dm.c 31.5 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.
 */
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struct dm_target_io {
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	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)
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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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#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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#define DMF_NOFLUSH_SUSPENDING 5
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struct mapped_device {
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	struct rw_semaphore io_lock;
	struct semaphore suspend_lock;
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	spinlock_t pushback_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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	struct bio_list pushback;
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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 */
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	_io_cache = KMEM_CACHE(dm_io, 0);
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	if (!_io_cache)
		return -ENOMEM;

	/* 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) {
		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 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 struct dm_target_io *alloc_tio(struct mapped_device *md)
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{
	return mempool_alloc(md->tio_pool, GFP_NOIO);
}

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

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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;

	/* Push-back supersedes any I/O errors */
	if (error && !(io->error > 0 && __noflush_suspending(io->md)))
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		io->error = error;

	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.
			 * This must be handled before the sleeper on
			 * suspend queue merges the pushback list.
			 */
			spin_lock_irqsave(&io->md->pushback_lock, flags);
			if (__noflush_suspending(io->md))
				bio_list_add(&io->md->pushback, io->bio);
			else
				/* noflush suspend was interrupted. */
				io->error = -EIO;
			spin_unlock_irqrestore(&io->md->pushback_lock, flags);
		}

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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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		if (io->error != DM_ENDIO_REQUEUE) {
			blk_add_trace_bio(io->md->queue, io->bio,
					  BLK_TA_COMPLETE);

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

static int clone_endio(struct bio *bio, unsigned int done, int error)
{
	int r = 0;
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	struct dm_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);
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		if (r < 0 || r == DM_ENDIO_REQUEUE)
			/*
			 * error and requeue request are handled
			 * in dec_pending().
			 */
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			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,
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		      struct dm_target_io *tio)
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{
	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 || r == DM_MAPIO_REQUEUE) {
		/* error the io and bail out, or requeue it if needed */
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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);
A
Alasdair G Kergon 已提交
673
	struct dm_target_io *tio;
L
Linus Torvalds 已提交
674 675 676 677 678 679 680 681 682 683 684 685 686 687 688

	/*
	 * 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,
S
Stefan Bader 已提交
689 690
				  bio->bi_vcnt - ci->idx, ci->sector_count,
				  ci->md->bs);
L
Linus Torvalds 已提交
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
		__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
713 714
		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
				  ci->md->bs);
L
Linus Torvalds 已提交
715 716 717 718 719 720 721 722
		__map_bio(ti, clone, tio);

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

	} else {
		/*
723
		 * Handle a bvec that must be split between two or more targets.
L
Linus Torvalds 已提交
724 725
		 */
		struct bio_vec *bv = bio->bi_io_vec + ci->idx;
726 727
		sector_t remaining = to_sector(bv->bv_len);
		unsigned int offset = 0;
L
Linus Torvalds 已提交
728

729 730 731 732
		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
733

734 735 736 737 738 739 740 741 742
				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
743 744
					   bv->bv_offset + offset, len,
					   ci->md->bs);
745 746 747 748 749 750 751

			__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
752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780

		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;

781
	start_io_acct(ci.io);
L
Linus Torvalds 已提交
782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799
	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;
800
	int rw = bio_data_dir(bio);
L
Linus Torvalds 已提交
801 802
	struct mapped_device *md = q->queuedata;

S
Stefan Bader 已提交
803 804 805 806 807 808 809 810 811
	/*
	 * There is no use in forwarding any barrier request since we can't
	 * guarantee it is (or can be) handled by the targets correctly.
	 */
	if (unlikely(bio_barrier(bio))) {
		bio_endio(bio, bio->bi_size, -EOPNOTSUPP);
		return 0;
	}

812
	down_read(&md->io_lock);
L
Linus Torvalds 已提交
813

814 815 816
	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
817 818 819 820 821
	/*
	 * If we're suspended we have to queue
	 * this io for later.
	 */
	while (test_bit(DMF_BLOCK_IO, &md->flags)) {
822
		up_read(&md->io_lock);
L
Linus Torvalds 已提交
823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840

		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.
		 */
841
		down_read(&md->io_lock);
L
Linus Torvalds 已提交
842 843 844
	}

	__split_bio(md, bio);
845
	up_read(&md->io_lock);
L
Linus Torvalds 已提交
846 847 848 849 850 851 852 853 854 855 856
	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) {
857
		ret = dm_table_flush_all(map);
L
Linus Torvalds 已提交
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894
		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);

