[linux-2.6-block.git] / include / linux / flex_array.h

#ifndef _FLEX_ARRAY_H
#define _FLEX_ARRAY_H

#include <linux/types.h>
#include <linux/reciprocal_div.h>
#include <asm/page.h>

#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE

struct flex_array_part;

/*
 * This is meant to replace cases where an array-like
 * structure has gotten too big to fit into kmalloc()
 * and the developer is getting tempted to use
 * vmalloc().
 */

struct flex_array {
	union {
		struct {
			int element_size;
			int total_nr_elements;
			int elems_per_part;
			struct reciprocal_value reciprocal_elems;
			struct flex_array_part *parts[];
		};
		/*
		 * This little trick makes sure that
		 * sizeof(flex_array) == PAGE_SIZE
		 */
		char padding[FLEX_ARRAY_BASE_SIZE];
	};
};

/* Number of bytes left in base struct flex_array, excluding metadata */
#define FLEX_ARRAY_BASE_BYTES_LEFT					\
	(FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))

/* Number of pointers in base to struct flex_array_part pages */
#define FLEX_ARRAY_NR_BASE_PTRS						\
	(FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))

/* Number of elements of size that fit in struct flex_array_part */
#define FLEX_ARRAY_ELEMENTS_PER_PART(size)				\
	(FLEX_ARRAY_PART_SIZE / size)

/*
 * Defines a statically allocated flex array and ensures its parameters are
 * valid.
 */
#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total)		\
	struct flex_array __arrayname = { { {				\
		.element_size = (__element_size),			\
		.total_nr_elements = (__total),				\
	} } };								\
	static inline void __arrayname##_invalid_parameter(void)	\
	{								\
		BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS *	\
			FLEX_ARRAY_ELEMENTS_PER_PART(__element_size));	\
	}

struct flex_array *flex_array_alloc(int element_size, unsigned int total,
		gfp_t flags);
int flex_array_prealloc(struct flex_array *fa, unsigned int start,
		unsigned int nr_elements, gfp_t flags);
void flex_array_free(struct flex_array *fa);
void flex_array_free_parts(struct flex_array *fa);
int flex_array_put(struct flex_array *fa, unsigned int element_nr, void *src,
		gfp_t flags);
int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
void *flex_array_get(struct flex_array *fa, unsigned int element_nr);
int flex_array_shrink(struct flex_array *fa);

#define flex_array_put_ptr(fa, nr, src, gfp) \
	flex_array_put(fa, nr, (void *)&(src), gfp)

void *flex_array_get_ptr(struct flex_array *fa, unsigned int element_nr);

#endif /* _FLEX_ARRAY_H */
Commit	Line	Data
534acc05 DH	1	#ifndef _FLEX_ARRAY_H
	2	#define _FLEX_ARRAY_H
	3
	4	#include <linux/types.h>
809fa972	5	#include <linux/reciprocal_div.h>
534acc05 DH	6	#include <asm/page.h>
	7
	8	#define FLEX_ARRAY_PART_SIZE PAGE_SIZE
	9	#define FLEX_ARRAY_BASE_SIZE PAGE_SIZE
	10
	11	struct flex_array_part;
	12
	13	/*
	14	* This is meant to replace cases where an array-like
	15	* structure has gotten too big to fit into kmalloc()
	16	* and the developer is getting tempted to use
	17	* vmalloc().
	18	*/
	19
	20	struct flex_array {
	21	union {
	22	struct {
	23	int element_size;
	24	int total_nr_elements;
704f15dd	25	int elems_per_part;
809fa972	26	struct reciprocal_value reciprocal_elems;
8e7ee270	27	struct flex_array_part *parts[];
534acc05 DH	28	};
	29	/*
	30	* This little trick makes sure that
	31	* sizeof(flex_array) == PAGE_SIZE
	32	*/
	33	char padding[FLEX_ARRAY_BASE_SIZE];
	34	};
	35	};
	36
45b588d6 DR	37	/* Number of bytes left in base struct flex_array, excluding metadata */
	38	#define FLEX_ARRAY_BASE_BYTES_LEFT \
	39	(FLEX_ARRAY_BASE_SIZE - offsetof(struct flex_array, parts))
	40
	41	/* Number of pointers in base to struct flex_array_part pages */
	42	#define FLEX_ARRAY_NR_BASE_PTRS \
	43	(FLEX_ARRAY_BASE_BYTES_LEFT / sizeof(struct flex_array_part *))
	44
	45	/* Number of elements of size that fit in struct flex_array_part */
	46	#define FLEX_ARRAY_ELEMENTS_PER_PART(size) \
	47	(FLEX_ARRAY_PART_SIZE / size)
	48
	49	/*
	50	* Defines a statically allocated flex array and ensures its parameters are
	51	* valid.
	52	*/
	53	#define DEFINE_FLEX_ARRAY(__arrayname, __element_size, __total) \
	54	struct flex_array __arrayname = { { { \
	55	.element_size = (__element_size), \
	56	.total_nr_elements = (__total), \
	57	} } }; \
	58	static inline void __arrayname##_invalid_parameter(void) \
	59	{ \
	60	BUILD_BUG_ON((__total) > FLEX_ARRAY_NR_BASE_PTRS * \
	61	FLEX_ARRAY_ELEMENTS_PER_PART(__element_size)); \
	62	}
534acc05	63
b62e408c DR	64	struct flex_array *flex_array_alloc(int element_size, unsigned int total,
	65	gfp_t flags);
	66	int flex_array_prealloc(struct flex_array *fa, unsigned int start,
5d30b10b	67	unsigned int nr_elements, gfp_t flags);
534acc05 DH	68	void flex_array_free(struct flex_array *fa);
534acc05 DH	69	void flex_array_free_parts(struct flex_array *fa);
b62e408c	70	int flex_array_put(struct flex_array fa, unsigned int element_nr, void src,
534acc05	71	gfp_t flags);
e6de3988	72	int flex_array_clear(struct flex_array *fa, unsigned int element_nr);
b62e408c	73	void flex_array_get(struct flex_array fa, unsigned int element_nr);
4af5a2f7	74	int flex_array_shrink(struct flex_array *fa);
534acc05	75
ea98eed9	76	#define flex_array_put_ptr(fa, nr, src, gfp) \
c41ab6a1	77	flex_array_put(fa, nr, (void *)&(src), gfp)
ea98eed9 EP	78
	79	void flex_array_get_ptr(struct flex_array fa, unsigned int element_nr);
	80
534acc05	81	#endif /* _FLEX_ARRAY_H */