dm.c 76.6 KB
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/*
 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
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 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
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 *
 * This file is released under the GPL.
 */

#include "dm.h"
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#include "dm-uevent.h"
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#include <linux/init.h>
#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/moduleparam.h>
#include <linux/blkpg.h>
#include <linux/bio.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/idr.h>
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#include <linux/hdreg.h>
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#include <linux/delay.h>
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#include <linux/wait.h>
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#include <linux/kthread.h>
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#include <trace/events/block.h>
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#define DM_MSG_PREFIX "core"

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#ifdef CONFIG_PRINTK
/*
 * ratelimit state to be used in DMXXX_LIMIT().
 */
DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
		       DEFAULT_RATELIMIT_INTERVAL,
		       DEFAULT_RATELIMIT_BURST);
EXPORT_SYMBOL(dm_ratelimit_state);
#endif

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/*
 * Cookies are numeric values sent with CHANGE and REMOVE
 * uevents while resuming, removing or renaming the device.
 */
#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
#define DM_COOKIE_LENGTH 24

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static const char *_name = DM_NAME;

static unsigned int major = 0;
static unsigned int _major = 0;

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static DEFINE_IDR(_minor_idr);

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static DEFINE_SPINLOCK(_minor_lock);
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static void do_deferred_remove(struct work_struct *w);

static DECLARE_WORK(deferred_remove_work, do_deferred_remove);

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static struct workqueue_struct *deferred_remove_workqueue;

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/*
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 * For bio-based dm.
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 * One of these is allocated per bio.
 */
struct dm_io {
	struct mapped_device *md;
	int error;
	atomic_t io_count;
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	struct bio *bio;
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	unsigned long start_time;
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	spinlock_t endio_lock;
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	struct dm_stats_aux stats_aux;
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};

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/*
 * For request-based dm.
 * One of these is allocated per request.
 */
struct dm_rq_target_io {
	struct mapped_device *md;
	struct dm_target *ti;
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	struct request *orig, *clone;
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	struct kthread_work work;
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	int error;
	union map_info info;
};

/*
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 * For request-based dm - the bio clones we allocate are embedded in these
 * structs.
 *
 * We allocate these with bio_alloc_bioset, using the front_pad parameter when
 * the bioset is created - this means the bio has to come at the end of the
 * struct.
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 */
struct dm_rq_clone_bio_info {
	struct bio *orig;
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	struct dm_rq_target_io *tio;
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	struct bio clone;
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};

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union map_info *dm_get_rq_mapinfo(struct request *rq)
{
	if (rq && rq->end_io_data)
		return &((struct dm_rq_target_io *)rq->end_io_data)->info;
	return NULL;
}
EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);

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#define MINOR_ALLOCED ((void *)-1)

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/*
 * Bits for the md->flags field.
 */
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#define DMF_BLOCK_IO_FOR_SUSPEND 0
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#define DMF_SUSPENDED 1
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#define DMF_FROZEN 2
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#define DMF_FREEING 3
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#define DMF_DELETING 4
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#define DMF_NOFLUSH_SUSPENDING 5
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#define DMF_MERGE_IS_OPTIONAL 6
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#define DMF_DEFERRED_REMOVE 7
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#define DMF_SUSPENDED_INTERNALLY 8
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/*
 * A dummy definition to make RCU happy.
 * struct dm_table should never be dereferenced in this file.
 */
struct dm_table {
	int undefined__;
};

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/*
 * Work processed by per-device workqueue.
 */
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struct mapped_device {
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	struct srcu_struct io_barrier;
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	struct mutex suspend_lock;
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	atomic_t holders;
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	atomic_t open_count;
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	/*
	 * The current mapping.
	 * Use dm_get_live_table{_fast} or take suspend_lock for
	 * dereference.
	 */
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	struct dm_table __rcu *map;
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	struct list_head table_devices;
	struct mutex table_devices_lock;

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	unsigned long flags;

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	struct request_queue *queue;
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	unsigned type;
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	/* Protect queue and type against concurrent access. */
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	struct mutex type_lock;

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	struct target_type *immutable_target_type;

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	struct gendisk *disk;
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	char name[16];
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	void *interface_ptr;

	/*
	 * A list of ios that arrived while we were suspended.
	 */
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	atomic_t pending[2];
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	wait_queue_head_t wait;
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	struct work_struct work;
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	struct bio_list deferred;
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	spinlock_t deferred_lock;
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	/*
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	 * Processing queue (flush)
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	 */
	struct workqueue_struct *wq;

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	/*
	 * io objects are allocated from here.
	 */
	mempool_t *io_pool;
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	mempool_t *rq_pool;
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	struct bio_set *bs;

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	/*
	 * Event handling.
	 */
	atomic_t event_nr;
	wait_queue_head_t eventq;
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	atomic_t uevent_seq;
	struct list_head uevent_list;
	spinlock_t uevent_lock; /* Protect access to uevent_list */
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	/*
	 * freeze/thaw support require holding onto a super block
	 */
	struct super_block *frozen_sb;
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	struct block_device *bdev;
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	/* forced geometry settings */
	struct hd_geometry geometry;
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	/* kobject and completion */
	struct dm_kobject_holder kobj_holder;
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	/* zero-length flush that will be cloned and submitted to targets */
	struct bio flush_bio;
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	/* the number of internal suspends */
	unsigned internal_suspend_count;

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	struct dm_stats stats;
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	struct kthread_worker kworker;
	struct task_struct *kworker_task;
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};

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/*
 * For mempools pre-allocation at the table loading time.
 */
struct dm_md_mempools {
	mempool_t *io_pool;
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	mempool_t *rq_pool;
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	struct bio_set *bs;
};

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struct table_device {
	struct list_head list;
	atomic_t count;
	struct dm_dev dm_dev;
};

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#define RESERVED_BIO_BASED_IOS		16
#define RESERVED_REQUEST_BASED_IOS	256
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#define RESERVED_MAX_IOS		1024
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static struct kmem_cache *_io_cache;
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static struct kmem_cache *_rq_tio_cache;
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static struct kmem_cache *_rq_cache;
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/*
 * Bio-based DM's mempools' reserved IOs set by the user.
 */
static unsigned reserved_bio_based_ios = RESERVED_BIO_BASED_IOS;

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/*
 * Request-based DM's mempools' reserved IOs set by the user.
 */
static unsigned reserved_rq_based_ios = RESERVED_REQUEST_BASED_IOS;

static unsigned __dm_get_reserved_ios(unsigned *reserved_ios,
				      unsigned def, unsigned max)
{
	unsigned ios = ACCESS_ONCE(*reserved_ios);
	unsigned modified_ios = 0;

	if (!ios)
		modified_ios = def;
	else if (ios > max)
		modified_ios = max;

	if (modified_ios) {
		(void)cmpxchg(reserved_ios, ios, modified_ios);
		ios = modified_ios;
	}

	return ios;
}

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unsigned dm_get_reserved_bio_based_ios(void)
{
	return __dm_get_reserved_ios(&reserved_bio_based_ios,
				     RESERVED_BIO_BASED_IOS, RESERVED_MAX_IOS);
}
EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);

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unsigned dm_get_reserved_rq_based_ios(void)
{
	return __dm_get_reserved_ios(&reserved_rq_based_ios,
				     RESERVED_REQUEST_BASED_IOS, RESERVED_MAX_IOS);
}
EXPORT_SYMBOL_GPL(dm_get_reserved_rq_based_ios);

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static int __init local_init(void)
{
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	int r = -ENOMEM;
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	/* allocate a slab for the dm_ios */
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	_io_cache = KMEM_CACHE(dm_io, 0);
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	if (!_io_cache)
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		return r;
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	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
	if (!_rq_tio_cache)
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		goto out_free_io_cache;
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	_rq_cache = kmem_cache_create("dm_clone_request", sizeof(struct request),
				      __alignof__(struct request), 0, NULL);
	if (!_rq_cache)
		goto out_free_rq_tio_cache;

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	r = dm_uevent_init();
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	if (r)
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		goto out_free_rq_cache;
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	deferred_remove_workqueue = alloc_workqueue("kdmremove", WQ_UNBOUND, 1);
	if (!deferred_remove_workqueue) {
		r = -ENOMEM;
		goto out_uevent_exit;
	}

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	_major = major;
	r = register_blkdev(_major, _name);
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	if (r < 0)
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		goto out_free_workqueue;
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	if (!_major)
		_major = r;

	return 0;
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out_free_workqueue:
	destroy_workqueue(deferred_remove_workqueue);
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out_uevent_exit:
	dm_uevent_exit();
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out_free_rq_cache:
	kmem_cache_destroy(_rq_cache);
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out_free_rq_tio_cache:
	kmem_cache_destroy(_rq_tio_cache);
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out_free_io_cache:
	kmem_cache_destroy(_io_cache);

	return r;
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}

static void local_exit(void)
{
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	flush_scheduled_work();
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	destroy_workqueue(deferred_remove_workqueue);
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	kmem_cache_destroy(_rq_cache);
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	kmem_cache_destroy(_rq_tio_cache);
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	kmem_cache_destroy(_io_cache);
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	unregister_blkdev(_major, _name);
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	dm_uevent_exit();
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	_major = 0;

	DMINFO("cleaned up");
}

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static int (*_inits[])(void) __initdata = {
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	local_init,
	dm_target_init,
	dm_linear_init,
	dm_stripe_init,
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	dm_io_init,
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	dm_kcopyd_init,
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	dm_interface_init,
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	dm_statistics_init,
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};

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static void (*_exits[])(void) = {
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	local_exit,
	dm_target_exit,
	dm_linear_exit,
	dm_stripe_exit,
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	dm_io_exit,
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	dm_kcopyd_exit,
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	dm_interface_exit,
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	dm_statistics_exit,
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};

static int __init dm_init(void)
{
	const int count = ARRAY_SIZE(_inits);

	int r, i;

	for (i = 0; i < count; i++) {
		r = _inits[i]();
		if (r)
			goto bad;
	}

	return 0;

      bad:
	while (i--)
		_exits[i]();

	return r;
}

static void __exit dm_exit(void)
{
	int i = ARRAY_SIZE(_exits);

	while (i--)
		_exits[i]();
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	/*
	 * Should be empty by this point.
	 */
	idr_destroy(&_minor_idr);
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}

/*
 * Block device functions
 */
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int dm_deleting_md(struct mapped_device *md)
{
	return test_bit(DMF_DELETING, &md->flags);
}

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static int dm_blk_open(struct block_device *bdev, fmode_t mode)
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{
	struct mapped_device *md;

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	spin_lock(&_minor_lock);

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	md = bdev->bd_disk->private_data;
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	if (!md)
		goto out;

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	if (test_bit(DMF_FREEING, &md->flags) ||
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	    dm_deleting_md(md)) {
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		md = NULL;
		goto out;
	}

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	dm_get(md);
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	atomic_inc(&md->open_count);
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out:
	spin_unlock(&_minor_lock);

	return md ? 0 : -ENXIO;
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}

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static void dm_blk_close(struct gendisk *disk, fmode_t mode)
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{
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	struct mapped_device *md;
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	spin_lock(&_minor_lock);

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	md = disk->private_data;
	if (WARN_ON(!md))
		goto out;

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	if (atomic_dec_and_test(&md->open_count) &&
	    (test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
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		queue_work(deferred_remove_workqueue, &deferred_remove_work);
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	dm_put(md);
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out:
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	spin_unlock(&_minor_lock);
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}

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int dm_open_count(struct mapped_device *md)
{
	return atomic_read(&md->open_count);
}

/*
 * Guarantees nothing is using the device before it's deleted.
 */
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int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
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{
	int r = 0;

	spin_lock(&_minor_lock);

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	if (dm_open_count(md)) {
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		r = -EBUSY;
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		if (mark_deferred)
			set_bit(DMF_DEFERRED_REMOVE, &md->flags);
	} else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
		r = -EEXIST;
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	else
		set_bit(DMF_DELETING, &md->flags);

	spin_unlock(&_minor_lock);

	return r;
}

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int dm_cancel_deferred_remove(struct mapped_device *md)
{
	int r = 0;

	spin_lock(&_minor_lock);

	if (test_bit(DMF_DELETING, &md->flags))
		r = -EBUSY;
	else
		clear_bit(DMF_DEFERRED_REMOVE, &md->flags);

	spin_unlock(&_minor_lock);

	return r;
}

static void do_deferred_remove(struct work_struct *w)
{
	dm_deferred_remove();
}

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sector_t dm_get_size(struct mapped_device *md)
{
	return get_capacity(md->disk);
}

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struct request_queue *dm_get_md_queue(struct mapped_device *md)
{
	return md->queue;
}

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struct dm_stats *dm_get_stats(struct mapped_device *md)
{
	return &md->stats;
}

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static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
	struct mapped_device *md = bdev->bd_disk->private_data;

	return dm_get_geometry(md, geo);
}

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static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
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			unsigned int cmd, unsigned long arg)
{
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	struct mapped_device *md = bdev->bd_disk->private_data;
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	int srcu_idx;
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	struct dm_table *map;
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	struct dm_target *tgt;
	int r = -ENOTTY;

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retry:
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	map = dm_get_live_table(md, &srcu_idx);

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	if (!map || !dm_table_get_size(map))
		goto out;

	/* We only support devices that have a single target */
	if (dm_table_get_num_targets(map) != 1)
		goto out;

	tgt = dm_table_get_target(map, 0);
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	if (!tgt->type->ioctl)
		goto out;
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	if (dm_suspended_md(md)) {
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		r = -EAGAIN;
		goto out;
	}

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	r = tgt->type->ioctl(tgt, cmd, arg);
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out:
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	dm_put_live_table(md, srcu_idx);
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	if (r == -ENOTCONN) {
		msleep(10);
		goto retry;
	}

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	return r;
}

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static struct dm_io *alloc_io(struct mapped_device *md)
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{
	return mempool_alloc(md->io_pool, GFP_NOIO);
}

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static void free_io(struct mapped_device *md, struct dm_io *io)
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{
	mempool_free(io, md->io_pool);
}

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static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
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{
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	bio_put(&tio->clone);
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}

