3 files changed, 14 insertions, 27 deletions

diff --git a/drivers/md/persistent-data/dm-block-manager.c b/drivers/md/persistent-data/dm-block-manager.c
index 4b5c504..ad1712e 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -584,22 +584,6 @@ int dm_bm_unlock(struct dm_block *b)
 }
 EXPORT_SYMBOL_GPL(dm_bm_unlock);
 
-int dm_bm_unlock_move(struct dm_block *b, dm_block_t n)
-{
-	struct buffer_aux *aux;
-
-	aux = dm_bufio_get_aux_data(to_buffer(b));
-
-	if (aux->write_locked) {
-		dm_bufio_mark_buffer_dirty(to_buffer(b));
-		bl_up_write(&aux->lock);
-	} else
-		bl_up_read(&aux->lock);
-
-	dm_bufio_release_move(to_buffer(b), n);
-	return 0;
-}
-
 int dm_bm_flush_and_unlock(struct dm_block_manager *bm,
 			   struct dm_block *superblock)
 {
diff --git a/drivers/md/persistent-data/dm-block-manager.h b/drivers/md/persistent-data/dm-block-manager.h
index 924833d..3278855 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -97,14 +97,6 @@ int dm_bm_write_lock_zero(struct dm_block_manager *bm, dm_block_t b,
 int dm_bm_unlock(struct dm_block *b);
 
 /*
- * An optimisation; we often want to copy a block's contents to a new
- * block.  eg, as part of the shadowing operation.  It's far better for
- * bufio to do this move behind the scenes than hold 2 locks and memcpy the
- * data.
- */
-int dm_bm_unlock_move(struct dm_block *b, dm_block_t n);
-
-/*
  * It's a common idiom to have a superblock that should be committed last.
  *
  * @superblock should be write-locked on entry. It will be unlocked during
diff --git a/drivers/md/persistent-data/dm-transaction-manager.c b/drivers/md/persistent-data/dm-transaction-manager.c
index b4f0583..d247a35 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -219,13 +219,24 @@ static int __shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,
 	if (r < 0)
 		return r;
 
-	r = dm_bm_unlock_move(orig_block, new);
-	if (r < 0) {
+	/*
+	 * It would be tempting to use dm_bm_unlock_move here, but some
+	 * code, such as the space maps, keeps using the old data structures
+	 * secure in the knowledge they won't be changed until the next
+	 * transaction.  Using unlock_move would force a synchronous read
+	 * since the old block would no longer be in the cache.
+	 */
+	r = dm_bm_write_lock_zero(tm->bm, new, v, result);
+	if (r) {
 		dm_bm_unlock(orig_block);
 		return r;
 	}
 
-	return dm_bm_write_lock(tm->bm, new, v, result);
+	memcpy(dm_block_data(*result), dm_block_data(orig_block),
+	       dm_bm_block_size(tm->bm));
+
+	dm_bm_unlock(orig_block);
+	return r;
 }
 
 int dm_tm_shadow_block(struct dm_transaction_manager *tm, dm_block_t orig,