diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0a9a89e..4ea396f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2437,6 +2437,16 @@ static int ext4_nonda_switch(struct super_block *sb)
 	free_blocks  = EXT4_C2B(sbi,
 		percpu_counter_read_positive(&sbi->s_freeclusters_counter));
 	dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
+	/*
+	 * Start pushing delalloc when 1/2 of free blocks are dirty.
+	 */
+	if (dirty_blocks && (free_blocks < 2 * dirty_blocks) &&
+	    !writeback_in_progress(sb->s_bdi) &&
+	    down_read_trylock(&sb->s_umount)) {
+		writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
+		up_read(&sb->s_umount);
+	}
+
 	if (2 * free_blocks < 3 * dirty_blocks ||
 		free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {
 		/*
@@ -2445,13 +2455,6 @@ static int ext4_nonda_switch(struct super_block *sb)
 		 */
 		return 1;
 	}
-	/*
-	 * Even if we don't switch but are nearing capacity,
-	 * start pushing delalloc when 1/2 of free blocks are dirty.
-	 */
-	if (free_blocks < 2 * dirty_blocks)
-		writeback_inodes_sb_if_idle(sb, WB_REASON_FS_FREE_SPACE);
-
 	return 0;
 }
 
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index be3efc4..5602d73 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -63,6 +63,7 @@ int writeback_in_progress(struct backing_dev_info *bdi)
 {
 	return test_bit(BDI_writeback_running, &bdi->state);
 }
+EXPORT_SYMBOL(writeback_in_progress);
 
 static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
 {