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static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
					    gfp_t gfp_mask)
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{
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	return mempool_alloc(md->io_pool, gfp_mask);
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}

static void free_rq_tio(struct dm_rq_target_io *tio)
{
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	mempool_free(tio, tio->md->io_pool);
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}

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static struct request *alloc_clone_request(struct mapped_device *md,
					   gfp_t gfp_mask)
{
	return mempool_alloc(md->rq_pool, gfp_mask);
}

static void free_clone_request(struct mapped_device *md, struct request *rq)
{
	mempool_free(rq, md->rq_pool);
}

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static int md_in_flight(struct mapped_device *md)
{
	return atomic_read(&md->pending[READ]) +
	       atomic_read(&md->pending[WRITE]);
}

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static void start_io_acct(struct dm_io *io)
{
	struct mapped_device *md = io->md;
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	struct bio *bio = io->bio;
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	int cpu;
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	int rw = bio_data_dir(bio);
622 623 624

	io->start_time = jiffies;

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	cpu = part_stat_lock();
	part_round_stats(cpu, &dm_disk(md)->part0);
	part_stat_unlock();
628 629
	atomic_set(&dm_disk(md)->part0.in_flight[rw],
		atomic_inc_return(&md->pending[rw]));
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	if (unlikely(dm_stats_used(&md->stats)))
632
		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_iter.bi_sector,
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				    bio_sectors(bio), false, 0, &io->stats_aux);
634 635
}

636
static void end_io_acct(struct dm_io *io)
637 638 639 640
{
	struct mapped_device *md = io->md;
	struct bio *bio = io->bio;
	unsigned long duration = jiffies - io->start_time;
641
	int pending;
642 643
	int rw = bio_data_dir(bio);

644
	generic_end_io_acct(rw, &dm_disk(md)->part0, io->start_time);
645

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	if (unlikely(dm_stats_used(&md->stats)))
647
		dm_stats_account_io(&md->stats, bio->bi_rw, bio->bi_iter.bi_sector,
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				    bio_sectors(bio), true, duration, &io->stats_aux);

650 651
	/*
	 * After this is decremented the bio must not be touched if it is
652
	 * a flush.
653
	 */
654 655
	pending = atomic_dec_return(&md->pending[rw]);
	atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
656
	pending += atomic_read(&md->pending[rw^0x1]);
657

658 659 660
	/* nudge anyone waiting on suspend queue */
	if (!pending)
		wake_up(&md->wait);
661 662
}

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/*
 * Add the bio to the list of deferred io.
 */
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static void queue_io(struct mapped_device *md, struct bio *bio)
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{
668
	unsigned long flags;
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670
	spin_lock_irqsave(&md->deferred_lock, flags);
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	bio_list_add(&md->deferred, bio);
672
	spin_unlock_irqrestore(&md->deferred_lock, flags);
673
	queue_work(md->wq, &md->work);
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}

/*
 * Everyone (including functions in this file), should use this
 * function to access the md->map field, and make sure they call
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 * dm_put_live_table() when finished.
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 */
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struct dm_table *dm_get_live_table(struct mapped_device *md, int *srcu_idx) __acquires(md->io_barrier)
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{
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	*srcu_idx = srcu_read_lock(&md->io_barrier);

	return srcu_dereference(md->map, &md->io_barrier);
}
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void dm_put_live_table(struct mapped_device *md, int srcu_idx) __releases(md->io_barrier)
{
	srcu_read_unlock(&md->io_barrier, srcu_idx);
}

void dm_sync_table(struct mapped_device *md)
{
	synchronize_srcu(&md->io_barrier);
	synchronize_rcu_expedited();
}

/*
 * A fast alternative to dm_get_live_table/dm_put_live_table.
 * The caller must not block between these two functions.
 */
static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU)
{
	rcu_read_lock();
	return rcu_dereference(md->map);
}
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static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
{
	rcu_read_unlock();
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}

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/*
 * Open a table device so we can use it as a map destination.
 */
static int open_table_device(struct table_device *td, dev_t dev,
			     struct mapped_device *md)
{
	static char *_claim_ptr = "I belong to device-mapper";
	struct block_device *bdev;

	int r;

	BUG_ON(td->dm_dev.bdev);

	bdev = blkdev_get_by_dev(dev, td->dm_dev.mode | FMODE_EXCL, _claim_ptr);
	if (IS_ERR(bdev))
		return PTR_ERR(bdev);

	r = bd_link_disk_holder(bdev, dm_disk(md));
	if (r) {
		blkdev_put(bdev, td->dm_dev.mode | FMODE_EXCL);
		return r;
	}

	td->dm_dev.bdev = bdev;
	return 0;
}

/*
 * Close a table device that we've been using.
 */
static void close_table_device(struct table_device *td, struct mapped_device *md)
{
	if (!td->dm_dev.bdev)
		return;

	bd_unlink_disk_holder(td->dm_dev.bdev, dm_disk(md));
	blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
	td->dm_dev.bdev = NULL;
}

static struct table_device *find_table_device(struct list_head *l, dev_t dev,
					      fmode_t mode) {
	struct table_device *td;

	list_for_each_entry(td, l, list)
		if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode)
			return td;

	return NULL;
}

int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
			struct dm_dev **result) {
	int r;
	struct table_device *td;

	mutex_lock(&md->table_devices_lock);
	td = find_table_device(&md->table_devices, dev, mode);
	if (!td) {
		td = kmalloc(sizeof(*td), GFP_KERNEL);
		if (!td) {
			mutex_unlock(&md->table_devices_lock);
			return -ENOMEM;
		}

		td->dm_dev.mode = mode;
		td->dm_dev.bdev = NULL;

		if ((r = open_table_device(td, dev, md))) {
			mutex_unlock(&md->table_devices_lock);
			kfree(td);
			return r;
		}

		format_dev_t(td->dm_dev.name, dev);

		atomic_set(&td->count, 0);
		list_add(&td->list, &md->table_devices);
	}
	atomic_inc(&td->count);
	mutex_unlock(&md->table_devices_lock);

	*result = &td->dm_dev;
	return 0;
}
EXPORT_SYMBOL_GPL(dm_get_table_device);

void dm_put_table_device(struct mapped_device *md, struct dm_dev *d)
{
	struct table_device *td = container_of(d, struct table_device, dm_dev);

	mutex_lock(&md->table_devices_lock);
	if (atomic_dec_and_test(&td->count)) {
		close_table_device(td, md);
		list_del(&td->list);
		kfree(td);
	}
	mutex_unlock(&md->table_devices_lock);
}
EXPORT_SYMBOL(dm_put_table_device);

static void free_table_devices(struct list_head *devices)
{
	struct list_head *tmp, *next;

	list_for_each_safe(tmp, next, devices) {
		struct table_device *td = list_entry(tmp, struct table_device, list);

		DMWARN("dm_destroy: %s still exists with %d references",
		       td->dm_dev.name, atomic_read(&td->count));
		kfree(td);
	}
}

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/*
 * Get the geometry associated with a dm device
 */
int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
{
	*geo = md->geometry;

	return 0;
}

/*
 * Set the geometry of a device.
 */
int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
{
	sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;

	if (geo->start > sz) {
		DMWARN("Start sector is beyond the geometry limits.");
		return -EINVAL;
	}

	md->geometry = *geo;

	return 0;
}

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/*-----------------------------------------------------------------
 * CRUD START:
 *   A more elegant soln is in the works that uses the queue
 *   merge fn, unfortunately there are a couple of changes to
 *   the block layer that I want to make for this.  So in the
 *   interests of getting something for people to use I give
 *   you this clearly demarcated crap.
 *---------------------------------------------------------------*/

864 865 866 867 868
static int __noflush_suspending(struct mapped_device *md)
{
	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
}

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/*
 * Decrements the number of outstanding ios that a bio has been
 * cloned into, completing the original io if necc.
 */
873
static void dec_pending(struct dm_io *io, int error)
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{
875
	unsigned long flags;
876 877 878
	int io_error;
	struct bio *bio;
	struct mapped_device *md = io->md;
879 880

	/* Push-back supersedes any I/O errors */
881 882 883 884 885 886
	if (unlikely(error)) {
		spin_lock_irqsave(&io->endio_lock, flags);
		if (!(io->error > 0 && __noflush_suspending(md)))
			io->error = error;
		spin_unlock_irqrestore(&io->endio_lock, flags);
	}
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	if (atomic_dec_and_test(&io->io_count)) {
889 890 891 892
		if (io->error == DM_ENDIO_REQUEUE) {
			/*
			 * Target requested pushing back the I/O.
			 */
893
			spin_lock_irqsave(&md->deferred_lock, flags);
894 895 896
			if (__noflush_suspending(md))
				bio_list_add_head(&md->deferred, io->bio);
			else
897 898
				/* noflush suspend was interrupted. */
				io->error = -EIO;
899
			spin_unlock_irqrestore(&md->deferred_lock, flags);
900 901
		}

902 903
		io_error = io->error;
		bio = io->bio;
904 905 906 907 908
		end_io_acct(io);
		free_io(md, io);

		if (io_error == DM_ENDIO_REQUEUE)
			return;
909

910
		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_iter.bi_size) {
911
			/*
912 913
			 * Preflush done for flush with data, reissue
			 * without REQ_FLUSH.
914
			 */
915 916
			bio->bi_rw &= ~REQ_FLUSH;
			queue_io(md, bio);
917
		} else {
918
			/* done with normal IO or empty flush */
919
			trace_block_bio_complete(md->queue, bio, io_error);
920
			bio_endio(bio, io_error);
921
		}
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	}
}

925 926 927 928 929 930 931 932
static void disable_write_same(struct mapped_device *md)
{
	struct queue_limits *limits = dm_get_queue_limits(md);

	/* device doesn't really support WRITE SAME, disable it */
	limits->max_write_same_sectors = 0;
}

933
static void clone_endio(struct bio *bio, int error)
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{
935
	int r = error;
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	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
937
	struct dm_io *io = tio->io;
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	struct mapped_device *md = tio->io->md;
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	dm_endio_fn endio = tio->ti->type->end_io;

	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
		error = -EIO;

	if (endio) {
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		r = endio(tio->ti, bio, error);
946 947 948 949 950
		if (r < 0 || r == DM_ENDIO_REQUEUE)
			/*
			 * error and requeue request are handled
			 * in dec_pending().
			 */
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			error = r;
952 953
		else if (r == DM_ENDIO_INCOMPLETE)
			/* The target will handle the io */
954
			return;
955 956 957 958
		else if (r) {
			DMWARN("unimplemented target endio return value: %d", r);
			BUG();
		}
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	}

961 962 963 964
	if (unlikely(r == -EREMOTEIO && (bio->bi_rw & REQ_WRITE_SAME) &&
		     !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors))
		disable_write_same(md);

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	free_tio(md, tio);
966
	dec_pending(io, error);
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}

969 970 971 972 973
/*
 * Partial completion handling for request-based dm
 */
static void end_clone_bio(struct bio *clone, int error)
{
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	struct dm_rq_clone_bio_info *info =
		container_of(clone, struct dm_rq_clone_bio_info, clone);
976 977
	struct dm_rq_target_io *tio = info->tio;
	struct bio *bio = info->orig;
978
	unsigned int nr_bytes = info->orig->bi_iter.bi_size;
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	bio_put(clone);

	if (tio->error)
		/*
		 * An error has already been detected on the request.
		 * Once error occurred, just let clone->end_io() handle
		 * the remainder.
		 */
		return;
	else if (error) {
		/*
		 * Don't notice the error to the upper layer yet.
		 * The error handling decision is made by the target driver,
		 * when the request is completed.
		 */
		tio->error = error;
		return;
	}

	/*
	 * I/O for the bio successfully completed.
	 * Notice the data completion to the upper layer.
	 */

	/*
	 * bios are processed from the head of the list.
	 * So the completing bio should always be rq->bio.
	 * If it's not, something wrong is happening.
	 */
	if (tio->orig->bio != bio)
		DMERR("bio completion is going in the middle of the request");

	/*
	 * Update the original request.
	 * Do not use blk_end_request() here, because it may complete
	 * the original request before the clone, and break the ordering.
	 */
	blk_update_request(tio->orig, 0, nr_bytes);
}

/*
 * Don't touch any member of the md after calling this function because
 * the md may be freed in dm_put() at the end of this function.
 * Or do dm_get() before calling this function and dm_put() later.
 */
1025
static void rq_completed(struct mapped_device *md, int rw, bool run_queue)
1026
{
1027
	atomic_dec(&md->pending[rw]);
1028 1029

	/* nudge anyone waiting on suspend queue */
1030
	if (!md_in_flight(md))
1031 1032
		wake_up(&md->wait);

1033 1034 1035 1036 1037 1038
	/*
	 * Run this off this callpath, as drivers could invoke end_io while
	 * inside their request_fn (and holding the queue lock). Calling
	 * back into ->request_fn() could deadlock attempting to grab the
	 * queue lock again.
	 */
1039
	if (run_queue)
1040
		blk_run_queue_async(md->queue);
1041 1042 1043 1044 1045 1046 1047

	/*
	 * dm_put() must be at the end of this function. See the comment above
	 */
	dm_put(md);
}

1048 1049 1050 1051 1052
static void free_rq_clone(struct request *clone)
{
	struct dm_rq_target_io *tio = clone->end_io_data;

	blk_rq_unprep_clone(clone);
1053 1054 1055 1056
	if (clone->q && clone->q->mq_ops)
		tio->ti->type->release_clone_rq(clone);
	else
		free_clone_request(tio->md, clone);
1057 1058 1059
	free_rq_tio(tio);
}

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Kiyoshi Ueda 已提交
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/*
 * Complete the clone and the original request.
1062 1063
 * Must be called without clone's queue lock held,
 * see end_clone_request() for more details.
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Kiyoshi Ueda 已提交
1064 1065 1066 1067 1068 1069 1070 1071
 */
static void dm_end_request(struct request *clone, int error)
{
	int rw = rq_data_dir(clone);
	struct dm_rq_target_io *tio = clone->end_io_data;
	struct mapped_device *md = tio->md;
	struct request *rq = tio->orig;