895
static void free_minor(int minor)
L
Linus Torvalds 已提交
896
{
897
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
898
	idr_remove(&_minor_idr, minor);
899
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
900 901 902 903 904
}

/*
 * See if the device with a specific minor # is free.
 */
905
static int specific_minor(struct mapped_device *md, int minor)
L
Linus Torvalds 已提交
906 907 908 909 910 911
{
	int r, m;

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

J
Jeff Mahoney 已提交
912 913 914 915
	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
	if (!r)
		return -ENOMEM;

916
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
917 918 919 920 921 922

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

923
	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
J
Jeff Mahoney 已提交
924
	if (r)
L
Linus Torvalds 已提交
925 926 927 928 929 930 931 932 933
		goto out;

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

out:
934
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
935 936 937
	return r;
}

938
static int next_free_minor(struct mapped_device *md, int *minor)
L
Linus Torvalds 已提交
939
{
940
	int r, m;
L
Linus Torvalds 已提交
941 942

	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
J
Jeff Mahoney 已提交
943 944 945
	if (!r)
		return -ENOMEM;

946
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
947

948
	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
L
Linus Torvalds 已提交
949 950 951 952 953 954 955 956 957 958 959 960 961
	if (r) {
		goto out;
	}

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

	*minor = m;

out:
962
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
963 964 965 966 967 968 969 970
	return r;
}

static struct block_device_operations dm_blk_dops;

/*
 * Allocate and initialise a blank device with a given minor.
 */
971
static struct mapped_device *alloc_dev(int minor)
L
Linus Torvalds 已提交
972 973 974
{
	int r;
	struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
975
	void *old_md;
L
Linus Torvalds 已提交
976 977 978 979 980 981

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

982 983 984
	if (!try_module_get(THIS_MODULE))
		goto bad0;

L
Linus Torvalds 已提交
985
	/* get a minor number for the dev */
986 987 988 989
	if (minor == DM_ANY_MINOR)
		r = next_free_minor(md, &minor);
	else
		r = specific_minor(md, minor);
L
Linus Torvalds 已提交
990 991 992 993
	if (r < 0)
		goto bad1;

	memset(md, 0, sizeof(*md));
994 995
	init_rwsem(&md->io_lock);
	init_MUTEX(&md->suspend_lock);
996
	spin_lock_init(&md->pushback_lock);
L
Linus Torvalds 已提交
997 998
	rwlock_init(&md->map_lock);
	atomic_set(&md->holders, 1);
999
	atomic_set(&md->open_count, 0);
L
Linus Torvalds 已提交
1000 1001 1002 1003
	atomic_set(&md->event_nr, 0);

	md->queue = blk_alloc_queue(GFP_KERNEL);
	if (!md->queue)
1004
		goto bad1_free_minor;
L
Linus Torvalds 已提交
1005 1006 1007 1008 1009

	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);
1010
	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
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1011 1012 1013
	md->queue->unplug_fn = dm_unplug_all;
	md->queue->issue_flush_fn = dm_flush_all;

1014
	md->io_pool = mempool_create_slab_pool(MIN_IOS, _io_cache);
K
Kiyoshi Ueda 已提交
1015 1016
	if (!md->io_pool)
		goto bad2;
L
Linus Torvalds 已提交
1017

1018
	md->tio_pool = mempool_create_slab_pool(MIN_IOS, _tio_cache);
L
Linus Torvalds 已提交
1019 1020 1021
	if (!md->tio_pool)
		goto bad3;

1022
	md->bs = bioset_create(16, 16);
S
Stefan Bader 已提交
1023 1024 1025
	if (!md->bs)
		goto bad_no_bioset;

L
Linus Torvalds 已提交
1026 1027 1028 1029
	md->disk = alloc_disk(1);
	if (!md->disk)
		goto bad4;

1030 1031 1032 1033
	atomic_set(&md->pending, 0);
	init_waitqueue_head(&md->wait);
	init_waitqueue_head(&md->eventq);

L
Linus Torvalds 已提交
1034 1035 1036 1037 1038 1039 1040
	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
1041
	format_dev_t(md->name, MKDEV(_major, minor));
L
Linus Torvalds 已提交
1042

1043
	/* Populate the mapping, nobody knows we exist yet */
1044
	spin_lock(&_minor_lock);
1045
	old_md = idr_replace(&_minor_idr, md, minor);
1046
	spin_unlock(&_minor_lock);
1047 1048 1049

