dm.c 60.7 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/buffer_head.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 <trace/events/block.h>
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#define DM_MSG_PREFIX "core"

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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_SPINLOCK(_minor_lock);
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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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};

/*
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 * For bio-based dm.
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 * One of these is allocated per target within a bio.  Hopefully
 * this will be simplified out one day.
 */
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struct dm_target_io {
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	struct dm_io *io;
	struct dm_target *ti;
	union map_info info;
};

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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;
	struct request *orig, clone;
	int error;
	union map_info info;
};

/*
 * For request-based dm.
 * One of these is allocated per bio.
 */
struct dm_rq_clone_bio_info {
	struct bio *orig;
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	struct dm_rq_target_io *tio;
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};

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union map_info *dm_get_mapinfo(struct bio *bio)
{
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	if (bio && bio->bi_private)
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		return &((struct dm_target_io *)bio->bi_private)->info;
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	return NULL;
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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_QUEUE_IO_TO_THREAD 6
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/*
 * Work processed by per-device workqueue.
 */
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struct mapped_device {
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	struct rw_semaphore io_lock;
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	struct mutex suspend_lock;
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	rwlock_t map_lock;
	atomic_t holders;
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	atomic_t open_count;
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	unsigned long flags;

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	struct request_queue *queue;
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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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	/*
	 * An error from the barrier request currently being processed.
	 */
	int barrier_error;

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	/*
	 * Protect barrier_error from concurrent endio processing
	 * in request-based dm.
	 */
	spinlock_t barrier_error_lock;

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	/*
	 * Processing queue (flush/barriers)
	 */
	struct workqueue_struct *wq;
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	struct work_struct barrier_work;

	/* A pointer to the currently processing pre/post flush request */
	struct request *flush_request;
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	/*
	 * The current mapping.
	 */
	struct dm_table *map;

	/*
	 * io objects are allocated from here.
	 */
	mempool_t *io_pool;
	mempool_t *tio_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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	/* For saving the address of __make_request for request based dm */
	make_request_fn *saved_make_request_fn;

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	/* sysfs handle */
	struct kobject kobj;
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	/* zero-length barrier that will be cloned and submitted to targets */
	struct bio barrier_bio;
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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;
	mempool_t *tio_pool;
	struct bio_set *bs;
};

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#define MIN_IOS 256
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static struct kmem_cache *_io_cache;
static struct kmem_cache *_tio_cache;
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static struct kmem_cache *_rq_tio_cache;
static struct kmem_cache *_rq_bio_info_cache;
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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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	/* allocate a slab for the target ios */
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	_tio_cache = KMEM_CACHE(dm_target_io, 0);
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	if (!_tio_cache)
		goto out_free_io_cache;
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	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
	if (!_rq_tio_cache)
		goto out_free_tio_cache;

	_rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0);
	if (!_rq_bio_info_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_bio_info_cache;
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	_major = major;
	r = register_blkdev(_major, _name);
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	if (r < 0)
		goto out_uevent_exit;
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	if (!_major)
		_major = r;

	return 0;
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out_uevent_exit:
	dm_uevent_exit();
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out_free_rq_bio_info_cache:
	kmem_cache_destroy(_rq_bio_info_cache);
out_free_rq_tio_cache:
	kmem_cache_destroy(_rq_tio_cache);
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out_free_tio_cache:
	kmem_cache_destroy(_tio_cache);
out_free_io_cache:
	kmem_cache_destroy(_io_cache);

	return r;
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}

static void local_exit(void)
{
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	kmem_cache_destroy(_rq_bio_info_cache);
	kmem_cache_destroy(_rq_tio_cache);
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	kmem_cache_destroy(_tio_cache);
	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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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,
};

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]();
}

/*
 * 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 int dm_blk_close(struct gendisk *disk, fmode_t mode)
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{
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	struct mapped_device *md = disk->private_data;
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	atomic_dec(&md->open_count);
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	dm_put(md);
	return 0;
}

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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.
 */
int dm_lock_for_deletion(struct mapped_device *md)
{
	int r = 0;

	spin_lock(&_minor_lock);

	if (dm_open_count(md))
		r = -EBUSY;
	else
		set_bit(DMF_DELETING, &md->flags);

	spin_unlock(&_minor_lock);

	return r;
}

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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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	struct dm_table *map = dm_get_live_table(md);
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	struct dm_target *tgt;
	int r = -ENOTTY;

	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 (dm_suspended_md(md)) {
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		r = -EAGAIN;
		goto out;
	}

	if (tgt->type->ioctl)
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		r = tgt->type->ioctl(tgt, cmd, arg);
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out:
	dm_table_put(map);

	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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{
	mempool_free(tio, md->tio_pool);
}

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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->tio_pool, gfp_mask);
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}

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

static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)
{
	return mempool_alloc(md->io_pool, GFP_ATOMIC);
}

static void free_bio_info(struct dm_rq_clone_bio_info *info)
{
	mempool_free(info, info->tio->md->io_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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	int cpu;
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	int rw = bio_data_dir(io->bio);
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	io->start_time = jiffies;

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	cpu = part_stat_lock();
	part_round_stats(cpu, &dm_disk(md)->part0);
	part_stat_unlock();
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	dm_disk(md)->part0.in_flight[rw] = atomic_inc_return(&md->pending[rw]);
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}

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static void end_io_acct(struct dm_io *io)
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{
	struct mapped_device *md = io->md;
	struct bio *bio = io->bio;
	unsigned long duration = jiffies - io->start_time;
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	int pending, cpu;
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	int rw = bio_data_dir(bio);

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	cpu = part_stat_lock();
	part_round_stats(cpu, &dm_disk(md)->part0);
	part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
	part_stat_unlock();
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	/*
	 * After this is decremented the bio must not be touched if it is
	 * a barrier.
	 */
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	dm_disk(md)->part0.in_flight[rw] = pending =
		atomic_dec_return(&md->pending[rw]);
	pending += atomic_read(&md->pending[rw^0x1]);
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	/* nudge anyone waiting on suspend queue */
	if (!pending)
		wake_up(&md->wait);
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}

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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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{
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	down_write(&md->io_lock);
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	spin_lock_irq(&md->deferred_lock);
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	bio_list_add(&md->deferred, bio);
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	spin_unlock_irq(&md->deferred_lock);
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	if (!test_and_set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags))
		queue_work(md->wq, &md->work);

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	up_write(&md->io_lock);
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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
 * dm_table_put() when finished.
 */
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struct dm_table *dm_get_live_table(struct mapped_device *md)
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{
	struct dm_table *t;
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	unsigned long flags;
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	read_lock_irqsave(&md->map_lock, flags);
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	t = md->map;
	if (t)
		dm_table_get(t);
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	read_unlock_irqrestore(&md->map_lock, flags);
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	return t;
}

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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.
 *---------------------------------------------------------------*/

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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.
 */
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static void dec_pending(struct dm_io *io, int error)
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{
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	unsigned long flags;
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	int io_error;
	struct bio *bio;
	struct mapped_device *md = io->md;
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	/* Push-back supersedes any I/O errors */
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	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)) {
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		if (io->error == DM_ENDIO_REQUEUE) {
			/*
			 * Target requested pushing back the I/O.
			 */
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			spin_lock_irqsave(&md->deferred_lock, flags);
616
			if (__noflush_suspending(md)) {
617
				if (!(io->bio->bi_rw & REQ_HARDBARRIER))
618 619 620
					bio_list_add_head(&md->deferred,
							  io->bio);
			} else
621 622
				/* noflush suspend was interrupted. */
				io->error = -EIO;
623
			spin_unlock_irqrestore(&md->deferred_lock, flags);
624 625
		}

626 627
		io_error = io->error;
		bio = io->bio;
628

629
		if (bio->bi_rw & REQ_HARDBARRIER) {
630 631 632 633 634
			/*
			 * There can be just one barrier request so we use
			 * a per-device variable for error reporting.
			 * Note that you can't touch the bio after end_io_acct
			 */
635
			if (!md->barrier_error && io_error != -EOPNOTSUPP)
636
				md->barrier_error = io_error;
637
			end_io_acct(io);
638
			free_io(md, io);
639 640
		} else {
			end_io_acct(io);
641
			free_io(md, io);
642

643 644
			if (io_error != DM_ENDIO_REQUEUE) {
				trace_block_bio_complete(md->queue, bio);
645

646 647
				bio_endio(bio, io_error);
			}
648
		}
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	}
}

652
static void clone_endio(struct bio *bio, int error)
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{
	int r = 0;
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Alasdair G Kergon 已提交
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	struct dm_target_io *tio = bio->bi_private;
656
	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) {
		r = endio(tio->ti, bio, error, &tio->info);
665 666 667 668 669
		if (r < 0 || r == DM_ENDIO_REQUEUE)
			/*
			 * error and requeue request are handled
			 * in dec_pending().
			 */
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			error = r;
671 672
		else if (r == DM_ENDIO_INCOMPLETE)
			/* The target will handle the io */
673
			return;
674 675 676 677
		else if (r) {
			DMWARN("unimplemented target endio return value: %d", r);
			BUG();
		}
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	}