1072
	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
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Kiyoshi Ueda 已提交
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		rq->errors = clone->errors;
		rq->resid_len = clone->resid_len;

		if (rq->sense)
			/*
			 * We are using the sense buffer of the original
			 * request.
			 * So setting the length of the sense data is enough.
			 */
			rq->sense_len = clone->sense_len;
	}

	free_rq_clone(clone);
1086 1087
	blk_end_request_all(rq, error);
	rq_completed(md, rw, true);
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Kiyoshi Ueda 已提交
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}

1090 1091
static void dm_unprep_request(struct request *rq)
{
1092 1093
	struct dm_rq_target_io *tio = rq->special;
	struct request *clone = tio->clone;
1094 1095 1096 1097

	rq->special = NULL;
	rq->cmd_flags &= ~REQ_DONTPREP;

1098 1099
	if (clone)
		free_rq_clone(clone);
1100 1101 1102 1103 1104
}

/*
 * Requeue the original request of a clone.
 */
1105 1106
static void dm_requeue_unmapped_original_request(struct mapped_device *md,
						 struct request *rq)
1107
{
1108
	int rw = rq_data_dir(rq);
1109 1110 1111 1112 1113 1114 1115 1116 1117
	struct request_queue *q = rq->q;
	unsigned long flags;

	dm_unprep_request(rq);

	spin_lock_irqsave(q->queue_lock, flags);
	blk_requeue_request(q, rq);
	spin_unlock_irqrestore(q->queue_lock, flags);

1118 1119 1120 1121 1122 1123 1124 1125
	rq_completed(md, rw, false);
}

static void dm_requeue_unmapped_request(struct request *clone)
{
	struct dm_rq_target_io *tio = clone->end_io_data;

	dm_requeue_unmapped_original_request(tio->md, tio->orig);
1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156
}

static void __stop_queue(struct request_queue *q)
{
	blk_stop_queue(q);
}

static void stop_queue(struct request_queue *q)
{
	unsigned long flags;

	spin_lock_irqsave(q->queue_lock, flags);
	__stop_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);
}

static void __start_queue(struct request_queue *q)
{
	if (blk_queue_stopped(q))
		blk_start_queue(q);
}

static void start_queue(struct request_queue *q)
{
	unsigned long flags;

	spin_lock_irqsave(q->queue_lock, flags);
	__start_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);
}

1157
static void dm_done(struct request *clone, int error, bool mapped)
1158
{
1159
	int r = error;
1160
	struct dm_rq_target_io *tio = clone->end_io_data;
1161
	dm_request_endio_fn rq_end_io = NULL;
1162

1163 1164 1165 1166 1167 1168
	if (tio->ti) {
		rq_end_io = tio->ti->type->rq_end_io;

		if (mapped && rq_end_io)
			r = rq_end_io(tio->ti, clone, error, &tio->info);
	}
1169

1170 1171 1172 1173
	if (unlikely(r == -EREMOTEIO && (clone->cmd_flags & REQ_WRITE_SAME) &&
		     !clone->q->limits.max_write_same_sectors))
		disable_write_same(tio->md);

1174
	if (r <= 0)
1175
		/* The target wants to complete the I/O */
1176 1177
		dm_end_request(clone, r);
	else if (r == DM_ENDIO_INCOMPLETE)
1178 1179
		/* The target will handle the I/O */
		return;
1180
	else if (r == DM_ENDIO_REQUEUE)
1181 1182 1183
		/* The target wants to requeue the I/O */
		dm_requeue_unmapped_request(clone);
	else {
1184
		DMWARN("unimplemented target endio return value: %d", r);
1185 1186 1187 1188
		BUG();
	}
}

1189 1190 1191 1192 1193 1194
/*
 * Request completion handler for request-based dm
 */
static void dm_softirq_done(struct request *rq)
{
	bool mapped = true;
1195 1196
	struct dm_rq_target_io *tio = rq->special;
	struct request *clone = tio->clone;
1197

1198 1199 1200 1201 1202 1203
	if (!clone) {
		blk_end_request_all(rq, tio->error);
		rq_completed(tio->md, rq_data_dir(rq), false);
		free_rq_tio(tio);
		return;
	}
1204 1205 1206 1207 1208 1209 1210

	if (rq->cmd_flags & REQ_FAILED)
		mapped = false;

	dm_done(clone, tio->error, mapped);
}

1211 1212 1213 1214
/*
 * Complete the clone and the original request with the error status
 * through softirq context.
 */
1215
static void dm_complete_request(struct request *rq, int error)
1216
{
1217
	struct dm_rq_target_io *tio = rq->special;
1218 1219 1220 1221 1222 1223 1224 1225 1226

	tio->error = error;
	blk_complete_request(rq);
}

/*
 * Complete the not-mapped clone and the original request with the error status
 * through softirq context.
 * Target's rq_end_io() function isn't called.
1227
 * This may be used when the target's map_rq() or clone_and_map_rq() functions fail.
1228
 */
1229
static void dm_kill_unmapped_request(struct request *rq, int error)
1230 1231
{
	rq->cmd_flags |= REQ_FAILED;
1232
	dm_complete_request(rq, error);
1233 1234 1235
}

/*
1236
 * Called with the clone's queue lock held
1237 1238 1239
 */
static void end_clone_request(struct request *clone, int error)
{
1240 1241
	struct dm_rq_target_io *tio = clone->end_io_data;

1242 1243 1244 1245 1246 1247 1248 1249 1250
	if (!clone->q->mq_ops) {
		/*
		 * For just cleaning up the information of the queue in which
		 * the clone was dispatched.
		 * The clone is *NOT* freed actually here because it is alloced
		 * from dm own mempool (REQ_ALLOCED isn't set).
		 */
		__blk_put_request(clone->q, clone);
	}
1251 1252 1253

	/*
	 * Actual request completion is done in a softirq context which doesn't
1254
	 * hold the clone's queue lock.  Otherwise, deadlock could occur because:
1255 1256 1257
	 *     - another request may be submitted by the upper level driver
	 *       of the stacking during the completion
	 *     - the submission which requires queue lock may be done
1258
	 *       against this clone's queue
1259
	 */
1260
	dm_complete_request(tio->orig, error);
1261 1262
}

1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
/*
 * Return maximum size of I/O possible at the supplied sector up to the current
 * target boundary.
 */
static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
{
	sector_t target_offset = dm_target_offset(ti, sector);

	return ti->len - target_offset;
}

static sector_t max_io_len(sector_t sector, struct dm_target *ti)
L
Linus Torvalds 已提交
1275
{
1276
	sector_t len = max_io_len_target_boundary(sector, ti);
1277
	sector_t offset, max_len;
L
Linus Torvalds 已提交
1278 1279

	/*
1280
	 * Does the target need to split even further?
L
Linus Torvalds 已提交
1281
	 */
1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
	if (ti->max_io_len) {
		offset = dm_target_offset(ti, sector);
		if (unlikely(ti->max_io_len & (ti->max_io_len - 1)))
			max_len = sector_div(offset, ti->max_io_len);
		else
			max_len = offset & (ti->max_io_len - 1);
		max_len = ti->max_io_len - max_len;

		if (len > max_len)
			len = max_len;
L
Linus Torvalds 已提交
1292 1293 1294 1295 1296
	}

	return len;
}

1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311
int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
{
	if (len > UINT_MAX) {
		DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
		      (unsigned long long)len, UINT_MAX);
		ti->error = "Maximum size of target IO is too large";
		return -EINVAL;
	}

	ti->max_io_len = (uint32_t) len;

	return 0;
}
EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);

1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351
/*
 * A target may call dm_accept_partial_bio only from the map routine.  It is
 * allowed for all bio types except REQ_FLUSH.
 *
 * dm_accept_partial_bio informs the dm that the target only wants to process
 * additional n_sectors sectors of the bio and the rest of the data should be
 * sent in a next bio.
 *
 * A diagram that explains the arithmetics:
 * +--------------------+---------------+-------+
 * |         1          |       2       |   3   |
 * +--------------------+---------------+-------+
 *
 * <-------------- *tio->len_ptr --------------->
 *                      <------- bi_size ------->
 *                      <-- n_sectors -->
 *
 * Region 1 was already iterated over with bio_advance or similar function.
 *	(it may be empty if the target doesn't use bio_advance)
 * Region 2 is the remaining bio size that the target wants to process.
 *	(it may be empty if region 1 is non-empty, although there is no reason
 *	 to make it empty)
 * The target requires that region 3 is to be sent in the next bio.
 *
 * If the target wants to receive multiple copies of the bio (via num_*bios, etc),
 * the partially processed part (the sum of regions 1+2) must be the same for all
 * copies of the bio.
 */
void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
{
	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
	unsigned bi_size = bio->bi_iter.bi_size >> SECTOR_SHIFT;
	BUG_ON(bio->bi_rw & REQ_FLUSH);
	BUG_ON(bi_size > *tio->len_ptr);
	BUG_ON(n_sectors > bi_size);
	*tio->len_ptr -= bi_size - n_sectors;
	bio->bi_iter.bi_size = n_sectors << SECTOR_SHIFT;
}
EXPORT_SYMBOL_GPL(dm_accept_partial_bio);

A
Alasdair G Kergon 已提交
1352
static void __map_bio(struct dm_target_io *tio)
L
Linus Torvalds 已提交
1353 1354
{
	int r;
1355
	sector_t sector;
S
Stefan Bader 已提交
1356
	struct mapped_device *md;
1357
	struct bio *clone = &tio->clone;
A
Alasdair G Kergon 已提交
1358
	struct dm_target *ti = tio->ti;
L
Linus Torvalds 已提交
1359 1360 1361 1362 1363 1364 1365 1366 1367

	clone->bi_end_io = clone_endio;

	/*
	 * Map the clone.  If r == 0 we don't need to do
	 * anything, the target has assumed ownership of
	 * this io.
	 */
	atomic_inc(&tio->io->io_count);
1368
	sector = clone->bi_iter.bi_sector;
M
Mikulas Patocka 已提交
1369
	r = ti->type->map(ti, clone);
1370
	if (r == DM_MAPIO_REMAPPED) {
L
Linus Torvalds 已提交
1371
		/* the bio has been remapped so dispatch it */
1372

1373 1374
		trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
				      tio->io->bio->bi_bdev->bd_dev, sector);
1375

L
Linus Torvalds 已提交
1376
		generic_make_request(clone);
1377 1378
	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
		/* error the io and bail out, or requeue it if needed */
S
Stefan Bader 已提交
1379 1380 1381
		md = tio->io->md;
		dec_pending(tio->io, r);
		free_tio(md, tio);
1382 1383 1384
	} else if (r) {
		DMWARN("unimplemented target map return value: %d", r);
		BUG();
L
Linus Torvalds 已提交
1385 1386 1387 1388 1389 1390 1391 1392 1393
	}
}

struct clone_info {
	struct mapped_device *md;
	struct dm_table *map;
	struct bio *bio;
	struct dm_io *io;
	sector_t sector;
1394
	unsigned sector_count;
L
Linus Torvalds 已提交
1395 1396
};

1397
static void bio_setup_sector(struct bio *bio, sector_t sector, unsigned len)
A
Alasdair G Kergon 已提交
1398
{
1399 1400
	bio->bi_iter.bi_sector = sector;
	bio->bi_iter.bi_size = to_bytes(len);
L
Linus Torvalds 已提交
1401 1402 1403 1404 1405
}

/*
 * Creates a bio that consists of range of complete bvecs.
 */
1406
static void clone_bio(struct dm_target_io *tio, struct bio *bio,
1407
		      sector_t sector, unsigned len)
L
Linus Torvalds 已提交
1408
{
1409
	struct bio *clone = &tio->clone;
L
Linus Torvalds 已提交
1410

1411 1412 1413 1414
	__bio_clone_fast(clone, bio);

	if (bio_integrity(bio))
		bio_integrity_clone(clone, bio, GFP_NOIO);
A
Alasdair G Kergon 已提交
1415

1416 1417 1418 1419 1420
	bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector));
	clone->bi_iter.bi_size = to_bytes(len);

	if (bio_integrity(bio))
		bio_integrity_trim(clone, 0, len);
L
Linus Torvalds 已提交
1421 1422
}

1423
static struct dm_target_io *alloc_tio(struct clone_info *ci,
1424
				      struct dm_target *ti,
1425
				      unsigned target_bio_nr)
1426
{
1427 1428 1429
	struct dm_target_io *tio;
	struct bio *clone;

1430
	clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);
1431
	tio = container_of(clone, struct dm_target_io, clone);
1432 1433 1434

	tio->io = ci->io;
	tio->ti = ti;
1435
	tio->target_bio_nr = target_bio_nr;
1436 1437 1438 1439

	return tio;
}

1440 1441
static void __clone_and_map_simple_bio(struct clone_info *ci,
				       struct dm_target *ti,
1442
				       unsigned target_bio_nr, unsigned *len)
1443
{
1444
	struct dm_target_io *tio = alloc_tio(ci, ti, target_bio_nr);
1445
	struct bio *clone = &tio->clone;
1446

1447 1448
	tio->len_ptr = len;

1449
	__bio_clone_fast(clone, ci->bio);
A
Alasdair G Kergon 已提交
1450
	if (len)
1451
		bio_setup_sector(clone, ci->sector, *len);
1452

A
Alasdair G Kergon 已提交
1453
	__map_bio(tio);
1454 1455
}

1456
static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
1457
				  unsigned num_bios, unsigned *len)
1458
{
1459
	unsigned target_bio_nr;
1460

1461
	for (target_bio_nr = 0; target_bio_nr < num_bios; target_bio_nr++)
1462
		__clone_and_map_simple_bio(ci, ti, target_bio_nr, len);
1463 1464
}

1465
static int __send_empty_flush(struct clone_info *ci)
1466
{
1467
	unsigned target_nr = 0;
1468 1469
	struct dm_target *ti;

1470
	BUG_ON(bio_has_data(ci->bio));
1471
	while ((ti = dm_table_get_target(ci->map, target_nr++)))
1472
		__send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
1473 1474 1475 1476

	return 0;
}

A
Alasdair G Kergon 已提交
1477
static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
1478
				     sector_t sector, unsigned *len)
M
Mike Snitzer 已提交
1479
{
1480
	struct bio *bio = ci->bio;
M
Mike Snitzer 已提交
1481
	struct dm_target_io *tio;
1482 1483
	unsigned target_bio_nr;
	unsigned num_target_bios = 1;
M
Mike Snitzer 已提交
1484

