dm.c 28.4 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;
 	struct bio_list deferred;

	/*
	 * 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
static kmem_cache_t *_io_cache;
static kmem_cache_t *_tio_cache;

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;

		else if (r > 0)
			/* the target wants another shot at the io */
			return 1;
	}

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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 > 0) {
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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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	}
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	else if (r < 0) {
		/* 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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	}
}

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;
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		do {
			if (offset) {
				ti = dm_table_find_target(ci->map, ci->sector);
				max = max_io_len(ci->md, ci->sector, ti);
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				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
707 708
					   bv->bv_offset + offset, len,
					   ci->md->bs);
709 710 711 712 713 714 715

			__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
716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744

		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;

745
	start_io_acct(ci.io);
L
Linus Torvalds 已提交
746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763
	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;
764
	int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
765 766
	struct mapped_device *md = q->queuedata;

767
	down_read(&md->io_lock);
L
Linus Torvalds 已提交
768

769 770 771
	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
772 773 774 775 776
	/*
	 * If we're suspended we have to queue
	 * this io for later.
	 */
	while (test_bit(DMF_BLOCK_IO, &md->flags)) {
777
		up_read(&md->io_lock);
L
Linus Torvalds 已提交
778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795

		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.
		 */
796
		down_read(&md->io_lock);
L
Linus Torvalds 已提交
797 798 799
	}

	__split_bio(md, bio);
800
	up_read(&md->io_lock);
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Linus Torvalds 已提交
801 802 803 804 805 806 807 808 809 810 811
	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) {
812
		ret = dm_table_flush_all(map);
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Linus Torvalds 已提交
813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849
		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);

850
static void free_minor(int minor)
L
Linus Torvalds 已提交
851
{
852
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
853
	idr_remove(&_minor_idr, minor);
854
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
855 856 857 858 859
}

/*
 * See if the device with a specific minor # is free.
 */
860
static int specific_minor(struct mapped_device *md, int minor)
L
Linus Torvalds 已提交
861 862 863 864 865 866
{
	int r, m;

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

J
Jeff Mahoney 已提交
867 868 869 870
	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
	if (!r)
		return -ENOMEM;

871
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
872 873 874 875 876 877

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

878
	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
J
Jeff Mahoney 已提交
879
	if (r)
L
Linus Torvalds 已提交
880 881 882 883 884 885 886 887 888
		goto out;

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

out:
889
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
890 891 892
	return r;
}

893
static int next_free_minor(struct mapped_device *md, int *minor)
L
Linus Torvalds 已提交
894
{
895
	int r, m;
L
Linus Torvalds 已提交
896 897

	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
J
Jeff Mahoney 已提交
898 899 900
	if (!r)
		return -ENOMEM;

901
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
902

903
	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
L
Linus Torvalds 已提交
904 905 906 907 908 909 910 911 912 913 914 915 916
	if (r) {
		goto out;
	}

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

	*minor = m;

out:
917
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
918 919 920 921 922 923 924 925
	return r;
}

static struct block_device_operations dm_blk_dops;

/*
 * Allocate and initialise a blank device with a given minor.
 */
926
static struct mapped_device *alloc_dev(int minor)
L
Linus Torvalds 已提交
927 928 929
{
	int r;
	struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
930
	void *old_md;
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Linus Torvalds 已提交
931 932 933 934 935 936

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

937 938 939
	if (!try_module_get(THIS_MODULE))
		goto bad0;

L
Linus Torvalds 已提交
940
	/* get a minor number for the dev */
941 942 943 944
	if (minor == DM_ANY_MINOR)
		r = next_free_minor(md, &minor);
	else
		r = specific_minor(md, minor);
L
Linus Torvalds 已提交
945 946 947 948
	if (r < 0)
		goto bad1;

	memset(md, 0, sizeof(*md));
949 950
	init_rwsem(&md->io_lock);
	init_MUTEX(&md->suspend_lock);
L
Linus Torvalds 已提交
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	rwlock_init(&md->map_lock);
	atomic_set(&md->holders, 1);
953
	atomic_set(&md->open_count, 0);
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954 955 956 957
	atomic_set(&md->event_nr, 0);

	md->queue = blk_alloc_queue(GFP_KERNEL);
	if (!md->queue)
958
		goto bad1_free_minor;
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Linus Torvalds 已提交
959 960 961 962 963