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	/*
	 * Store md for cleanup instead of tio which is about to get freed.
	 */
	bio->bi_private = md->bs;

	free_tio(md, tio);
686 687
	bio_put(bio);
	dec_pending(io, error);
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}

690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739
/*
 * Partial completion handling for request-based dm
 */
static void end_clone_bio(struct bio *clone, int error)
{
	struct dm_rq_clone_bio_info *info = clone->bi_private;
	struct dm_rq_target_io *tio = info->tio;
	struct bio *bio = info->orig;
	unsigned int nr_bytes = info->orig->bi_size;

	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);
}

740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756
static void store_barrier_error(struct mapped_device *md, int error)
{
	unsigned long flags;

	spin_lock_irqsave(&md->barrier_error_lock, flags);
	/*
	 * Basically, the first error is taken, but:
	 *   -EOPNOTSUPP supersedes any I/O error.
	 *   Requeue request supersedes any I/O error but -EOPNOTSUPP.
	 */
	if (!md->barrier_error || error == -EOPNOTSUPP ||
	    (md->barrier_error != -EOPNOTSUPP &&
	     error == DM_ENDIO_REQUEUE))
		md->barrier_error = error;
	spin_unlock_irqrestore(&md->barrier_error_lock, flags);
}

757 758 759 760 761
/*
 * 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.
 */
762
static void rq_completed(struct mapped_device *md, int rw, int run_queue)
763
{
764
	atomic_dec(&md->pending[rw]);
765 766

	/* nudge anyone waiting on suspend queue */
767
	if (!md_in_flight(md))
768 769 770
		wake_up(&md->wait);

	if (run_queue)
771
		blk_run_queue(md->queue);
772 773 774 775 776 777 778

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

779 780 781 782 783 784 785 786
static void free_rq_clone(struct request *clone)
{
	struct dm_rq_target_io *tio = clone->end_io_data;

	blk_rq_unprep_clone(clone);
	free_rq_tio(tio);
}

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/*
 * Complete the clone and the original request.
 * Must be called without queue lock.
 */
static void dm_end_request(struct request *clone, int error)
{
	int rw = rq_data_dir(clone);
794
	int run_queue = 1;
795
	bool is_barrier = clone->cmd_flags & REQ_HARDBARRIER;
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	struct dm_rq_target_io *tio = clone->end_io_data;
	struct mapped_device *md = tio->md;
	struct request *rq = tio->orig;

800
	if (rq->cmd_type == REQ_TYPE_BLOCK_PC && !is_barrier) {
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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);

815 816 817 818 819 820
	if (unlikely(is_barrier)) {
		if (unlikely(error))
			store_barrier_error(md, error);
		run_queue = 0;
	} else
		blk_end_request_all(rq, error);
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Kiyoshi Ueda 已提交
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822
	rq_completed(md, rw, run_queue);
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Kiyoshi Ueda 已提交
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}

825 826 827 828 829 830 831
static void dm_unprep_request(struct request *rq)
{
	struct request *clone = rq->special;

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

832
	free_rq_clone(clone);
833 834 835 836 837 838 839
}

/*
 * Requeue the original request of a clone.
 */
void dm_requeue_unmapped_request(struct request *clone)
{
840
	int rw = rq_data_dir(clone);
841 842 843 844 845 846
	struct dm_rq_target_io *tio = clone->end_io_data;
	struct mapped_device *md = tio->md;
	struct request *rq = tio->orig;
	struct request_queue *q = rq->q;
	unsigned long flags;

847
	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
848 849 850 851 852 853 854 855 856
		/*
		 * Barrier clones share an original request.
		 * Leave it to dm_end_request(), which handles this special
		 * case.
		 */
		dm_end_request(clone, DM_ENDIO_REQUEUE);
		return;
	}

857 858 859 860 861 862 863 864
	dm_unprep_request(rq);

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

865
	rq_completed(md, rw, 0);
866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897
}
EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);

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);
}

898
static void dm_done(struct request *clone, int error, bool mapped)
899
{
900
	int r = error;
901 902 903
	struct dm_rq_target_io *tio = clone->end_io_data;
	dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;

904 905
	if (mapped && rq_end_io)
		r = rq_end_io(tio->ti, clone, error, &tio->info);
906

907
	if (r <= 0)
908
		/* The target wants to complete the I/O */
909 910
		dm_end_request(clone, r);
	else if (r == DM_ENDIO_INCOMPLETE)
911 912
		/* The target will handle the I/O */
		return;
913
	else if (r == DM_ENDIO_REQUEUE)
914 915 916
		/* The target wants to requeue the I/O */
		dm_requeue_unmapped_request(clone);
	else {
917
		DMWARN("unimplemented target endio return value: %d", r);
918 919 920 921
		BUG();
	}
}

922 923 924 925 926 927 928 929 930 931 932 933 934 935 936
/*
 * Request completion handler for request-based dm
 */
static void dm_softirq_done(struct request *rq)
{
	bool mapped = true;
	struct request *clone = rq->completion_data;
	struct dm_rq_target_io *tio = clone->end_io_data;

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

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

937 938 939 940 941 942 943 944 945
/*
 * Complete the clone and the original request with the error status
 * through softirq context.
 */
static void dm_complete_request(struct request *clone, int error)
{
	struct dm_rq_target_io *tio = clone->end_io_data;
	struct request *rq = tio->orig;

946
	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
947 948 949 950 951 952 953 954 955 956 957 958
		/*
		 * Barrier clones share an original request.  So can't use
		 * softirq_done with the original.
		 * Pass the clone to dm_done() directly in this special case.
		 * It is safe (even if clone->q->queue_lock is held here)
		 * because there is no I/O dispatching during the completion
		 * of barrier clone.
		 */
		dm_done(clone, error, true);
		return;
	}

959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974
	tio->error = error;
	rq->completion_data = clone;
	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.
 * This may be used when the target's map_rq() function fails.
 */
void dm_kill_unmapped_request(struct request *clone, int error)
{
	struct dm_rq_target_io *tio = clone->end_io_data;
	struct request *rq = tio->orig;

975
	if (unlikely(clone->cmd_flags & REQ_HARDBARRIER)) {
976 977 978 979 980 981 982 983 984 985
		/*
		 * Barrier clones share an original request.
		 * Leave it to dm_end_request(), which handles this special
		 * case.
		 */
		BUG_ON(error > 0);
		dm_end_request(clone, error);
		return;
	}

986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014
	rq->cmd_flags |= REQ_FAILED;
	dm_complete_request(clone, error);
}
EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);

/*
 * Called with the queue lock held
 */
static void end_clone_request(struct request *clone, int error)
{
	/*
	 * 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 and REQ_ALLOCED isn't set in clone->cmd_flags.
	 */
	__blk_put_request(clone->q, clone);

	/*
	 * Actual request completion is done in a softirq context which doesn't
	 * hold the queue lock.  Otherwise, deadlock could occur because:
	 *     - 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
	 *       against this queue
	 */
	dm_complete_request(clone, error);
}

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static sector_t max_io_len(struct mapped_device *md,
			   sector_t sector, struct dm_target *ti)
{
	sector_t offset = sector - ti->begin;
	sector_t len = ti->len - offset;

	/*
	 * Does the target need to split even further ?
	 */
	if (ti->split_io) {
		sector_t boundary;
		boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
			   - offset;
		if (len > boundary)
			len = boundary;
	}

	return len;
}

static void __map_bio(struct dm_target *ti, struct bio *clone,
A
Alasdair G Kergon 已提交
1036
		      struct dm_target_io *tio)
L
Linus Torvalds 已提交
1037 1038
{
	int r;
1039
	sector_t sector;
S
Stefan Bader 已提交
1040
	struct mapped_device *md;
L
Linus Torvalds 已提交
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050

	clone->bi_end_io = clone_endio;
	clone->bi_private = tio;

	/*
	 * 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);
1051
	sector = clone->bi_sector;
L
Linus Torvalds 已提交
1052
	r = ti->type->map(ti, clone, &tio->info);
1053
	if (r == DM_MAPIO_REMAPPED) {
L
Linus Torvalds 已提交
1054
		/* the bio has been remapped so dispatch it */
1055

1056
		trace_block_remap(bdev_get_queue(clone->bi_bdev), clone,
1057
				    tio->io->bio->bi_bdev->bd_dev, sector);
1058

L
Linus Torvalds 已提交
1059
		generic_make_request(clone);
1060 1061
	} 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
1062 1063 1064 1065 1066 1067
		md = tio->io->md;
		dec_pending(tio->io, r);
		/*
		 * Store bio_set for cleanup.
		 */
		clone->bi_private = md->bs;
L
Linus Torvalds 已提交
1068
		bio_put(clone);
S
Stefan Bader 已提交
1069
		free_tio(md, tio);
1070 1071 1072
	} else if (r) {
		DMWARN("unimplemented target map return value: %d", r);
		BUG();
L
Linus Torvalds 已提交
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085
	}
}

struct clone_info {
	struct mapped_device *md;
	struct dm_table *map;
	struct bio *bio;
	struct dm_io *io;
	sector_t sector;
	sector_t sector_count;
	unsigned short idx;
};

