Merge branch 'quilt/device-mapper'

7 files changed, 264 insertions, 210 deletions

diff --git a/drivers/md/dm-exception-store.c b/drivers/md/dm-exception-store.c
index 7dbe652efb5a..2b7907b6dd09 100644
--- a/drivers/md/dm-exception-store.c
+++ b/drivers/md/dm-exception-store.c
@@ -172,7 +172,8 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
 	}
 
 	/* Validate the chunk size against the device block size */
-	if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
+	if (chunk_size %
+	    (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9)) {
 		*error = "Chunk size is not a multiple of device blocksize";
 		return -EINVAL;
 	}
@@ -190,6 +191,7 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
 }
 
 int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+			      struct dm_snapshot *snap,
 			      unsigned *args_used,
 			      struct dm_exception_store **store)
 {
@@ -198,7 +200,7 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
 	struct dm_exception_store *tmp_store;
 	char persistent;
 
-	if (argc < 3) {
+	if (argc < 2) {
 		ti->error = "Insufficient exception store arguments";
 		return -EINVAL;
 	}
@@ -209,14 +211,15 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
 		return -ENOMEM;
 	}
 
-	persistent = toupper(*argv[1]);
+	persistent = toupper(*argv[0]);
 	if (persistent == 'P')
 		type = get_type("P");
 	else if (persistent == 'N')
 		type = get_type("N");
 	else {
 		ti->error = "Persistent flag is not P or N";
-		return -EINVAL;
+		r = -EINVAL;
+		goto bad_type;
 	}
 
 	if (!type) {
@@ -226,32 +229,23 @@ int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
 	}
 
 	tmp_store->type = type;
-	tmp_store->ti = ti;
-
-	r = dm_get_device(ti, argv[0], 0, 0,
-			  FMODE_READ | FMODE_WRITE, &tmp_store->cow);
-	if (r) {
-		ti->error = "Cannot get COW device";
-		goto bad_cow;
-	}
+	tmp_store->snap = snap;
 
-	r = set_chunk_size(tmp_store, argv[2], &ti->error);
+	r = set_chunk_size(tmp_store, argv[1], &ti->error);
 	if (r)
-		goto bad_ctr;
+		goto bad;
 
 	r = type->ctr(tmp_store, 0, NULL);
 	if (r) {
 		ti->error = "Exception store type constructor failed";
-		goto bad_ctr;
+		goto bad;
 	}
 
-	*args_used = 3;
+	*args_used = 2;
 	*store = tmp_store;
 	return 0;
 
-bad_ctr:
-	dm_put_device(ti, tmp_store->cow);
-bad_cow:
+bad:
 	put_type(type);
 bad_type:
 	kfree(tmp_store);
@@ -262,7 +256,6 @@ EXPORT_SYMBOL(dm_exception_store_create);
 void dm_exception_store_destroy(struct dm_exception_store *store)
 {
 	store->type->dtr(store);
-	dm_put_device(store->ti, store->cow);
 	put_type(store->type);
 	kfree(store);
 }
diff --git a/drivers/md/dm-exception-store.h b/drivers/md/dm-exception-store.h
index 8a223a48802c..bb8874653de1 100644
--- a/drivers/md/dm-exception-store.h
+++ b/drivers/md/dm-exception-store.h
@@ -26,7 +26,7 @@ typedef sector_t chunk_t;
  * of chunks that follow contiguously.  Remaining bits hold the number of the
  * chunk within the device.
  */
-struct dm_snap_exception {
+struct dm_exception {
 	struct list_head hash_list;
 
 	chunk_t old_chunk;
@@ -64,13 +64,13 @@ struct dm_exception_store_type {
 	 * Find somewhere to store the next exception.
 	 */
 	int (*prepare_exception) (struct dm_exception_store *store,
-				  struct dm_snap_exception *e);
+				  struct dm_exception *e);
 
 	/*
 	 * Update the metadata with this exception.
 	 */
 	void (*commit_exception) (struct dm_exception_store *store,
-				  struct dm_snap_exception *e,
+				  struct dm_exception *e,
 				  void (*callback) (void *, int success),
 				  void *callback_context);
 
@@ -86,19 +86,19 @@ struct dm_exception_store_type {
 	/*
 	 * Return how full the snapshot is.
 	 */
-	void (*fraction_full) (struct dm_exception_store *store,
-			       sector_t *numerator,
-			       sector_t *denominator);
+	void (*usage) (struct dm_exception_store *store,
+		       sector_t *total_sectors, sector_t *sectors_allocated,
+		       sector_t *metadata_sectors);
 
 	/* For internal device-mapper use only. */
 	struct list_head list;
 };
 
+struct dm_snapshot;
+
 struct dm_exception_store {
 	struct dm_exception_store_type *type;
-	struct dm_target *ti;
-
-	struct dm_dev *cow;
+	struct dm_snapshot *snap;
 
 	/* Size of data blocks saved - must be a power of 2 */
 	unsigned chunk_size;
@@ -109,6 +109,11 @@ struct dm_exception_store {
 };
 