1485 1486 1487 1488 1489
	/*
	 * Does the target want to receive duplicate copies of the bio?
	 */
	if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
		num_target_bios = ti->num_write_bios(ti, bio);
A
Alasdair G Kergon 已提交
1490

1491
	for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
1492
		tio = alloc_tio(ci, ti, target_bio_nr);
1493 1494
		tio->len_ptr = len;
		clone_bio(tio, bio, sector, *len);
1495 1496
		__map_bio(tio);
	}
M
Mike Snitzer 已提交
1497 1498
}

1499
typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);
M
Mike Snitzer 已提交
1500

1501
static unsigned get_num_discard_bios(struct dm_target *ti)
M
Mike Snitzer 已提交
1502
{
1503
	return ti->num_discard_bios;
M
Mike Snitzer 已提交
1504 1505
}

1506
static unsigned get_num_write_same_bios(struct dm_target *ti)
M
Mike Snitzer 已提交
1507
{
1508
	return ti->num_write_same_bios;
M
Mike Snitzer 已提交
1509 1510 1511 1512 1513 1514
}

typedef bool (*is_split_required_fn)(struct dm_target *ti);

static bool is_split_required_for_discard(struct dm_target *ti)
{
1515
	return ti->split_discard_bios;
M
Mike Snitzer 已提交
1516 1517
}

1518 1519 1520
static int __send_changing_extent_only(struct clone_info *ci,
				       get_num_bios_fn get_num_bios,
				       is_split_required_fn is_split_required)
M
Mike Snitzer 已提交
1521 1522
{
	struct dm_target *ti;
1523
	unsigned len;
1524
	unsigned num_bios;
M
Mike Snitzer 已提交
1525

1526 1527 1528 1529
	do {
		ti = dm_table_find_target(ci->map, ci->sector);
		if (!dm_target_is_valid(ti))
			return -EIO;
M
Mike Snitzer 已提交
1530 1531

		/*
M
Mike Snitzer 已提交
1532 1533
		 * Even though the device advertised support for this type of
		 * request, that does not mean every target supports it, and
M
Mike Snitzer 已提交
1534
		 * reconfiguration might also have changed that since the
1535
		 * check was performed.
M
Mike Snitzer 已提交
1536
		 */
1537 1538
		num_bios = get_num_bios ? get_num_bios(ti) : 0;
		if (!num_bios)
1539
			return -EOPNOTSUPP;
M
Mike Snitzer 已提交
1540

M
Mike Snitzer 已提交
1541
		if (is_split_required && !is_split_required(ti))
1542
			len = min((sector_t)ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
1543
		else
1544
			len = min((sector_t)ci->sector_count, max_io_len(ci->sector, ti));
1545

1546
		__send_duplicate_bios(ci, ti, num_bios, &len);
1547 1548 1549

		ci->sector += len;
	} while (ci->sector_count -= len);
M
Mike Snitzer 已提交
1550 1551 1552 1553

	return 0;
}

1554
static int __send_discard(struct clone_info *ci)
M
Mike Snitzer 已提交
1555
{
1556 1557
	return __send_changing_extent_only(ci, get_num_discard_bios,
					   is_split_required_for_discard);
M
Mike Snitzer 已提交
1558 1559
}

1560
static int __send_write_same(struct clone_info *ci)
M
Mike Snitzer 已提交
1561
{
1562
	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
M
Mike Snitzer 已提交
1563 1564
}

A
Alasdair G Kergon 已提交
1565 1566 1567
/*
 * Select the correct strategy for processing a non-flush bio.
 */
1568
static int __split_and_process_non_flush(struct clone_info *ci)
L
Linus Torvalds 已提交
1569
{
1570
	struct bio *bio = ci->bio;
1571
	struct dm_target *ti;
1572
	unsigned len;
L
Linus Torvalds 已提交
1573

M
Mike Snitzer 已提交
1574
	if (unlikely(bio->bi_rw & REQ_DISCARD))
1575
		return __send_discard(ci);
M
Mike Snitzer 已提交
1576
	else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
1577
		return __send_write_same(ci);
M
Mike Snitzer 已提交
1578

1579 1580 1581 1582
	ti = dm_table_find_target(ci->map, ci->sector);
	if (!dm_target_is_valid(ti))
		return -EIO;

1583
	len = min_t(sector_t, max_io_len(ci->sector, ti), ci->sector_count);
L
Linus Torvalds 已提交
1584

1585
	__clone_and_map_data_bio(ci, ti, ci->sector, &len);
L
Linus Torvalds 已提交
1586

1587 1588
	ci->sector += len;
	ci->sector_count -= len;
L
Linus Torvalds 已提交
1589

1590
	return 0;
L
Linus Torvalds 已提交
1591 1592 1593
}

/*
1594
 * Entry point to split a bio into clones and submit them to the targets.
L
Linus Torvalds 已提交
1595
 */
M
Mikulas Patocka 已提交
1596 1597
static void __split_and_process_bio(struct mapped_device *md,
				    struct dm_table *map, struct bio *bio)
L
Linus Torvalds 已提交
1598 1599
{
	struct clone_info ci;
1600
	int error = 0;
L
Linus Torvalds 已提交
1601

M
Mikulas Patocka 已提交
1602
	if (unlikely(!map)) {
1603
		bio_io_error(bio);
1604 1605
		return;
	}
1606

M
Mikulas Patocka 已提交
1607
	ci.map = map;
L
Linus Torvalds 已提交
1608 1609 1610 1611 1612 1613
	ci.md = md;
	ci.io = alloc_io(md);
	ci.io->error = 0;
	atomic_set(&ci.io->io_count, 1);
	ci.io->bio = bio;
	ci.io->md = md;
1614
	spin_lock_init(&ci.io->endio_lock);
1615
	ci.sector = bio->bi_iter.bi_sector;
L
Linus Torvalds 已提交
1616

1617
	start_io_acct(ci.io);
A
Alasdair G Kergon 已提交
1618

1619 1620 1621
	if (bio->bi_rw & REQ_FLUSH) {
		ci.bio = &ci.md->flush_bio;
		ci.sector_count = 0;
1622
		error = __send_empty_flush(&ci);
1623 1624
		/* dec_pending submits any data associated with flush */
	} else {
1625
		ci.bio = bio;
1626
		ci.sector_count = bio_sectors(bio);
1627
		while (ci.sector_count && !error)
1628
			error = __split_and_process_non_flush(&ci);
1629
	}
L
Linus Torvalds 已提交
1630 1631

	/* drop the extra reference count */
1632
	dec_pending(ci.io, error);
L
Linus Torvalds 已提交
1633 1634 1635 1636 1637
}
/*-----------------------------------------------------------------
 * CRUD END
 *---------------------------------------------------------------*/

M
Milan Broz 已提交
1638 1639 1640 1641 1642
static int dm_merge_bvec(struct request_queue *q,
			 struct bvec_merge_data *bvm,
			 struct bio_vec *biovec)
{
	struct mapped_device *md = q->queuedata;
M
Mikulas Patocka 已提交
1643
	struct dm_table *map = dm_get_live_table_fast(md);
M
Milan Broz 已提交
1644 1645
	struct dm_target *ti;
	sector_t max_sectors;
1646
	int max_size = 0;
M
Milan Broz 已提交
1647 1648

	if (unlikely(!map))
1649
		goto out;
M
Milan Broz 已提交
1650 1651

	ti = dm_table_find_target(map, bvm->bi_sector);
1652
	if (!dm_target_is_valid(ti))
M
Mikulas Patocka 已提交
1653
		goto out;
M
Milan Broz 已提交
1654 1655 1656 1657

	/*
	 * Find maximum amount of I/O that won't need splitting
	 */
1658
	max_sectors = min(max_io_len(bvm->bi_sector, ti),
1659
			  (sector_t) queue_max_sectors(q));
M
Milan Broz 已提交
1660
	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
1661
	if (unlikely(max_size < 0)) /* this shouldn't _ever_ happen */
M
Milan Broz 已提交
1662 1663 1664 1665 1666 1667 1668 1669 1670
		max_size = 0;

	/*
	 * merge_bvec_fn() returns number of bytes
	 * it can accept at this offset
	 * max is precomputed maximal io size
	 */
	if (max_size && ti->type->merge)
		max_size = ti->type->merge(ti, bvm, biovec, max_size);
1671 1672
	/*
	 * If the target doesn't support merge method and some of the devices
1673 1674 1675 1676
	 * provided their merge_bvec method (we know this by looking for the
	 * max_hw_sectors that dm_set_device_limits may set), then we can't
	 * allow bios with multiple vector entries.  So always set max_size
	 * to 0, and the code below allows just one page.
1677 1678 1679
	 */
	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
		max_size = 0;
M
Milan Broz 已提交
1680

1681
out:
M
Mikulas Patocka 已提交
1682
	dm_put_live_table_fast(md);
M
Milan Broz 已提交
1683 1684 1685 1686 1687 1688 1689 1690 1691
	/*
	 * Always allow an entire first page
	 */
	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
		max_size = biovec->bv_len;

	return max_size;
}

L
Linus Torvalds 已提交
1692 1693 1694 1695
/*
 * The request function that just remaps the bio built up by
 * dm_merge_bvec.
 */
1696
static void _dm_request(struct request_queue *q, struct bio *bio)
L
Linus Torvalds 已提交
1697
{
1698
	int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
1699
	struct mapped_device *md = q->queuedata;
M
Mikulas Patocka 已提交
1700 1701
	int srcu_idx;
	struct dm_table *map;
L
Linus Torvalds 已提交
1702

M
Mikulas Patocka 已提交
1703
	map = dm_get_live_table(md, &srcu_idx);
L
Linus Torvalds 已提交
1704

1705
	generic_start_io_acct(rw, bio_sectors(bio), &dm_disk(md)->part0);
1706

1707 1708
	/* if we're suspended, we have to queue this io for later */
	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
M
Mikulas Patocka 已提交
1709
		dm_put_live_table(md, srcu_idx);
L
Linus Torvalds 已提交
1710

1711 1712 1713
		if (bio_rw(bio) != READA)
			queue_io(md, bio);
		else
A
Alasdair G Kergon 已提交
1714
			bio_io_error(bio);
1715
		return;
L
Linus Torvalds 已提交
1716 1717
	}

M
Mikulas Patocka 已提交
1718 1719
	__split_and_process_bio(md, map, bio);
	dm_put_live_table(md, srcu_idx);
1720
	return;
1721 1722
}

M
Mikulas Patocka 已提交
1723
int dm_request_based(struct mapped_device *md)
1724 1725 1726 1727
{
	return blk_queue_stackable(md->queue);
}

1728
static void dm_request(struct request_queue *q, struct bio *bio)
1729 1730 1731 1732
{
	struct mapped_device *md = q->queuedata;

	if (dm_request_based(md))
1733 1734 1735
		blk_queue_bio(q, bio);
	else
		_dm_request(q, bio);
1736 1737
}

1738
static void dm_dispatch_clone_request(struct request *clone, struct request *rq)
1739 1740 1741
{
	int r;

1742 1743
	if (blk_queue_io_stat(clone->q))
		clone->cmd_flags |= REQ_IO_STAT;
1744

1745 1746
	clone->start_time = jiffies;
	r = blk_insert_cloned_request(clone->q, clone);
1747
	if (r)
1748
		/* must complete clone in terms of original request */
1749 1750 1751 1752 1753 1754 1755
		dm_complete_request(rq, r);
}

static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
				 void *data)
{
	struct dm_rq_target_io *tio = data;
1756 1757
	struct dm_rq_clone_bio_info *info =
		container_of(bio, struct dm_rq_clone_bio_info, clone);
1758 1759 1760 1761 1762 1763 1764 1765 1766

	info->orig = bio_orig;
	info->tio = tio;
	bio->bi_end_io = end_clone_bio;

	return 0;
}

static int setup_clone(struct request *clone, struct request *rq,
1767
		       struct dm_rq_target_io *tio, gfp_t gfp_mask)
1768
{
1769
	int r;
1770

1771
	r = blk_rq_prep_clone(clone, rq, tio->md->bs, gfp_mask,
1772 1773 1774
			      dm_rq_bio_constructor, tio);
	if (r)
		return r;
1775

1776 1777 1778
	clone->cmd = rq->cmd;
	clone->cmd_len = rq->cmd_len;
	clone->sense = rq->sense;
1779 1780 1781
	clone->end_io = end_clone_request;
	clone->end_io_data = tio;

1782 1783
	tio->clone = clone;

1784 1785 1786
	return 0;
}

K
Kiyoshi Ueda 已提交
1787
static struct request *clone_rq(struct request *rq, struct mapped_device *md,
1788
				struct dm_rq_target_io *tio, gfp_t gfp_mask)
1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804
{
	struct request *clone = alloc_clone_request(md, gfp_mask);

	if (!clone)
		return NULL;

	blk_rq_init(NULL, clone);
	if (setup_clone(clone, rq, tio, gfp_mask)) {
		/* -ENOMEM */
		free_clone_request(md, clone);
		return NULL;
	}

	return clone;
}

1805 1806
static void map_tio_request(struct kthread_work *work);

1807 1808
static struct dm_rq_target_io *prep_tio(struct request *rq,
					struct mapped_device *md, gfp_t gfp_mask)
K
Kiyoshi Ueda 已提交
1809 1810
{
	struct dm_rq_target_io *tio;
1811 1812
	int srcu_idx;
	struct dm_table *table;
K
Kiyoshi Ueda 已提交
1813 1814 1815 1816 1817 1818 1819

	tio = alloc_rq_tio(md, gfp_mask);
	if (!tio)
		return NULL;

	tio->md = md;
	tio->ti = NULL;
1820
	tio->clone = NULL;
K
Kiyoshi Ueda 已提交
1821 1822 1823
	tio->orig = rq;
	tio->error = 0;
	memset(&tio->info, 0, sizeof(tio->info));
1824
	init_kthread_work(&tio->work, map_tio_request);
K
Kiyoshi Ueda 已提交
1825