P
Peter Osterlund 已提交
1086 1087
static void dm_bio_destructor(struct bio *bio)
{
S
Stefan Bader 已提交
1088 1089 1090
	struct bio_set *bs = bio->bi_private;

	bio_free(bio, bs);
P
Peter Osterlund 已提交
1091 1092
}

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/*
 * Creates a little bio that is just does part of a bvec.
 */
static struct bio *split_bvec(struct bio *bio, sector_t sector,
			      unsigned short idx, unsigned int offset,
S
Stefan Bader 已提交
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			      unsigned int len, struct bio_set *bs)
L
Linus Torvalds 已提交
1099 1100 1101 1102
{
	struct bio *clone;
	struct bio_vec *bv = bio->bi_io_vec + idx;

S
Stefan Bader 已提交
1103
	clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
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Peter Osterlund 已提交
1104
	clone->bi_destructor = dm_bio_destructor;
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1105 1106 1107 1108
	*clone->bi_io_vec = *bv;

	clone->bi_sector = sector;
	clone->bi_bdev = bio->bi_bdev;
1109
	clone->bi_rw = bio->bi_rw & ~REQ_HARDBARRIER;
L
Linus Torvalds 已提交
1110 1111 1112 1113
	clone->bi_vcnt = 1;
	clone->bi_size = to_bytes(len);
	clone->bi_io_vec->bv_offset = offset;
	clone->bi_io_vec->bv_len = clone->bi_size;
M
Martin K. Petersen 已提交
1114
	clone->bi_flags |= 1 << BIO_CLONED;
L
Linus Torvalds 已提交
1115

M
Martin K. Petersen 已提交
1116
	if (bio_integrity(bio)) {
1117
		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
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Martin K. Petersen 已提交
1118 1119 1120 1121
		bio_integrity_trim(clone,
				   bio_sector_offset(bio, idx, offset), len);
	}

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1122 1123 1124 1125 1126 1127 1128 1129
	return clone;
}

/*
 * Creates a bio that consists of range of complete bvecs.
 */
static struct bio *clone_bio(struct bio *bio, sector_t sector,
			     unsigned short idx, unsigned short bv_count,
S
Stefan Bader 已提交
1130
			     unsigned int len, struct bio_set *bs)
L
Linus Torvalds 已提交
1131 1132 1133
{
	struct bio *clone;

S
Stefan Bader 已提交
1134 1135
	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
	__bio_clone(clone, bio);
1136
	clone->bi_rw &= ~REQ_HARDBARRIER;
S
Stefan Bader 已提交
1137
	clone->bi_destructor = dm_bio_destructor;
L
Linus Torvalds 已提交
1138 1139 1140 1141 1142 1143
	clone->bi_sector = sector;
	clone->bi_idx = idx;
	clone->bi_vcnt = idx + bv_count;
	clone->bi_size = to_bytes(len);
	clone->bi_flags &= ~(1 << BIO_SEG_VALID);

M
Martin K. Petersen 已提交
1144
	if (bio_integrity(bio)) {
1145
		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
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Martin K. Petersen 已提交
1146 1147 1148 1149 1150 1151

		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
			bio_integrity_trim(clone,
					   bio_sector_offset(bio, idx, 0), len);
	}

L
Linus Torvalds 已提交
1152 1153 1154
	return clone;
}

1155 1156
static struct dm_target_io *alloc_tio(struct clone_info *ci,
				      struct dm_target *ti)
1157
{
1158
	struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO);
1159 1160 1161 1162

	tio->io = ci->io;
	tio->ti = ti;
	memset(&tio->info, 0, sizeof(tio->info));
1163 1164 1165 1166 1167 1168 1169 1170 1171 1172

	return tio;
}

static void __flush_target(struct clone_info *ci, struct dm_target *ti,
			  unsigned flush_nr)
{
	struct dm_target_io *tio = alloc_tio(ci, ti);
	struct bio *clone;

1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196
	tio->info.flush_request = flush_nr;

	clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);
	__bio_clone(clone, ci->bio);
	clone->bi_destructor = dm_bio_destructor;

	__map_bio(ti, clone, tio);
}

static int __clone_and_map_empty_barrier(struct clone_info *ci)
{
	unsigned target_nr = 0, flush_nr;
	struct dm_target *ti;

	while ((ti = dm_table_get_target(ci->map, target_nr++)))
		for (flush_nr = 0; flush_nr < ti->num_flush_requests;
		     flush_nr++)
			__flush_target(ci, ti, flush_nr);

	ci->sector_count = 0;

	return 0;
}

1197
static int __clone_and_map(struct clone_info *ci)
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Linus Torvalds 已提交
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{
	struct bio *clone, *bio = ci->bio;
1200 1201
	struct dm_target *ti;
	sector_t len = 0, max;
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Alasdair G Kergon 已提交
1202
	struct dm_target_io *tio;
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Linus Torvalds 已提交
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1204 1205 1206
	if (unlikely(bio_empty_barrier(bio)))
		return __clone_and_map_empty_barrier(ci);

1207 1208 1209 1210 1211 1212
	ti = dm_table_find_target(ci->map, ci->sector);
	if (!dm_target_is_valid(ti))
		return -EIO;

	max = max_io_len(ci->md, ci->sector, ti);

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	/*
	 * Allocate a target io object.
	 */
1216
	tio = alloc_tio(ci, ti);
L
Linus Torvalds 已提交
1217 1218 1219 1220 1221 1222 1223

	if (ci->sector_count <= max) {
		/*
		 * Optimise for the simple case where we can do all of
		 * the remaining io with a single clone.
		 */
		clone = clone_bio(bio, ci->sector, ci->idx,
S
Stefan Bader 已提交
1224 1225
				  bio->bi_vcnt - ci->idx, ci->sector_count,
				  ci->md->bs);
L
Linus Torvalds 已提交
1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247
		__map_bio(ti, clone, tio);
		ci->sector_count = 0;

	} else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
		/*
		 * There are some bvecs that don't span targets.
		 * Do as many of these as possible.
		 */
		int i;
		sector_t remaining = max;
		sector_t bv_len;

		for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
			bv_len = to_sector(bio->bi_io_vec[i].bv_len);

			if (bv_len > remaining)
				break;

			remaining -= bv_len;
			len += bv_len;
		}

S
Stefan Bader 已提交
1248 1249
		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
				  ci->md->bs);
L
Linus Torvalds 已提交
1250 1251 1252 1253 1254 1255 1256 1257
		__map_bio(ti, clone, tio);

		ci->sector += len;
		ci->sector_count -= len;
		ci->idx = i;

	} else {
		/*
1258
		 * Handle a bvec that must be split between two or more targets.
L
Linus Torvalds 已提交
1259 1260
		 */
		struct bio_vec *bv = bio->bi_io_vec + ci->idx;
1261 1262
		sector_t remaining = to_sector(bv->bv_len);
		unsigned int offset = 0;
L
Linus Torvalds 已提交
1263

1264 1265 1266
		do {
			if (offset) {
				ti = dm_table_find_target(ci->map, ci->sector);
1267 1268 1269
				if (!dm_target_is_valid(ti))
					return -EIO;

1270
				max = max_io_len(ci->md, ci->sector, ti);
L
Linus Torvalds 已提交
1271

1272
				tio = alloc_tio(ci, ti);
1273 1274 1275 1276 1277
			}

			len = min(remaining, max);

			clone = split_bvec(bio, ci->sector, ci->idx,
S
Stefan Bader 已提交
1278 1279
					   bv->bv_offset + offset, len,
					   ci->md->bs);
1280 1281 1282 1283 1284 1285 1286

			__map_bio(ti, clone, tio);

			ci->sector += len;
			ci->sector_count -= len;
			offset += to_bytes(len);
		} while (remaining -= len);
L
Linus Torvalds 已提交
1287 1288 1289

		ci->idx++;
	}
1290 1291

	return 0;
L
Linus Torvalds 已提交
1292 1293 1294
}

/*
M
Mikulas Patocka 已提交
1295
 * Split the bio into several clones and submit it to targets.
L
Linus Torvalds 已提交
1296
 */
1297
static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
L
Linus Torvalds 已提交
1298 1299
{
	struct clone_info ci;
1300
	int error = 0;
L
Linus Torvalds 已提交
1301

1302
	ci.map = dm_get_live_table(md);
1303
	if (unlikely(!ci.map)) {
1304
		if (!(bio->bi_rw & REQ_HARDBARRIER))
1305 1306
			bio_io_error(bio);
		else
1307 1308
			if (!md->barrier_error)
				md->barrier_error = -EIO;
1309 1310
		return;
	}
1311

L
Linus Torvalds 已提交
1312 1313 1314 1315 1316 1317 1318
	ci.md = md;
	ci.bio = bio;
	ci.io = alloc_io(md);
	ci.io->error = 0;
	atomic_set(&ci.io->io_count, 1);
	ci.io->bio = bio;
	ci.io->md = md;
1319
	spin_lock_init(&ci.io->endio_lock);
L
Linus Torvalds 已提交
1320 1321
	ci.sector = bio->bi_sector;
	ci.sector_count = bio_sectors(bio);
1322 1323
	if (unlikely(bio_empty_barrier(bio)))
		ci.sector_count = 1;
L
Linus Torvalds 已提交
1324 1325
	ci.idx = bio->bi_idx;

