diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 64d08f94485d..1874aee69c86 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -318,6 +318,20 @@ void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
 		try_merge_map(tree, em);
 }
 
+static inline void setup_extent_mapping(struct extent_map_tree *tree,
+					struct extent_map *em,
+					int modified)
+{
+	atomic_inc(&em->refs);
+	em->mod_start = em->start;
+	em->mod_len = em->len;
+
+	if (modified)
+		list_move(&em->list, &tree->modified_extents);
+	else
+		try_merge_map(tree, em);
+}
+
 /**
  * add_extent_mapping - add new extent map to the extent tree
  * @tree:	tree to insert new map in
@@ -337,15 +351,7 @@ int add_extent_mapping(struct extent_map_tree *tree,
 	if (ret)
 		goto out;
 
-	atomic_inc(&em->refs);
-
-	em->mod_start = em->start;
-	em->mod_len = em->len;
-
-	if (modified)
-		list_move(&em->list, &tree->modified_extents);
-	else
-		try_merge_map(tree, em);
+	setup_extent_mapping(tree, em, modified);
 out:
 	return ret;
 }
@@ -432,3 +438,18 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 	RB_CLEAR_NODE(&em->rb_node);
 	return ret;
 }
+
+void replace_extent_mapping(struct extent_map_tree *tree,
+			    struct extent_map *cur,
+			    struct extent_map *new,
+			    int modified)
+{
+	WARN_ON(test_bit(EXTENT_FLAG_PINNED, &cur->flags));
+	ASSERT(extent_map_in_tree(cur));
+	if (!test_bit(EXTENT_FLAG_LOGGING, &cur->flags))
+		list_del_init(&cur->list);
+	rb_replace_node(&cur->rb_node, &new->rb_node, &tree->map);
+	RB_CLEAR_NODE(&cur->rb_node);
+
+	setup_extent_mapping(tree, new, modified);
+}
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index f0a645a14d6e..e7fd8a56a140 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -68,6 +68,10 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 int add_extent_mapping(struct extent_map_tree *tree,
 		       struct extent_map *em, int modified);
 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
+void replace_extent_mapping(struct extent_map_tree *tree,
+			    struct extent_map *cur,
+			    struct extent_map *new,
+			    int modified);
 
 struct extent_map *alloc_extent_map(void);
 void free_extent_map(struct extent_map *em);
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 762ca32bd988..31e48b947060 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -591,7 +591,6 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 		clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 		clear_bit(EXTENT_FLAG_LOGGING, &flags);
 		modified = !list_empty(&em->list);
-		remove_extent_mapping(em_tree, em);
 		if (no_splits)
 			goto next;
 
@@ -622,8 +621,7 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 			split->bdev = em->bdev;
 			split->flags = flags;
 			split->compress_type = em->compress_type;
-			ret = add_extent_mapping(em_tree, split, modified);
-			BUG_ON(ret); /* Logic error */
+			replace_extent_mapping(em_tree, em, split, modified);
 			free_extent_map(split);
 			split = split2;
 			split2 = NULL;
@@ -661,12 +659,20 @@ void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
 				split->orig_block_len = 0;
 			}
 
-			ret = add_extent_mapping(em_tree, split, modified);
-			BUG_ON(ret); /* Logic error */
+			if (extent_map_in_tree(em)) {
+				replace_extent_mapping(em_tree, em, split,
+						       modified);
+			} else {
+				ret = add_extent_mapping(em_tree, split,
+							 modified);
+				ASSERT(ret == 0); /* Logic error */
+			}
 			free_extent_map(split);
 			split = NULL;
 		}
 next:
+		if (extent_map_in_tree(em))
+			remove_extent_mapping(em_tree, em);
 		write_unlock(&em_tree->lock);
 
 		/* once for us */