 /*
+ * Obtain the cow device used by a given snapshot.
+ */
+struct dm_dev *dm_snap_cow(struct dm_snapshot *snap);
+
+/*
  * Funtions to manipulate consecutive chunks
  */
 #  if defined(CONFIG_LBDAF) || (BITS_PER_LONG == 64)
@@ -120,12 +125,12 @@ static inline chunk_t dm_chunk_number(chunk_t chunk)
 	return chunk & (chunk_t)((1ULL << DM_CHUNK_NUMBER_BITS) - 1ULL);
 }
 
-static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
+static inline unsigned dm_consecutive_chunk_count(struct dm_exception *e)
 {
 	return e->new_chunk >> DM_CHUNK_NUMBER_BITS;
 }
 
-static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
+static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e)
 {
 	e->new_chunk += (1ULL << DM_CHUNK_NUMBER_BITS);
 
@@ -140,12 +145,12 @@ static inline chunk_t dm_chunk_number(chunk_t chunk)
 	return chunk;
 }
 
-static inline unsigned dm_consecutive_chunk_count(struct dm_snap_exception *e)
+static inline unsigned dm_consecutive_chunk_count(struct dm_exception *e)
 {
 	return 0;
 }
 
-static inline void dm_consecutive_chunk_count_inc(struct dm_snap_exception *e)
+static inline void dm_consecutive_chunk_count_inc(struct dm_exception *e)
 {
 }
 
@@ -162,7 +167,7 @@ static inline sector_t get_dev_size(struct block_device *bdev)
 static inline chunk_t sector_to_chunk(struct dm_exception_store *store,
 				      sector_t sector)
 {
-	return (sector & ~store->chunk_mask) >> store->chunk_shift;
+	return sector >> store->chunk_shift;
 }
 
 int dm_exception_store_type_register(struct dm_exception_store_type *type);
@@ -173,6 +178,7 @@ int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
 				      char **error);
 
 int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
+			      struct dm_snapshot *snap,
 			      unsigned *args_used,
 			      struct dm_exception_store **store);
 void dm_exception_store_destroy(struct dm_exception_store *store);
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index a67942931582..1292c3e877b5 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -634,9 +634,9 @@ static struct mapped_device *find_device(struct dm_ioctl *param)
 		 * Sneakily write in both the name and the uuid
 		 * while we have the cell.
 		 */
-		strncpy(param->name, hc->name, sizeof(param->name));
+		strlcpy(param->name, hc->name, sizeof(param->name));
 		if (hc->uuid)
-			strncpy(param->uuid, hc->uuid, sizeof(param->uuid)-1);
+			strlcpy(param->uuid, hc->uuid, sizeof(param->uuid));
 		else
 			param->uuid[0] = '\0';
 
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index 0c746420c008..157999ebd236 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -214,7 +214,7 @@ static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
 		    int metadata)
 {
 	struct dm_io_region where = {
-		.bdev = ps->store->cow->bdev,
+		.bdev = dm_snap_cow(ps->store->snap)->bdev,
 		.sector = ps->store->chunk_size * chunk,
 		.count = ps->store->chunk_size,
 	};
@@ -294,7 +294,8 @@ static int read_header(struct pstore *ps, int *new_snapshot)
 	 */
 	if (!ps->store->chunk_size) {
 		ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
-		    bdev_logical_block_size(ps->store->cow->bdev) >> 9);
+		    bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
+					    bdev) >> 9);
 		ps->store->chunk_mask = ps->store->chunk_size - 1;
 		ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1;
 		chunk_size_supplied = 0;
@@ -489,11 +490,22 @@ static struct pstore *get_info(struct dm_exception_store *store)
 	return (struct pstore *) store->context;
 }
 
-static void persistent_fraction_full(struct dm_exception_store *store,
-				     sector_t *numerator, sector_t *denominator)
+static void persistent_usage(struct dm_exception_store *store,
+			     sector_t *total_sectors,
+			     sector_t *sectors_allocated,
+			     sector_t *metadata_sectors)
 {
-	*numerator = get_info(store)->next_free * store->chunk_size;
-	*denominator = get_dev_size(store->cow->bdev);
+	struct pstore *ps = get_info(store);
+
+	*sectors_allocated = ps->next_free * store->chunk_size;
+	*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
+
+	/*
+	 * First chunk is the fixed header.
+	 * Then there are (ps->current_area + 1) metadata chunks, each one
+	 * separated from the next by ps->exceptions_per_area data chunks.
+	 */
+	*metadata_sectors = (ps->current_area + 2) * store->chunk_size;
 }
 
 static void persistent_dtr(struct dm_exception_store *store)
@@ -552,44 +564,40 @@ static int persistent_read_metadata(struct dm_exception_store *store,
 		ps->current_area = 0;
 		zero_memory_area(ps);
 		r = zero_disk_area(ps, 0);
-		if (r) {
+		if (r)
 			DMWARN("zero_disk_area(0) failed");
-			return r;
-		}
-	} else {
-		/*
-		 * Sanity checks.
-		 */
-		if (ps->version != SNAPSHOT_DISK_VERSION) {
-			DMWARN("unable to handle snapshot disk version %d",
-			       ps->version);
-			return -EINVAL;
-		}
+		return r;
+	}
+	/*
+	 * Sanity checks.
+	 */
+	if (ps->version != SNAPSHOT_DISK_VERSION) {
+		DMWARN("unable to handle snapshot disk version %d",
+		       ps->version);
+		return -EINVAL;
+	}
 