1326
	start_io_acct(ci.io);
1327 1328
	while (ci.sector_count && !error)
		error = __clone_and_map(&ci);
L
Linus Torvalds 已提交
1329 1330

	/* drop the extra reference count */
1331
	dec_pending(ci.io, error);
L
Linus Torvalds 已提交
1332 1333 1334 1335 1336 1337
	dm_table_put(ci.map);
}
/*-----------------------------------------------------------------
 * CRUD END
 *---------------------------------------------------------------*/

M
Milan Broz 已提交
1338 1339 1340 1341 1342
static int dm_merge_bvec(struct request_queue *q,
			 struct bvec_merge_data *bvm,
			 struct bio_vec *biovec)
{
	struct mapped_device *md = q->queuedata;
1343
	struct dm_table *map = dm_get_live_table(md);
M
Milan Broz 已提交
1344 1345
	struct dm_target *ti;
	sector_t max_sectors;
1346
	int max_size = 0;
M
Milan Broz 已提交
1347 1348

	if (unlikely(!map))
1349
		goto out;
M
Milan Broz 已提交
1350 1351

	ti = dm_table_find_target(map, bvm->bi_sector);
1352 1353
	if (!dm_target_is_valid(ti))
		goto out_table;
M
Milan Broz 已提交
1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370

	/*
	 * Find maximum amount of I/O that won't need splitting
	 */
	max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
			  (sector_t) BIO_MAX_SECTORS);
	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
	if (max_size < 0)
		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);
1371 1372 1373 1374 1375 1376 1377 1378 1379 1380
	/*
	 * If the target doesn't support merge method and some of the devices
	 * provided their merge_bvec method (we know this by looking at
	 * queue_max_hw_sectors), 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.
	 */
	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)

		max_size = 0;
M
Milan Broz 已提交
1381

1382
out_table:
1383 1384 1385
	dm_table_put(map);

out:
M
Milan Broz 已提交
1386 1387 1388 1389 1390 1391 1392 1393 1394
	/*
	 * 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
1395 1396 1397 1398
/*
 * The request function that just remaps the bio built up by
 * dm_merge_bvec.
 */
1399
static int _dm_request(struct request_queue *q, struct bio *bio)
L
Linus Torvalds 已提交
1400
{
1401
	int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
1402
	struct mapped_device *md = q->queuedata;
T
Tejun Heo 已提交
1403
	int cpu;
L
Linus Torvalds 已提交
1404

1405
	down_read(&md->io_lock);
L
Linus Torvalds 已提交
1406

T
Tejun Heo 已提交
1407 1408 1409 1410
	cpu = part_stat_lock();
	part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
	part_stat_unlock();
1411

L
Linus Torvalds 已提交
1412
	/*
1413 1414
	 * If we're suspended or the thread is processing barriers
	 * we have to queue this io for later.
L
Linus Torvalds 已提交
1415
	 */
1416
	if (unlikely(test_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags)) ||
1417
	    unlikely(bio->bi_rw & REQ_HARDBARRIER)) {
1418
		up_read(&md->io_lock);
L
Linus Torvalds 已提交
1419

A
Alasdair G Kergon 已提交
1420 1421 1422 1423 1424
		if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) &&
		    bio_rw(bio) == READA) {
			bio_io_error(bio);
			return 0;
		}
L
Linus Torvalds 已提交
1425

M
Mikulas Patocka 已提交
1426
		queue_io(md, bio);
L
Linus Torvalds 已提交
1427

M
Mikulas Patocka 已提交
1428
		return 0;
L
Linus Torvalds 已提交
1429 1430
	}

1431
	__split_and_process_bio(md, bio);
1432
	up_read(&md->io_lock);
1433
	return 0;
L
Linus Torvalds 已提交
1434 1435
}

1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457
static int dm_make_request(struct request_queue *q, struct bio *bio)
{
	struct mapped_device *md = q->queuedata;

	return md->saved_make_request_fn(q, bio); /* call __make_request() */
}

static int dm_request_based(struct mapped_device *md)
{
	return blk_queue_stackable(md->queue);
}

static int dm_request(struct request_queue *q, struct bio *bio)
{
	struct mapped_device *md = q->queuedata;

	if (dm_request_based(md))
		return dm_make_request(q, bio);

	return _dm_request(q, bio);
}

1458 1459
static bool dm_rq_is_flush_request(struct request *rq)
{
1460
	if (rq->cmd_flags & REQ_FLUSH)
1461 1462 1463 1464 1465
		return true;
	else
		return false;
}

1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510
void dm_dispatch_request(struct request *rq)
{
	int r;

	if (blk_queue_io_stat(rq->q))
		rq->cmd_flags |= REQ_IO_STAT;

	rq->start_time = jiffies;
	r = blk_insert_cloned_request(rq->q, rq);
	if (r)
		dm_complete_request(rq, r);
}
EXPORT_SYMBOL_GPL(dm_dispatch_request);

static void dm_rq_bio_destructor(struct bio *bio)
{
	struct dm_rq_clone_bio_info *info = bio->bi_private;
	struct mapped_device *md = info->tio->md;

	free_bio_info(info);
	bio_free(bio, md->bs);
}

static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
				 void *data)
{
	struct dm_rq_target_io *tio = data;
	struct mapped_device *md = tio->md;
	struct dm_rq_clone_bio_info *info = alloc_bio_info(md);

	if (!info)
		return -ENOMEM;

	info->orig = bio_orig;
	info->tio = tio;
	bio->bi_end_io = end_clone_bio;
	bio->bi_private = info;
	bio->bi_destructor = dm_rq_bio_destructor;

	return 0;
}

static int setup_clone(struct request *clone, struct request *rq,
		       struct dm_rq_target_io *tio)
{
1511
	int r;
1512

1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527
	if (dm_rq_is_flush_request(rq)) {
		blk_rq_init(NULL, clone);
		clone->cmd_type = REQ_TYPE_FS;
		clone->cmd_flags |= (REQ_HARDBARRIER | WRITE);
	} else {
		r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
				      dm_rq_bio_constructor, tio);
		if (r)
			return r;

		clone->cmd = rq->cmd;
		clone->cmd_len = rq->cmd_len;
		clone->sense = rq->sense;
		clone->buffer = rq->buffer;
	}
1528 1529 1530 1531 1532 1533 1534

	clone->end_io = end_clone_request;
	clone->end_io_data = tio;

	return 0;
}

K
Kiyoshi Ueda 已提交
1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560
static struct request *clone_rq(struct request *rq, struct mapped_device *md,
				gfp_t gfp_mask)
{
	struct request *clone;
	struct dm_rq_target_io *tio;

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

	tio->md = md;
	tio->ti = NULL;
	tio->orig = rq;
	tio->error = 0;
	memset(&tio->info, 0, sizeof(tio->info));

	clone = &tio->clone;
	if (setup_clone(clone, rq, tio)) {
		/* -ENOMEM */
		free_rq_tio(tio);
		return NULL;
	}

	return clone;
}

1561 1562 1563 1564 1565 1566 1567 1568
/*
 * Called with the queue lock held.
 */
static int dm_prep_fn(struct request_queue *q, struct request *rq)
{
	struct mapped_device *md = q->queuedata;
	struct request *clone;

1569 1570 1571
	if (unlikely(dm_rq_is_flush_request(rq)))
		return BLKPREP_OK;

1572 1573 1574 1575 1576
	if (unlikely(rq->special)) {
		DMWARN("Already has something in rq->special.");
		return BLKPREP_KILL;
	}

K
Kiyoshi Ueda 已提交
1577 1578
	clone = clone_rq(rq, md, GFP_ATOMIC);
	if (!clone)
1579 1580 1581 1582 1583 1584 1585 1586
		return BLKPREP_DEFER;

	rq->special = clone;
	rq->cmd_flags |= REQ_DONTPREP;

	return BLKPREP_OK;
}

1587 1588 1589 1590 1591 1592 1593
/*
 * Returns:
 * 0  : the request has been processed (not requeued)
 * !0 : the request has been requeued
 */
static int map_request(struct dm_target *ti, struct request *clone,
		       struct mapped_device *md)
1594
{
1595
	int r, requeued = 0;
1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614
	struct dm_rq_target_io *tio = clone->end_io_data;

	/*
	 * 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);

	tio->ti = ti;
	r = ti->type->map_rq(ti, clone, &tio->info);
	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 */
1615 1616
		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
				     blk_rq_pos(tio->orig));
1617 1618 1619 1620 1621
		dm_dispatch_request(clone);
		break;
	case DM_MAPIO_REQUEUE:
		/* The target wants to requeue the I/O */
		dm_requeue_unmapped_request(clone);
1622
		requeued = 1;
1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633
		break;
	default:
		if (r > 0) {
			DMWARN("unimplemented target map return value: %d", r);
			BUG();
		}

