Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 25d985e..473f039 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -9,15 +9,23 @@
 #define EXTENT_MAP_LAST_BYTE ((u64)-4)
 #define EXTENT_MAP_HOLE ((u64)-3)
 #define EXTENT_MAP_INLINE ((u64)-2)
+/* used only during fiemap calls */
 #define EXTENT_MAP_DELALLOC ((u64)-1)
 
-/* bits for the flags field */
-#define EXTENT_FLAG_PINNED 0 /* this entry not yet on disk, don't free it */
-#define EXTENT_FLAG_COMPRESSED 1
-#define EXTENT_FLAG_PREALLOC 3 /* pre-allocated extent */
-#define EXTENT_FLAG_LOGGING 4 /* Logging this extent */
-#define EXTENT_FLAG_FILLING 5 /* Filling in a preallocated extent */
-#define EXTENT_FLAG_FS_MAPPING 6 /* filesystem extent mapping type */
+/* bits for the extent_map::flags field */
+enum {
+	/* this entry not yet on disk, don't free it */
+	EXTENT_FLAG_PINNED,
+	EXTENT_FLAG_COMPRESSED,
+	/* pre-allocated extent */
+	EXTENT_FLAG_PREALLOC,
+	/* Logging this extent */
+	EXTENT_FLAG_LOGGING,
+	/* Filling in a preallocated extent */
+	EXTENT_FLAG_FILLING,
+	/* filesystem extent mapping type */
+	EXTENT_FLAG_FS_MAPPING,
+};
 
 struct extent_map {
 	struct rb_node rb_node;
@@ -49,7 +57,7 @@
 };
 
 struct extent_map_tree {
-	struct rb_root map;
+	struct rb_root_cached map;
 	struct list_head modified_extents;
 	rwlock_t lock;
 };
@@ -78,7 +86,7 @@
 					 u64 start, u64 len);
 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 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,