-		/*
-		 * Metadata are valid, but snapshot is invalidated
-		 */
-		if (!ps->valid)
-			return 1;
+	/*
+	 * Metadata are valid, but snapshot is invalidated
+	 */
+	if (!ps->valid)
+		return 1;
 
-		/*
-		 * Read the metadata.
-		 */
-		r = read_exceptions(ps, callback, callback_context);
-		if (r)
-			return r;
-	}
+	/*
+	 * Read the metadata.
+	 */
+	r = read_exceptions(ps, callback, callback_context);
 
-	return 0;
+	return r;
 }
 
 static int persistent_prepare_exception(struct dm_exception_store *store,
-					struct dm_snap_exception *e)
+					struct dm_exception *e)
 {
 	struct pstore *ps = get_info(store);
 	uint32_t stride;
 	chunk_t next_free;
-	sector_t size = get_dev_size(store->cow->bdev);
+	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
 
 	/* Is there enough room ? */
 	if (size < ((ps->next_free + 1) * store->chunk_size))
@@ -611,7 +619,7 @@ static int persistent_prepare_exception(struct dm_exception_store *store,
 }
 
 static void persistent_commit_exception(struct dm_exception_store *store,
-					struct dm_snap_exception *e,
+					struct dm_exception *e,
 					void (*callback) (void *, int success),
 					void *callback_context)
 {
@@ -726,8 +734,7 @@ static unsigned persistent_status(struct dm_exception_store *store,
 	case STATUSTYPE_INFO:
 		break;
 	case STATUSTYPE_TABLE:
-		DMEMIT(" %s P %llu", store->cow->name,
-		       (unsigned long long)store->chunk_size);
+		DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
 	}
 
 	return sz;
@@ -742,7 +749,7 @@ static struct dm_exception_store_type _persistent_type = {
 	.prepare_exception = persistent_prepare_exception,
 	.commit_exception = persistent_commit_exception,
 	.drop_snapshot = persistent_drop_snapshot,
-	.fraction_full = persistent_fraction_full,
+	.usage = persistent_usage,
 	.status = persistent_status,
 };
 
@@ -755,7 +762,7 @@ static struct dm_exception_store_type _persistent_compat_type = {
 	.prepare_exception = persistent_prepare_exception,
 	.commit_exception = persistent_commit_exception,
 	.drop_snapshot = persistent_drop_snapshot,
-	.fraction_full = persistent_fraction_full,
+	.usage = persistent_usage,
 	.status = persistent_status,
 };
 
diff --git a/drivers/md/dm-snap-transient.c b/drivers/md/dm-snap-transient.c
index cde5aa558e6d..a0898a66a2f8 100644
--- a/drivers/md/dm-snap-transient.c
+++ b/drivers/md/dm-snap-transient.c
@@ -36,10 +36,10 @@ static int transient_read_metadata(struct dm_exception_store *store,
 }
 
 static int transient_prepare_exception(struct dm_exception_store *store,
-				       struct dm_snap_exception *e)
+				       struct dm_exception *e)
 {
 	struct transient_c *tc = store->context;
-	sector_t size = get_dev_size(store->cow->bdev);
+	sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
 
 	if (size < (tc->next_free + store->chunk_size))
 		return -1;
@@ -51,7 +51,7 @@ static int transient_prepare_exception(struct dm_exception_store *store,
 }
 
 static void transient_commit_exception(struct dm_exception_store *store,
-				       struct dm_snap_exception *e,
+				       struct dm_exception *e,
 				       void (*callback) (void *, int success),
 				       void *callback_context)
 {
@@ -59,11 +59,14 @@ static void transient_commit_exception(struct dm_exception_store *store,
 	callback(callback_context, 1);
 }
 
-static void transient_fraction_full(struct dm_exception_store *store,
-				    sector_t *numerator, sector_t *denominator)
+static void transient_usage(struct dm_exception_store *store,
+			    sector_t *total_sectors,
+			    sector_t *sectors_allocated,
+			    sector_t *metadata_sectors)
 {
-	*numerator = ((struct transient_c *) store->context)->next_free;
-	*denominator = get_dev_size(store->cow->bdev);
+	*sectors_allocated = ((struct transient_c *) store->context)->next_free;
+	*total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
+	*metadata_sectors = 0;
 }
 
 static int transient_ctr(struct dm_exception_store *store,
@@ -91,8 +94,7 @@ static unsigned transient_status(struct dm_exception_store *store,
 	case STATUSTYPE_INFO:
 		break;
 	case STATUSTYPE_TABLE:
-		DMEMIT(" %s N %llu", store->cow->name,
-		       (unsigned long long)store->chunk_size);
+		DMEMIT(" N %llu", (unsigned long long)store->chunk_size);
 	}
 
 	return sz;
@@ -106,7 +108,7 @@ static struct dm_exception_store_type _transient_type = {
 	.read_metadata = transient_read_metadata,
 	.prepare_exception = transient_prepare_exception,
 	.commit_exception = transient_commit_exception,
-	.fraction_full = transient_fraction_full,
+	.usage = transient_usage,
 	.status = transient_status,
 };
 