		/* The target wants to complete the I/O */
		dm_kill_unmapped_request(clone, r);
		break;
	}
1634 1635

	return requeued;
1636 1637 1638 1639 1640 1641 1642 1643 1644
}

/*
 * 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;
1645
	struct dm_table *map = dm_get_live_table(md);
1646
	struct dm_target *ti;
1647
	struct request *rq, *clone;
1648 1649

	/*
1650 1651 1652 1653
	 * 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().
1654 1655 1656 1657 1658 1659
	 */
	while (!blk_queue_plugged(q) && !blk_queue_stopped(q)) {
		rq = blk_peek_request(q);
		if (!rq)
			goto plug_and_out;

1660 1661 1662 1663 1664 1665 1666 1667
		if (unlikely(dm_rq_is_flush_request(rq))) {
			BUG_ON(md->flush_request);
			md->flush_request = rq;
			blk_start_request(rq);
			queue_work(md->wq, &md->barrier_work);
			goto out;
		}

1668 1669 1670 1671 1672
		ti = dm_table_find_target(map, blk_rq_pos(rq));
		if (ti->type->busy && ti->type->busy(ti))
			goto plug_and_out;

		blk_start_request(rq);
1673 1674 1675
		clone = rq->special;
		atomic_inc(&md->pending[rq_data_dir(clone)]);

1676
		spin_unlock(q->queue_lock);
1677 1678 1679
		if (map_request(ti, clone, md))
			goto requeued;

1680 1681 1682 1683 1684
		spin_lock_irq(q->queue_lock);
	}

	goto out;

1685 1686 1687
requeued:
	spin_lock_irq(q->queue_lock);

1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708
plug_and_out:
	if (!elv_queue_empty(q))
		/* Some requests still remain, retry later */
		blk_plug_device(q);

out:
	dm_table_put(map);

	return;
}

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;
1709
	struct dm_table *map = dm_get_live_table(md);
1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720

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

	dm_table_put(map);

	return r;
}

1721
static void dm_unplug_all(struct request_queue *q)
L
Linus Torvalds 已提交
1722 1723
{
	struct mapped_device *md = q->queuedata;
1724
	struct dm_table *map = dm_get_live_table(md);
L
Linus Torvalds 已提交
1725 1726

	if (map) {
1727 1728 1729
		if (dm_request_based(md))
			generic_unplug_device(q);

L
Linus Torvalds 已提交
1730 1731 1732 1733 1734 1735 1736
		dm_table_unplug_all(map);
		dm_table_put(map);
	}
}

static int dm_any_congested(void *congested_data, int bdi_bits)
{
1737 1738 1739
	int r = bdi_bits;
	struct mapped_device *md = congested_data;
	struct dm_table *map;
L
Linus Torvalds 已提交
1740

1741
	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
1742
		map = dm_get_live_table(md);
1743
		if (map) {
1744 1745 1746 1747 1748 1749 1750 1751 1752 1753
			/*
			 * 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);

1754 1755 1756 1757
			dm_table_put(map);
		}
	}

L
Linus Torvalds 已提交
1758 1759 1760 1761 1762 1763 1764 1765
	return r;
}

/*-----------------------------------------------------------------
 * An IDR is used to keep track of allocated minor numbers.
 *---------------------------------------------------------------*/
static DEFINE_IDR(_minor_idr);

1766
static void free_minor(int minor)
L
Linus Torvalds 已提交
1767
{
1768
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1769
	idr_remove(&_minor_idr, minor);
1770
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1771 1772 1773 1774 1775
}

/*
 * See if the device with a specific minor # is free.
 */
1776
static int specific_minor(int minor)
L
Linus Torvalds 已提交
1777 1778 1779 1780 1781 1782
{
	int r, m;

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

J
Jeff Mahoney 已提交
1783 1784 1785 1786
	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
	if (!r)
		return -ENOMEM;

1787
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1788 1789 1790 1791 1792 1793

	if (idr_find(&_minor_idr, minor)) {
		r = -EBUSY;
		goto out;
	}

1794
	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
J
Jeff Mahoney 已提交
1795
	if (r)
L
Linus Torvalds 已提交
1796 1797 1798 1799 1800 1801 1802 1803 1804
		goto out;

	if (m != minor) {
		idr_remove(&_minor_idr, m);
		r = -EBUSY;
		goto out;
	}

out:
1805
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1806 1807 1808
	return r;
}

1809
static int next_free_minor(int *minor)
L
Linus Torvalds 已提交
1810
{
1811
	int r, m;
L
Linus Torvalds 已提交
1812 1813

	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
J
Jeff Mahoney 已提交
1814 1815 1816
	if (!r)
		return -ENOMEM;

1817
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1818

1819
	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
1820
	if (r)
L
Linus Torvalds 已提交
1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831
		goto out;

	if (m >= (1 << MINORBITS)) {
		idr_remove(&_minor_idr, m);
		r = -ENOSPC;
		goto out;
	}

	*minor = m;

out:
1832
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1833 1834 1835
	return r;
}

1836
static const struct block_device_operations dm_blk_dops;
L
Linus Torvalds 已提交
1837

1838
static void dm_wq_work(struct work_struct *work);
1839
static void dm_rq_barrier_work(struct work_struct *work);
1840

L
Linus Torvalds 已提交
1841 1842 1843
/*
 * Allocate and initialise a blank device with a given minor.
 */
1844
static struct mapped_device *alloc_dev(int minor)
L
Linus Torvalds 已提交
1845 1846
{
	int r;
1847
	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
1848
	void *old_md;
L
Linus Torvalds 已提交
1849 1850 1851 1852 1853 1854

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

1855
	if (!try_module_get(THIS_MODULE))
M
Milan Broz 已提交
1856
		goto bad_module_get;
1857

L
Linus Torvalds 已提交
1858
	/* get a minor number for the dev */
1859
	if (minor == DM_ANY_MINOR)
1860
		r = next_free_minor(&minor);
1861
	else
1862
		r = specific_minor(minor);
L
Linus Torvalds 已提交
1863
	if (r < 0)
M
Milan Broz 已提交
1864
		goto bad_minor;
L
Linus Torvalds 已提交
1865

1866
	init_rwsem(&md->io_lock);
1867
	mutex_init(&md->suspend_lock);
1868
	spin_lock_init(&md->deferred_lock);
1869
	spin_lock_init(&md->barrier_error_lock);
L
Linus Torvalds 已提交
1870 1871
	rwlock_init(&md->map_lock);
	atomic_set(&md->holders, 1);
1872
	atomic_set(&md->open_count, 0);
L
Linus Torvalds 已提交
1873
	atomic_set(&md->event_nr, 0);
M
Mike Anderson 已提交
1874 1875 1876
	atomic_set(&md->uevent_seq, 0);
	INIT_LIST_HEAD(&md->uevent_list);
	spin_lock_init(&md->uevent_lock);
L
Linus Torvalds 已提交
1877

K
Kiyoshi Ueda 已提交
1878
	md->queue = blk_init_queue(dm_request_fn, NULL);
L
Linus Torvalds 已提交
1879
	if (!md->queue)
M
Milan Broz 已提交
1880
		goto bad_queue;
L
Linus Torvalds 已提交
1881

K
Kiyoshi Ueda 已提交
1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893
	/*
	 * 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,
	 * although we initialized the queue using blk_init_queue().
	 * 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->saved_make_request_fn = md->queue->make_request_fn;
L
Linus Torvalds 已提交
1894 1895 1896 1897
	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);
1898
	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
L
Linus Torvalds 已提交
1899
	md->queue->unplug_fn = dm_unplug_all;
M
Milan Broz 已提交
1900
	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
K
Kiyoshi Ueda 已提交
1901 1902 1903
	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);
1904
	blk_queue_ordered(md->queue, QUEUE_ORDERED_DRAIN_FLUSH);
S
Stefan Bader 已提交
1905

L
Linus Torvalds 已提交
1906 1907
	md->disk = alloc_disk(1);
	if (!md->disk)
M
Milan Broz 已提交
1908
		goto bad_disk;
L
Linus Torvalds 已提交
1909

1910 1911
	atomic_set(&md->pending[0], 0);
	atomic_set(&md->pending[1], 0);
1912
	init_waitqueue_head(&md->wait);
1913
	INIT_WORK(&md->work, dm_wq_work);
1914
	INIT_WORK(&md->barrier_work, dm_rq_barrier_work);
1915 1916
	init_waitqueue_head(&md->eventq);

L
Linus Torvalds 已提交
1917 1918 1919 1920 1921 1922 1923
	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
1924
	format_dev_t(md->name, MKDEV(_major, minor));
L
Linus Torvalds 已提交
1925

1926 1927 1928 1929
	md->wq = create_singlethread_workqueue("kdmflush");
	if (!md->wq)
		goto bad_thread;

M
Mikulas Patocka 已提交
1930 1931 1932 1933
	md->bdev = bdget_disk(md->disk, 0);
	if (!md->bdev)
		goto bad_bdev;

