dm.c 28.7 KB
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/*
 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
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 * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
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 *
 * This file is released under the GPL.
 */

#include "dm.h"
#include "dm-bio-list.h"

#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 <linux/blktrace_api.h>
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#include <linux/smp_lock.h>
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#define DM_MSG_PREFIX "core"

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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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/*
 * One of these is allocated per bio.
 */
struct dm_io {
	struct mapped_device *md;
	int error;
	struct bio *bio;
	atomic_t io_count;
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	unsigned long start_time;
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};

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

union map_info *dm_get_mapinfo(struct bio *bio)
{
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	if (bio && bio->bi_private)
		return &((struct target_io *)bio->bi_private)->info;
	return NULL;
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}

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#define MINOR_ALLOCED ((void *)-1)

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/*
 * Bits for the md->flags field.
 */
#define DMF_BLOCK_IO 0
#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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struct mapped_device {
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	struct rw_semaphore io_lock;
	struct semaphore 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;

	request_queue_t *queue;
	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.
	 */
	atomic_t pending;
	wait_queue_head_t wait;
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	struct bio_list deferred;
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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;

	/*
	 * freeze/thaw support require holding onto a super block
	 */
	struct super_block *frozen_sb;
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	struct block_device *suspended_bdev;
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	/* forced geometry settings */
	struct hd_geometry geometry;
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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 int __init local_init(void)
{
	int r;

	/* allocate a slab for the dm_ios */
	_io_cache = kmem_cache_create("dm_io",
				      sizeof(struct dm_io), 0, 0, NULL, NULL);
	if (!_io_cache)
		return -ENOMEM;

	/* allocate a slab for the target ios */
	_tio_cache = kmem_cache_create("dm_tio", sizeof(struct target_io),
				       0, 0, NULL, NULL);
	if (!_tio_cache) {
		kmem_cache_destroy(_io_cache);
		return -ENOMEM;
	}

	_major = major;
	r = register_blkdev(_major, _name);
	if (r < 0) {
		kmem_cache_destroy(_tio_cache);
		kmem_cache_destroy(_io_cache);
		return r;
	}

	if (!_major)
		_major = r;

	return 0;
}

static void local_exit(void)
{
	kmem_cache_destroy(_tio_cache);
	kmem_cache_destroy(_io_cache);

	if (unregister_blkdev(_major, _name) < 0)
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		DMERR("unregister_blkdev failed");
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	_major = 0;

	DMINFO("cleaned up");
}

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

void (*_exits[])(void) = {
	local_exit,
	dm_target_exit,
	dm_linear_exit,
	dm_stripe_exit,
	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
 */
static int dm_blk_open(struct inode *inode, struct file *file)
{
	struct mapped_device *md;

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	spin_lock(&_minor_lock);

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

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	if (test_bit(DMF_FREEING, &md->flags) ||
	    test_bit(DMF_DELETING, &md->flags)) {
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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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}

static int dm_blk_close(struct inode *inode, struct file *file)
{
	struct mapped_device *md;

	md = inode->i_bdev->bd_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 inode *inode, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	struct mapped_device *md;
	struct dm_table *map;
	struct dm_target *tgt;
	int r = -ENOTTY;

	/* We don't really need this lock, but we do need 'inode'. */
	unlock_kernel();

	md = inode->i_bdev->bd_disk->private_data;

	map = dm_get_table(md);

	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);

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

	if (tgt->type->ioctl)
		r = tgt->type->ioctl(tgt, inode, file, cmd, arg);

out:
	dm_table_put(map);

	lock_kernel();
	return r;
}

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

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

static inline struct target_io *alloc_tio(struct mapped_device *md)
{
	return mempool_alloc(md->tio_pool, GFP_NOIO);
}

static inline void free_tio(struct mapped_device *md, struct target_io *tio)
{
	mempool_free(tio, md->tio_pool);
}

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static void start_io_acct(struct dm_io *io)
{
	struct mapped_device *md = io->md;

	io->start_time = jiffies;

	preempt_disable();
	disk_round_stats(dm_disk(md));
	preempt_enable();
	dm_disk(md)->in_flight = atomic_inc_return(&md->pending);
}