1826 1827 1828 1829 1830 1831 1832
	table = dm_get_live_table(md, &srcu_idx);
	if (!dm_table_mq_request_based(table)) {
		if (!clone_rq(rq, md, tio, gfp_mask)) {
			dm_put_live_table(md, srcu_idx);
			free_rq_tio(tio);
			return NULL;
		}
K
Kiyoshi Ueda 已提交
1833
	}
1834
	dm_put_live_table(md, srcu_idx);
K
Kiyoshi Ueda 已提交
1835

1836
	return tio;
K
Kiyoshi Ueda 已提交
1837 1838
}

1839 1840 1841 1842 1843 1844
/*
 * Called with the queue lock held.
 */
static int dm_prep_fn(struct request_queue *q, struct request *rq)
{
	struct mapped_device *md = q->queuedata;
1845
	struct dm_rq_target_io *tio;
1846 1847 1848 1849 1850 1851

	if (unlikely(rq->special)) {
		DMWARN("Already has something in rq->special.");
		return BLKPREP_KILL;
	}

1852 1853
	tio = prep_tio(rq, md, GFP_ATOMIC);
	if (!tio)
1854 1855
		return BLKPREP_DEFER;

1856
	rq->special = tio;
1857 1858 1859 1860 1861
	rq->cmd_flags |= REQ_DONTPREP;

	return BLKPREP_OK;
}

1862 1863
/*
 * Returns:
1864 1865 1866
 * 0                : the request has been processed
 * DM_MAPIO_REQUEUE : the original request needs to be requeued
 * < 0              : the request was completed due to failure
1867
 */
1868
static int map_request(struct dm_target *ti, struct request *rq,
1869
		       struct mapped_device *md)
1870
{
1871
	int r;
1872
	struct dm_rq_target_io *tio = rq->special;
1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892
	struct request *clone = NULL;

	if (tio->clone) {
		clone = tio->clone;
		r = ti->type->map_rq(ti, clone, &tio->info);
	} else {
		r = ti->type->clone_and_map_rq(ti, rq, &tio->info, &clone);
		if (r < 0) {
			/* The target wants to complete the I/O */
			dm_kill_unmapped_request(rq, r);
			return r;
		}
		if (IS_ERR(clone))
			return DM_MAPIO_REQUEUE;
		if (setup_clone(clone, rq, tio, GFP_KERNEL)) {
			/* -ENOMEM */
			ti->type->release_clone_rq(clone);
			return DM_MAPIO_REQUEUE;
		}
	}
1893 1894 1895 1896 1897 1898 1899

	switch (r) {
	case DM_MAPIO_SUBMITTED:
		/* The target has taken the I/O to submit by itself later */
		break;
	case DM_MAPIO_REMAPPED:
		/* The target has remapped the I/O so dispatch it */
1900
		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
1901 1902
				     blk_rq_pos(rq));
		dm_dispatch_clone_request(clone, rq);
1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914
		break;
	case DM_MAPIO_REQUEUE:
		/* The target wants to requeue the I/O */
		dm_requeue_unmapped_request(clone);
		break;
	default:
		if (r > 0) {
			DMWARN("unimplemented target map return value: %d", r);
			BUG();
		}

		/* The target wants to complete the I/O */
1915
		dm_kill_unmapped_request(rq, r);
1916
		return r;
1917
	}
1918

1919
	return 0;
1920 1921
}

1922
static void map_tio_request(struct kthread_work *work)
1923
{
1924
	struct dm_rq_target_io *tio = container_of(work, struct dm_rq_target_io, work);
1925 1926
	struct request *rq = tio->orig;
	struct mapped_device *md = tio->md;
1927

1928 1929
	if (map_request(tio->ti, rq, md) == DM_MAPIO_REQUEUE)
		dm_requeue_unmapped_original_request(md, rq);
1930 1931
}

1932
static void dm_start_request(struct mapped_device *md, struct request *orig)
1933 1934
{
	blk_start_request(orig);
1935
	atomic_inc(&md->pending[rq_data_dir(orig)]);
1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946

	/*
	 * Hold the md reference here for the in-flight I/O.
	 * We can't rely on the reference count by device opener,
	 * because the device may be closed during the request completion
	 * when all bios are completed.
	 * See the comment in rq_completed() too.
	 */
	dm_get(md);
}

1947 1948 1949 1950 1951 1952 1953
/*
 * q->request_fn for request-based dm.
 * Called with the queue lock held.
 */
static void dm_request_fn(struct request_queue *q)
{
	struct mapped_device *md = q->queuedata;
M
Mikulas Patocka 已提交
1954 1955
	int srcu_idx;
	struct dm_table *map = dm_get_live_table(md, &srcu_idx);
1956
	struct dm_target *ti;
1957
	struct request *rq;
1958
	struct dm_rq_target_io *tio;
1959
	sector_t pos;
1960 1961

	/*
1962 1963 1964 1965
	 * For suspend, check blk_queue_stopped() and increment
	 * ->pending within a single queue_lock not to increment the
	 * number of in-flight I/Os after the queue is stopped in
	 * dm_suspend().
1966
	 */
J
Jens Axboe 已提交
1967
	while (!blk_queue_stopped(q)) {
1968 1969
		rq = blk_peek_request(q);
		if (!rq)
J
Jens Axboe 已提交
1970
			goto delay_and_out;
1971

1972 1973 1974 1975 1976 1977
		/* always use block 0 to find the target for flushes for now */
		pos = 0;
		if (!(rq->cmd_flags & REQ_FLUSH))
			pos = blk_rq_pos(rq);

		ti = dm_table_find_target(map, pos);
1978 1979
		if (!dm_target_is_valid(ti)) {
			/*
1980
			 * Must perform setup, that rq_completed() requires,
1981 1982 1983
			 * before calling dm_kill_unmapped_request
			 */
			DMERR_LIMIT("request attempted access beyond the end of device");
1984 1985
			dm_start_request(md, rq);
			dm_kill_unmapped_request(rq, -EIO);
1986 1987
			continue;
		}
1988

1989
		if (ti->type->busy && ti->type->busy(ti))
J
Jens Axboe 已提交
1990
			goto delay_and_out;
1991

1992
		dm_start_request(md, rq);
1993

1994 1995 1996 1997
		tio = rq->special;
		/* Establish tio->ti before queuing work (map_tio_request) */
		tio->ti = ti;
		queue_kthread_work(&md->kworker, &tio->work);
1998
		BUG_ON(!irqs_disabled());
1999 2000 2001 2002
	}

	goto out;

J
Jens Axboe 已提交
2003 2004
delay_and_out:
	blk_delay_queue(q, HZ / 10);
2005
out:
M
Mikulas Patocka 已提交
2006
	dm_put_live_table(md, srcu_idx);
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
}

int dm_underlying_device_busy(struct request_queue *q)
{
	return blk_lld_busy(q);
}
EXPORT_SYMBOL_GPL(dm_underlying_device_busy);

static int dm_lld_busy(struct request_queue *q)
{
	int r;
	struct mapped_device *md = q->queuedata;
M
Mikulas Patocka 已提交
2019
	struct dm_table *map = dm_get_live_table_fast(md);
2020 2021 2022 2023 2024 2025

	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
		r = 1;
	else
		r = dm_table_any_busy_target(map);

M
Mikulas Patocka 已提交
2026
	dm_put_live_table_fast(md);
2027 2028 2029 2030

	return r;
}

L
Linus Torvalds 已提交
2031 2032
static int dm_any_congested(void *congested_data, int bdi_bits)
{
2033 2034 2035
	int r = bdi_bits;
	struct mapped_device *md = congested_data;
	struct dm_table *map;
L
Linus Torvalds 已提交
2036

2037
	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
M
Mikulas Patocka 已提交
2038
		map = dm_get_live_table_fast(md);
2039
		if (map) {
2040 2041 2042 2043 2044 2045 2046 2047 2048
			/*
			 * Request-based dm cares about only own queue for
			 * the query about congestion status of request_queue
			 */
			if (dm_request_based(md))
				r = md->queue->backing_dev_info.state &
				    bdi_bits;
			else
				r = dm_table_any_congested(map, bdi_bits);
2049
		}
M
Mikulas Patocka 已提交
2050
		dm_put_live_table_fast(md);
2051 2052
	}

L
Linus Torvalds 已提交
2053 2054 2055 2056 2057 2058
	return r;
}

/*-----------------------------------------------------------------
 * An IDR is used to keep track of allocated minor numbers.
 *---------------------------------------------------------------*/
2059
static void free_minor(int minor)
L
Linus Torvalds 已提交
2060
{
2061
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
2062
	idr_remove(&_minor_idr, minor);
2063
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
2064 2065 2066 2067 2068
}

/*
 * See if the device with a specific minor # is free.
 */
2069
static int specific_minor(int minor)
L
Linus Torvalds 已提交
2070
{
T
Tejun Heo 已提交
2071
	int r;
L
Linus Torvalds 已提交
2072 2073 2074 2075

	if (minor >= (1 << MINORBITS))
		return -EINVAL;

T
Tejun Heo 已提交
2076
	idr_preload(GFP_KERNEL);
2077
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
2078

T
Tejun Heo 已提交
2079
	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT);
L
Linus Torvalds 已提交
2080

2081
	spin_unlock(&_minor_lock);
T
Tejun Heo 已提交
2082 2083 2084 2085
	idr_preload_end();
	if (r < 0)
		return r == -ENOSPC ? -EBUSY : r;
	return 0;
L
Linus Torvalds 已提交
2086 2087
}

2088
static int next_free_minor(int *minor)
L
Linus Torvalds 已提交
2089
{
T
Tejun Heo 已提交
2090
	int r;
J
Jeff Mahoney 已提交
2091

T
Tejun Heo 已提交
2092
	idr_preload(GFP_KERNEL);
2093
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
2094

T
Tejun Heo 已提交
2095
	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT);
L
Linus Torvalds 已提交
2096

2097
	spin_unlock(&_minor_lock);
T
Tejun Heo 已提交
2098 2099 2100 2101 2102
	idr_preload_end();
	if (r < 0)
		return r;
	*minor = r;
	return 0;
L
Linus Torvalds 已提交
2103 2104
}

2105
static const struct block_device_operations dm_blk_dops;
L
Linus Torvalds 已提交
2106

2107 2108
static void dm_wq_work(struct work_struct *work);

2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129
static void dm_init_md_queue(struct mapped_device *md)
{
	/*
	 * Request-based dm devices cannot be stacked on top of bio-based dm
	 * devices.  The type of this dm device has not been decided yet.
	 * The type is decided at the first table loading time.
	 * To prevent problematic device stacking, clear the queue flag
	 * for request stacking support until then.
	 *
	 * This queue is new, so no concurrency on the queue_flags.
	 */
	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);

	md->queue->queuedata = md;
	md->queue->backing_dev_info.congested_fn = dm_any_congested;
	md->queue->backing_dev_info.congested_data = md;
	blk_queue_make_request(md->queue, dm_request);
	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
}

L
Linus Torvalds 已提交
2130 2131 2132
/*
 * Allocate and initialise a blank device with a given minor.
 */
2133
static struct mapped_device *alloc_dev(int minor)
L
Linus Torvalds 已提交
2134 2135
{
	int r;
2136
	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
2137
	void *old_md;
L
Linus Torvalds 已提交
2138 2139 2140 2141 2142 2143

	if (!md) {
		DMWARN("unable to allocate device, out of memory.");
		return NULL;
	}

2144
	if (!try_module_get(THIS_MODULE))
M
Milan Broz 已提交
2145
		goto bad_module_get;
2146

L
Linus Torvalds 已提交
2147
	/* get a minor number for the dev */
2148
	if (minor == DM_ANY_MINOR)
2149
		r = next_free_minor(&minor);
2150
	else
2151
		r = specific_minor(minor);
L
Linus Torvalds 已提交
2152
	if (r < 0)
M
Milan Broz 已提交
2153
		goto bad_minor;
L
Linus Torvalds 已提交
2154

M
Mikulas Patocka 已提交
2155 2156 2157 2158
	r = init_srcu_struct(&md->io_barrier);
	if (r < 0)
		goto bad_io_barrier;

2159
	md->type = DM_TYPE_NONE;
2160
	mutex_init(&md->suspend_lock);
2161
	mutex_init(&md->type_lock);
2162
	mutex_init(&md->table_devices_lock);
2163
	spin_lock_init(&md->deferred_lock);
L
Linus Torvalds 已提交
2164
	atomic_set(&md->holders, 1);
2165
	atomic_set(&md->open_count, 0);
L
Linus Torvalds 已提交
2166
	atomic_set(&md->event_nr, 0);
M
Mike Anderson 已提交
2167 2168
	atomic_set(&md->uevent_seq, 0);
	INIT_LIST_HEAD(&md->uevent_list);
2169
	INIT_LIST_HEAD(&md->table_devices);
M
Mike Anderson 已提交
2170
	spin_lock_init(&md->uevent_lock);
L
Linus Torvalds 已提交
2171

2172
	md->queue = blk_alloc_queue(GFP_KERNEL);
L
Linus Torvalds 已提交
2173
	if (!md->queue)
M
Milan Broz 已提交
2174
		goto bad_queue;
L
Linus Torvalds 已提交
2175

2176
	dm_init_md_queue(md);
S
Stefan Bader 已提交
2177

L
Linus Torvalds 已提交
2178 2179
	md->disk = alloc_disk(1);
	if (!md->disk)
M
Milan Broz 已提交
2180
		goto bad_disk;
L
Linus Torvalds 已提交
2181

2182 2183
	atomic_set(&md->pending[0], 0);
	atomic_set(&md->pending[1], 0);
2184
	init_waitqueue_head(&md->wait);
2185
	INIT_WORK(&md->work, dm_wq_work);
2186
	init_waitqueue_head(&md->eventq);
2187
	init_completion(&md->kobj_holder.completion);
2188
	md->kworker_task = NULL;
2189

L
Linus Torvalds 已提交
2190 2191 2192 2193 2194 2195 2196
	md->disk->major = _major;
	md->disk->first_minor = minor;
	md->disk->fops = &dm_blk_dops;
	md->disk->queue = md->queue;
	md->disk->private_data = md;
	sprintf(md->disk->disk_name, "dm-%d", minor);
	add_disk(md->disk);
M
Mike Anderson 已提交
2197
	format_dev_t(md->name, MKDEV(_major, minor));
L
Linus Torvalds 已提交
2198