1934
	/* Populate the mapping, nobody knows we exist yet */
1935
	spin_lock(&_minor_lock);
1936
	old_md = idr_replace(&_minor_idr, md, minor);
1937
	spin_unlock(&_minor_lock);
1938 1939 1940

	BUG_ON(old_md != MINOR_ALLOCED);

L
Linus Torvalds 已提交
1941 1942
	return md;

M
Mikulas Patocka 已提交
1943 1944
bad_bdev:
	destroy_workqueue(md->wq);
1945
bad_thread:
1946
	del_gendisk(md->disk);
1947
	put_disk(md->disk);
M
Milan Broz 已提交
1948
bad_disk:
1949
	blk_cleanup_queue(md->queue);
M
Milan Broz 已提交
1950
bad_queue:
L
Linus Torvalds 已提交
1951
	free_minor(minor);
M
Milan Broz 已提交
1952
bad_minor:
1953
	module_put(THIS_MODULE);
M
Milan Broz 已提交
1954
bad_module_get:
L
Linus Torvalds 已提交
1955 1956 1957 1958
	kfree(md);
	return NULL;
}

J
Jun'ichi Nomura 已提交
1959 1960
static void unlock_fs(struct mapped_device *md);

L
Linus Torvalds 已提交
1961 1962
static void free_dev(struct mapped_device *md)
{
1963
	int minor = MINOR(disk_devt(md->disk));
1964

M
Mikulas Patocka 已提交
1965 1966
	unlock_fs(md);
	bdput(md->bdev);
1967
	destroy_workqueue(md->wq);
K
Kiyoshi Ueda 已提交
1968 1969 1970 1971 1972 1973
	if (md->tio_pool)
		mempool_destroy(md->tio_pool);
	if (md->io_pool)
		mempool_destroy(md->io_pool);
	if (md->bs)
		bioset_free(md->bs);
M
Martin K. Petersen 已提交
1974
	blk_integrity_unregister(md->disk);
L
Linus Torvalds 已提交
1975
	del_gendisk(md->disk);
1976
	free_minor(minor);
J
Jeff Mahoney 已提交
1977 1978 1979 1980 1981

	spin_lock(&_minor_lock);
	md->disk->private_data = NULL;
	spin_unlock(&_minor_lock);

L
Linus Torvalds 已提交
1982
	put_disk(md->disk);
1983
	blk_cleanup_queue(md->queue);
1984
	module_put(THIS_MODULE);
L
Linus Torvalds 已提交
1985 1986 1987
	kfree(md);
}

K
Kiyoshi Ueda 已提交
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
	struct dm_md_mempools *p;

	if (md->io_pool && md->tio_pool && md->bs)
		/* the md already has necessary mempools */
		goto out;

	p = dm_table_get_md_mempools(t);
	BUG_ON(!p || md->io_pool || md->tio_pool || md->bs);

	md->io_pool = p->io_pool;
	p->io_pool = NULL;
	md->tio_pool = p->tio_pool;
	p->tio_pool = NULL;
	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
2011 2012 2013 2014 2015
/*
 * Bind a table to the device.
 */
static void event_callback(void *context)
{
M
Mike Anderson 已提交
2016 2017
	unsigned long flags;
	LIST_HEAD(uevents);
L
Linus Torvalds 已提交
2018 2019
	struct mapped_device *md = (struct mapped_device *) context;

M
Mike Anderson 已提交
2020 2021 2022 2023
	spin_lock_irqsave(&md->uevent_lock, flags);
	list_splice_init(&md->uevent_list, &uevents);
	spin_unlock_irqrestore(&md->uevent_lock, flags);

2024
	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
M
Mike Anderson 已提交
2025

L
Linus Torvalds 已提交
2026 2027 2028 2029
	atomic_inc(&md->event_nr);
	wake_up(&md->eventq);
}

2030
static void __set_size(struct mapped_device *md, sector_t size)
L
Linus Torvalds 已提交
2031
{
2032
	set_capacity(md->disk, size);
L
Linus Torvalds 已提交
2033

2034 2035 2036
	mutex_lock(&md->bdev->bd_inode->i_mutex);
	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
	mutex_unlock(&md->bdev->bd_inode->i_mutex);
L
Linus Torvalds 已提交
2037 2038
}

2039 2040 2041 2042 2043
/*
 * 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
2044
{
2045
	struct dm_table *old_map;
2046
	struct request_queue *q = md->queue;
L
Linus Torvalds 已提交
2047
	sector_t size;
2048
	unsigned long flags;
L
Linus Torvalds 已提交
2049 2050

	size = dm_table_get_size(t);
D
Darrick J. Wong 已提交
2051 2052 2053 2054 2055 2056 2057

	/*
	 * Wipe any geometry if the size of the table changed.
	 */
	if (size != get_capacity(md->disk))
		memset(&md->geometry, 0, sizeof(md->geometry));

M
Mikulas Patocka 已提交
2058
	__set_size(md, size);
2059

2060 2061
	dm_table_event_callback(t, event_callback, md);

K
Kiyoshi Ueda 已提交
2062 2063 2064 2065 2066 2067 2068 2069 2070 2071 2072 2073
	/*
	 * 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);

2074
	write_lock_irqsave(&md->map_lock, flags);
2075
	old_map = md->map;
L
Linus Torvalds 已提交
2076
	md->map = t;
2077
	dm_table_set_restrictions(t, q, limits);
2078
	write_unlock_irqrestore(&md->map_lock, flags);
L
Linus Torvalds 已提交
2079

2080
	return old_map;
L
Linus Torvalds 已提交
2081 2082
}

2083 2084 2085 2086
/*
 * Returns unbound table for the caller to free.
 */
static struct dm_table *__unbind(struct mapped_device *md)
L
Linus Torvalds 已提交
2087 2088
{
	struct dm_table *map = md->map;
2089
	unsigned long flags;
L
Linus Torvalds 已提交
2090 2091

	if (!map)
2092
		return NULL;
L
Linus Torvalds 已提交
2093 2094

	dm_table_event_callback(map, NULL, NULL);
2095
	write_lock_irqsave(&md->map_lock, flags);
L
Linus Torvalds 已提交
2096
	md->map = NULL;
2097
	write_unlock_irqrestore(&md->map_lock, flags);
2098 2099

	return map;
L
Linus Torvalds 已提交
2100 2101 2102 2103 2104
}

/*
 * Constructor for a new device.
 */
2105
int dm_create(int minor, struct mapped_device **result)
L
Linus Torvalds 已提交
2106 2107 2108
{
	struct mapped_device *md;

2109
	md = alloc_dev(minor);
L
Linus Torvalds 已提交
2110 2111 2112
	if (!md)
		return -ENXIO;

M
Milan Broz 已提交
2113 2114
	dm_sysfs_init(md);

L
Linus Torvalds 已提交
2115 2116 2117 2118
	*result = md;
	return 0;
}

2119
static struct mapped_device *dm_find_md(dev_t dev)
L
Linus Torvalds 已提交
2120 2121 2122 2123 2124 2125 2126
{
	struct mapped_device *md;
	unsigned minor = MINOR(dev);

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

2127
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
2128 2129

	md = idr_find(&_minor_idr, minor);
J
Jeff Mahoney 已提交
2130
	if (md && (md == MINOR_ALLOCED ||
2131
		   (MINOR(disk_devt(dm_disk(md))) != minor) ||
A
Alasdair G Kergon 已提交
2132
		   test_bit(DMF_FREEING, &md->flags))) {
2133
		md = NULL;
J
Jeff Mahoney 已提交
2134 2135
		goto out;
	}
L
Linus Torvalds 已提交
2136

J
Jeff Mahoney 已提交
2137
out:
2138
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
2139

2140 2141 2142
	return md;
}

2143 2144 2145 2146 2147 2148 2149 2150 2151 2152
struct mapped_device *dm_get_md(dev_t dev)
{
	struct mapped_device *md = dm_find_md(dev);

	if (md)
		dm_get(md);

	return md;
}

A
Alasdair G Kergon 已提交
2153
void *dm_get_mdptr(struct mapped_device *md)
2154
{
A
Alasdair G Kergon 已提交
2155
	return md->interface_ptr;
L
Linus Torvalds 已提交
2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167
}

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);
}

2168 2169 2170 2171 2172 2173
const char *dm_device_name(struct mapped_device *md)
{
	return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);

L
Linus Torvalds 已提交
2174 2175
void dm_put(struct mapped_device *md)
{
M
Mike Anderson 已提交
2176
	struct dm_table *map;
L
Linus Torvalds 已提交
2177

J
Jeff Mahoney 已提交
2178 2179
	BUG_ON(test_bit(DMF_FREEING, &md->flags));

2180
	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
2181
		map = dm_get_live_table(md);
2182 2183
		idr_replace(&_minor_idr, MINOR_ALLOCED,
			    MINOR(disk_devt(dm_disk(md))));
J
Jeff Mahoney 已提交
2184
		set_bit(DMF_FREEING, &md->flags);
2185
		spin_unlock(&_minor_lock);
2186
		if (!dm_suspended_md(md)) {
L
Linus Torvalds 已提交
2187 2188 2189
			dm_table_presuspend_targets(map);
			dm_table_postsuspend_targets(map);
		}
M
Milan Broz 已提交
2190
		dm_sysfs_exit(md);
M
Mike Anderson 已提交
2191
		dm_table_put(map);
2192
		dm_table_destroy(__unbind(md));
L
Linus Torvalds 已提交
2193 2194 2195
		free_dev(md);
	}
}
E
Edward Goggin 已提交
2196
EXPORT_SYMBOL_GPL(dm_put);
L
Linus Torvalds 已提交
2197