	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);
964
	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
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965 966 967
	md->queue->unplug_fn = dm_unplug_all;
	md->queue->issue_flush_fn = dm_flush_all;

968
	md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
L
Linus Torvalds 已提交
969 970 971
 	if (!md->io_pool)
 		goto bad2;

972
	md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
L
Linus Torvalds 已提交
973 974 975
	if (!md->tio_pool)
		goto bad3;

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Stefan Bader 已提交
976 977 978 979
	md->bs = bioset_create(16, 16, 4);
	if (!md->bs)
		goto bad_no_bioset;

L
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980 981 982 983
	md->disk = alloc_disk(1);
	if (!md->disk)
		goto bad4;

984 985 986 987
	atomic_set(&md->pending, 0);
	init_waitqueue_head(&md->wait);
	init_waitqueue_head(&md->eventq);

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Linus Torvalds 已提交
988 989 990 991 992 993 994
	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
995
	format_dev_t(md->name, MKDEV(_major, minor));
L
Linus Torvalds 已提交
996

997
	/* Populate the mapping, nobody knows we exist yet */
998
	spin_lock(&_minor_lock);
999
	old_md = idr_replace(&_minor_idr, md, minor);
1000
	spin_unlock(&_minor_lock);
1001 1002 1003

	BUG_ON(old_md != MINOR_ALLOCED);

L
Linus Torvalds 已提交
1004 1005 1006
	return md;

 bad4:
S
Stefan Bader 已提交
1007 1008
	bioset_free(md->bs);
 bad_no_bioset:
L
Linus Torvalds 已提交
1009 1010 1011 1012
	mempool_destroy(md->tio_pool);
 bad3:
	mempool_destroy(md->io_pool);
 bad2:
1013
	blk_cleanup_queue(md->queue);
1014
 bad1_free_minor:
L
Linus Torvalds 已提交
1015 1016
	free_minor(minor);
 bad1:
1017 1018
	module_put(THIS_MODULE);
 bad0:
L
Linus Torvalds 已提交
1019 1020 1021 1022 1023 1024
	kfree(md);
	return NULL;
}

static void free_dev(struct mapped_device *md)
{
1025
	int minor = md->disk->first_minor;
1026

1027 1028 1029 1030
	if (md->suspended_bdev) {
		thaw_bdev(md->suspended_bdev, NULL);
		bdput(md->suspended_bdev);
	}
L
Linus Torvalds 已提交
1031 1032
	mempool_destroy(md->tio_pool);
	mempool_destroy(md->io_pool);
S
Stefan Bader 已提交
1033
	bioset_free(md->bs);
L
Linus Torvalds 已提交
1034
	del_gendisk(md->disk);
1035
	free_minor(minor);
J
Jeff Mahoney 已提交
1036 1037 1038 1039 1040

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

L
Linus Torvalds 已提交
1041
	put_disk(md->disk);
1042
	blk_cleanup_queue(md->queue);
1043
	module_put(THIS_MODULE);
L
Linus Torvalds 已提交
1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057
	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);
}

1058
static void __set_size(struct mapped_device *md, sector_t size)
L
Linus Torvalds 已提交
1059
{
1060
	set_capacity(md->disk, size);
L
Linus Torvalds 已提交
1061

1062
	mutex_lock(&md->suspended_bdev->bd_inode->i_mutex);
1063
	i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
1064
	mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex);
L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070 1071 1072
}

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
1073 1074 1075 1076 1077 1078 1079

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

1080
	__set_size(md, size);
L
Linus Torvalds 已提交
1081 1082 1083
	if (size == 0)
		return 0;

1084 1085 1086
	dm_table_get(t);
	dm_table_event_callback(t, event_callback, md);

L
Linus Torvalds 已提交
1087 1088
	write_lock(&md->map_lock);
	md->map = t;
1089
	dm_table_set_restrictions(t, q);
L
Linus Torvalds 已提交
1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111
	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.
 */
1112
int dm_create(int minor, struct mapped_device **result)
L
Linus Torvalds 已提交
1113 1114 1115
{
	struct mapped_device *md;

1116
	md = alloc_dev(minor);
L
Linus Torvalds 已提交
1117 1118 1119 1120 1121 1122 1123
	if (!md)
		return -ENXIO;