	BUG_ON(old_md != MINOR_ALLOCED);

L
Linus Torvalds 已提交
1050 1051 1052
	return md;

 bad4:
S
Stefan Bader 已提交
1053 1054
	bioset_free(md->bs);
 bad_no_bioset:
L
Linus Torvalds 已提交
1055 1056 1057 1058
	mempool_destroy(md->tio_pool);
 bad3:
	mempool_destroy(md->io_pool);
 bad2:
1059
	blk_cleanup_queue(md->queue);
1060
 bad1_free_minor:
L
Linus Torvalds 已提交
1061 1062
	free_minor(minor);
 bad1:
1063 1064
	module_put(THIS_MODULE);
 bad0:
L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070
	kfree(md);
	return NULL;
}

static void free_dev(struct mapped_device *md)
{
1071
	int minor = md->disk->first_minor;
1072

1073 1074 1075 1076
	if (md->suspended_bdev) {
		thaw_bdev(md->suspended_bdev, NULL);
		bdput(md->suspended_bdev);
	}
L
Linus Torvalds 已提交
1077 1078
	mempool_destroy(md->tio_pool);
	mempool_destroy(md->io_pool);
S
Stefan Bader 已提交
1079
	bioset_free(md->bs);
L
Linus Torvalds 已提交
1080
	del_gendisk(md->disk);
1081
	free_minor(minor);
J
Jeff Mahoney 已提交
1082 1083 1084 1085 1086

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

L
Linus Torvalds 已提交
1087
	put_disk(md->disk);
1088
	blk_cleanup_queue(md->queue);
1089
	module_put(THIS_MODULE);
L
Linus Torvalds 已提交
1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
	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);
}

1104
static void __set_size(struct mapped_device *md, sector_t size)
L
Linus Torvalds 已提交
1105
{
1106
	set_capacity(md->disk, size);
L
Linus Torvalds 已提交
1107

1108
	mutex_lock(&md->suspended_bdev->bd_inode->i_mutex);
1109
	i_size_write(md->suspended_bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
1110
	mutex_unlock(&md->suspended_bdev->bd_inode->i_mutex);
L
Linus Torvalds 已提交
1111 1112 1113 1114 1115 1116 1117 1118
}

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
1119 1120 1121 1122 1123 1124 1125

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

1126 1127
	if (md->suspended_bdev)
		__set_size(md, size);
L
Linus Torvalds 已提交
1128 1129 1130
	if (size == 0)
		return 0;

1131 1132 1133
	dm_table_get(t);
	dm_table_event_callback(t, event_callback, md);

L
Linus Torvalds 已提交
1134 1135
	write_lock(&md->map_lock);
	md->map = t;
1136
	dm_table_set_restrictions(t, q);
L
Linus Torvalds 已提交
1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
	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.
 */
1159
int dm_create(int minor, struct mapped_device **result)
L
Linus Torvalds 已提交
1160 1161 1162
{
	struct mapped_device *md;

1163
	md = alloc_dev(minor);
L
Linus Torvalds 已提交
1164 1165 1166 1167 1168 1169 1170
	if (!md)
		return -ENXIO;

	*result = md;
	return 0;
}

1171
static struct mapped_device *dm_find_md(dev_t dev)
L
Linus Torvalds 已提交
1172 1173 1174 1175 1176 1177 1178
{
	struct mapped_device *md;
	unsigned minor = MINOR(dev);

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

1179
	spin_lock(&_minor_lock);
L
Linus Torvalds 已提交
1180 1181

	md = idr_find(&_minor_idr, minor);
J
Jeff Mahoney 已提交
1182 1183
	if (md && (md == MINOR_ALLOCED ||
		   (dm_disk(md)->first_minor != minor) ||
A
Alasdair G Kergon 已提交
1184
		   test_bit(DMF_FREEING, &md->flags))) {
1185
		md = NULL;
J
Jeff Mahoney 已提交
1186 1187
		goto out;
	}
L
Linus Torvalds 已提交
1188

J
Jeff Mahoney 已提交
1189
out:
1190
	spin_unlock(&_minor_lock);
L
Linus Torvalds 已提交
1191

1192 1193 1194
	return md;
}

1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
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
1205
void *dm_get_mdptr(struct mapped_device *md)
1206
{
A
Alasdair G Kergon 已提交
1207
	return md->interface_ptr;
L
Linus Torvalds 已提交
1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219
}