2198
static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
2199 2200
{
	int r = 0;
2201 2202 2203 2204 2205
	DECLARE_WAITQUEUE(wait, current);

	dm_unplug_all(md->queue);

	add_wait_queue(&md->wait, &wait);
2206 2207

	while (1) {
2208
		set_current_state(interruptible);
2209 2210

		smp_mb();
2211
		if (!md_in_flight(md))
2212 2213
			break;

2214 2215
		if (interruptible == TASK_INTERRUPTIBLE &&
		    signal_pending(current)) {
2216 2217 2218 2219 2220 2221 2222 2223
			r = -EINTR;
			break;
		}

		io_schedule();
	}
	set_current_state(TASK_RUNNING);

2224 2225
	remove_wait_queue(&md->wait, &wait);

2226 2227 2228
	return r;
}

M
Mikulas Patocka 已提交
2229
static void dm_flush(struct mapped_device *md)
2230 2231
{
	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2232 2233 2234 2235 2236 2237 2238

	bio_init(&md->barrier_bio);
	md->barrier_bio.bi_bdev = md->bdev;
	md->barrier_bio.bi_rw = WRITE_BARRIER;
	__split_and_process_bio(md, &md->barrier_bio);

	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
2239 2240 2241 2242
}

static void process_barrier(struct mapped_device *md, struct bio *bio)
{
2243 2244
	md->barrier_error = 0;

M
Mikulas Patocka 已提交
2245
	dm_flush(md);
2246

2247 2248 2249
	if (!bio_empty_barrier(bio)) {
		__split_and_process_bio(md, bio);
		dm_flush(md);
2250 2251 2252
	}

	if (md->barrier_error != DM_ENDIO_REQUEUE)
M
Mikulas Patocka 已提交
2253
		bio_endio(bio, md->barrier_error);
2254 2255 2256 2257 2258
	else {
		spin_lock_irq(&md->deferred_lock);
		bio_list_add_head(&md->deferred, bio);
		spin_unlock_irq(&md->deferred_lock);
	}
2259 2260
}

L
Linus Torvalds 已提交
2261 2262 2263
/*
 * Process the deferred bios
 */
2264
static void dm_wq_work(struct work_struct *work)
L
Linus Torvalds 已提交
2265
{
2266 2267
	struct mapped_device *md = container_of(work, struct mapped_device,
						work);
2268
	struct bio *c;
L
Linus Torvalds 已提交
2269

2270 2271
	down_write(&md->io_lock);

2272
	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
A
Alasdair G Kergon 已提交
2273 2274 2275 2276 2277
		spin_lock_irq(&md->deferred_lock);
		c = bio_list_pop(&md->deferred);
		spin_unlock_irq(&md->deferred_lock);

		if (!c) {
2278
			clear_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
A
Alasdair G Kergon 已提交
2279 2280
			break;
		}
2281

2282 2283
		up_write(&md->io_lock);

K
Kiyoshi Ueda 已提交
2284 2285 2286
		if (dm_request_based(md))
			generic_make_request(c);
		else {
2287
			if (c->bi_rw & REQ_HARDBARRIER)
K
Kiyoshi Ueda 已提交
2288 2289 2290 2291
				process_barrier(md, c);
			else
				__split_and_process_bio(md, c);
		}
2292 2293

		down_write(&md->io_lock);
2294
	}
M
Milan Broz 已提交
2295

2296
	up_write(&md->io_lock);
L
Linus Torvalds 已提交
2297 2298
}

2299
static void dm_queue_flush(struct mapped_device *md)
2300
{
2301 2302
	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
	smp_mb__after_clear_bit();
2303
	queue_work(md->wq, &md->work);
2304 2305
}

2306 2307 2308 2309 2310 2311 2312 2313 2314 2315 2316
static void dm_rq_set_flush_nr(struct request *clone, unsigned flush_nr)
{
	struct dm_rq_target_io *tio = clone->end_io_data;

	tio->info.flush_request = flush_nr;
}

/* Issue barrier requests to targets and wait for their completion. */
static int dm_rq_barrier(struct mapped_device *md)
{
	int i, j;
2317
	struct dm_table *map = dm_get_live_table(md);
2318 2319 2320 2321 2322 2323 2324 2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 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
	unsigned num_targets = dm_table_get_num_targets(map);
	struct dm_target *ti;
	struct request *clone;

	md->barrier_error = 0;

	for (i = 0; i < num_targets; i++) {
		ti = dm_table_get_target(map, i);
		for (j = 0; j < ti->num_flush_requests; j++) {
			clone = clone_rq(md->flush_request, md, GFP_NOIO);
			dm_rq_set_flush_nr(clone, j);
			atomic_inc(&md->pending[rq_data_dir(clone)]);
			map_request(ti, clone, md);
		}
	}

	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
	dm_table_put(map);

	return md->barrier_error;
}

static void dm_rq_barrier_work(struct work_struct *work)
{
	int error;
	struct mapped_device *md = container_of(work, struct mapped_device,
						barrier_work);
	struct request_queue *q = md->queue;
	struct request *rq;
	unsigned long flags;

	/*
	 * Hold the md reference here and leave it at the last part so that
	 * the md can't be deleted by device opener when the barrier request
	 * completes.
	 */
	dm_get(md);

	error = dm_rq_barrier(md);

	rq = md->flush_request;
	md->flush_request = NULL;

	if (error == DM_ENDIO_REQUEUE) {
		spin_lock_irqsave(q->queue_lock, flags);
		blk_requeue_request(q, rq);
		spin_unlock_irqrestore(q->queue_lock, flags);
	} else
		blk_end_request_all(rq, error);

	blk_run_queue(q);

	dm_put(md);
}

L
Linus Torvalds 已提交
2373
/*
2374
 * Swap in a new table, returning the old one for the caller to destroy.
L
Linus Torvalds 已提交
2375
 */
2376
struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
L
Linus Torvalds 已提交
2377
{
2378
	struct dm_table *map = ERR_PTR(-EINVAL);
2379
	struct queue_limits limits;
2380
	int r;
L
Linus Torvalds 已提交
2381

2382
	mutex_lock(&md->suspend_lock);
L
Linus Torvalds 已提交
2383 2384

	/* device must be suspended */
2385
	if (!dm_suspended_md(md))
2386
		goto out;
L
Linus Torvalds 已提交
2387

2388
	r = dm_calculate_queue_limits(table, &limits);
2389 2390
	if (r) {
		map = ERR_PTR(r);
2391
		goto out;
2392
	}
2393

K
Kiyoshi Ueda 已提交
2394 2395 2396 2397 2398 2399 2400
	/* cannot change the device type, once a table is bound */
	if (md->map &&
	    (dm_table_get_type(md->map) != dm_table_get_type(table))) {
		DMWARN("can't change the device type after a table is bound");
		goto out;
	}

2401
	map = __bind(md, table, &limits);
L
Linus Torvalds 已提交
2402

2403
out:
2404
	mutex_unlock(&md->suspend_lock);
2405
	return map;
L
Linus Torvalds 已提交
2406 2407 2408 2409 2410 2411
}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
2412
static int lock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
2413
{
2414
	int r;
L
Linus Torvalds 已提交
2415 2416

	WARN_ON(md->frozen_sb);
2417

2418
	md->frozen_sb = freeze_bdev(md->bdev);
2419
	if (IS_ERR(md->frozen_sb)) {
2420
		r = PTR_ERR(md->frozen_sb);
2421 2422
		md->frozen_sb = NULL;
		return r;
2423 2424
	}

2425 2426
	set_bit(DMF_FROZEN, &md->flags);

L
Linus Torvalds 已提交
2427 2428 2429
	return 0;
}

2430
static void unlock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
2431
{
2432 2433 2434
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

2435
	thaw_bdev(md->bdev, md->frozen_sb);
L
Linus Torvalds 已提交
2436
	md->frozen_sb = NULL;
2437
	clear_bit(DMF_FROZEN, &md->flags);
L
Linus Torvalds 已提交
2438 2439 2440 2441 2442 2443 2444 2445 2446
}

/*
 * 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.
 */
2447 2448 2449
/*
 * Suspend mechanism in request-based dm.
 *
K
Kiyoshi Ueda 已提交
2450 2451 2452
 * 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.
2453
 *
K
Kiyoshi Ueda 已提交
2454
 * To abort suspend, start the request_queue.
2455
 */
2456
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
L
Linus Torvalds 已提交
2457
{
2458
	struct dm_table *map = NULL;
2459
	int r = 0;
2460
	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
2461
	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
L
Linus Torvalds 已提交
2462

