Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
new file mode 100644
index 0000000..243ff68
--- /dev/null
+++ b/drivers/md/dm.c
@@ -0,0 +1,1194 @@
+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-bio-list.h"
+
+#include <linux/init.h>
+#include <linux/module.h>
+#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>
+
+static const char *_name = DM_NAME;
+
+static unsigned int major = 0;
+static unsigned int _major = 0;
+
+/*
+ * One of these is allocated per bio.
+ */
+struct dm_io {
+ struct mapped_device *md;
+ int error;
+ struct bio *bio;
+ atomic_t io_count;
+};
+
+/*
+ * 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)
+{
+ if (bio && bio->bi_private)
+ return &((struct target_io *)bio->bi_private)->info;
+ return NULL;
+}
+
+/*
+ * Bits for the md->flags field.
+ */
+#define DMF_BLOCK_IO 0
+#define DMF_SUSPENDED 1
+#define DMF_FS_LOCKED 2
+
+struct mapped_device {
+ struct rw_semaphore lock;
+ rwlock_t map_lock;
+ atomic_t holders;
+
+ unsigned long flags;
+
+ request_queue_t *queue;
+ struct gendisk *disk;
+
+ 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;
+
+ /*
+ * 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;
+};
+
+#define MIN_IOS 256
+static kmem_cache_t *_io_cache;
+static kmem_cache_t *_tio_cache;
+
+static struct bio_set *dm_set;
+
+static int __init local_init(void)
+{
+ int r;
+
+ dm_set = bioset_create(16, 16, 4);
+ if (!dm_set)
+ return -ENOMEM;
+
+ /* 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);
+
+ bioset_free(dm_set);
+
+ if (unregister_blkdev(_major, _name) < 0)
+ DMERR("devfs_unregister_blkdev failed");
+
+ _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;
+
+ md = inode->i_bdev->bd_disk->private_data;
+ dm_get(md);
+ return 0;
+}
+
+static int dm_blk_close(struct inode *inode, struct file *file)
+{
+ struct mapped_device *md;
+
+ md = inode->i_bdev->bd_disk->private_data;
+ dm_put(md);
+ return 0;
+}
+
+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);
+}
+
+/*
+ * Add the bio to the list of deferred io.
+ */
+static int queue_io(struct mapped_device *md, struct bio *bio)
+{
+ down_write(&md->lock);
+
+ if (!test_bit(DMF_BLOCK_IO, &md->flags)) {
+ up_write(&md->lock);
+ return 1;
+ }
+
+ bio_list_add(&md->deferred, bio);
+
+ up_write(&md->lock);
+ 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;
+}
+
+/*-----------------------------------------------------------------
+ * 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.
+ */
+static inline void dec_pending(struct dm_io *io, int error)
+{
+ if (error)
+ io->error = error;
+
+ if (atomic_dec_and_test(&io->io_count)) {
+ if (atomic_dec_and_test(&io->md->pending))
+ /* nudge anyone waiting on suspend queue */
+ wake_up(&io->md->wait);
+
+ 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;
+ struct dm_io *io = tio->io;
+ 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;
+ }
+
+ free_tio(io->md, tio);
+ dec_pending(io, error);
+ bio_put(bio);
+ 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;
+
+ /*
+ * 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);
+ r = ti->type->map(ti, clone, &tio->info);
+ if (r > 0)
+ /* the bio has been remapped so dispatch it */
+ generic_make_request(clone);
+
+ else if (r < 0) {
+ /* error the io and bail out */
+ struct dm_io *io = tio->io;
+ free_tio(tio->io->md, tio);
+ dec_pending(io, -EIO);
+ bio_put(clone);
+ }
+}
+
+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;
+};
+
+/*
+ * 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,
+ unsigned int len)
+{
+ struct bio *clone;
+ struct bio_vec *bv = bio->bi_io_vec + idx;
+
+ clone = bio_alloc_bioset(GFP_NOIO, 1, dm_set);
+ *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,
+ unsigned int len)
+{
+ struct bio *clone;
+
+ clone = bio_clone(bio, GFP_NOIO);
+ 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,
+ bio->bi_vcnt - ci->idx, ci->sector_count);
+ __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;
+ }
+
+ clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len);
+ __map_bio(ti, clone, tio);
+
+ ci->sector += len;
+ ci->sector_count -= len;
+ ci->idx = i;
+
+ } else {
+ /*
+ * Create two copy bios to deal with io that has
+ * been split across a target.
