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

/*
 * bvec iterator
 *
 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 */
#ifndef __LINUX_BVEC_ITER_H
#define __LINUX_BVEC_ITER_H

#include <linux/kernel.h>
#include <linux/bug.h>

/*
 * was unsigned short, but we might as well be ready for > 64kB I/O pages
 */
struct bio_vec {
	struct page	*bv_page;
	unsigned int	bv_len;
	unsigned int	bv_offset;
};

struct bvec_iter {
	sector_t		bi_sector;	/* device address in 512 byte
						   sectors */
	unsigned int		bi_size;	/* residual I/O count */

	unsigned int		bi_idx;		/* current index into bvl_vec */

	unsigned int            bi_bvec_done;	/* number of bytes completed in
						   current bvec */
};

/*
 * various member access, note that bio_data should of course not be used
 * on highmem page vectors
 */
#define __bvec_iter_bvec(bvec, iter)	(&(bvec)[(iter).bi_idx])

#define bvec_iter_page(bvec, iter)				\
	(__bvec_iter_bvec((bvec), (iter))->bv_page)

#define bvec_iter_len(bvec, iter)				\
	min((iter).bi_size,					\
	    __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)

#define bvec_iter_offset(bvec, iter)				\
	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)

#define bvec_iter_bvec(bvec, iter)				\
((struct bio_vec) {						\
	.bv_page	= bvec_iter_page((bvec), (iter)),	\
	.bv_len		= bvec_iter_len((bvec), (iter)),	\
	.bv_offset	= bvec_iter_offset((bvec), (iter)),	\
})

static inline void bvec_iter_advance(const struct bio_vec *bv,
				     struct bvec_iter *iter,
				     unsigned bytes)
{
	WARN_ONCE(bytes > iter->bi_size,
		  "Attempted to advance past end of bvec iter\n");

	while (bytes) {
		unsigned iter_len = bvec_iter_len(bv, *iter);
		unsigned len = min(bytes, iter_len);

		bytes -= len;
		iter->bi_size -= len;
		iter->bi_bvec_done += len;

		if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
			iter->bi_bvec_done = 0;
			iter->bi_idx++;
		}
	}
}

#define for_each_bvec(bvl, bio_vec, iter, start)			\
	for (iter = (start);						\
	     (iter).bi_size &&						\
		((bvl = bvec_iter_bvec((bio_vec), (iter))), 1);	\
	     bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))

#endif /* __LINUX_BVEC_ITER_H */
Commit	Line	Data
8fc55455 ML	1	/*
	2	* bvec iterator
	3	*
	4	* Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	*
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public Licens
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
	19	*/
	20	#ifndef __LINUX_BVEC_ITER_H
	21	#define __LINUX_BVEC_ITER_H
	22
0781e79e ML	23	#include <linux/kernel.h>
	24	#include <linux/bug.h>
	25
	26	/*
	27	* was unsigned short, but we might as well be ready for > 64kB I/O pages
	28	*/
	29	struct bio_vec {
	30	struct page *bv_page;
	31	unsigned int bv_len;
	32	unsigned int bv_offset;
	33	};
	34
	35	struct bvec_iter {
	36	sector_t bi_sector; /* device address in 512 byte
	37	sectors */
	38	unsigned int bi_size; /* residual I/O count */
	39
	40	unsigned int bi_idx; /* current index into bvl_vec */
	41
	42	unsigned int bi_bvec_done; /* number of bytes completed in
	43	current bvec */
	44	};
8fc55455 ML	45
	46	/*
	47	* various member access, note that bio_data should of course not be used
	48	* on highmem page vectors
	49	*/
	50	#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
	51
	52	#define bvec_iter_page(bvec, iter) \
	53	(__bvec_iter_bvec((bvec), (iter))->bv_page)
	54
	55	#define bvec_iter_len(bvec, iter) \
	56	min((iter).bi_size, \
	57	__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
	58
	59	#define bvec_iter_offset(bvec, iter) \
	60	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
	61
	62	#define bvec_iter_bvec(bvec, iter) \
	63	((struct bio_vec) { \
	64	.bv_page = bvec_iter_page((bvec), (iter)), \
	65	.bv_len = bvec_iter_len((bvec), (iter)), \
	66	.bv_offset = bvec_iter_offset((bvec), (iter)), \
	67	})
	68
80f162ff ML	69	static inline void bvec_iter_advance(const struct bio_vec *bv,
80f162ff ML	70	struct bvec_iter *iter,
8fc55455 ML	71	unsigned bytes)
	72	{
	73	WARN_ONCE(bytes > iter->bi_size,
	74	"Attempted to advance past end of bvec iter\n");
	75
	76	while (bytes) {
1ea049b2 JB	77	unsigned iter_len = bvec_iter_len(bv, *iter);
1ea049b2 JB	78	unsigned len = min(bytes, iter_len);
8fc55455 ML	79
	80	bytes -= len;
	81	iter->bi_size -= len;
	82	iter->bi_bvec_done += len;
	83
	84	if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
	85	iter->bi_bvec_done = 0;
	86	iter->bi_idx++;
	87	}
	88	}
	89	}
	90
	91	#define for_each_bvec(bvl, bio_vec, iter, start) \
	92	for (iter = (start); \
	93	(iter).bi_size && \
	94	((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
	95	bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
	96
	97	#endif /* __LINUX_BVEC_ITER_H */