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

	preempt_disable();
	disk_round_stats(dm_disk(md));
	preempt_enable();
	dm_disk(md)->in_flight = pending = atomic_dec_return(&md->pending);

	disk_stat_add(dm_disk(md), ticks[rw], duration);

	return !pending;
}

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/*
 * Add the bio to the list of deferred io.
 */
static int queue_io(struct mapped_device *md, struct bio *bio)
{
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	down_write(&md->io_lock);
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	if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
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		up_write(&md->io_lock);
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		return 1;
	}

	bio_list_add(&md->deferred, bio);

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	up_write(&md->io_lock);
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	return 0;		/* deferred successfully */
}

/*
 * 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.
 */
struct dm_table *dm_get_table(struct mapped_device *md)
{
	struct dm_table *t;

	read_lock(&md->map_lock);
	t = md->map;
	if (t)
		dm_table_get(t);
	read_unlock(&md->map_lock);

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

/*
 * 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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{
	if (error)
		io->error = error;

	if (atomic_dec_and_test(&io->io_count)) {
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		if (end_io_acct(io))
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			/* nudge anyone waiting on suspend queue */
			wake_up(&io->md->wait);

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		blk_add_trace_bio(io->md->queue, io->bio, BLK_TA_COMPLETE);

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		bio_endio(io->bio, io->bio->bi_size, io->error);
		free_io(io->md, io);
	}
}

static int clone_endio(struct bio *bio, unsigned int done, int error)
{
	int r = 0;
	struct target_io *tio = bio->bi_private;
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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->bi_size)
		return 1;

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

	if (endio) {
		r = endio(tio->ti, bio, error, &tio->info);
		if (r < 0)
			error = r;
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		else if (r == DM_ENDIO_INCOMPLETE)
			/* The target will handle the io */
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			return 1;
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		else if (r) {
			DMWARN("unimplemented target endio return value: %d", r);
			BUG();
		}
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	}

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	dec_pending(tio->io, error);

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

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	bio_put(bio);
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	free_tio(md, tio);
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	return r;
}

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,
		      struct target_io *tio)
{
	int r;
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	sector_t sector;
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	struct mapped_device *md;
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	/*
	 * Sanity checks.
	 */
	BUG_ON(!clone->bi_size);

	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);
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	sector = clone->bi_sector;
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	r = ti->type->map(ti, clone, &tio->info);
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	if (r == DM_MAPIO_REMAPPED) {
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		/* the bio has been remapped so dispatch it */
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		blk_add_trace_remap(bdev_get_queue(clone->bi_bdev), clone,
				    tio->io->bio->bi_bdev->bd_dev, sector,
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				    clone->bi_sector);

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		generic_make_request(clone);
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	} else if (r < 0) {
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		/* error the io and bail out */
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		md = tio->io->md;
		dec_pending(tio->io, r);
		/*
		 * Store bio_set for cleanup.
		 */
		clone->bi_private = md->bs;
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		bio_put(clone);
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		free_tio(md, tio);
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	} else if (r) {
		DMWARN("unimplemented target map return value: %d", r);
		BUG();
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	}
}

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;
};

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static void dm_bio_destructor(struct bio *bio)
{
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	struct bio_set *bs = bio->bi_private;

	bio_free(bio, bs);
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}

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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,
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			      unsigned int len, struct bio_set *bs)
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{
	struct bio *clone;
	struct bio_vec *bv = bio->bi_io_vec + idx;

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	clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
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	clone->bi_destructor = dm_bio_destructor;
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	*clone->bi_io_vec = *bv;

	clone->bi_sector = sector;
	clone->bi_bdev = bio->bi_bdev;
	clone->bi_rw = bio->bi_rw;
	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;

	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,
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			     unsigned int len, struct bio_set *bs)
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{
	struct bio *clone;

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	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
	__bio_clone(clone, bio);
	clone->bi_destructor = dm_bio_destructor;
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	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);

	return clone;
}

static void __clone_and_map(struct clone_info *ci)
{
	struct bio *clone, *bio = ci->bio;
	struct dm_target *ti = dm_table_find_target(ci->map, ci->sector);
	sector_t len = 0, max = max_io_len(ci->md, ci->sector, ti);
	struct target_io *tio;

	/*
	 * Allocate a target io object.
	 */
	tio = alloc_tio(ci->md);
	tio->io = ci->io;
	tio->ti = ti;
	memset(&tio->info, 0, sizeof(tio->info));

	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,
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				  bio->bi_vcnt - ci->idx, ci->sector_count,
				  ci->md->bs);
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		__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;
		}