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);
}

1220 1221 1222 1223 1224 1225
const char *dm_device_name(struct mapped_device *md)
{
	return md->name;
}
EXPORT_SYMBOL_GPL(dm_device_name);

L
Linus Torvalds 已提交
1226 1227
void dm_put(struct mapped_device *md)
{
M
Mike Anderson 已提交
1228
	struct dm_table *map;
L
Linus Torvalds 已提交
1229

J
Jeff Mahoney 已提交
1230 1231
	BUG_ON(test_bit(DMF_FREEING, &md->flags));

1232
	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
M
Mike Anderson 已提交
1233
		map = dm_get_table(md);
1234
		idr_replace(&_minor_idr, MINOR_ALLOCED, dm_disk(md)->first_minor);
J
Jeff Mahoney 已提交
1235
		set_bit(DMF_FREEING, &md->flags);
1236
		spin_unlock(&_minor_lock);
1237
		if (!dm_suspended(md)) {
L
Linus Torvalds 已提交
1238 1239 1240 1241
			dm_table_presuspend_targets(map);
			dm_table_postsuspend_targets(map);
		}
		__unbind(md);
M
Mike Anderson 已提交
1242
		dm_table_put(map);
L
Linus Torvalds 已提交
1243 1244 1245
		free_dev(md);
	}
}
E
Edward Goggin 已提交
1246
EXPORT_SYMBOL_GPL(dm_put);
L
Linus Torvalds 已提交
1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267

/*
 * 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)
{
1268
	int r = -EINVAL;
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1270
	down(&md->suspend_lock);
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1271 1272

	/* device must be suspended */
1273
	if (!dm_suspended(md))
1274
		goto out;
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1276 1277 1278 1279 1280
	/* without bdev, the device size cannot be changed */
	if (!md->suspended_bdev)
		if (get_capacity(md->disk) != dm_table_get_size(table))
			goto out;

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

1284
out:
1285
	up(&md->suspend_lock);
1286
	return r;
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}

/*
 * Functions to lock and unlock any filesystem running on the
 * device.
 */
1293
static int lock_fs(struct mapped_device *md)
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{
1295
	int r;
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	WARN_ON(md->frozen_sb);
1298

1299
	md->frozen_sb = freeze_bdev(md->suspended_bdev);
1300
	if (IS_ERR(md->frozen_sb)) {
1301
		r = PTR_ERR(md->frozen_sb);
1302 1303
		md->frozen_sb = NULL;
		return r;
1304 1305
	}

1306 1307
	set_bit(DMF_FROZEN, &md->flags);

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	/* don't bdput right now, we don't want the bdev
1309
	 * to go away while it is locked.
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	 */
	return 0;
}

1314
static void unlock_fs(struct mapped_device *md)
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{
1316 1317 1318
	if (!test_bit(DMF_FROZEN, &md->flags))
		return;

1319
	thaw_bdev(md->suspended_bdev, md->frozen_sb);
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	md->frozen_sb = NULL;
1321
	clear_bit(DMF_FROZEN, &md->flags);
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}

/*
 * 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.
 */
1331
int dm_suspend(struct mapped_device *md, unsigned suspend_flags)
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1332
{
1333
	struct dm_table *map = NULL;
1334
	unsigned long flags;
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1335
	DECLARE_WAITQUEUE(wait, current);
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Jun'ichi Nomura 已提交
1336
	struct bio *def;
1337
	int r = -EINVAL;
1338
	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
1339
	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
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1341 1342 1343
	down(&md->suspend_lock);

	if (dm_suspended(md))
1344
		goto out_unlock;
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	map = dm_get_table(md);

1348 1349 1350 1351 1352 1353 1354
	/*
	 * 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);

1355 1356 1357
	/* This does not get reverted if there's an error later. */
	dm_table_presuspend_targets(map);

1358 1359 1360 1361 1362 1363 1364 1365
	/* bdget() can stall if the pending I/Os are not flushed */
	if (!noflush) {
		md->suspended_bdev = bdget_disk(md->disk, 0);
		if (!md->suspended_bdev) {
			DMWARN("bdget failed in dm_suspend");
			r = -ENOMEM;
			goto flush_and_out;
		}
1366 1367
	}