T
Tejun Heo 已提交
2199
	md->wq = alloc_workqueue("kdmflush", WQ_MEM_RECLAIM, 0);
2200 2201 2202
	if (!md->wq)
		goto bad_thread;

M
Mikulas Patocka 已提交
2203 2204 2205 2206
	md->bdev = bdget_disk(md->disk, 0);
	if (!md->bdev)
		goto bad_bdev;

2207 2208 2209 2210
	bio_init(&md->flush_bio);
	md->flush_bio.bi_bdev = md->bdev;
	md->flush_bio.bi_rw = WRITE_FLUSH;

M
Mikulas Patocka 已提交
2211 2212
	dm_stats_init(&md->stats);

2213
	/* Populate the mapping, nobody knows we exist yet */
2214
	spin_lock(&_minor_lock);
2215
	old_md = idr_replace(&_minor_idr, md, minor);
2216
	spin_unlock(&_minor_lock);
2217 2218 2219

	BUG_ON(old_md != MINOR_ALLOCED);

L
Linus Torvalds 已提交
2220 2221
	return md;

M
Mikulas Patocka 已提交
2222 2223
bad_bdev:
	destroy_workqueue(md->wq);
2224
bad_thread:
2225
	del_gendisk(md->disk);
2226
	put_disk(md->disk);
M
Milan Broz 已提交
2227
bad_disk:
2228
	blk_cleanup_queue(md->queue);
M
Milan Broz 已提交
2229
bad_queue:
M
Mikulas Patocka 已提交
2230 2231
	cleanup_srcu_struct(&md->io_barrier);
bad_io_barrier:
L
Linus Torvalds 已提交
2232
	free_minor(minor);
M
Milan Broz 已提交
2233
bad_minor:
2234
	module_put(THIS_MODULE);
M
Milan Broz 已提交
2235
bad_module_get:
L
Linus Torvalds 已提交
2236 2237 2238 2239
	kfree(md);
	return NULL;
}

J
Jun'ichi Nomura 已提交
2240 2241
static void unlock_fs(struct mapped_device *md);

L
Linus Torvalds 已提交
2242 2243
static void free_dev(struct mapped_device *md)
{
2244
	int minor = MINOR(disk_devt(md->disk));
2245

M
Mikulas Patocka 已提交
2246
	unlock_fs(md);
2247
	destroy_workqueue(md->wq);
2248 2249 2250

	if (md->kworker_task)
		kthread_stop(md->kworker_task);
K
Kiyoshi Ueda 已提交
2251 2252
	if (md->io_pool)
		mempool_destroy(md->io_pool);
2253 2254
	if (md->rq_pool)
		mempool_destroy(md->rq_pool);
K
Kiyoshi Ueda 已提交
2255 2256
	if (md->bs)
		bioset_free(md->bs);
2257

M
Mikulas Patocka 已提交
2258
	cleanup_srcu_struct(&md->io_barrier);
2259
	free_table_devices(&md->table_devices);
2260
	dm_stats_cleanup(&md->stats);
J
Jeff Mahoney 已提交
2261 2262 2263 2264

	spin_lock(&_minor_lock);
	md->disk->private_data = NULL;
	spin_unlock(&_minor_lock);
2265 2266 2267
	if (blk_get_integrity(md->disk))
		blk_integrity_unregister(md->disk);
	del_gendisk(md->disk);
L
Linus Torvalds 已提交
2268
	put_disk(md->disk);
2269
	blk_cleanup_queue(md->queue);
2270 2271 2272
	bdput(md->bdev);
	free_minor(minor);

2273
	module_put(THIS_MODULE);
L
Linus Torvalds 已提交
2274 2275 2276
	kfree(md);
}

K
Kiyoshi Ueda 已提交
2277 2278
static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
M
Mikulas Patocka 已提交
2279
	struct dm_md_mempools *p = dm_table_get_md_mempools(t);
K
Kiyoshi Ueda 已提交
2280

J
Jun'ichi Nomura 已提交
2281
	if (md->io_pool && md->bs) {
2282 2283 2284 2285 2286 2287 2288 2289 2290 2291
		/* The md already has necessary mempools. */
		if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
			/*
			 * Reload bioset because front_pad may have changed
			 * because a different table was loaded.
			 */
			bioset_free(md->bs);
			md->bs = p->bs;
			p->bs = NULL;
		}
2292 2293 2294 2295 2296 2297 2298 2299
		/*
		 * There's no need to reload with request-based dm
		 * because the size of front_pad doesn't change.
		 * Note for future: If you are to reload bioset,
		 * prep-ed requests in the queue may refer
		 * to bio from the old bioset, so you must walk
		 * through the queue to unprep.
		 */
K
Kiyoshi Ueda 已提交
2300
		goto out;
M
Mikulas Patocka 已提交
2301
	}
K
Kiyoshi Ueda 已提交
2302

2303
	BUG_ON(!p || md->io_pool || md->rq_pool || md->bs);
K
Kiyoshi Ueda 已提交
2304 2305 2306

	md->io_pool = p->io_pool;
	p->io_pool = NULL;
2307 2308
	md->rq_pool = p->rq_pool;
	p->rq_pool = NULL;
K
Kiyoshi Ueda 已提交
2309 2310 2311 2312 2313 2314 2315 2316
	md->bs = p->bs;
	p->bs = NULL;

out:
	/* mempool bind completed, now no need any mempools in the table */
	dm_table_free_md_mempools(t);
}

L
Linus Torvalds 已提交
2317 2318 2319 2320 2321
/*
 * Bind a table to the device.
 */
static void event_callback(void *context)
{
M
Mike Anderson 已提交
2322 2323
	unsigned long flags;
	LIST_HEAD(uevents);
L
Linus Torvalds 已提交
2324 2325
	struct mapped_device *md = (struct mapped_device *) context;

M
Mike Anderson 已提交
2326 2327 2328 2329
	spin_lock_irqsave(&md->uevent_lock, flags);
	list_splice_init(&md->uevent_list, &uevents);
	spin_unlock_irqrestore(&md->uevent_lock, flags);

2330
	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
M
Mike Anderson 已提交
2331

L
Linus Torvalds 已提交
2332 2333 2334 2335
	atomic_inc(&md->event_nr);
	wake_up(&md->eventq);
}

2336 2337 2338
/*
 * Protected by md->suspend_lock obtained by dm_swap_table().
 */
2339
static void __set_size(struct mapped_device *md, sector_t size)
L
Linus Torvalds 已提交
2340
{
2341
	set_capacity(md->disk, size);
L
Linus Torvalds 已提交
2342

2343
	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
L
Linus Torvalds 已提交
2344 2345
}

2346 2347 2348 2349 2350 2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368 2369 2370 2371 2372 2373 2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386 2387 2388 2389 2390 2391 2392 2393 2394 2395 2396 2397 2398
/*
 * Return 1 if the queue has a compulsory merge_bvec_fn function.
 *
 * If this function returns 0, then the device is either a non-dm
 * device without a merge_bvec_fn, or it is a dm device that is
 * able to split any bios it receives that are too big.
 */
int dm_queue_merge_is_compulsory(struct request_queue *q)
{
	struct mapped_device *dev_md;

	if (!q->merge_bvec_fn)
		return 0;

	if (q->make_request_fn == dm_request) {
		dev_md = q->queuedata;
		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
			return 0;
	}

	return 1;
}

static int dm_device_merge_is_compulsory(struct dm_target *ti,
					 struct dm_dev *dev, sector_t start,
					 sector_t len, void *data)
{
	struct block_device *bdev = dev->bdev;
	struct request_queue *q = bdev_get_queue(bdev);

	return dm_queue_merge_is_compulsory(q);
}

/*
 * Return 1 if it is acceptable to ignore merge_bvec_fn based
 * on the properties of the underlying devices.
 */
static int dm_table_merge_is_optional(struct dm_table *table)
{
	unsigned i = 0;
	struct dm_target *ti;

	while (i < dm_table_get_num_targets(table)) {
		ti = dm_table_get_target(table, i++);

		if (ti->type->iterate_devices &&
		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
			return 0;
	}

	return 1;
}

2399 2400 2401 2402 2403
/*
 * Returns old map, which caller must destroy.
 */
static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
			       struct queue_limits *limits)
L
Linus Torvalds 已提交
2404
{
2405
	struct dm_table *old_map;
2406
	struct request_queue *q = md->queue;
L
Linus Torvalds 已提交
2407
	sector_t size;
2408
	int merge_is_optional;
L
Linus Torvalds 已提交
2409 2410

	size = dm_table_get_size(t);
D
Darrick J. Wong 已提交
2411 2412 2413 2414

	/*
	 * Wipe any geometry if the size of the table changed.
	 */
M
Mikulas Patocka 已提交
2415
	if (size != dm_get_size(md))
D
Darrick J. Wong 已提交
2416 2417
		memset(&md->geometry, 0, sizeof(md->geometry));

M
Mikulas Patocka 已提交
2418
	__set_size(md, size);
2419

2420 2421
	dm_table_event_callback(t, event_callback, md);

K
Kiyoshi Ueda 已提交
2422 2423 2424 2425 2426 2427 2428 2429 2430 2431 2432 2433
	/*
	 * The queue hasn't been stopped yet, if the old table type wasn't
	 * for request-based during suspension.  So stop it to prevent
	 * I/O mapping before resume.
	 * This must be done before setting the queue restrictions,
	 * because request-based dm may be run just after the setting.
	 */
	if (dm_table_request_based(t) && !blk_queue_stopped(q))
		stop_queue(q);

	__bind_mempools(md, t);

2434 2435
	merge_is_optional = dm_table_merge_is_optional(t);

2436
	old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
M
Mikulas Patocka 已提交
2437
	rcu_assign_pointer(md->map, t);
2438 2439
	md->immutable_target_type = dm_table_get_immutable_target_type(t);

2440
	dm_table_set_restrictions(t, q, limits);
2441 2442 2443 2444
	if (merge_is_optional)
		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
	else
		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
2445 2446
	if (old_map)
		dm_sync_table(md);
L
Linus Torvalds 已提交
2447

2448
	return old_map;
L
Linus Torvalds 已提交
2449 2450
}

2451 2452 2453 2454
/*
 * Returns unbound table for the caller to free.
 */
static struct dm_table *__unbind(struct mapped_device *md)
L
Linus Torvalds 已提交
2455
{
2456
	struct dm_table *map = rcu_dereference_protected(md->map, 1);
L
Linus Torvalds 已提交
2457 2458

	if (!map)
2459
		return NULL;
L
Linus Torvalds 已提交
2460 2461

	dm_table_event_callback(map, NULL, NULL);
2462
	RCU_INIT_POINTER(md->map, NULL);
M
Mikulas Patocka 已提交
2463
	dm_sync_table(md);
2464 2465

	return map;
L
Linus Torvalds 已提交
2466 2467 2468 2469 2470
}

/*
 * Constructor for a new device.
 */
2471
int dm_create(int minor, struct mapped_device **result)
L
Linus Torvalds 已提交
2472 2473 2474
{
	struct mapped_device *md;

2475
	md = alloc_dev(minor);
L
Linus Torvalds 已提交
2476 2477 2478
	if (!md)
		return -ENXIO;

M
Milan Broz 已提交
2479 2480
	dm_sysfs_init(md);

L
Linus Torvalds 已提交
2481 2482 2483 2484
	*result = md;
	return 0;
}

2485 2486 2487 2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500
/*
 * Functions to manage md->type.
 * All are required to hold md->type_lock.
 */
void dm_lock_md_type(struct mapped_device *md)
{
	mutex_lock(&md->type_lock);
}

void dm_unlock_md_type(struct mapped_device *md)
{
	mutex_unlock(&md->type_lock);
}

void dm_set_md_type(struct mapped_device *md, unsigned type)
{
2501
	BUG_ON(!mutex_is_locked(&md->type_lock));
2502 2503 2504 2505 2506
	md->type = type;
}

unsigned dm_get_md_type(struct mapped_device *md)
{
2507
	BUG_ON(!mutex_is_locked(&md->type_lock));
2508 2509 2510
	return md->type;
}

2511 2512 2513 2514 2515 2516 2517 2518
static bool dm_md_type_request_based(struct mapped_device *md)
{
	unsigned table_type = dm_get_md_type(md);

	return (table_type == DM_TYPE_REQUEST_BASED ||
		table_type == DM_TYPE_MQ_REQUEST_BASED);
}

2519 2520 2521 2522 2523
struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
{
	return md->immutable_target_type;
}

2524 2525 2526 2527 2528 2529 2530 2531 2532 2533 2534
/*
 * The queue_limits are only valid as long as you have a reference
 * count on 'md'.
 */
struct queue_limits *dm_get_queue_limits(struct mapped_device *md)
{
	BUG_ON(!atomic_read(&md->holders));
	return &md->queue->limits;
}
EXPORT_SYMBOL_GPL(dm_get_queue_limits);

2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555
/*
 * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
 */
static int dm_init_request_based_queue(struct mapped_device *md)
{
	struct request_queue *q = NULL;

	if (md->queue->elevator)
		return 1;

	/* Fully initialize the queue */
	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
	if (!q)
		return 0;

	md->queue = q;
	dm_init_md_queue(md);
	blk_queue_softirq_done(md->queue, dm_softirq_done);
	blk_queue_prep_rq(md->queue, dm_prep_fn);
	blk_queue_lld_busy(md->queue, dm_lld_busy);

2556 2557 2558 2559 2560
	/* Also initialize the request-based DM worker thread */
	init_kthread_worker(&md->kworker);
	md->kworker_task = kthread_run(kthread_worker_fn, &md->kworker,
				       "kdmwork-%s", dm_device_name(md));

2561 2562 2563 2564 2565 2566 2567 2568 2569 2570
	elv_register_queue(md->queue);

	return 1;
}

/*
 * Setup the DM device's queue based on md's type
 */
int dm_setup_md_queue(struct mapped_device *md)
{
2571
	if (dm_md_type_request_based(md) && !dm_init_request_based_queue(md)) {
2572 2573 2574 2575 2576 2577 2578
		DMWARN("Cannot initialize queue for request-based mapped device");
		return -EINVAL;
	}

	return 0;
}

2579
struct mapped_device *dm_get_md(dev_t dev)
L
Linus Torvalds 已提交
2580 2581 2582 2583 2584 2585 2586
{
	struct mapped_device *md;
	unsigned minor = MINOR(dev);