2463
	mutex_lock(&md->suspend_lock);
2464

2465
	if (dm_suspended_md(md)) {
M
Milan Broz 已提交
2466
		r = -EINVAL;
2467
		goto out_unlock;
M
Milan Broz 已提交
2468
	}
L
Linus Torvalds 已提交
2469

2470
	map = dm_get_live_table(md);
L
Linus Torvalds 已提交
2471

2472 2473 2474 2475 2476 2477 2478
	/*
	 * 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);

2479 2480 2481
	/* This does not get reverted if there's an error later. */
	dm_table_presuspend_targets(map);

M
Mikulas Patocka 已提交
2482
	/*
K
Kiyoshi Ueda 已提交
2483 2484 2485 2486
	 * 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
2487 2488 2489 2490
	 */
	if (!noflush && do_lockfs) {
		r = lock_fs(md);
		if (r)
K
Kiyoshi Ueda 已提交
2491
			goto out;
2492
	}
L
Linus Torvalds 已提交
2493 2494

	/*
2495 2496 2497 2498 2499 2500 2501 2502 2503 2504 2505 2506 2507 2508
	 * 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
	 * __split_and_process_bio from dm_request, we set
	 * DMF_QUEUE_IO_TO_THREAD.
	 *
	 * To quiesce the thread (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND
	 * and call flush_workqueue(md->wq). flush_workqueue will wait until
	 * dm_wq_work exits and DMF_BLOCK_IO_FOR_SUSPEND will prevent any
	 * further calls to __split_and_process_bio from dm_wq_work.
L
Linus Torvalds 已提交
2509
	 */
2510
	down_write(&md->io_lock);
2511 2512
	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
	set_bit(DMF_QUEUE_IO_TO_THREAD, &md->flags);
2513
	up_write(&md->io_lock);
L
Linus Torvalds 已提交
2514

2515 2516 2517 2518 2519
	/*
	 * Request-based dm uses md->wq for barrier (dm_rq_barrier_work) which
	 * can be kicked until md->queue is stopped.  So stop md->queue before
	 * flushing md->wq.
	 */
2520
	if (dm_request_based(md))
K
Kiyoshi Ueda 已提交
2521
		stop_queue(md->queue);
2522

2523 2524
	flush_workqueue(md->wq);

L
Linus Torvalds 已提交
2525
	/*
2526 2527 2528
	 * 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
2529
	 */
2530
	r = dm_wait_for_completion(md, TASK_INTERRUPTIBLE);
L
Linus Torvalds 已提交
2531

2532
	down_write(&md->io_lock);
2533
	if (noflush)
2534
		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
2535
	up_write(&md->io_lock);
2536

L
Linus Torvalds 已提交
2537
	/* were we interrupted ? */
2538
	if (r < 0) {
2539
		dm_queue_flush(md);
M
Milan Broz 已提交
2540

2541
		if (dm_request_based(md))
K
Kiyoshi Ueda 已提交
2542
			start_queue(md->queue);
2543

2544
		unlock_fs(md);
2545
		goto out; /* pushback list is already flushed, so skip flush */
2546
	}
L
Linus Torvalds 已提交
2547

2548 2549 2550 2551 2552 2553
	/*
	 * If dm_wait_for_completion returned 0, the device is completely
	 * quiescent now. There is no request-processing activity. All new
	 * requests are being added to md->deferred list.
	 */

2554
	set_bit(DMF_SUSPENDED, &md->flags);
2555

2556 2557
	dm_table_postsuspend_targets(map);

2558 2559
out:
	dm_table_put(map);
2560 2561

out_unlock:
2562
	mutex_unlock(&md->suspend_lock);
2563
	return r;
L
Linus Torvalds 已提交
2564 2565 2566 2567
}

int dm_resume(struct mapped_device *md)
{
2568 2569
	int r = -EINVAL;
	struct dm_table *map = NULL;
L
Linus Torvalds 已提交
2570

2571
	mutex_lock(&md->suspend_lock);
2572
	if (!dm_suspended_md(md))
2573 2574
		goto out;

2575
	map = dm_get_live_table(md);
2576
	if (!map || !dm_table_get_size(map))
2577
		goto out;
L
Linus Torvalds 已提交
2578

2579 2580 2581
	r = dm_table_resume_targets(map);
	if (r)
		goto out;
2582

2583
	dm_queue_flush(md);
2584

2585 2586 2587 2588 2589 2590 2591 2592
	/*
	 * 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);

2593 2594 2595 2596
	unlock_fs(md);

	clear_bit(DMF_SUSPENDED, &md->flags);

L
Linus Torvalds 已提交
2597
	dm_table_unplug_all(map);
2598 2599 2600
	r = 0;
out:
	dm_table_put(map);
2601
	mutex_unlock(&md->suspend_lock);
2602

2603
	return r;
L
Linus Torvalds 已提交
2604 2605 2606 2607 2608
}

/*-----------------------------------------------------------------
 * Event notification.
 *---------------------------------------------------------------*/
2609
int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
M
Milan Broz 已提交
2610
		       unsigned cookie)
2611
{
M
Milan Broz 已提交
2612 2613 2614 2615
	char udev_cookie[DM_COOKIE_LENGTH];
	char *envp[] = { udev_cookie, NULL };

	if (!cookie)
2616
		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
M
Milan Broz 已提交
2617 2618 2619
	else {
		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
			 DM_COOKIE_ENV_VAR_NAME, cookie);
2620 2621
		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
					  action, envp);
M
Milan Broz 已提交
2622
	}
2623 2624
}

M
Mike Anderson 已提交
2625 2626 2627 2628 2629
uint32_t dm_next_uevent_seq(struct mapped_device *md)
{
	return atomic_add_return(1, &md->uevent_seq);
}

L
Linus Torvalds 已提交
2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640
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
2641 2642 2643 2644 2645 2646 2647 2648 2649
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
2650 2651 2652 2653 2654 2655 2656 2657 2658
/*
 * 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
2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675
struct kobject *dm_kobject(struct mapped_device *md)
{
	return &md->kobj;
}

/*
 * struct mapped_device should not be exported outside of dm.c
 * so use this check to verify that kobj is part of md structure
 */
struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
{
	struct mapped_device *md;

	md = container_of(kobj, struct mapped_device, kobj);
	if (&md->kobj != kobj)
		return NULL;

2676
	if (test_bit(DMF_FREEING, &md->flags) ||
M
Mike Anderson 已提交
2677
	    dm_deleting_md(md))
2678 2679
		return NULL;

M
Milan Broz 已提交
2680 2681 2682 2683
	dm_get(md);
	return md;
}

2684
int dm_suspended_md(struct mapped_device *md)
L
Linus Torvalds 已提交
2685 2686 2687 2688
{
	return test_bit(DMF_SUSPENDED, &md->flags);
}

2689 2690
int dm_suspended(struct dm_target *ti)
{
2691
	return dm_suspended_md(dm_table_get_md(ti->table));
2692 2693 2694
}
EXPORT_SYMBOL_GPL(dm_suspended);

2695 2696
int dm_noflush_suspending(struct dm_target *ti)
{
2697
	return __noflush_suspending(dm_table_get_md(ti->table));
2698 2699 2700
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);

K
Kiyoshi Ueda 已提交
2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721 2722 2723 2724 2725 2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738 2739 2740 2741 2742 2743 2744 2745 2746 2747 2748 2749 2750 2751 2752 2753 2754 2755
struct dm_md_mempools *dm_alloc_md_mempools(unsigned type)
{
	struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);

	if (!pools)
		return NULL;

	pools->io_pool = (type == DM_TYPE_BIO_BASED) ?
			 mempool_create_slab_pool(MIN_IOS, _io_cache) :
			 mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache);
	if (!pools->io_pool)
		goto free_pools_and_out;

	pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?
			  mempool_create_slab_pool(MIN_IOS, _tio_cache) :
			  mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);
	if (!pools->tio_pool)
		goto free_io_pool_and_out;

	pools->bs = (type == DM_TYPE_BIO_BASED) ?
		    bioset_create(16, 0) : bioset_create(MIN_IOS, 0);
	if (!pools->bs)
		goto free_tio_pool_and_out;

	return pools;

free_tio_pool_and_out:
	mempool_destroy(pools->tio_pool);

free_io_pool_and_out:
	mempool_destroy(pools->io_pool);

free_pools_and_out:
	kfree(pools);

	return NULL;
}

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

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

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

	if (pools->bs)
		bioset_free(pools->bs);

	kfree(pools);
}

2756
static const struct block_device_operations dm_blk_dops = {
L
Linus Torvalds 已提交
2757 2758
	.open = dm_blk_open,
	.release = dm_blk_close,
2759
	.ioctl = dm_blk_ioctl,
D
Darrick J. Wong 已提交
2760
	.getgeo = dm_blk_getgeo,
L
Linus Torvalds 已提交
2761 2762 2763 2764 2765 2766 2767 2768 2769 2770 2771 2772 2773 2774 2775 2776
	.owner = THIS_MODULE
};

EXPORT_SYMBOL(dm_get_mapinfo);

/*
 * 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");
MODULE_DESCRIPTION(DM_NAME " driver");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");