@@ -118,7 +120,7 @@ static struct dm_exception_store_type _transient_compat_type = {
 	.read_metadata = transient_read_metadata,
 	.prepare_exception = transient_prepare_exception,
 	.commit_exception = transient_commit_exception,
-	.fraction_full = transient_fraction_full,
+	.usage = transient_usage,
 	.status = transient_status,
 };
 
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 3a3ba46e6d4b..9e660ce05c26 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -49,7 +49,7 @@
 #define DM_TRACKED_CHUNK_HASH(x)	((unsigned long)(x) & \
 					 (DM_TRACKED_CHUNK_HASH_SIZE - 1))
 
-struct exception_table {
+struct dm_exception_table {
 	uint32_t hash_mask;
 	unsigned hash_shift;
 	struct list_head *table;
@@ -59,6 +59,9 @@ struct dm_snapshot {
 	struct rw_semaphore lock;
 
 	struct dm_dev *origin;
+	struct dm_dev *cow;
+
+	struct dm_target *ti;
 
 	/* List of snapshots per Origin */
 	struct list_head list;
@@ -73,8 +76,8 @@ struct dm_snapshot {
 
 	atomic_t pending_exceptions_count;
 
-	struct exception_table pending;
-	struct exception_table complete;
+	struct dm_exception_table pending;
+	struct dm_exception_table complete;
 
 	/*
 	 * pe_lock protects all pending_exception operations and access
@@ -97,6 +100,12 @@ struct dm_snapshot {
 	struct hlist_head tracked_chunk_hash[DM_TRACKED_CHUNK_HASH_SIZE];
 };
 
+struct dm_dev *dm_snap_cow(struct dm_snapshot *s)
+{
+	return s->cow;
+}
+EXPORT_SYMBOL(dm_snap_cow);
+
 static struct workqueue_struct *ksnapd;
 static void flush_queued_bios(struct work_struct *work);
 
@@ -116,7 +125,7 @@ static int bdev_equal(struct block_device *lhs, struct block_device *rhs)
 }
 
 struct dm_snap_pending_exception {
-	struct dm_snap_exception e;
+	struct dm_exception e;
 
 	/*
 	 * Origin buffers waiting for this to complete are held
@@ -351,8 +360,8 @@ static void unregister_snapshot(struct dm_snapshot *s)
  * The lowest hash_shift bits of the chunk number are ignored, allowing
  * some consecutive chunks to be grouped together.
  */
-static int init_exception_table(struct exception_table *et, uint32_t size,
-				unsigned hash_shift)
+static int dm_exception_table_init(struct dm_exception_table *et,
+				   uint32_t size, unsigned hash_shift)
 {
 	unsigned int i;
 
@@ -368,10 +377,11 @@ static int init_exception_table(struct exception_table *et, uint32_t size,
 	return 0;
 }
 
-static void exit_exception_table(struct exception_table *et, struct kmem_cache *mem)
+static void dm_exception_table_exit(struct dm_exception_table *et,
+				    struct kmem_cache *mem)
 {
 	struct list_head *slot;
-	struct dm_snap_exception *ex, *next;
+	struct dm_exception *ex, *next;
 	int i, size;
 
 	size = et->hash_mask + 1;
@@ -385,19 +395,12 @@ static void exit_exception_table(struct exception_table *et, struct kmem_cache *
 	vfree(et->table);
 }
 
-static uint32_t exception_hash(struct exception_table *et, chunk_t chunk)
+static uint32_t exception_hash(struct dm_exception_table *et, chunk_t chunk)
 {
 	return (chunk >> et->hash_shift) & et->hash_mask;
 }
 
-static void insert_exception(struct exception_table *eh,
-			     struct dm_snap_exception *e)
-{
-	struct list_head *l = &eh->table[exception_hash(eh, e->old_chunk)];
-	list_add(&e->hash_list, l);
-}
-
-static void remove_exception(struct dm_snap_exception *e)
+static void dm_remove_exception(struct dm_exception *e)
 {
 	list_del(&e->hash_list);
 }
@@ -406,11 +409,11 @@ static void remove_exception(struct dm_snap_exception *e)
  * Return the exception data for a sector, or NULL if not
  * remapped.
  */
-static struct dm_snap_exception *lookup_exception(struct exception_table *et,
-						  chunk_t chunk)
+static struct dm_exception *dm_lookup_exception(struct dm_exception_table *et,
+						chunk_t chunk)
 {
 	struct list_head *slot;
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 
 	slot = &et->table[exception_hash(et, chunk)];
 	list_for_each_entry (e, slot, hash_list)
@@ -421,9 +424,9 @@ static struct dm_snap_exception *lookup_exception(struct exception_table *et,
 	return NULL;
 }
 
-static struct dm_snap_exception *alloc_exception(void)
+static struct dm_exception *alloc_completed_exception(void)
 {
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 
 	e = kmem_cache_alloc(exception_cache, GFP_NOIO);
 	if (!e)
@@ -432,7 +435,7 @@ static struct dm_snap_exception *alloc_exception(void)
 	return e;
 }
 
-static void free_exception(struct dm_snap_exception *e)
+static void free_completed_exception(struct dm_exception *e)
 {
 	kmem_cache_free(exception_cache, e);
 }
@@ -457,12 +460,11 @@ static void free_pending_exception(struct dm_snap_pending_exception *pe)
 	atomic_dec(&s->pending_exceptions_count);
 }
 