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		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
				  ci->md->bs);
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		__map_bio(ti, clone, tio);

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

	} else {
		/*
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		 * Handle a bvec that must be split between two or more targets.
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		 */
		struct bio_vec *bv = bio->bi_io_vec + ci->idx;
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		sector_t remaining = to_sector(bv->bv_len);
		unsigned int offset = 0;
L
Linus Torvalds 已提交
696

697 698 699 700
		do {
			if (offset) {
				ti = dm_table_find_target(ci->map, ci->sector);
				max = max_io_len(ci->md, ci->sector, ti);
L
Linus Torvalds 已提交
701

702 703 704 705 706 707 708 709 710
				tio = alloc_tio(ci->md);
				tio->io = ci->io;
				tio->ti = ti;
				memset(&tio->info, 0, sizeof(tio->info));
			}

			len = min(remaining, max);

			clone = split_bvec(bio, ci->sector, ci->idx,
S
Stefan Bader 已提交
711 712
					   bv->bv_offset + offset, len,
					   ci->md->bs);
713 714 715 716 717 718 719

			__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
720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748

		ci->idx++;
	}
}

/*
 * Split the bio into several clones.
 */
static void __split_bio(struct mapped_device *md, struct bio *bio)
{
	struct clone_info ci;

	ci.map = dm_get_table(md);
	if (!ci.map) {
		bio_io_error(bio, bio->bi_size);
		return;
	}

	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;
	ci.sector = bio->bi_sector;
	ci.sector_count = bio_sectors(bio);
	ci.idx = bio->bi_idx;

749
	start_io_acct(ci.io);
L
Linus Torvalds 已提交
750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767
	while (ci.sector_count)
		__clone_and_map(&ci);

	/* drop the extra reference count */
	dec_pending(ci.io, 0);
	dm_table_put(ci.map);
}
/*-----------------------------------------------------------------
 * CRUD END
 *---------------------------------------------------------------*/

/*
 * The request function that just remaps the bio built up by
 * dm_merge_bvec.
 */
static int dm_request(request_queue_t *q, struct bio *bio)
{
	int r;
768
	int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
769 770
	struct mapped_device *md = q->queuedata;

771
	down_read(&md->io_lock);
L
Linus Torvalds 已提交
772

773 774 775
	disk_stat_inc(dm_disk(md), ios[rw]);
	disk_stat_add(dm_disk(md), sectors[rw], bio_sectors(bio));

L
Linus Torvalds 已提交
776 777 778 779 780
	/*
	 * If we're suspended we have to queue
	 * this io for later.
	 */
	while (test_bit(DMF_BLOCK_IO, &md->flags)) {
781
		up_read(&md->io_lock);
L
Linus Torvalds 已提交
782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799

		if (bio_rw(bio) == READA) {
			bio_io_error(bio, bio->bi_size);
			return 0;
		}

		r = queue_io(md, bio);
		if (r < 0) {
			bio_io_error(bio, bio->bi_size);
			return 0;

		} else if (r == 0)
			return 0;	/* deferred successfully */

		/*
		 * We're in a while loop, because someone could suspend
		 * before we get to the following read lock.
		 */
800
		down_read(&md->io_lock);
L
Linus Torvalds 已提交
801 802 803
	}

	__split_bio(md, bio);
804
	up_read(&md->io_lock);
L
Linus Torvalds 已提交
805 806 807 808 809 810 811 812 813 814 815
	return 0;
}

static int dm_flush_all(request_queue_t *q, struct gendisk *disk,
			sector_t *error_sector)
{
	struct mapped_device *md = q->queuedata;
	struct dm_table *map = dm_get_table(md);
	int ret = -ENXIO;

	if (map) {
816
		ret = dm_table_flush_all(map);
L
Linus Torvalds 已提交
817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853
		dm_table_put(map);
	}

	return ret;
}

static void dm_unplug_all(request_queue_t *q)
{
	struct mapped_device *md = q->queuedata;
	struct dm_table *map = dm_get_table(md);

	if (map) {
		dm_table_unplug_all(map);
		dm_table_put(map);
	}
}

static int dm_any_congested(void *congested_data, int bdi_bits)
{
	int r;
	struct mapped_device *md = (struct mapped_device *) congested_data;
	struct dm_table *map = dm_get_table(md);

	if (!map || test_bit(DMF_BLOCK_IO, &md->flags))
		r = bdi_bits;
	else
		r = dm_table_any_congested(map, bdi_bits);

	dm_table_put(map);
	return r;
}

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

854
static void free_minor(int minor)
L
Linus Torvalds 已提交
855
{
856
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
857
	idr_remove(&_minor_idr, minor);
858
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
859 860 861 862 863
}

