btrfs: define separate btrfs_set/get_XX helpers

There are helpers for all type widths defined via macro and optionally
can use a token which is a cached pointer to avoid repeated mapping of
the extent buffer.

The token value is known at compile time, when it's valid it's always
address of a local variable, otherwise it's NULL passed by the
token-less helpers.

This can be utilized to remove some branching as the helpers are used
frequenlty.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/ctree.h

@@ -1335,17 +1335,10 @@ u##bits btrfs_get_token_##bits(const struct extent_buffer *eb,		\
 void btrfs_set_token_##bits(struct extent_buffer *eb, const void *ptr,	\
 			    unsigned long off, u##bits val,		\
 			    struct btrfs_map_token *token);		\
-static inline u##bits btrfs_get_##bits(const struct extent_buffer *eb,	\
-				       const void *ptr,			\
-				       unsigned long off)		\
-{									\
-	return btrfs_get_token_##bits(eb, ptr, off, NULL);		\
-}									\
-static inline void btrfs_set_##bits(struct extent_buffer *eb, void *ptr,\
-				    unsigned long off, u##bits val)	\
-{									\
-       btrfs_set_token_##bits(eb, ptr, off, val, NULL);			\
-}
+u##bits btrfs_get_##bits(const struct extent_buffer *eb,		\
+			 const void *ptr, unsigned long off);		\
+void btrfs_set_##bits(struct extent_buffer *eb, void *ptr,		\
+		      unsigned long off, u##bits val);
 
 DECLARE_BTRFS_SETGET_BITS(8)
 DECLARE_BTRFS_SETGET_BITS(16)

fs/btrfs/struct-funcs.c

@@ -33,6 +33,8 @@ static inline void put_unaligned_le8(u8 val, void *p)
  *
  * The extent buffer api is used to do the page spanning work required to
  * have a metadata blocksize different from the page size.
+ *
+ * There are 2 variants defined, one with a token pointer and one without.
  */
 
 #define DEFINE_BTRFS_SETGET_BITS(bits)					\
@@ -75,6 +77,31 @@ u##bits btrfs_get_token_##bits(const struct extent_buffer *eb,		\
 	}								\
 	return res;							\
 }									\
+u##bits btrfs_get_##bits(const struct extent_buffer *eb,		\
+			 const void *ptr, unsigned long off)		\
+{									\
+	unsigned long part_offset = (unsigned long)ptr;			\
+	unsigned long offset = part_offset + off;			\
+	void *p;							\
+	int err;							\
+	char *kaddr;							\
+	unsigned long map_start;					\
+	unsigned long map_len;						\
+	int size = sizeof(u##bits);					\
+	u##bits res;							\
+									\
+	err = map_private_extent_buffer(eb, offset, size,		\
+					&kaddr, &map_start, &map_len);	\
+	if (err) {							\
+		__le##bits leres;					\
+									\
+		read_extent_buffer(eb, &leres, offset, size);		\
+		return le##bits##_to_cpu(leres);			\
+	}								\
+	p = kaddr + part_offset - map_start;				\
+	res = get_unaligned_le##bits(p + off);				\
+	return res;							\
+}									\
 void btrfs_set_token_##bits(struct extent_buffer *eb,			\
 			    const void *ptr, unsigned long off,		\
 			    u##bits val,				\
@@ -113,6 +140,30 @@ void btrfs_set_token_##bits(struct extent_buffer *eb,			\
 		token->offset = map_start;				\
 		token->eb = eb;						\
 	}								\
+}									\
+void btrfs_set_##bits(struct extent_buffer *eb, void *ptr,		\
+		      unsigned long off, u##bits val)			\
+{									\
+	unsigned long part_offset = (unsigned long)ptr;			\
+	unsigned long offset = part_offset + off;			\
+	void *p;							\
+	int err;							\
+	char *kaddr;							\
+	unsigned long map_start;					\
+	unsigned long map_len;						\
+	int size = sizeof(u##bits);					\
+									\
+	err = map_private_extent_buffer(eb, offset, size,		\
+			&kaddr, &map_start, &map_len);			\
+	if (err) {							\
+		__le##bits val2;					\
+									\
+		val2 = cpu_to_le##bits(val);				\
+		write_extent_buffer(eb, &val2, offset, size);		\
+		return;							\
+	}								\
+	p = kaddr + part_offset - map_start;				\
+	put_unaligned_le##bits(val, p + off);				\
 }
 
 DEFINE_BTRFS_SETGET_BITS(8)