-static void insert_completed_exception(struct dm_snapshot *s,
-				       struct dm_snap_exception *new_e)
+static void dm_insert_exception(struct dm_exception_table *eh,
+				struct dm_exception *new_e)
 {
-	struct exception_table *eh = &s->complete;
 	struct list_head *l;
-	struct dm_snap_exception *e = NULL;
+	struct dm_exception *e = NULL;
 
 	l = &eh->table[exception_hash(eh, new_e->old_chunk)];
 
@@ -478,7 +480,7 @@ static void insert_completed_exception(struct dm_snapshot *s,
 		    new_e->new_chunk == (dm_chunk_number(e->new_chunk) +
 					 dm_consecutive_chunk_count(e) + 1)) {
 			dm_consecutive_chunk_count_inc(e);
-			free_exception(new_e);
+			free_completed_exception(new_e);
 			return;
 		}
 
@@ -488,7 +490,7 @@ static void insert_completed_exception(struct dm_snapshot *s,
 			dm_consecutive_chunk_count_inc(e);
 			e->old_chunk--;
 			e->new_chunk--;
-			free_exception(new_e);
+			free_completed_exception(new_e);
 			return;
 		}
 
@@ -507,9 +509,9 @@ out:
 static int dm_add_exception(void *context, chunk_t old, chunk_t new)
 {
 	struct dm_snapshot *s = context;
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 
-	e = alloc_exception();
+	e = alloc_completed_exception();
 	if (!e)
 		return -ENOMEM;
 
@@ -518,11 +520,30 @@ static int dm_add_exception(void *context, chunk_t old, chunk_t new)
 	/* Consecutive_count is implicitly initialised to zero */
 	e->new_chunk = new;
 
-	insert_completed_exception(s, e);
+	dm_insert_exception(&s->complete, e);
 
 	return 0;
 }
 
+#define min_not_zero(l, r) (((l) == 0) ? (r) : (((r) == 0) ? (l) : min(l, r)))
+
+/*
+ * Return a minimum chunk size of all snapshots that have the specified origin.
+ * Return zero if the origin has no snapshots.
+ */
+static sector_t __minimum_chunk_size(struct origin *o)
+{
+	struct dm_snapshot *snap;
+	unsigned chunk_size = 0;
+
+	if (o)
+		list_for_each_entry(snap, &o->snapshots, list)
+			chunk_size = min_not_zero(chunk_size,
+						  snap->store->chunk_size);
+
+	return chunk_size;
+}
+
 /*
  * Hard coded magic.
  */
@@ -546,7 +567,7 @@ static int init_hash_tables(struct dm_snapshot *s)
 	 * Calculate based on the size of the original volume or
 	 * the COW volume...
 	 */
-	cow_dev_size = get_dev_size(s->store->cow->bdev);
+	cow_dev_size = get_dev_size(s->cow->bdev);
 	origin_dev_size = get_dev_size(s->origin->bdev);
 	max_buckets = calc_max_buckets();
 
@@ -554,8 +575,8 @@ static int init_hash_tables(struct dm_snapshot *s)
 	hash_size = min(hash_size, max_buckets);
 
 	hash_size = rounddown_pow_of_two(hash_size);
-	if (init_exception_table(&s->complete, hash_size,
-				 DM_CHUNK_CONSECUTIVE_BITS))
+	if (dm_exception_table_init(&s->complete, hash_size,
+				    DM_CHUNK_CONSECUTIVE_BITS))
 		return -ENOMEM;
 
 	/*
@@ -566,8 +587,8 @@ static int init_hash_tables(struct dm_snapshot *s)
 	if (hash_size < 64)
 		hash_size = 64;
 
-	if (init_exception_table(&s->pending, hash_size, 0)) {
-		exit_exception_table(&s->complete, exception_cache);
+	if (dm_exception_table_init(&s->pending, hash_size, 0)) {
+		dm_exception_table_exit(&s->complete, exception_cache);
 		return -ENOMEM;
 	}
 
@@ -582,45 +603,55 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	struct dm_snapshot *s;
 	int i;
 	int r = -EINVAL;
-	char *origin_path;
-	struct dm_exception_store *store;
+	char *origin_path, *cow_path;
 	unsigned args_used;
 
 	if (argc != 4) {
 		ti->error = "requires exactly 4 arguments";
 		r = -EINVAL;
-		goto bad_args;
+		goto bad;
 	}
 
 	origin_path = argv[0];
 	argv++;
 	argc--;
 
-	r = dm_exception_store_create(ti, argc, argv, &args_used, &store);
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s) {
+		ti->error = "Cannot allocate snapshot context private "
+		    "structure";
+		r = -ENOMEM;
+		goto bad;
+	}
+
+	cow_path = argv[0];
+	argv++;
+	argc--;
+
+	r = dm_get_device(ti, cow_path, 0, 0,
+			  FMODE_READ | FMODE_WRITE, &s->cow);
+	if (r) {
+		ti->error = "Cannot get COW device";
+		goto bad_cow;
+	}
+
+	r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
 	if (r) {
 		ti->error = "Couldn't create exception store";
 		r = -EINVAL;
-		goto bad_args;
+		goto bad_store;
 	}
 
 	argv += args_used;
 	argc -= args_used;
 
