Edit File: device-mapper.h
/* * 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; /* * Type of table, mapped_device's mempool and request_queue */ enum dm_queue_mode { DM_TYPE_NONE = 0, DM_TYPE_BIO_BASED = 1, DM_TYPE_REQUEST_BASED = 2, DM_TYPE_MQ_REQUEST_BASED = 3, DM_TYPE_DAX_BIO_BASED = 4, }; 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, 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); 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_prepare_ioctl_fn) (struct dm_target *ti, struct block_device **bdev); 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); /* * Returns: * < 0 : error * >= 0 : the number of bytes accessible at the address */ typedef long (*dm_dax_direct_access_fn) (struct dm_target *ti, pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn); typedef int (*dm_dax_memcpy_fromiovecend_fn)(struct dm_target *ti, pgoff_t pgoff, void *addr, const struct iovec *iov, int offset, int len); typedef int (*dm_dax_memcpy_toiovecend_fn)(struct dm_target *ti, pgoff_t pgoff, const struct iovec *iov, void *addr, int offset, int len); #define PAGE_SECTORS (PAGE_SIZE / 512) void dm_error(const char *message); struct dm_dev { struct block_device *bdev; struct dax_device *dax_dev; fmode_t mode; char name[16]; }; dev_t dm_get_dev_t(const char *path); /* * 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_prepare_ioctl_fn prepare_ioctl; dm_merge_fn merge; dm_busy_fn busy; dm_iterate_devices_fn iterate_devices; dm_io_hints_fn io_hints; dm_dax_direct_access_fn direct_access; dm_dax_memcpy_fromiovecend_fn dax_memcpy_fromiovecend; dm_dax_memcpy_toiovecend_fn dax_memcpy_toiovecend; /* 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) /* * Indicates that a target may replace any target; even immutable targets. * .map, .map_rq, .clone_and_map_rq and .release_clone_rq are all defined. */ #define DM_TARGET_WILDCARD 0x00000008 #define dm_target_is_wildcard(type) ((type)->features & DM_TARGET_WILDCARD) /* * 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 io for the * target to use. */ unsigned per_io_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; 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(const 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(const 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); 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); /* * Target can use this to set the table's type. * Can only ever be called from a target's ctr. * Useful for "hybrid" target (supports both bio-based * and request-based). */ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type); /* * 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" #define DM_RATELIMIT(pr_func, fmt, ...) \ do { \ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, \ DEFAULT_RATELIMIT_BURST); \ \ if (__ratelimit(&rs)) \ pr_func(DM_FMT(fmt), ##__VA_ARGS__); \ } while (0) #define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n" #define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__) #define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__) #define DMERR_LIMIT(fmt, ...) DM_RATELIMIT(pr_err, fmt, ##__VA_ARGS__) #define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__) #define DMWARN_LIMIT(fmt, ...) DM_RATELIMIT(pr_warn, fmt, ##__VA_ARGS__) #define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__) #define DMINFO_LIMIT(fmt, ...) DM_RATELIMIT(pr_info, fmt, ##__VA_ARGS__) #ifdef CONFIG_DM_DEBUG #define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__) #define DMDEBUG_LIMIT(fmt, ...) DM_RATELIMIT(pr_debug, fmt, ##__VA_ARGS__) #else #define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__) #define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__) #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_MAPIO_DELAY_REQUEUE 3 #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 */