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linux/include/linux/device-mapper.h
Milan Broz 983c7db347 dm crypt: always disable discard_zeroes_data 
If optional discard support in dm-crypt is enabled, discards requests
bypass the crypt queue and blocks of the underlying device are discarded.
For the read path, discarded blocks are handled the same as normal
ciphertext blocks, thus decrypted.

So if the underlying device announces discarded regions return zeroes,
dm-crypt must disable this flag because after decryption there is just
random noise instead of zeroes.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2011-09-25 23:26:21 +01:00

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/*
* 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_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;
unsigned long long ll;
unsigned target_request_nr;
};
/*
* 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);
typedef int (*dm_map_request_fn) (struct dm_target *ti, 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,
union map_info *map_context);
typedef int (*dm_request_endio_fn) (struct dm_target *ti,
struct request *clone, 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, 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);
typedef int (*iterate_devices_callout_fn) (struct dm_target *ti,
struct dm_dev *dev,
sector_t start, sector_t len,
void *data);
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);
/*
* Combine device limits.
*/
int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
sector_t start, sector_t len, void *data);
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
*/
/*
* Target features
*/
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_endio_fn end_io;
dm_request_endio_fn rq_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;
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;
};
struct dm_target {
struct dm_table *table;
struct target_type *type;
/* target limits */
sector_t begin;
sector_t len;
/* Always a power of 2 */
sector_t split_io;
/*
* A number of zero-length barrier requests that will be submitted
* to the target for the purpose of flushing cache.
*
* The request number will be placed in union map_info->target_request_nr.
* It is a responsibility of the target driver to remap these requests
* to the real underlying devices.
*/
unsigned num_flush_requests;
/*
* The number of discard requests that will be submitted to the
* target. map_info->request_nr is used just like num_flush_requests.
*/
unsigned num_discard_requests;
/* target specific data */
void *private;
/* Used to provide an error string from the ctr */
char *error;
/*
* Set if this target needs to receive discards regardless of
* whether or not its underlying devices have support.
*/
unsigned discards_supported:1;
/*
* Set if this target does not return zeroes on discarded blocks.
*/
unsigned 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);
};
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);
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_mapinfo(struct bio *bio);
union map_info *dm_get_rq_mapinfo(struct request *rq);
/*
* 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);
/*
* Table reference counting.
*/
struct dm_table *dm_get_live_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);
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);
/*
* 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 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 (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))
#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);
}
/*-----------------------------------------------------------------
* Helper for block layer and dm core operations
*---------------------------------------------------------------*/
void dm_dispatch_request(struct request *rq);
void dm_requeue_unmapped_request(struct request *rq);
void dm_kill_unmapped_request(struct request *rq, int error);
int dm_underlying_device_busy(struct request_queue *q);
#endif /* _LINUX_DEVICE_MAPPER_H */
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