-	s = kmalloc(sizeof(*s), GFP_KERNEL);
-	if (!s) {
-		ti->error = "Cannot allocate snapshot context private "
-		    "structure";
-		r = -ENOMEM;
-		goto bad_snap;
-	}
-
 	r = dm_get_device(ti, origin_path, 0, ti->len, FMODE_READ, &s->origin);
 	if (r) {
 		ti->error = "Cannot get origin device";
 		goto bad_origin;
 	}
 
-	s->store = store;
+	s->ti = ti;
 	s->valid = 1;
 	s->active = 0;
 	atomic_set(&s->pending_exceptions_count, 0);
@@ -702,19 +733,22 @@ bad_pending_pool:
 	dm_kcopyd_client_destroy(s->kcopyd_client);
 
 bad_kcopyd:
-	exit_exception_table(&s->pending, pending_cache);
-	exit_exception_table(&s->complete, exception_cache);
+	dm_exception_table_exit(&s->pending, pending_cache);
+	dm_exception_table_exit(&s->complete, exception_cache);
 
 bad_hash_tables:
 	dm_put_device(ti, s->origin);
 
 bad_origin:
-	kfree(s);
+	dm_exception_store_destroy(s->store);
 
-bad_snap:
-	dm_exception_store_destroy(store);
+bad_store:
+	dm_put_device(ti, s->cow);
 
-bad_args:
+bad_cow:
+	kfree(s);
+
+bad:
 	return r;
 }
 
@@ -723,8 +757,8 @@ static void __free_exceptions(struct dm_snapshot *s)
 	dm_kcopyd_client_destroy(s->kcopyd_client);
 	s->kcopyd_client = NULL;
 
-	exit_exception_table(&s->pending, pending_cache);
-	exit_exception_table(&s->complete, exception_cache);
+	dm_exception_table_exit(&s->pending, pending_cache);
+	dm_exception_table_exit(&s->complete, exception_cache);
 }
 
 static void snapshot_dtr(struct dm_target *ti)
@@ -763,6 +797,8 @@ static void snapshot_dtr(struct dm_target *ti)
 
 	dm_exception_store_destroy(s->store);
 
+	dm_put_device(ti, s->cow);
+
 	kfree(s);
 }
 
@@ -825,7 +861,7 @@ static void __invalidate_snapshot(struct dm_snapshot *s, int err)
 
 	s->valid = 0;
 
-	dm_table_event(s->store->ti->table);
+	dm_table_event(s->ti->table);
 }
 
 static void get_pending_exception(struct dm_snap_pending_exception *pe)
@@ -863,7 +899,7 @@ static struct bio *put_pending_exception(struct dm_snap_pending_exception *pe)
 
 static void pending_complete(struct dm_snap_pending_exception *pe, int success)
 {
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 	struct dm_snapshot *s = pe->snap;
 	struct bio *origin_bios = NULL;
 	struct bio *snapshot_bios = NULL;
@@ -877,7 +913,7 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
 		goto out;
 	}
 
-	e = alloc_exception();
+	e = alloc_completed_exception();
 	if (!e) {
 		down_write(&s->lock);
 		__invalidate_snapshot(s, -ENOMEM);
@@ -888,7 +924,7 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
 
 	down_write(&s->lock);
 	if (!s->valid) {
-		free_exception(e);
+		free_completed_exception(e);
 		error = 1;
 		goto out;
 	}
@@ -904,10 +940,10 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success)
 	 * Add a proper exception, and remove the
 	 * in-flight exception from the list.
 	 */
-	insert_completed_exception(s, e);
+	dm_insert_exception(&s->complete, e);
 
  out:
-	remove_exception(&pe->e);
+	dm_remove_exception(&pe->e);
 	snapshot_bios = bio_list_get(&pe->snapshot_bios);
 	origin_bios = put_pending_exception(pe);
 
@@ -963,7 +999,7 @@ static void start_copy(struct dm_snap_pending_exception *pe)
 	src.sector = chunk_to_sector(s->store, pe->e.old_chunk);
 	src.count = min((sector_t)s->store->chunk_size, dev_size - src.sector);
 
-	dest.bdev = s->store->cow->bdev;
+	dest.bdev = s->cow->bdev;
 	dest.sector = chunk_to_sector(s->store, pe->e.new_chunk);
 	dest.count = src.count;
 
@@ -975,7 +1011,7 @@ static void start_copy(struct dm_snap_pending_exception *pe)
 static struct dm_snap_pending_exception *
 __lookup_pending_exception(struct dm_snapshot *s, chunk_t chunk)
 {
-	struct dm_snap_exception *e = lookup_exception(&s->pending, chunk);
+	struct dm_exception *e = dm_lookup_exception(&s->pending, chunk);
 
 	if (!e)
 		return NULL;
@@ -1016,15 +1052,15 @@ __find_pending_exception(struct dm_snapshot *s,
 	}
 
 	get_pending_exception(pe);
-	insert_exception(&s->pending, &pe->e);
+	dm_insert_exception(&s->pending, &pe->e);
 
