[linux-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>
#include <linux/errno.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 bool bvec_iter_advance(const struct bio_vec *bv,
		struct bvec_iter *iter, unsigned bytes)
{
	if (WARN_ONCE(bytes > iter->bi_size,
		     "Attempted to advance past end of bvec iter\n")) {
		iter->bi_size = 0;
		return false;
	}

	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++;
		}
	}
	return true;
}

static inline bool bvec_iter_rewind(const struct bio_vec *bv,
				     struct bvec_iter *iter,
				     unsigned int bytes)
{
	while (bytes) {
		unsigned len = min(bytes, iter->bi_bvec_done);

		if (iter->bi_bvec_done == 0) {
			if (WARN_ONCE(iter->bi_idx == 0,
				      "Attempted to rewind iter beyond "
				      "bvec's boundaries\n")) {
				return false;
			}
			iter->bi_idx--;
			iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len;
			continue;
		}
		bytes -= len;
		iter->bi_size += len;
		iter->bi_bvec_done -= len;
	}
	return true;
}

#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))

/* for iterating one bio from start to end */
#define BVEC_ITER_ALL_INIT (struct bvec_iter)				\
{									\
	.bi_sector	= 0,						\
	.bi_size	= UINT_MAX,					\
	.bi_idx		= 0,						\
	.bi_bvec_done	= 0,						\
}

#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>
0781e79e ML	24	#include <linux/bug.h>
b1fb2c52	25	#include <linux/errno.h>
0781e79e ML	26
	27	/*
	28	* was unsigned short, but we might as well be ready for > 64kB I/O pages
	29	*/
	30	struct bio_vec {
	31	struct page *bv_page;
	32	unsigned int bv_len;
	33	unsigned int bv_offset;
	34	};
	35
	36	struct bvec_iter {
	37	sector_t bi_sector; /* device address in 512 byte
	38	sectors */
	39	unsigned int bi_size; /* residual I/O count */
	40
	41	unsigned int bi_idx; /* current index into bvl_vec */
	42
	43	unsigned int bi_bvec_done; /* number of bytes completed in
	44	current bvec */
	45	};
8fc55455 ML	46
	47	/*
	48	* various member access, note that bio_data should of course not be used
	49	* on highmem page vectors
	50	*/
	51	#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
	52
	53	#define bvec_iter_page(bvec, iter) \
	54	(__bvec_iter_bvec((bvec), (iter))->bv_page)
	55
	56	#define bvec_iter_len(bvec, iter) \
	57	min((iter).bi_size, \
	58	__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
	59
	60	#define bvec_iter_offset(bvec, iter) \
	61	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
	62
	63	#define bvec_iter_bvec(bvec, iter) \
	64	((struct bio_vec) { \
	65	.bv_page = bvec_iter_page((bvec), (iter)), \
	66	.bv_len = bvec_iter_len((bvec), (iter)), \
	67	.bv_offset = bvec_iter_offset((bvec), (iter)), \
	68	})
	69
b1fb2c52 DM	70	static inline bool bvec_iter_advance(const struct bio_vec *bv,
b1fb2c52 DM	71	struct bvec_iter *iter, unsigned bytes)
8fc55455	72	{
b1fb2c52 DM	73	if (WARN_ONCE(bytes > iter->bi_size,
	74	"Attempted to advance past end of bvec iter\n")) {
	75	iter->bi_size = 0;
	76	return false;
	77	}
8fc55455 ML	78
8fc55455 ML	79	while (bytes) {
1ea049b2 JB	80	unsigned iter_len = bvec_iter_len(bv, *iter);
1ea049b2 JB	81	unsigned len = min(bytes, iter_len);
8fc55455 ML	82
	83	bytes -= len;
	84	iter->bi_size -= len;
	85	iter->bi_bvec_done += len;
	86
	87	if (iter->bi_bvec_done == __bvec_iter_bvec(bv, *iter)->bv_len) {
	88	iter->bi_bvec_done = 0;
	89	iter->bi_idx++;
	90	}
	91	}
b1fb2c52	92	return true;
8fc55455 ML	93	}
8fc55455 ML	94
f9df1cd9 DM	95	static inline bool bvec_iter_rewind(const struct bio_vec *bv,
	96	struct bvec_iter *iter,
	97	unsigned int bytes)
	98	{
	99	while (bytes) {
	100	unsigned len = min(bytes, iter->bi_bvec_done);
	101
	102	if (iter->bi_bvec_done == 0) {
	103	if (WARN_ONCE(iter->bi_idx == 0,
	104	"Attempted to rewind iter beyond "
	105	"bvec's boundaries\n")) {
	106	return false;
	107	}
	108	iter->bi_idx--;
	109	iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len;
	110	continue;
	111	}
	112	bytes -= len;
	113	iter->bi_size += len;
	114	iter->bi_bvec_done -= len;
	115	}
	116	return true;
	117	}
	118
8fc55455 ML	119	#define for_each_bvec(bvl, bio_vec, iter, start) \
	120	for (iter = (start); \
	121	(iter).bi_size && \
	122	((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
	123	bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
	124
3c892a09 ML	125	/* for iterating one bio from start to end */
	126	#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
	127	{ \
	128	.bi_sector = 0, \
	129	.bi_size = UINT_MAX, \
	130	.bi_idx = 0, \
	131	.bi_bvec_done = 0, \
	132	}
	133
8fc55455	134	#endif /* __LINUX_BVEC_ITER_H */