	*result = md;
	return 0;
}

1124
static struct mapped_device *dm_find_md(dev_t dev)
L
Linus Torvalds 已提交
1125 1126 1127 1128 1129 1130 1131
{
	struct mapped_device *md;
	unsigned minor = MINOR(dev);

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

1132
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1133 1134

	md = idr_find(&_minor_idr, minor);
J
Jeff Mahoney 已提交
1135 1136
	if (md && (md == MINOR_ALLOCED ||
		   (dm_disk(md)->first_minor != minor) ||
A
Alasdair G Kergon 已提交
1137
		   test_bit(DMF_FREEING, &md->flags))) {
1138
		md = NULL;
J
Jeff Mahoney 已提交
1139 1140
		goto out;
	}
L
Linus Torvalds 已提交
1141

J
Jeff Mahoney 已提交
1142
out:
1143
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1144

1145 1146 1147
	return md;
}

1148 1149 1150 1151 1152 1153 1154 1155 1156 1157
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
1158
void *dm_get_mdptr(struct mapped_device *md)
1159
{
A
Alasdair G Kergon 已提交
1160
	return md->interface_ptr;
L
Linus Torvalds 已提交
1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172
}

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);
}

1173 1174 1175 1176 1177 1178
const char *dm_device_name(struct mapped_device *md)
{
	return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);

L
Linus Torvalds 已提交
1179 1180
void dm_put(struct mapped_device *md)
{
M
Mike Anderson 已提交
1181
	struct dm_table *map;
L
Linus Torvalds 已提交
1182

J
Jeff Mahoney 已提交
1183 1184
	BUG_ON(test_bit(DMF_FREEING, &md->flags));

1185
	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
M
Mike Anderson 已提交
1186
		map = dm_get_table(md);
1187
		idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
J
Jeff Mahoney 已提交
1188
		set_bit(DMF_FREEING, &md->flags);
1189
		spin_unlock(&_minor_lock);
1190
		if (!dm_suspended(md)) {
L
Linus Torvalds 已提交
1191 1192 1193 1194
			dm_table_presuspend_targets(map);
			dm_table_postsuspend_targets(map);
		}
		__unbind(md);
M
Mike Anderson 已提交
1195
		dm_table_put(map);
L
Linus Torvalds 已提交
1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
		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)
{
1220
	int r = -EINVAL;
L
Linus Torvalds 已提交
1221

1222
	down(&md->suspend_lock);
L
Linus Torvalds 已提交
1223 1224

	/* device must be suspended */
1225
	if (!dm_suspended(md))
1226
		goto out;
L
Linus Torvalds 已提交
1227 1228 1229 1230

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

1231
out:
1232
	up(&md->suspend_lock);
1233
	return r;
L
Linus Torvalds 已提交
1234 1235 1236 1237 1238 1239
}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
1240
static int lock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
1241
{
1242
	int r;
L
Linus Torvalds 已提交
1243 1244

	WARN_ON(md->frozen_sb);
1245

1246
	md->frozen_sb = freeze_bdev(md->suspended_bdev);
1247
	if (IS_ERR(md->frozen_sb)) {
1248
		r = PTR_ERR(md->frozen_sb);
1249 1250
		md->frozen_sb = NULL;
		return r;
1251 1252
	}

1253 1254
	set_bit(DMF_FROZEN, &md->flags);

L
Linus Torvalds 已提交
1255
	/* don't bdput right now, we don't want the bdev
1256
	 * to go away while it is locked.
L
Linus Torvalds 已提交
1257 1258 1259 1260
	 */
	return 0;
}

1261
static void unlock_fs(struct mapped_device *md)
L
Linus Torvalds 已提交
1262
{
1263 1264 1265
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

1266
	thaw_bdev(md->suspended_bdev, md->frozen_sb);
L
Linus Torvalds 已提交
1267
	md->frozen_sb = NULL;
1268
	clear_bit(DMF_FROZEN, &md->flags);
L
Linus Torvalds 已提交
1269 1270 1271 1272 1273 1274 1275 1276 1277
}