 	return pe;
 }
 
-static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e,
+static void remap_exception(struct dm_snapshot *s, struct dm_exception *e,
 			    struct bio *bio, chunk_t chunk)
 {
-	bio->bi_bdev = s->store->cow->bdev;
+	bio->bi_bdev = s->cow->bdev;
 	bio->bi_sector = chunk_to_sector(s->store,
 					 dm_chunk_number(e->new_chunk) +
 					 (chunk - e->old_chunk)) +
@@ -1035,14 +1071,14 @@ static void remap_exception(struct dm_snapshot *s, struct dm_snap_exception *e,
 static int snapshot_map(struct dm_target *ti, struct bio *bio,
 			union map_info *map_context)
 {
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 	struct dm_snapshot *s = ti->private;
 	int r = DM_MAPIO_REMAPPED;
 	chunk_t chunk;
 	struct dm_snap_pending_exception *pe = NULL;
 
 	if (unlikely(bio_empty_barrier(bio))) {
-		bio->bi_bdev = s->store->cow->bdev;
+		bio->bi_bdev = s->cow->bdev;
 		return DM_MAPIO_REMAPPED;
 	}
 
@@ -1063,7 +1099,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 	}
 
 	/* If the block is already remapped - use that, else remap it */
-	e = lookup_exception(&s->complete, chunk);
+	e = dm_lookup_exception(&s->complete, chunk);
 	if (e) {
 		remap_exception(s, e, bio, chunk);
 		goto out_unlock;
@@ -1087,7 +1123,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio,
 				goto out_unlock;
 			}
 
-			e = lookup_exception(&s->complete, chunk);
+			e = dm_lookup_exception(&s->complete, chunk);
 			if (e) {
 				free_pending_exception(pe);
 				remap_exception(s, e, bio, chunk);
@@ -1159,14 +1195,17 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
 		if (!snap->valid)
 			DMEMIT("Invalid");
 		else {
-			if (snap->store->type->fraction_full) {
-				sector_t numerator, denominator;
-				snap->store->type->fraction_full(snap->store,
-								 &numerator,
-								 &denominator);
-				DMEMIT("%llu/%llu",
-				       (unsigned long long)numerator,
-				       (unsigned long long)denominator);
+			if (snap->store->type->usage) {
+				sector_t total_sectors, sectors_allocated,
+					 metadata_sectors;
+				snap->store->type->usage(snap->store,
+							 &total_sectors,
+							 &sectors_allocated,
+							 &metadata_sectors);
+				DMEMIT("%llu/%llu %llu",
+				       (unsigned long long)sectors_allocated,
+				       (unsigned long long)total_sectors,
+				       (unsigned long long)metadata_sectors);
 			}
 			else
 				DMEMIT("Unknown");
@@ -1179,7 +1218,7 @@ static int snapshot_status(struct dm_target *ti, status_type_t type,
 		 * to make private copies if the output is to
 		 * make sense.
 		 */
-		DMEMIT("%s", snap->origin->name);
+		DMEMIT("%s %s", snap->origin->name, snap->cow->name);
 		snap->store->type->status(snap->store, type, result + sz,
 					  maxlen - sz);
 		break;
@@ -1206,7 +1245,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
 {
 	int r = DM_MAPIO_REMAPPED, first = 0;
 	struct dm_snapshot *snap;
-	struct dm_snap_exception *e;
+	struct dm_exception *e;
 	struct dm_snap_pending_exception *pe, *next_pe, *primary_pe = NULL;
 	chunk_t chunk;
 	LIST_HEAD(pe_queue);
@@ -1221,7 +1260,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
 			goto next_snapshot;
 
 		/* Nothing to do if writing beyond end of snapshot */
-		if (bio->bi_sector >= dm_table_get_size(snap->store->ti->table))
+		if (bio->bi_sector >= dm_table_get_size(snap->ti->table))
 			goto next_snapshot;
 
 		/*
@@ -1238,7 +1277,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
 		 * ref_count is initialised to 1 so pending_complete()
 		 * won't destroy the primary_pe while we're inside this loop.
 		 */
-		e = lookup_exception(&snap->complete, chunk);
+		e = dm_lookup_exception(&snap->complete, chunk);
 		if (e)
 			goto next_snapshot;
 
@@ -1253,7 +1292,7 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
 				goto next_snapshot;
 			}
 
-			e = lookup_exception(&snap->complete, chunk);
+			e = dm_lookup_exception(&snap->complete, chunk);
 			if (e) {
 				free_pending_exception(pe);
 				goto next_snapshot;
@@ -1391,8 +1430,6 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
 	return (bio_rw(bio) == WRITE) ? do_origin(dev, bio) : DM_MAPIO_REMAPPED;
 }
 
-#define min_not_zero(l, r) (l == 0) ? r : ((r == 0) ? l : min(l, r))
-
 /*
  * Set the target "split_io" field to the minimum of all the snapshots'
  * chunk sizes.
@@ -1400,19 +1437,12 @@ static int origin_map(struct dm_target *ti, struct bio *bio,
 static void origin_resume(struct dm_target *ti)
 {
 	struct dm_dev *dev = ti->private;
-	struct dm_snapshot *snap;
-	struct origin *o;
-	unsigned chunk_size = 0;
 
 	down_read(&_origins_lock);
-	o = __lookup_origin(dev->bdev);
-	if (o)
-		list_for_each_entry (snap, &o->snapshots, list)
-			chunk_size = min_not_zero(chunk_size,
-						  snap->store->chunk_size);
-	up_read(&_origins_lock);
 