	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
		return NULL;

2587
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
2588 2589

	md = idr_find(&_minor_idr, minor);
2590 2591 2592 2593 2594 2595 2596 2597 2598
	if (md) {
		if ((md == MINOR_ALLOCED ||
		     (MINOR(disk_devt(dm_disk(md))) != minor) ||
		     dm_deleting_md(md) ||
		     test_bit(DMF_FREEING, &md->flags))) {
			md = NULL;
			goto out;
		}
		dm_get(md);
J
Jeff Mahoney 已提交
2599
	}
L
Linus Torvalds 已提交
2600

J
Jeff Mahoney 已提交
2601
out:
2602
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
2603

2604 2605
	return md;
}
A
Alasdair G Kergon 已提交
2606
EXPORT_SYMBOL_GPL(dm_get_md);
2607

A
Alasdair G Kergon 已提交
2608
void *dm_get_mdptr(struct mapped_device *md)
2609
{
A
Alasdair G Kergon 已提交
2610
	return md->interface_ptr;
L
Linus Torvalds 已提交
2611 2612 2613 2614 2615 2616 2617 2618 2619 2620
}

void dm_set_mdptr(struct mapped_device *md, void *ptr)
{
	md->interface_ptr = ptr;
}

void dm_get(struct mapped_device *md)
{
	atomic_inc(&md->holders);
2621
	BUG_ON(test_bit(DMF_FREEING, &md->flags));
L
Linus Torvalds 已提交
2622 2623
}

2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636
int dm_hold(struct mapped_device *md)
{
	spin_lock(&_minor_lock);
	if (test_bit(DMF_FREEING, &md->flags)) {
		spin_unlock(&_minor_lock);
		return -EBUSY;
	}
	dm_get(md);
	spin_unlock(&_minor_lock);
	return 0;
}
EXPORT_SYMBOL_GPL(dm_hold);

2637 2638 2639 2640 2641 2642
const char *dm_device_name(struct mapped_device *md)
{
	return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);

2643
static void __dm_destroy(struct mapped_device *md, bool wait)
L
Linus Torvalds 已提交
2644
{
M
Mike Anderson 已提交
2645
	struct dm_table *map;
M
Mikulas Patocka 已提交
2646
	int srcu_idx;
L
Linus Torvalds 已提交
2647

2648
	might_sleep();
J
Jeff Mahoney 已提交
2649

M
Mikulas Patocka 已提交
2650
	map = dm_get_live_table(md, &srcu_idx);
2651 2652

	spin_lock(&_minor_lock);
2653 2654 2655 2656
	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
	set_bit(DMF_FREEING, &md->flags);
	spin_unlock(&_minor_lock);

2657 2658 2659
	if (dm_request_based(md))
		flush_kthread_worker(&md->kworker);

2660 2661 2662 2663 2664
	/*
	 * Take suspend_lock so that presuspend and postsuspend methods
	 * do not race with internal suspend.
	 */
	mutex_lock(&md->suspend_lock);
2665 2666 2667
	if (!dm_suspended_md(md)) {
		dm_table_presuspend_targets(map);
		dm_table_postsuspend_targets(map);
L
Linus Torvalds 已提交
2668
	}
2669
	mutex_unlock(&md->suspend_lock);
2670

M
Mikulas Patocka 已提交
2671 2672 2673
	/* dm_put_live_table must be before msleep, otherwise deadlock is possible */
	dm_put_live_table(md, srcu_idx);

2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685 2686 2687 2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704
	/*
	 * Rare, but there may be I/O requests still going to complete,
	 * for example.  Wait for all references to disappear.
	 * No one should increment the reference count of the mapped_device,
	 * after the mapped_device state becomes DMF_FREEING.
	 */
	if (wait)
		while (atomic_read(&md->holders))
			msleep(1);
	else if (atomic_read(&md->holders))
		DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
		       dm_device_name(md), atomic_read(&md->holders));

	dm_sysfs_exit(md);
	dm_table_destroy(__unbind(md));
	free_dev(md);
}

void dm_destroy(struct mapped_device *md)
{
	__dm_destroy(md, true);
}

void dm_destroy_immediate(struct mapped_device *md)
{
	__dm_destroy(md, false);
}

void dm_put(struct mapped_device *md)
{
	atomic_dec(&md->holders);
L
Linus Torvalds 已提交
2705
}
E
Edward Goggin 已提交
2706
EXPORT_SYMBOL_GPL(dm_put);
L
Linus Torvalds 已提交
2707

2708
static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2709 2710
{
	int r = 0;
2711 2712 2713
	DECLARE_WAITQUEUE(wait, current);

	add_wait_queue(&md->wait, &wait);
2714 2715

	while (1) {
2716
		set_current_state(interruptible);
2717

2718
		if (!md_in_flight(md))
2719 2720
			break;

2721 2722
		if (interruptible == TASK_INTERRUPTIBLE &&
		    signal_pending(current)) {
2723 2724 2725 2726 2727 2728 2729 2730
			r = -EINTR;
			break;
		}

		io_schedule();
	}
	set_current_state(TASK_RUNNING);

2731 2732
	remove_wait_queue(&md->wait, &wait);

2733 2734 2735
	return r;
}

L
Linus Torvalds 已提交
2736 2737 2738
/*
 * Process the deferred bios
 */
2739
static void dm_wq_work(struct work_struct *work)
L
Linus Torvalds 已提交
2740
{
2741 2742
	struct mapped_device *md = container_of(work, struct mapped_device,
						work);
2743
	struct bio *c;
M
Mikulas Patocka 已提交
2744 2745
	int srcu_idx;
	struct dm_table *map;
L
Linus Torvalds 已提交
2746

M
Mikulas Patocka 已提交
2747
	map = dm_get_live_table(md, &srcu_idx);
2748

2749
	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
A
Alasdair G Kergon 已提交
2750 2751 2752 2753
		spin_lock_irq(&md->deferred_lock);
		c = bio_list_pop(&md->deferred);
		spin_unlock_irq(&md->deferred_lock);

2754
		if (!c)
A
Alasdair G Kergon 已提交
2755
			break;
2756

K
Kiyoshi Ueda 已提交
2757 2758
		if (dm_request_based(md))
			generic_make_request(c);
2759
		else
M
Mikulas Patocka 已提交
2760
			__split_and_process_bio(md, map, c);
2761
	}
M
Milan Broz 已提交
2762

M
Mikulas Patocka 已提交
2763
	dm_put_live_table(md, srcu_idx);
L
Linus Torvalds 已提交
2764 2765
}

2766
static void dm_queue_flush(struct mapped_device *md)
2767
{
2768
	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2769
	smp_mb__after_atomic();
2770
	queue_work(md->wq, &md->work);
2771 2772
}

L
Linus Torvalds 已提交
2773
/*
2774
 * Swap in a new table, returning the old one for the caller to destroy.
L
Linus Torvalds 已提交
2775
 */
2776
struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
L
Linus Torvalds 已提交
2777
{
2778
	struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL);
2779
	struct queue_limits limits;
2780
	int r;
L
Linus Torvalds 已提交
2781

2782
	mutex_lock(&md->suspend_lock);
L
Linus Torvalds 已提交
2783 2784

	/* device must be suspended */
2785
	if (!dm_suspended_md(md))
2786
		goto out;
L
Linus Torvalds 已提交
2787

2788 2789 2790 2791 2792 2793 2794
	/*
	 * If the new table has no data devices, retain the existing limits.
	 * This helps multipath with queue_if_no_path if all paths disappear,
	 * then new I/O is queued based on these limits, and then some paths
	 * reappear.
	 */
	if (dm_table_has_no_data_devices(table)) {
M
Mikulas Patocka 已提交
2795
		live_map = dm_get_live_table_fast(md);
2796 2797
		if (live_map)
			limits = md->queue->limits;
M
Mikulas Patocka 已提交
2798
		dm_put_live_table_fast(md);
2799 2800
	}

2801 2802 2803 2804 2805 2806
	if (!live_map) {
		r = dm_calculate_queue_limits(table, &limits);
		if (r) {
			map = ERR_PTR(r);
			goto out;
		}
2807
	}
2808

2809
	map = __bind(md, table, &limits);
L
Linus Torvalds 已提交
2810

2811
out:
2812
	mutex_unlock(&md->suspend_lock);
2813
	return map;
L
Linus Torvalds 已提交
2814 2815 2816 2817 2818 2819
}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
2820
static int lock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
2821
{
2822
	int r;
L
Linus Torvalds 已提交
2823 2824

	WARN_ON(md->frozen_sb);
2825

2826
	md->frozen_sb = freeze_bdev(md->bdev);
2827
	if (IS_ERR(md->frozen_sb)) {
2828
		r = PTR_ERR(md->frozen_sb);
2829 2830
		md->frozen_sb = NULL;
		return r;
2831 2832
	}

2833 2834
	set_bit(DMF_FROZEN, &md->flags);

L
Linus Torvalds 已提交
2835 2836 2837
	return 0;
}

2838
static void unlock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
2839
{
2840 2841 2842
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

2843
	thaw_bdev(md->bdev, md->frozen_sb);
L
Linus Torvalds 已提交
2844
	md->frozen_sb = NULL;
2845
	clear_bit(DMF_FROZEN, &md->flags);
L
Linus Torvalds 已提交
2846 2847 2848
}

/*
2849 2850 2851
 * If __dm_suspend returns 0, the device is completely quiescent
 * now. There is no request-processing activity. All new requests
 * are being added to md->deferred list.
2852
 *
2853
 * Caller must hold md->suspend_lock
2854
 */
2855 2856
static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
			unsigned suspend_flags, int interruptible)
L
Linus Torvalds 已提交
2857
{
2858 2859 2860
	bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG;
	bool noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG;
	int r;
L
Linus Torvalds 已提交
2861

2862 2863 2864 2865 2866 2867 2868
	/*
	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
	 * This flag is cleared before dm_suspend returns.
	 */
	if (noflush)
		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);

2869 2870 2871 2872
	/*
	 * This gets reverted if there's an error later and the targets
	 * provide the .presuspend_undo hook.
	 */
2873 2874
	dm_table_presuspend_targets(map);

M
Mikulas Patocka 已提交
2875
	/*
K
Kiyoshi Ueda 已提交
2876 2877 2878 2879
	 * Flush I/O to the device.
	 * Any I/O submitted after lock_fs() may not be flushed.
	 * noflush takes precedence over do_lockfs.
	 * (lock_fs() flushes I/Os and waits for them to complete.)
M
Mikulas Patocka 已提交
2880 2881 2882
	 */
	if (!noflush && do_lockfs) {
		r = lock_fs(md);
2883 2884
		if (r) {
			dm_table_presuspend_undo_targets(map);
2885
			return r;
2886
		}
2887
	}
L
Linus Torvalds 已提交
2888 2889

	/*
2890 2891 2892 2893 2894 2895 2896
	 * Here we must make sure that no processes are submitting requests
	 * to target drivers i.e. no one may be executing
	 * __split_and_process_bio. This is called from dm_request and
	 * dm_wq_work.
	 *
	 * To get all processes out of __split_and_process_bio in dm_request,
	 * we take the write lock. To prevent any process from reentering
2897 2898 2899
	 * __split_and_process_bio from dm_request and quiesce the thread
	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
	 * flush_workqueue(md->wq).
L
Linus Torvalds 已提交
2900
	 */
2901
	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
2902 2903
	if (map)
		synchronize_srcu(&md->io_barrier);
L
Linus Torvalds 已提交
2904

2905
	/*
2906 2907
	 * Stop md->queue before flushing md->wq in case request-based
	 * dm defers requests to md->wq from md->queue.
2908
	 */
2909
	if (dm_request_based(md)) {
K
Kiyoshi Ueda 已提交
2910
		stop_queue(md->queue);
2911 2912
		flush_kthread_worker(&md->kworker);
	}
2913

2914 2915
	flush_workqueue(md->wq);

L
Linus Torvalds 已提交
2916
	/*
2917 2918 2919
	 * At this point no more requests are entering target request routines.
	 * We call dm_wait_for_completion to wait for all existing requests
	 * to finish.
L
Linus Torvalds 已提交
2920
	 */
2921
	r = dm_wait_for_completion(md, interruptible);
L
Linus Torvalds 已提交
2922

2923
	if (noflush)
2924
		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2925 2926
	if (map)
		synchronize_srcu(&md->io_barrier);
2927

L
Linus Torvalds 已提交
2928
	/* were we interrupted ? */
2929
	if (r < 0) {
2930
		dm_queue_flush(md);
M
Milan Broz 已提交
2931

2932
		if (dm_request_based(md))
K
Kiyoshi Ueda 已提交
2933
			start_queue(md->queue);
2934

2935
		unlock_fs(md);
2936
		dm_table_presuspend_undo_targets(map);
2937
		/* pushback list is already flushed, so skip flush */
2938
	}
L
Linus Torvalds 已提交
2939

2940 2941 2942 2943 2944 2945 2946 2947 2948 2949 2950 2951 2952 2953 2954 2955 2956 2957 2958 2959 2960 2961 2962 2963 2964 2965 2966 2967 2968 2969 2970 2971 2972 2973 2974 2975 2976 2977 2978 2979 2980
	return r;
}

/*
 * We need to be able to change a mapping table under a mounted
 * filesystem.  For example we might want to move some data in
 * the background.  Before the table can be swapped with
 * dm_bind_table, dm_suspend must be called to flush any in
 * flight bios and ensure that any further io gets deferred.
 */
/*
 * Suspend mechanism in request-based dm.
 *
 * 1. Flush all I/Os by lock_fs() if needed.
 * 2. Stop dispatching any I/O by stopping the request_queue.
 * 3. Wait for all in-flight I/Os to be completed or requeued.
 *
 * To abort suspend, start the request_queue.
 */
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
{
	struct dm_table *map = NULL;
	int r = 0;

retry:
	mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);

	if (dm_suspended_md(md)) {
		r = -EINVAL;
		goto out_unlock;
	}

	if (dm_suspended_internally_md(md)) {
		/* already internally suspended, wait for internal resume */
		mutex_unlock(&md->suspend_lock);
		r = wait_on_bit(&md->flags, DMF_SUSPENDED_INTERNALLY, TASK_INTERRUPTIBLE);
		if (r)
			return r;
		goto retry;
	}