+ */
+ struct bio_vec *bv = bio->bi_io_vec + ci->idx;
+
+ clone = split_bvec(bio, ci->sector, ci->idx,
+ bv->bv_offset, max);
+ __map_bio(ti, clone, tio);
+
+ ci->sector += max;
+ ci->sector_count -= max;
+ ti = dm_table_find_target(ci->map, ci->sector);
+
+ len = to_sector(bv->bv_len) - max;
+ clone = split_bvec(bio, ci->sector, ci->idx,
+ bv->bv_offset + to_bytes(max), len);
+ tio = alloc_tio(ci->md);
+ tio->io = ci->io;
+ tio->ti = ti;
+ memset(&tio->info, 0, sizeof(tio->info));
+ __map_bio(ti, clone, tio);
+
+ ci->sector += len;
+ ci->sector_count -= len;
+ 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;
+
+ atomic_inc(&md->pending);
+ 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;
+ struct mapped_device *md = q->queuedata;
+
+ down_read(&md->lock);
+
+ /*
+ * If we're suspended we have to queue
+ * this io for later.
+ */
+ while (test_bit(DMF_BLOCK_IO, &md->flags)) {
+ up_read(&md->lock);
+
+ 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.
+ */
+ down_read(&md->lock);
+ }
+
+ __split_bio(md, bio);
+ up_read(&md->lock);
+ 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) {
+ ret = dm_table_flush_all(md->map);
+ 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 DECLARE_MUTEX(_minor_lock);
+static DEFINE_IDR(_minor_idr);
+
+static void free_minor(unsigned int minor)
+{
+ down(&_minor_lock);
+ idr_remove(&_minor_idr, minor);
+ up(&_minor_lock);
+}
+
+/*
+ * See if the device with a specific minor # is free.
+ */
+static int specific_minor(struct mapped_device *md, unsigned int minor)
+{
+ int r, m;
+
+ if (minor >= (1 << MINORBITS))
+ return -EINVAL;
+
+ down(&_minor_lock);
+
+ if (idr_find(&_minor_idr, minor)) {
+ r = -EBUSY;
+ goto out;
+ }
+
+ r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+ if (!r) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ r = idr_get_new_above(&_minor_idr, md, minor, &m);
+ if (r) {
+ goto out;
+ }
+
+ if (m != minor) {
+ idr_remove(&_minor_idr, m);
+ r = -EBUSY;
+ goto out;
+ }
+
+out:
+ up(&_minor_lock);
+ return r;
+}
+
+static int next_free_minor(struct mapped_device *md, unsigned int *minor)
+{
+ int r;
+ unsigned int m;
+
+ down(&_minor_lock);
+
+ r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+ if (!r) {
+ r = -ENOMEM;
+ goto out;
+ }
+
+ r = idr_get_new(&_minor_idr, md, &m);
+ if (r) {
+ goto out;
+ }
+
+ if (m >= (1 << MINORBITS)) {
+ idr_remove(&_minor_idr, m);
+ r = -ENOSPC;
+ goto out;
+ }
+
+ *minor = m;
+
+out:
+ up(&_minor_lock);
+ return r;
+}
+
+static struct block_device_operations dm_blk_dops;
+
+/*
+ * Allocate and initialise a blank device with a given minor.