1368 1369 1370 1371 1372
	/*
	 * Flush I/O to the device.
	 * noflush supersedes do_lockfs, because lock_fs() needs to flush I/Os.
	 */
	if (do_lockfs && !noflush) {
1373 1374 1375 1376
		r = lock_fs(md);
		if (r)
			goto out;
	}
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	/*
1379
	 * First we set the BLOCK_IO flag so no more ios will be mapped.
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1380
	 */
1381 1382
	down_write(&md->io_lock);
	set_bit(DMF_BLOCK_IO, &md->flags);
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1383 1384

	add_wait_queue(&md->wait, &wait);
1385
	up_write(&md->io_lock);
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1386 1387

	/* unplug */
1388
	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);

1405
	down_write(&md->io_lock);
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	remove_wait_queue(&md->wait, &wait);

1408 1409 1410 1411 1412 1413 1414 1415
	if (noflush) {
		spin_lock_irqsave(&md->pushback_lock, flags);
		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
		bio_list_merge_head(&md->deferred, &md->pushback);
		bio_list_init(&md->pushback);
		spin_unlock_irqrestore(&md->pushback_lock, flags);
	}

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	/* were we interrupted ? */
1417
	r = -EINTR;
1418
	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);
1422 1423
		up_write(&md->io_lock);
		unlock_fs(md);
1424
		goto out; /* pushback list is already flushed, so skip flush */
1425 1426
	}
	up_write(&md->io_lock);
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1427

1428
	dm_table_postsuspend_targets(map);
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1429

1430
	set_bit(DMF_SUSPENDED, &md->flags);
1431

1432
	r = 0;
1433

1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452
flush_and_out:
	if (r && noflush) {
		/*
		 * Because there may be already I/Os in the pushback list,
		 * flush them before return.
		 */
		down_write(&md->io_lock);

		spin_lock_irqsave(&md->pushback_lock, flags);
		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
		bio_list_merge_head(&md->deferred, &md->pushback);
		bio_list_init(&md->pushback);
		spin_unlock_irqrestore(&md->pushback_lock, flags);

		def = bio_list_get(&md->deferred);
		__flush_deferred_io(md, def);
		up_write(&md->io_lock);
	}

1453
out:
1454 1455 1456 1457 1458
	if (r && md->suspended_bdev) {
		bdput(md->suspended_bdev);
		md->suspended_bdev = NULL;
	}

1459
	dm_table_put(map);
1460 1461

out_unlock:
1462
	up(&md->suspend_lock);
1463
	return r;
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}

int dm_resume(struct mapped_device *md)
{
1468
	int r = -EINVAL;
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1469
	struct bio *def;
1470
	struct dm_table *map = NULL;
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1471

1472 1473
	down(&md->suspend_lock);
	if (!dm_suspended(md))
1474 1475 1476
		goto out;

	map = dm_get_table(md);
1477
	if (!map || !dm_table_get_size(map))
1478
		goto out;
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1479

1480 1481 1482
	r = dm_table_resume_targets(map);
	if (r)
		goto out;
1483 1484

	down_write(&md->io_lock);
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1485 1486 1487 1488
	clear_bit(DMF_BLOCK_IO, &md->flags);

	def = bio_list_get(&md->deferred);
	__flush_deferred_io(md, def);
1489 1490 1491 1492
	up_write(&md->io_lock);

	unlock_fs(md);

1493 1494 1495 1496
	if (md->suspended_bdev) {
		bdput(md->suspended_bdev);
		md->suspended_bdev = NULL;
	}
1497

1498 1499
	clear_bit(DMF_SUSPENDED, &md->flags);

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	dm_table_unplug_all(map);

1502 1503
	kobject_uevent(&md->disk->kobj, KOBJ_CHANGE);

1504
	r = 0;
1505

1506 1507
out:
	dm_table_put(map);
1508 1509
	up(&md->suspend_lock);

1510
	return r;
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}

/*-----------------------------------------------------------------
 * 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);
}

1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551
int dm_noflush_suspending(struct dm_target *ti)
{
	struct mapped_device *md = dm_table_get_md(ti->table);
	int r = __noflush_suspending(md);

	dm_put(md);

	return r;
}
EXPORT_SYMBOL_GPL(dm_noflush_suspending);

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static struct block_device_operations dm_blk_dops = {
	.open = dm_blk_open,
	.release = dm_blk_close,
1555
	.ioctl = dm_blk_ioctl,
D
Darrick J. Wong 已提交
1556
	.getgeo = dm_blk_getgeo,
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1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
	.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");