diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 26a654d..0aa4b6b 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -61,7 +61,7 @@
 {
 	if (!blk_queue_dax(bdev->bd_queue))
 		return NULL;
-	return fs_dax_get_by_host(bdev->bd_disk->disk_name);
+	return dax_get_by_host(bdev->bd_disk->disk_name);
 }
 EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
 #endif
diff --git a/fs/dax.c b/fs/dax.c
index 1f1f020..35da144 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -937,12 +937,11 @@
  * on persistent storage prior to completion of the operation.
  */
 int dax_writeback_mapping_range(struct address_space *mapping,
-		struct block_device *bdev, struct writeback_control *wbc)
+		struct dax_device *dax_dev, struct writeback_control *wbc)
 {
 	XA_STATE(xas, &mapping->i_pages, wbc->range_start >> PAGE_SHIFT);
 	struct inode *inode = mapping->host;
 	pgoff_t end_index = wbc->range_end >> PAGE_SHIFT;
-	struct dax_device *dax_dev;
 	void *entry;
 	int ret = 0;
 	unsigned int scanned = 0;
@@ -953,10 +952,6 @@
 	if (!mapping->nrexceptional || wbc->sync_mode != WB_SYNC_ALL)
 		return 0;
 
-	dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
-	if (!dax_dev)
-		return -EIO;
-
 	trace_dax_writeback_range(inode, xas.xa_index, end_index);
 
 	tag_pages_for_writeback(mapping, xas.xa_index, end_index);
@@ -977,7 +972,6 @@
 		xas_lock_irq(&xas);
 	}
 	xas_unlock_irq(&xas);
-	put_dax(dax_dev);
 	trace_dax_writeback_range_done(inode, xas.xa_index, end_index);
 	return ret;
 }
@@ -1207,6 +1201,9 @@
 		lockdep_assert_held(&inode->i_rwsem);
 	}
 
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		flags |= IOMAP_NOWAIT;
+
 	while (iov_iter_count(iter)) {
 		ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
 				iter, dax_iomap_actor);
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 119667e..c885cf7 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -960,8 +960,9 @@
 static int
 ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
-	return dax_writeback_mapping_range(mapping,
-			mapping->host->i_sb->s_bdev, wbc);
+	struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
+
+	return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
 }
 
 const struct address_space_operations ext2_aops = {
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 3313168..1305b81 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2867,7 +2867,7 @@
 	percpu_down_read(&sbi->s_journal_flag_rwsem);
 	trace_ext4_writepages(inode, wbc);
 
-	ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
+	ret = dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
 	trace_ext4_writepages_result(inode, wbc, ret,
 				     nr_to_write - wbc->nr_to_write);
 	percpu_up_read(&sbi->s_journal_flag_rwsem);
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 3a688eb..58e937b 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -587,7 +587,7 @@
 
 	xfs_iflags_clear(ip, XFS_ITRUNCATED);
 	return dax_writeback_mapping_range(mapping,
-			xfs_inode_buftarg(ip)->bt_bdev, wbc);
+			xfs_inode_buftarg(ip)->bt_daxdev, wbc);
 }
 
 STATIC sector_t
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 9bd8528..328c2db 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -129,11 +129,6 @@
 			sectors);
 }
 
-static inline struct dax_device *fs_dax_get_by_host(const char *host)
-{
-	return dax_get_by_host(host);
-}
-
 static inline void fs_put_dax(struct dax_device *dax_dev)
 {
 	put_dax(dax_dev);
@@ -141,7 +136,7 @@
 
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev);
 int dax_writeback_mapping_range(struct address_space *mapping,
-		struct block_device *bdev, struct writeback_control *wbc);
+		struct dax_device *dax_dev, struct writeback_control *wbc);
 
 struct page *dax_layout_busy_page(struct address_space *mapping);
 dax_entry_t dax_lock_page(struct page *page);
@@ -160,11 +155,6 @@
 	return false;
 }
 
-static inline struct dax_device *fs_dax_get_by_host(const char *host)
-{
-	return NULL;
-}
-
 static inline void fs_put_dax(struct dax_device *dax_dev)
 {
 }
@@ -180,7 +170,7 @@
 }
 
 static inline int dax_writeback_mapping_range(struct address_space *mapping,
-		struct block_device *bdev, struct writeback_control *wbc)
+		struct dax_device *dax_dev, struct writeback_control *wbc)
 {
 	return -EOPNOTSUPP;
 }