/*
 * See if the device with a specific minor # is free.
 */
864
static int specific_minor(struct mapped_device *md, int minor)
L
Linus Torvalds 已提交
865 866 867 868 869 870
{
	int r, m;

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

J
Jeff Mahoney 已提交
871 872 873 874
	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
	if (!r)
		return -ENOMEM;

875
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
876 877 878 879 880 881

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

882
	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
J
Jeff Mahoney 已提交
883
	if (r)
L
Linus Torvalds 已提交
884 885 886 887 888 889 890 891 892
		goto out;

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

out:
893
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
894 895 896
	return r;
}

897
static int next_free_minor(struct mapped_device *md, int *minor)
L
Linus Torvalds 已提交
898
{
899
	int r, m;
L
Linus Torvalds 已提交
900 901

	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
J
Jeff Mahoney 已提交
902 903 904
	if (!r)
		return -ENOMEM;

905
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
906

907
	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
L
Linus Torvalds 已提交
908 909 910 911 912 913 914 915 916 917 918 919 920
	if (r) {
		goto out;
	}

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

	*minor = m;

out:
921
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
922 923 924 925 926 927 928 929
	return r;
}

static struct block_device_operations dm_blk_dops;

/*
 * Allocate and initialise a blank device with a given minor.
 */
930
static struct mapped_device *alloc_dev(int minor)
L
Linus Torvalds 已提交
931 932 933
{
	int r;
	struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
934
	void *old_md;
L
Linus Torvalds 已提交
935 936 937 938 939 940

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

941 942 943
	if (!try_module_get(THIS_MODULE))
		goto bad0;

L
Linus Torvalds 已提交
944
	/* get a minor number for the dev */
945 946 947 948
	if (minor == DM_ANY_MINOR)
		r = next_free_minor(md, &minor);
	else
		r = specific_minor(md, minor);
L
Linus Torvalds 已提交
949 950 951 952
	if (r < 0)
		goto bad1;

	memset(md, 0, sizeof(*md));
953 954
	init_rwsem(&md->io_lock);
	init_MUTEX(&md->suspend_lock);
L
Linus Torvalds 已提交
955 956
	rwlock_init(&md->map_lock);
	atomic_set(&md->holders, 1);
957
	atomic_set(&md->open_count, 0);
L
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958 959 960 961
	atomic_set(&md->event_nr, 0);

	md->queue = blk_alloc_queue(GFP_KERNEL);
	if (!md->queue)
962
		goto bad1_free_minor;
L
Linus Torvalds 已提交
963 964 965 966 967

	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);
968
	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
L
Linus Torvalds 已提交
969 970 971
	md->queue->unplug_fn = dm_unplug_all;
	md->queue->issue_flush_fn = dm_flush_all;

972
	md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
K
Kiyoshi Ueda 已提交
973 974
	if (!md->io_pool)
		goto bad2;
L
Linus Torvalds 已提交
975

976
	md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
L
Linus Torvalds 已提交
977 978 979
	if (!md->tio_pool)
		goto bad3;

S
Stefan Bader 已提交
980 981 982 983
	md->bs = bioset_create(16, 16, 4);
	if (!md->bs)
		goto bad_no_bioset;

L
Linus Torvalds 已提交
984 985 986 987
	md->disk = alloc_disk(1);
	if (!md->disk)
		goto bad4;

988 989 990 991
	atomic_set(&md->pending, 0);
	init_waitqueue_head(&md->wait);
	init_waitqueue_head(&md->eventq);

L
Linus Torvalds 已提交
992 993 994 995 996 997 998
	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
999
	format_dev_t(md->name, MKDEV(_major, minor));
L
Linus Torvalds 已提交
1000

1001
	/* Populate the mapping, nobody knows we exist yet */
1002
	spin_lock(&_minor_lock);
1003
	old_md = idr_replace(&_minor_idr, md, minor);
1004
	spin_unlock(&_minor_lock);
1005 1006 1007

	BUG_ON(old_md != MINOR_ALLOCED);

