Commit cb495113 authored by David Sterba's avatar David Sterba
Browse files

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: default avatarDavid Sterba <dsterba@suse.com>
parent 6ff49c6a

fs/btrfs/ctree.h

+4 −11
Original line number Diff line number Diff line
@@ -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

+51 −0
Original line number Diff line number Diff line
@@ -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)

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