+ */
+static struct mapped_device *alloc_dev(unsigned int minor, int persistent)
+{
+ int r;
+ struct mapped_device *md = kmalloc(sizeof(*md), GFP_KERNEL);
+
+ if (!md) {
+ DMWARN("unable to allocate device, out of memory.");
+ return NULL;
+ }
+
+ /* get a minor number for the dev */
+ r = persistent ? specific_minor(md, minor) : next_free_minor(md, &minor);
+ if (r < 0)
+ goto bad1;
+
+ memset(md, 0, sizeof(*md));
+ init_rwsem(&md->lock);
+ rwlock_init(&md->map_lock);
+ atomic_set(&md->holders, 1);
+ atomic_set(&md->event_nr, 0);
+
+ md->queue = blk_alloc_queue(GFP_KERNEL);
+ if (!md->queue)
+ goto bad1;
+
+ 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);
+ md->queue->unplug_fn = dm_unplug_all;
+ md->queue->issue_flush_fn = dm_flush_all;
+
+ md->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
+ mempool_free_slab, _io_cache);
+ if (!md->io_pool)
+ goto bad2;
+
+ md->tio_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
+ mempool_free_slab, _tio_cache);
+ if (!md->tio_pool)
+ goto bad3;
+
+ md->disk = alloc_disk(1);
+ if (!md->disk)
+ goto bad4;
+
+ 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);
+
+ atomic_set(&md->pending, 0);
+ init_waitqueue_head(&md->wait);
+ init_waitqueue_head(&md->eventq);
+
+ return md;
+
+ bad4:
+ mempool_destroy(md->tio_pool);
+ bad3:
+ mempool_destroy(md->io_pool);
+ bad2:
+ blk_put_queue(md->queue);
+ free_minor(minor);
+ bad1:
+ kfree(md);
+ return NULL;
+}
+
+static void free_dev(struct mapped_device *md)
+{
+ free_minor(md->disk->first_minor);
+ mempool_destroy(md->tio_pool);
+ mempool_destroy(md->io_pool);
+ del_gendisk(md->disk);
+ put_disk(md->disk);
+ blk_put_queue(md->queue);
+ 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);
+}
+
+static void __set_size(struct gendisk *disk, sector_t size)
+{
+ struct block_device *bdev;
+
+ set_capacity(disk, size);
+ bdev = bdget_disk(disk, 0);
+ if (bdev) {
+ down(&bdev->bd_inode->i_sem);
+ i_size_write(bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
+ up(&bdev->bd_inode->i_sem);
+ bdput(bdev);
+ }
+}
+
+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);
+ __set_size(md->disk, size);
+ if (size == 0)
+ return 0;
+
+ write_lock(&md->map_lock);
+ md->map = t;
+ write_unlock(&md->map_lock);
+
+ dm_table_get(t);
+ dm_table_event_callback(md->map, event_callback, md);
+ dm_table_set_restrictions(t, q);
+ 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.
+ */
+static int create_aux(unsigned int minor, int persistent,
+ struct mapped_device **result)
+{
+ struct mapped_device *md;
+
+ md = alloc_dev(minor, persistent);
+ if (!md)
+ return -ENXIO;
+
+ *result = md;
+ return 0;
+}
+
+int dm_create(struct mapped_device **result)
+{
+ return create_aux(0, 0, result);
+}
+
+int dm_create_with_minor(unsigned int minor, struct mapped_device **result)
+{
+ return create_aux(minor, 1, result);
+}
+
+void *dm_get_mdptr(dev_t dev)
+{
+ struct mapped_device *md;
+ void *mdptr = NULL;
+ unsigned minor = MINOR(dev);
+
+ if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
+ return NULL;
+
+ down(&_minor_lock);
+
+ md = idr_find(&_minor_idr, minor);
+
+ if (md && (dm_disk(md)->first_minor == minor))
+ mdptr = md->interface_ptr;
+
+ up(&_minor_lock);
+
+ return mdptr;
+}
+
+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);
+}
+
+void dm_put(struct mapped_device *md)
+{
+ struct dm_table *map = dm_get_table(md);
+
+ if (atomic_dec_and_test(&md->holders)) {
+ if (!test_bit(DMF_SUSPENDED, &md->flags) && map) {
+ dm_table_presuspend_targets(map);
+ dm_table_postsuspend_targets(map);
+ }
+ __unbind(md);
+ free_dev(md);
+ }
+
+ dm_table_put(map);
+}
+
+/*
+ * 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)
+{
+ int r;
+
+ down_write(&md->lock);
+
+ /* device must be suspended */
+ if (!test_bit(DMF_SUSPENDED, &md->flags)) {
+ up_write(&md->lock);
+ return -EPERM;
+ }
+
+ __unbind(md);
+ r = __bind(md, table);
+ if (r)
+ return r;
+
+ up_write(&md->lock);
+ return 0;
+}
+
+/*
+ * Functions to lock and unlock any filesystem running on the
+ * device.