L
Linus Torvalds 已提交
1008 1009 1010
	return md;

 bad4:
S
Stefan Bader 已提交
1011 1012
	bioset_free(md->bs);
 bad_no_bioset:
L
Linus Torvalds 已提交
1013 1014 1015 1016
	mempool_destroy(md->tio_pool);
 bad3:
	mempool_destroy(md->io_pool);
 bad2:
1017
	blk_cleanup_queue(md->queue);
1018
 bad1_free_minor:
L
Linus Torvalds 已提交
1019 1020
	free_minor(minor);
 bad1:
1021 1022
	module_put(THIS_MODULE);
 bad0:
L
Linus Torvalds 已提交
1023 1024 1025 1026 1027 1028
	kfree(md);
	return NULL;
}

static void free_dev(struct mapped_device *md)
{
1029
	int minor = md->disk->first_minor;
1030

1031 1032 1033 1034
	if (md->suspended_bdev) {
		thaw_bdev(md->suspended_bdev, NULL);
		bdput(md->suspended_bdev);
	}
L
Linus Torvalds 已提交
1035 1036
	mempool_destroy(md->tio_pool);
	mempool_destroy(md->io_pool);
S
Stefan Bader 已提交
1037
	bioset_free(md->bs);
L
Linus Torvalds 已提交
1038
	del_gendisk(md->disk);
1039
	free_minor(minor);
J
Jeff Mahoney 已提交
1040 1041 1042 1043 1044

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

L
Linus Torvalds 已提交
1045
	put_disk(md->disk);
1046
	blk_cleanup_queue(md->queue);
1047
	module_put(THIS_MODULE);
L
Linus Torvalds 已提交
1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061
	kfree(md);
}

/*
 * Bind a table to the device.
 */
static void event_callback(void *context)
{
	struct mapped_device *md = (struct mapped_device *) context;

	atomic_inc(&md->event_nr);
	wake_up(&md->eventq);
}

1062
static void __set_size(struct mapped_device *md, sector_t size)
L
Linus Torvalds 已提交
1063
{
1064
	set_capacity(md->disk, size);
L
Linus Torvalds 已提交
1065

1066
	mutex_lock(&md->suspended_bdev->bd_inode->i_mutex);
1067
	i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
1068
	mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex);
L
Linus Torvalds 已提交
1069 1070 1071 1072 1073 1074 1075 1076
}

static int __bind(struct mapped_device *md, struct dm_table *t)
{
	request_queue_t *q = md->queue;
	sector_t size;

	size = dm_table_get_size(t);
D
Darrick J. Wong 已提交
1077 1078 1079 1080 1081 1082 1083

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

1084
	__set_size(md, size);
L
Linus Torvalds 已提交
1085 1086 1087
	if (size == 0)
		return 0;

1088 1089 1090
	dm_table_get(t);
	dm_table_event_callback(t, event_callback, md);

L
Linus Torvalds 已提交
1091 1092
	write_lock(&md->map_lock);
	md->map = t;
1093
	dm_table_set_restrictions(t, q);
L
Linus Torvalds 已提交
1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115
	write_unlock(&md->map_lock);

	return 0;
}

static void __unbind(struct mapped_device *md)
{
	struct dm_table *map = md->map;

	if (!map)
		return;

	dm_table_event_callback(map, NULL, NULL);
	write_lock(&md->map_lock);
	md->map = NULL;
	write_unlock(&md->map_lock);
	dm_table_put(map);
}

/*
 * Constructor for a new device.
 */
1116
int dm_create(int minor, struct mapped_device **result)
L
Linus Torvalds 已提交
1117 1118 1119
{
	struct mapped_device *md;

1120
	md = alloc_dev(minor);
L
Linus Torvalds 已提交
1121 1122 1123 1124 1125 1126 1127
	if (!md)
		return -ENXIO;

	*result = md;
	return 0;
}

1128
static struct mapped_device *dm_find_md(dev_t dev)
L
Linus Torvalds 已提交
1129 1130 1131 1132 1133 1134 1135
{
	struct mapped_device *md;
	unsigned minor = MINOR(dev);

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

1136
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1137 1138

	md = idr_find(&_minor_idr, minor);
J
Jeff Mahoney 已提交
1139 1140
	if (md && (md == MINOR_ALLOCED ||
		   (dm_disk(md)->first_minor != minor) ||
A
Alasdair G Kergon 已提交
1141
		   test_bit(DMF_FREEING, &md->flags))) {
1142
		md = NULL;
J
Jeff Mahoney 已提交
1143 1144
		goto out;
	}
L
Linus Torvalds 已提交
1145