-	ti->split_io = chunk_size;
+	ti->split_io = __minimum_chunk_size(__lookup_origin(dev->bdev));
+
+	up_read(&_origins_lock);
 }
 
 static int origin_status(struct dm_target *ti, status_type_t type, char *result,
@@ -1455,7 +1485,7 @@ static struct target_type origin_target = {
 
 static struct target_type snapshot_target = {
 	.name    = "snapshot",
-	.version = {1, 7, 0},
+	.version = {1, 8, 0},
 	.module  = THIS_MODULE,
 	.ctr     = snapshot_ctr,
 	.dtr     = snapshot_dtr,
@@ -1494,7 +1524,7 @@ static int __init dm_snapshot_init(void)
 		goto bad2;
 	}
 
-	exception_cache = KMEM_CACHE(dm_snap_exception, 0);
+	exception_cache = KMEM_CACHE(dm_exception, 0);
 	if (!exception_cache) {
 		DMERR("Couldn't create exception cache.");
 		r = -ENOMEM;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 724efc63904d..68b66f3e4607 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -430,9 +430,10 @@ static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
 	mempool_free(tio, md->tio_pool);
 }
 
-static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md)
+static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
+					    gfp_t gfp_mask)
 {
-	return mempool_alloc(md->tio_pool, GFP_ATOMIC);
+	return mempool_alloc(md->tio_pool, gfp_mask);
 }
 
 static void free_rq_tio(struct dm_rq_target_io *tio)
@@ -450,6 +451,12 @@ static void free_bio_info(struct dm_rq_clone_bio_info *info)
 	mempool_free(info, info->tio->md->io_pool);
 }
 
+static int md_in_flight(struct mapped_device *md)
+{
+	return atomic_read(&md->pending[READ]) +
+	       atomic_read(&md->pending[WRITE]);
+}
+
 static void start_io_acct(struct dm_io *io)
 {
 	struct mapped_device *md = io->md;
@@ -1436,6 +1443,32 @@ static int setup_clone(struct request *clone, struct request *rq,
 	return 0;
 }
 
+static struct request *clone_rq(struct request *rq, struct mapped_device *md,
+				gfp_t gfp_mask)
+{
+	struct request *clone;
+	struct dm_rq_target_io *tio;
+
+	tio = alloc_rq_tio(md, gfp_mask);
+	if (!tio)
+		return NULL;
+
+	tio->md = md;
+	tio->ti = NULL;
+	tio->orig = rq;
+	tio->error = 0;
+	memset(&tio->info, 0, sizeof(tio->info));
+
+	clone = &tio->clone;
+	if (setup_clone(clone, rq, tio)) {
+		/* -ENOMEM */
+		free_rq_tio(tio);
+		return NULL;
+	}
+
+	return clone;
+}
+
 static int dm_rq_flush_suspending(struct mapped_device *md)
 {
 	return !md->suspend_rq.special;
@@ -1447,7 +1480,6 @@ static int dm_rq_flush_suspending(struct mapped_device *md)
 static int dm_prep_fn(struct request_queue *q, struct request *rq)
 {
 	struct mapped_device *md = q->queuedata;
-	struct dm_rq_target_io *tio;
 	struct request *clone;
 
 	if (unlikely(rq == &md->suspend_rq)) {
@@ -1463,35 +1495,20 @@ static int dm_prep_fn(struct request_queue *q, struct request *rq)
 		return BLKPREP_KILL;
 	}
 
-	tio = alloc_rq_tio(md); /* Only one for each original request */
-	if (!tio)
-		/* -ENOMEM */
+	clone = clone_rq(rq, md, GFP_ATOMIC);
+	if (!clone)
 		return BLKPREP_DEFER;
 
-	tio->md = md;
-	tio->ti = NULL;
-	tio->orig = rq;
-	tio->error = 0;
-	memset(&tio->info, 0, sizeof(tio->info));
-
-	clone = &tio->clone;
-	if (setup_clone(clone, rq, tio)) {
-		/* -ENOMEM */
-		free_rq_tio(tio);
-		return BLKPREP_DEFER;
-	}
-
 	rq->special = clone;
 	rq->cmd_flags |= REQ_DONTPREP;
 
 	return BLKPREP_OK;
 }
 
-static void map_request(struct dm_target *ti, struct request *rq,
+static void map_request(struct dm_target *ti, struct request *clone,
 			struct mapped_device *md)
 {
 	int r;
-	struct request *clone = rq->special;
 	struct dm_rq_target_io *tio = clone->end_io_data;
 
 	/*
@@ -1568,7 +1585,7 @@ static void dm_request_fn(struct request_queue *q)
 
 		blk_start_request(rq);
 		spin_unlock(q->queue_lock);
-		map_request(ti, rq, md);
+		map_request(ti, rq->special, md);
 		spin_lock_irq(q->queue_lock);
 	}
 
@@ -2098,8 +2115,7 @@ static int dm_wait_for_completion(struct mapped_device *md, int interruptible)
 				break;
 			}
 			spin_unlock_irqrestore(q->queue_lock, flags);
-		} else if (!atomic_read(&md->pending[0]) &&
-					!atomic_read(&md->pending[1]))
+		} else if (!md_in_flight(md))
 			break;
 
 		if (interruptible == TASK_INTERRUPTIBLE &&