2981
	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
2982 2983 2984 2985

	r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE);
	if (r)
		goto out_unlock;
2986

2987
	set_bit(DMF_SUSPENDED, &md->flags);
2988

2989 2990
	dm_table_postsuspend_targets(map);

2991
out_unlock:
2992
	mutex_unlock(&md->suspend_lock);
2993
	return r;
L
Linus Torvalds 已提交
2994 2995
}

2996 2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018
static int __dm_resume(struct mapped_device *md, struct dm_table *map)
{
	if (map) {
		int r = dm_table_resume_targets(map);
		if (r)
			return r;
	}

	dm_queue_flush(md);

	/*
	 * Flushing deferred I/Os must be done after targets are resumed
	 * so that mapping of targets can work correctly.
	 * Request-based dm is queueing the deferred I/Os in its request_queue.
	 */
	if (dm_request_based(md))
		start_queue(md->queue);

	unlock_fs(md);

	return 0;
}

L
Linus Torvalds 已提交
3019 3020
int dm_resume(struct mapped_device *md)
{
3021 3022
	int r = -EINVAL;
	struct dm_table *map = NULL;
L
Linus Torvalds 已提交
3023

3024 3025 3026
retry:
	mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);

3027
	if (!dm_suspended_md(md))
3028 3029
		goto out;

3030 3031 3032 3033 3034 3035 3036 3037 3038
	if (dm_suspended_internally_md(md)) {
		/* already internally suspended, wait for internal resume */
		mutex_unlock(&md->suspend_lock);
		r = wait_on_bit(&md->flags, DMF_SUSPENDED_INTERNALLY, TASK_INTERRUPTIBLE);
		if (r)
			return r;
		goto retry;
	}

3039
	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
3040
	if (!map || !dm_table_get_size(map))
3041
		goto out;
L
Linus Torvalds 已提交
3042

3043
	r = __dm_resume(md, map);
3044 3045
	if (r)
		goto out;
3046 3047 3048

	clear_bit(DMF_SUSPENDED, &md->flags);

3049 3050
	r = 0;
out:
3051
	mutex_unlock(&md->suspend_lock);
3052

3053
	return r;
L
Linus Torvalds 已提交
3054 3055
}

M
Mikulas Patocka 已提交
3056 3057 3058 3059 3060 3061
/*
 * Internal suspend/resume works like userspace-driven suspend. It waits
 * until all bios finish and prevents issuing new bios to the target drivers.
 * It may be used only from the kernel.
 */

3062
static void __dm_internal_suspend(struct mapped_device *md, unsigned suspend_flags)
M
Mikulas Patocka 已提交
3063
{
3064 3065
	struct dm_table *map = NULL;

3066
	if (md->internal_suspend_count++)
3067 3068 3069 3070 3071 3072 3073
		return; /* nested internal suspend */

	if (dm_suspended_md(md)) {
		set_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
		return; /* nest suspend */
	}

3074
	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
3075 3076 3077 3078 3079 3080 3081 3082 3083 3084 3085 3086 3087 3088 3089 3090

	/*
	 * Using TASK_UNINTERRUPTIBLE because only NOFLUSH internal suspend is
	 * supported.  Properly supporting a TASK_INTERRUPTIBLE internal suspend
	 * would require changing .presuspend to return an error -- avoid this
	 * until there is a need for more elaborate variants of internal suspend.
	 */
	(void) __dm_suspend(md, map, suspend_flags, TASK_UNINTERRUPTIBLE);

	set_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);

	dm_table_postsuspend_targets(map);
}

static void __dm_internal_resume(struct mapped_device *md)
{
3091 3092 3093
	BUG_ON(!md->internal_suspend_count);

	if (--md->internal_suspend_count)
3094 3095
		return; /* resume from nested internal suspend */

M
Mikulas Patocka 已提交
3096
	if (dm_suspended_md(md))
3097 3098 3099 3100 3101 3102 3103 3104 3105 3106 3107 3108 3109 3110 3111 3112 3113 3114 3115 3116 3117 3118 3119 3120 3121 3122 3123 3124 3125 3126 3127 3128 3129 3130 3131 3132 3133 3134 3135
		goto done; /* resume from nested suspend */

	/*
	 * NOTE: existing callers don't need to call dm_table_resume_targets
	 * (which may fail -- so best to avoid it for now by passing NULL map)
	 */
	(void) __dm_resume(md, NULL);

done:
	clear_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
	smp_mb__after_atomic();
	wake_up_bit(&md->flags, DMF_SUSPENDED_INTERNALLY);
}

void dm_internal_suspend_noflush(struct mapped_device *md)
{
	mutex_lock(&md->suspend_lock);
	__dm_internal_suspend(md, DM_SUSPEND_NOFLUSH_FLAG);
	mutex_unlock(&md->suspend_lock);
}
EXPORT_SYMBOL_GPL(dm_internal_suspend_noflush);

void dm_internal_resume(struct mapped_device *md)
{
	mutex_lock(&md->suspend_lock);
	__dm_internal_resume(md);
	mutex_unlock(&md->suspend_lock);
}
EXPORT_SYMBOL_GPL(dm_internal_resume);

/*
 * Fast variants of internal suspend/resume hold md->suspend_lock,
 * which prevents interaction with userspace-driven suspend.
 */

void dm_internal_suspend_fast(struct mapped_device *md)
{
	mutex_lock(&md->suspend_lock);
	if (dm_suspended_md(md) || dm_suspended_internally_md(md))
M
Mikulas Patocka 已提交
3136 3137 3138 3139 3140 3141 3142
		return;

	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
	synchronize_srcu(&md->io_barrier);
	flush_workqueue(md->wq);
	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
}
3143
EXPORT_SYMBOL_GPL(dm_internal_suspend_fast);
M
Mikulas Patocka 已提交
3144

3145
void dm_internal_resume_fast(struct mapped_device *md)
M
Mikulas Patocka 已提交
3146
{
3147
	if (dm_suspended_md(md) || dm_suspended_internally_md(md))
M
Mikulas Patocka 已提交
3148 3149 3150 3151 3152 3153 3154
		goto done;

	dm_queue_flush(md);

done:
	mutex_unlock(&md->suspend_lock);
}
3155
EXPORT_SYMBOL_GPL(dm_internal_resume_fast);
M
Mikulas Patocka 已提交
3156

L
Linus Torvalds 已提交
3157 3158 3159
/*-----------------------------------------------------------------
 * Event notification.
 *---------------------------------------------------------------*/
3160
int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
M
Milan Broz 已提交
3161
		       unsigned cookie)
3162
{
M
Milan Broz 已提交
3163 3164 3165 3166
	char udev_cookie[DM_COOKIE_LENGTH];
	char *envp[] = { udev_cookie, NULL };

	if (!cookie)
3167
		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
M
Milan Broz 已提交
3168 3169 3170
	else {
		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
			 DM_COOKIE_ENV_VAR_NAME, cookie);
3171 3172
		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
					  action, envp);
M
Milan Broz 已提交
3173
	}
3174 3175
}

M
Mike Anderson 已提交
3176 3177 3178 3179 3180
uint32_t dm_next_uevent_seq(struct mapped_device *md)
{
	return atomic_add_return(1, &md->uevent_seq);
}

L
Linus Torvalds 已提交
3181 3182 3183 3184 3185 3186 3187 3188 3189 3190 3191
uint32_t dm_get_event_nr(struct mapped_device *md)
{
	return atomic_read(&md->event_nr);
}

int dm_wait_event(struct mapped_device *md, int event_nr)
{
	return wait_event_interruptible(md->eventq,
			(event_nr != atomic_read(&md->event_nr)));
}

M
Mike Anderson 已提交
3192 3193 3194 3195 3196 3197 3198 3199 3200
void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
{
	unsigned long flags;

	spin_lock_irqsave(&md->uevent_lock, flags);
	list_add(elist, &md->uevent_list);
	spin_unlock_irqrestore(&md->uevent_lock, flags);
}

L
Linus Torvalds 已提交
3201 3202 3203 3204 3205 3206 3207 3208 3209
/*
 * The gendisk is only valid as long as you have a reference
 * count on 'md'.
 */
struct gendisk *dm_disk(struct mapped_device *md)
{
	return md->disk;
}

M
Milan Broz 已提交
3210 3211
struct kobject *dm_kobject(struct mapped_device *md)
{
3212
	return &md->kobj_holder.kobj;
M
Milan Broz 已提交
3213 3214 3215 3216 3217 3218
}

struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
{
	struct mapped_device *md;

3219
	md = container_of(kobj, struct mapped_device, kobj_holder.kobj);
M
Milan Broz 已提交
3220

3221
	if (test_bit(DMF_FREEING, &md->flags) ||
M
Mike Anderson 已提交
3222
	    dm_deleting_md(md))
3223 3224
		return NULL;

M
Milan Broz 已提交
3225 3226 3227 3228
	dm_get(md);
	return md;
}

3229
int dm_suspended_md(struct mapped_device *md)
L
Linus Torvalds 已提交
3230 3231 3232 3233
{
	return test_bit(DMF_SUSPENDED, &md->flags);
}

3234 3235 3236 3237 3238
int dm_suspended_internally_md(struct mapped_device *md)
{
	return test_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
}

M
Mikulas Patocka 已提交
3239 3240 3241 3242 3243
int dm_test_deferred_remove_flag(struct mapped_device *md)
{
	return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
}

3244 3245
int dm_suspended(struct dm_target *ti)
{
3246
	return dm_suspended_md(dm_table_get_md(ti->table));
3247 3248 3249
}
EXPORT_SYMBOL_GPL(dm_suspended);

3250 3251
int dm_noflush_suspending(struct dm_target *ti)
{
3252
	return __noflush_suspending(dm_table_get_md(ti->table));
3253 3254 3255
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);

M
Mikulas Patocka 已提交
3256
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size)
K
Kiyoshi Ueda 已提交
3257
{
J
Jun'ichi Nomura 已提交
3258 3259
	struct dm_md_mempools *pools = kzalloc(sizeof(*pools), GFP_KERNEL);
	struct kmem_cache *cachep;
3260
	unsigned int pool_size = 0;
J
Jun'ichi Nomura 已提交
3261
	unsigned int front_pad;
K
Kiyoshi Ueda 已提交
3262 3263 3264 3265

	if (!pools)
		return NULL;

3266 3267
	switch (type) {
	case DM_TYPE_BIO_BASED:
J
Jun'ichi Nomura 已提交
3268
		cachep = _io_cache;
3269
		pool_size = dm_get_reserved_bio_based_ios();
J
Jun'ichi Nomura 已提交
3270
		front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) + offsetof(struct dm_target_io, clone);
3271 3272
		break;
	case DM_TYPE_REQUEST_BASED:
3273
		pool_size = dm_get_reserved_rq_based_ios();
3274 3275 3276
		pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);
		if (!pools->rq_pool)
			goto out;
3277 3278 3279 3280 3281
		/* fall through to setup remaining rq-based pools */
	case DM_TYPE_MQ_REQUEST_BASED:
		cachep = _rq_tio_cache;
		if (!pool_size)
			pool_size = dm_get_reserved_rq_based_ios();
J
Jun'ichi Nomura 已提交
3282 3283 3284
		front_pad = offsetof(struct dm_rq_clone_bio_info, clone);
		/* per_bio_data_size is not used. See __bind_mempools(). */
		WARN_ON(per_bio_data_size != 0);
3285 3286
		break;
	default:
J
Jun'ichi Nomura 已提交
3287
		goto out;
3288
	}
K
Kiyoshi Ueda 已提交
3289

3290
	pools->io_pool = mempool_create_slab_pool(pool_size, cachep);
J
Jun'ichi Nomura 已提交
3291 3292
	if (!pools->io_pool)
		goto out;
K
Kiyoshi Ueda 已提交
3293

J
Junichi Nomura 已提交
3294
	pools->bs = bioset_create_nobvec(pool_size, front_pad);
K
Kiyoshi Ueda 已提交
3295
	if (!pools->bs)
J
Jun'ichi Nomura 已提交
3296
		goto out;
K
Kiyoshi Ueda 已提交
3297

3298
	if (integrity && bioset_integrity_create(pools->bs, pool_size))
J
Jun'ichi Nomura 已提交
3299
		goto out;
3300

K
Kiyoshi Ueda 已提交
3301 3302
	return pools;

J
Jun'ichi Nomura 已提交
3303 3304
out:
	dm_free_md_mempools(pools);
K
Kiyoshi Ueda 已提交
3305 3306 3307 3308 3309 3310 3311 3312 3313 3314 3315 3316

	return NULL;
}

void dm_free_md_mempools(struct dm_md_mempools *pools)
{
	if (!pools)
		return;

	if (pools->io_pool)
		mempool_destroy(pools->io_pool);

3317 3318 3319
	if (pools->rq_pool)
		mempool_destroy(pools->rq_pool);

K
Kiyoshi Ueda 已提交
3320 3321 3322 3323 3324 3325
	if (pools->bs)
		bioset_free(pools->bs);

	kfree(pools);
}

3326
static const struct block_device_operations dm_blk_dops = {
L
Linus Torvalds 已提交
3327 3328
	.open = dm_blk_open,
	.release = dm_blk_close,
3329
	.ioctl = dm_blk_ioctl,
D
Darrick J. Wong 已提交
3330
	.getgeo = dm_blk_getgeo,
L
Linus Torvalds 已提交
3331 3332 3333 3334 3335 3336 3337 3338 3339 3340 3341
	.owner = THIS_MODULE
};

/*
 * module hooks
 */
module_init(dm_init);
module_exit(dm_exit);

module_param(major, uint, 0);
MODULE_PARM_DESC(major, "The major number of the device mapper");
3342

3343 3344 3345
module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");

3346 3347 3348
module_param(reserved_rq_based_ios, uint, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(reserved_rq_based_ios, "Reserved IOs in request-based mempools");

L
Linus Torvalds 已提交
3349 3350 3351
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");