J
Jeff Mahoney 已提交
1146
out:
1147
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1148

1149 1150 1151
	return md;
}

1152 1153 1154 1155 1156 1157 1158 1159 1160 1161
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
1162
void *dm_get_mdptr(struct mapped_device *md)
1163
{
A
Alasdair G Kergon 已提交
1164
	return md->interface_ptr;
L
Linus Torvalds 已提交
1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176
}

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);
}

1177 1178 1179 1180 1181 1182
const char *dm_device_name(struct mapped_device *md)
{
	return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);

L
Linus Torvalds 已提交
1183 1184
void dm_put(struct mapped_device *md)
{
M
Mike Anderson 已提交
1185
	struct dm_table *map;
L
Linus Torvalds 已提交
1186

J
Jeff Mahoney 已提交
1187 1188
	BUG_ON(test_bit(DMF_FREEING, &md->flags));

1189
	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
M
Mike Anderson 已提交
1190
		map = dm_get_table(md);
1191
		idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
J
Jeff Mahoney 已提交
1192
		set_bit(DMF_FREEING, &md->flags);
1193
		spin_unlock(&_minor_lock);
1194
		if (!dm_suspended(md)) {
L
Linus Torvalds 已提交
1195 1196 1197 1198
			dm_table_presuspend_targets(map);
			dm_table_postsuspend_targets(map);
		}
		__unbind(md);
M
Mike Anderson 已提交
1199
		dm_table_put(map);
L
Linus Torvalds 已提交
1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223
		free_dev(md);
	}
}

/*
 * Process the deferred bios
 */
static void __flush_deferred_io(struct mapped_device *md, struct bio *c)
{
	struct bio *n;

	while (c) {
		n = c->bi_next;
		c->bi_next = NULL;
		__split_bio(md, c);
		c = n;
	}
}

/*
 * Swap in a new table (destroying old one).
 */
int dm_swap_table(struct mapped_device *md, struct dm_table *table)
{
1224
	int r = -EINVAL;
L
Linus Torvalds 已提交
1225

1226
	down(&md->suspend_lock);
L
Linus Torvalds 已提交
1227 1228

	/* device must be suspended */
1229
	if (!dm_suspended(md))
1230
		goto out;
L
Linus Torvalds 已提交
1231 1232 1233 1234

	__unbind(md);
	r = __bind(md, table);

1235
out:
1236
	up(&md->suspend_lock);
1237
	return r;
L
Linus Torvalds 已提交
1238 1239 1240 1241 1242 1243
}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
1244
static int lock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
1245
{
1246
	int r;
L
Linus Torvalds 已提交
1247 1248

	WARN_ON(md->frozen_sb);
1249

1250
	md->frozen_sb = freeze_bdev(md->suspended_bdev);
1251
	if (IS_ERR(md->frozen_sb)) {
1252
		r = PTR_ERR(md->frozen_sb);
1253 1254
		md->frozen_sb = NULL;
		return r;
1255 1256
	}

1257 1258
	set_bit(DMF_FROZEN, &md->flags);

L
Linus Torvalds 已提交
1259
	/* don't bdput right now, we don't want the bdev
1260
	 * to go away while it is locked.
L
Linus Torvalds 已提交
1261 1262 1263 1264
	 */
	return 0;
}

1265
static void unlock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
1266
{
1267 1268 1269
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

1270
	thaw_bdev(md->suspended_bdev, md->frozen_sb);
L
Linus Torvalds 已提交
1271
	md->frozen_sb = NULL;
1272
	clear_bit(DMF_FROZEN, &md->flags);
L
Linus Torvalds 已提交
1273 1274 1275 1276 1277 1278 1279 1280 1281
}

/*
 * 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.
 */
1282
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
L
Linus Torvalds 已提交
1283
{
1284
	struct dm_table *map = NULL;
L
Linus Torvalds 已提交
1285
	DECLARE_WAITQUEUE(wait, current);
J
Jun'ichi Nomura 已提交
1286
	struct bio *def;
1287
	int r = -EINVAL;
1288
	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
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1290 1291 1292
	down(&md->suspend_lock);

	if (dm_suspended(md))
1293
		goto out_unlock;
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	map = dm_get_table(md);