+ */
+static int __lock_fs(struct mapped_device *md)
+{
+ struct block_device *bdev;
+
+ if (test_and_set_bit(DMF_FS_LOCKED, &md->flags))
+ return 0;
+
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev) {
+ DMWARN("bdget failed in __lock_fs");
+ return -ENOMEM;
+ }
+
+ WARN_ON(md->frozen_sb);
+ md->frozen_sb = freeze_bdev(bdev);
+ /* don't bdput right now, we don't want the bdev
+ * to go away while it is locked. We'll bdput
+ * in __unlock_fs
+ */
+ return 0;
+}
+
+static int __unlock_fs(struct mapped_device *md)
+{
+ struct block_device *bdev;
+
+ if (!test_and_clear_bit(DMF_FS_LOCKED, &md->flags))
+ return 0;
+
+ bdev = bdget_disk(md->disk, 0);
+ if (!bdev) {
+ DMWARN("bdget failed in __unlock_fs");
+ return -ENOMEM;
+ }
+
+ thaw_bdev(bdev, md->frozen_sb);
+ md->frozen_sb = NULL;
+ bdput(bdev);
+ bdput(bdev);
+ return 0;
+}
+
+/*
+ * 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.
+ */
+int dm_suspend(struct mapped_device *md)
+{
+ struct dm_table *map;
+ DECLARE_WAITQUEUE(wait, current);
+
+ /* Flush I/O to the device. */
+ down_read(&md->lock);
+ if (test_bit(DMF_BLOCK_IO, &md->flags)) {
+ up_read(&md->lock);
+ return -EINVAL;
+ }
+
+ map = dm_get_table(md);
+ if (map)
+ dm_table_presuspend_targets(map);
+ __lock_fs(md);
+
+ up_read(&md->lock);
+
+ /*
+ * First we set the BLOCK_IO flag so no more ios will be
+ * mapped.
+ */
+ down_write(&md->lock);
+ if (test_bit(DMF_BLOCK_IO, &md->flags)) {
+ /*
+ * If we get here we know another thread is
+ * trying to suspend as well, so we leave the fs
+ * locked for this thread.
+ */
+ up_write(&md->lock);
+ return -EINVAL;
+ }
+
+ set_bit(DMF_BLOCK_IO, &md->flags);
+ add_wait_queue(&md->wait, &wait);
+ up_write(&md->lock);
+
+ /* unplug */
+ if (map) {
+ dm_table_unplug_all(map);
+ dm_table_put(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);
+
+ down_write(&md->lock);
+ remove_wait_queue(&md->wait, &wait);
+
+ /* were we interrupted ? */
+ if (atomic_read(&md->pending)) {
+ __unlock_fs(md);
+ clear_bit(DMF_BLOCK_IO, &md->flags);
+ up_write(&md->lock);
+ return -EINTR;
+ }
+
+ set_bit(DMF_SUSPENDED, &md->flags);
+
+ map = dm_get_table(md);
+ if (map)
+ dm_table_postsuspend_targets(map);
+ dm_table_put(map);
+ up_write(&md->lock);
+
+ return 0;
+}
+
+int dm_resume(struct mapped_device *md)
+{
+ struct bio *def;
+ struct dm_table *map = dm_get_table(md);
+
+ down_write(&md->lock);
+ if (!map ||
+ !test_bit(DMF_SUSPENDED, &md->flags) ||
+ !dm_table_get_size(map)) {
+ up_write(&md->lock);
+ dm_table_put(map);
+ return -EINVAL;
+ }
+
+ dm_table_resume_targets(map);
+ clear_bit(DMF_SUSPENDED, &md->flags);
+ clear_bit(DMF_BLOCK_IO, &md->flags);
+
+ def = bio_list_get(&md->deferred);
+ __flush_deferred_io(md, def);
+ up_write(&md->lock);
+ __unlock_fs(md);
+ dm_table_unplug_all(map);
+ dm_table_put(map);
+
+ return 0;
+}
+
+/*-----------------------------------------------------------------
+ * 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,
+ .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");