimit() __ratelimit(&dm_ratelimit_state) +#else +#define dm_ratelimit() 0 +#endif + +#define DMCRIT(f, arg...) \ + printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg) + +#define DMERR(f, arg...) \ + printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg) +#define DMERR_LIMIT(f, arg...) \ + do { \ + if (dm_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 (dm_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 (dm_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 (dm_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 + +#define dm_sector_div64(x, y)( \ +{ \ + u64 _res; \ + (x) = div64_u64_rem(x, y, &_res); \ + _res; \ +} \ +) + +/* + * 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)) + +#define dm_array_too_big(fixed, obj, num) \ + ((num) > (UINT_MAX - (fixed)) / (obj)) + +/* + * Sector offset taken relative to the start of the target instead of + * relative to the start of the device. + */ +#define dm_target_offset(ti, sector) ((sector) - (ti)->begin) + +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 */ |