1297 1298 1299
	/* This does not get reverted if there's an error later. */
	dm_table_presuspend_targets(map);

1300 1301 1302 1303 1304 1305 1306
	md->suspended_bdev = bdget_disk(md->disk, 0);
	if (!md->suspended_bdev) {
		DMWARN("bdget failed in dm_suspend");
		r = -ENOMEM;
		goto out;
	}

1307
	/* Flush I/O to the device. */
1308 1309 1310 1311 1312
	if (do_lockfs) {
		r = lock_fs(md);
		if (r)
			goto out;
	}
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1313 1314

	/*
1315
	 * First we set the BLOCK_IO flag so no more ios will be mapped.
L
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1316
	 */
1317 1318
	down_write(&md->io_lock);
	set_bit(DMF_BLOCK_IO, &md->flags);
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1319 1320

	add_wait_queue(&md->wait, &wait);
1321
	up_write(&md->io_lock);
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1322 1323

	/* unplug */
1324
	if (map)
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		dm_table_unplug_all(map);

	/*
	 * Then we wait for the already mapped ios to
	 * complete.
	 */
	while (1) {
		set_current_state(TASK_INTERRUPTIBLE);

		if (!atomic_read(&md->pending) || signal_pending(current))
			break;

		io_schedule();
	}
	set_current_state(TASK_RUNNING);

1341
	down_write(&md->io_lock);
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	remove_wait_queue(&md->wait, &wait);

	/* were we interrupted ? */
1345
	r = -EINTR;
1346
	if (atomic_read(&md->pending)) {
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		clear_bit(DMF_BLOCK_IO, &md->flags);
		def = bio_list_get(&md->deferred);
		__flush_deferred_io(md, def);
1350 1351 1352 1353 1354
		up_write(&md->io_lock);
		unlock_fs(md);
		goto out;
	}
	up_write(&md->io_lock);
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1355

1356
	dm_table_postsuspend_targets(map);
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1357

1358
	set_bit(DMF_SUSPENDED, &md->flags);
1359

1360
	r = 0;
1361

1362
out:
1363 1364 1365 1366 1367
	if (r && md->suspended_bdev) {
		bdput(md->suspended_bdev);
		md->suspended_bdev = NULL;
	}

1368
	dm_table_put(map);
1369 1370

out_unlock:
1371
	up(&md->suspend_lock);
1372
	return r;
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1373 1374 1375 1376
}

int dm_resume(struct mapped_device *md)
{
1377
	int r = -EINVAL;
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1378
	struct bio *def;
1379
	struct dm_table *map = NULL;
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1380

1381 1382
	down(&md->suspend_lock);
	if (!dm_suspended(md))
1383 1384 1385
		goto out;

	map = dm_get_table(md);
1386
	if (!map || !dm_table_get_size(map))
1387
		goto out;
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1388

1389 1390 1391
	r = dm_table_resume_targets(map);
	if (r)
		goto out;
1392 1393

	down_write(&md->io_lock);
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1394 1395 1396 1397
	clear_bit(DMF_BLOCK_IO, &md->flags);

	def = bio_list_get(&md->deferred);
	__flush_deferred_io(md, def);
1398 1399 1400 1401
	up_write(&md->io_lock);

	unlock_fs(md);

1402 1403 1404
	bdput(md->suspended_bdev);
	md->suspended_bdev = NULL;

1405 1406
	clear_bit(DMF_SUSPENDED, &md->flags);

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1407 1408
	dm_table_unplug_all(map);

1409 1410
	kobject_uevent(&md->disk->kobj, KOBJ_CHANGE);

1411
	r = 0;
1412

1413 1414
out:
	dm_table_put(map);
1415 1416
	up(&md->suspend_lock);

1417
	return r;
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1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450
}

/*-----------------------------------------------------------------
 * Event notification.
 *---------------------------------------------------------------*/
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)));
}

/*
 * 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;
}

int dm_suspended(struct mapped_device *md)
{
	return test_bit(DMF_SUSPENDED, &md->flags);
}

static struct block_device_operations dm_blk_dops = {
	.open = dm_blk_open,
	.release = dm_blk_close,
1451
	.ioctl = dm_blk_ioctl,
D
Darrick J. Wong 已提交
1452
	.getgeo = dm_blk_getgeo,
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1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468
	.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");