/*
 * 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.
 */
1278
int dm_suspend(struct mapped_device *md, int do_lockfs)
L
Linus Torvalds 已提交
1279
{
1280
	struct dm_table *map = NULL;
L
Linus Torvalds 已提交
1281
	DECLARE_WAITQUEUE(wait, current);
J
Jun'ichi Nomura 已提交
1282
	struct bio *def;
1283
	int r = -EINVAL;
L
Linus Torvalds 已提交
1284

1285 1286 1287
	down(&md->suspend_lock);

	if (dm_suspended(md))
1288
		goto out_unlock;
L
Linus Torvalds 已提交
1289 1290 1291

	map = dm_get_table(md);

1292 1293 1294
	/* This does not get reverted if there's an error later. */
	dm_table_presuspend_targets(map);

1295 1296 1297 1298 1299 1300 1301
	md->suspended_bdev = bdget_disk(md->disk, 0);
	if (!md->suspended_bdev) {
		DMWARN("bdget failed in dm_suspend");
		r = -ENOMEM;
		goto out;
	}

1302
	/* Flush I/O to the device. */
1303 1304 1305 1306 1307
	if (do_lockfs) {
		r = lock_fs(md);
		if (r)
			goto out;
	}
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Linus Torvalds 已提交
1308 1309

	/*
1310
	 * First we set the BLOCK_IO flag so no more ios will be mapped.
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1311
	 */
1312 1313
	down_write(&md->io_lock);
	set_bit(DMF_BLOCK_IO, &md->flags);
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1314 1315

	add_wait_queue(&md->wait, &wait);
1316
	up_write(&md->io_lock);
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1317 1318

	/* unplug */
1319
	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);

1336
	down_write(&md->io_lock);
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1337 1338 1339
	remove_wait_queue(&md->wait, &wait);

	/* were we interrupted ? */
1340
	r = -EINTR;
1341
	if (atomic_read(&md->pending)) {
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Jun'ichi Nomura 已提交
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		clear_bit(DMF_BLOCK_IO, &md->flags);
		def = bio_list_get(&md->deferred);
		__flush_deferred_io(md, def);
1345 1346 1347 1348 1349
		up_write(&md->io_lock);
		unlock_fs(md);
		goto out;
	}
	up_write(&md->io_lock);
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1350

1351
	dm_table_postsuspend_targets(map);
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1352

1353
	set_bit(DMF_SUSPENDED, &md->flags);
1354

1355
	r = 0;
1356

1357
out:
1358 1359 1360 1361 1362
	if (r && md->suspended_bdev) {
		bdput(md->suspended_bdev);
		md->suspended_bdev = NULL;
	}

1363
	dm_table_put(map);
1364 1365

out_unlock:
1366
	up(&md->suspend_lock);
1367
	return r;
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1368 1369 1370 1371
}

int dm_resume(struct mapped_device *md)
{
1372
	int r = -EINVAL;
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1373
	struct bio *def;
1374
	struct dm_table *map = NULL;
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1375

1376 1377
	down(&md->suspend_lock);
	if (!dm_suspended(md))
1378 1379 1380
		goto out;

	map = dm_get_table(md);
1381
	if (!map || !dm_table_get_size(map))
1382
		goto out;
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1383

1384 1385 1386
	r = dm_table_resume_targets(map);
	if (r)
		goto out;
1387 1388

	down_write(&md->io_lock);
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1389 1390 1391 1392
	clear_bit(DMF_BLOCK_IO, &md->flags);

	def = bio_list_get(&md->deferred);
	__flush_deferred_io(md, def);
1393 1394 1395 1396
	up_write(&md->io_lock);

	unlock_fs(md);

1397 1398 1399
	bdput(md->suspended_bdev);
	md->suspended_bdev = NULL;

1400 1401
	clear_bit(DMF_SUSPENDED, &md->flags);

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1402 1403
	dm_table_unplug_all(map);

1404 1405
	kobject_uevent(&md->disk->kobj, KOBJ_CHANGE);

1406
	r = 0;
1407

1408 1409
out:
	dm_table_put(map);
1410 1411
	up(&md->suspend_lock);

1412
	return r;
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1413 1414 1415 1416 1417 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
}

/*-----------------------------------------------------------------
 * 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,
1446
	.ioctl = dm_blk_ioctl,
D
Darrick J. Wong 已提交
1447
	.getgeo = dm_blk_getgeo,
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1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463
	.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");