[mirror_ubuntu-hirsute-kernel.git] / include / linux / bvec.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * bvec iterator
 *
 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
 */
#ifndef __LINUX_BVEC_ITER_H
#define __LINUX_BVEC_ITER_H

#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/mm.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 */
};

struct bvec_iter_all {
	struct bio_vec	bv;
	int		idx;
	unsigned	done;
};

/*
 * 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])

/* multi-page (mp_bvec) helpers */
#define mp_bvec_iter_page(bvec, iter)				\
	(__bvec_iter_bvec((bvec), (iter))->bv_page)

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

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

#define mp_bvec_iter_page_idx(bvec, iter)			\
	(mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)

#define mp_bvec_iter_bvec(bvec, iter)				\
((struct bio_vec) {						\
	.bv_page	= mp_bvec_iter_page((bvec), (iter)),	\
	.bv_len		= mp_bvec_iter_len((bvec), (iter)),	\
	.bv_offset	= mp_bvec_iter_offset((bvec), (iter)),	\
})

/* For building single-page bvec in flight */
 #define bvec_iter_offset(bvec, iter)				\
	(mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)

#define bvec_iter_len(bvec, iter)				\
	min_t(unsigned, mp_bvec_iter_len((bvec), (iter)),		\
	      PAGE_SIZE - bvec_iter_offset((bvec), (iter)))

#define bvec_iter_page(bvec, iter)				\
	(mp_bvec_iter_page((bvec), (iter)) +			\
	 mp_bvec_iter_page_idx((bvec), (iter)))

#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) {
		const struct bio_vec *cur = bv + iter->bi_idx;
		unsigned len = min3(bytes, iter->bi_size,
				    cur->bv_len - iter->bi_bvec_done);

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

		if (iter->bi_bvec_done == cur->bv_len) {
			iter->bi_bvec_done = 0;
			iter->bi_idx++;
		}
	}
	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,						\
}

static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
{
	iter_all->done = 0;
	iter_all->idx = 0;

	return &iter_all->bv;
}

static inline struct page *bvec_nth_page(struct page *page, int idx)
{
	return idx == 0 ? page : nth_page(page, idx);
}

static inline void bvec_advance(const struct bio_vec *bvec,
				struct bvec_iter_all *iter_all)
{
	struct bio_vec *bv = &iter_all->bv;

	if (iter_all->done) {
		bv->bv_page++;
		bv->bv_offset = 0;
	} else {
		bv->bv_page = bvec_nth_page(bvec->bv_page, bvec->bv_offset /
					    PAGE_SIZE);
		bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
	}
	bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
			   bvec->bv_len - iter_all->done);
	iter_all->done += bv->bv_len;

	if (iter_all->done == bvec->bv_len) {
		iter_all->idx++;
		iter_all->done = 0;
	}
}

/*
 * Get the last single-page segment from the multi-page bvec and store it
 * in @seg
 */
static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
					struct bio_vec *seg)
{
	unsigned total = bvec->bv_offset + bvec->bv_len;
	unsigned last_page = (total - 1) / PAGE_SIZE;

	seg->bv_page = bvec->bv_page + last_page;

	/* the whole segment is inside the last page */
	if (bvec->bv_offset >= last_page * PAGE_SIZE) {
		seg->bv_offset = bvec->bv_offset % PAGE_SIZE;
		seg->bv_len = bvec->bv_len;
	} else {
		seg->bv_offset = 0;
		seg->bv_len = total - last_page * PAGE_SIZE;
	}
}

#endif /* __LINUX_BVEC_ITER_H */
Commit	Line	Data
8c16567d	1	/* SPDX-License-Identifier: GPL-2.0 */
8fc55455 ML	2	/*
	3	* bvec iterator
	4	*
	5	* Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
8fc55455 ML	6	*/
	7	#ifndef __LINUX_BVEC_ITER_H
	8	#define __LINUX_BVEC_ITER_H
	9
0781e79e ML	10	#include <linux/kernel.h>
0781e79e ML	11	#include <linux/bug.h>
b1fb2c52	12	#include <linux/errno.h>
3d75ca0a	13	#include <linux/mm.h>
0781e79e ML	14
	15	/*
	16	* was unsigned short, but we might as well be ready for > 64kB I/O pages
	17	*/
	18	struct bio_vec {
	19	struct page *bv_page;
	20	unsigned int bv_len;
	21	unsigned int bv_offset;
	22	};
	23
	24	struct bvec_iter {
	25	sector_t bi_sector; /* device address in 512 byte
	26	sectors */
	27	unsigned int bi_size; /* residual I/O count */
	28
	29	unsigned int bi_idx; /* current index into bvl_vec */
	30
	31	unsigned int bi_bvec_done; /* number of bytes completed in
	32	current bvec */
	33	};
8fc55455	34
6dc4f100 ML	35	struct bvec_iter_all {
	36	struct bio_vec bv;
	37	int idx;
	38	unsigned done;
	39	};
	40
8fc55455 ML	41	/*
	42	* various member access, note that bio_data should of course not be used
	43	* on highmem page vectors
	44	*/
	45	#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
	46
3d75ca0a ML	47	/* multi-page (mp_bvec) helpers */
3d75ca0a ML	48	#define mp_bvec_iter_page(bvec, iter) \
8fc55455 ML	49	(__bvec_iter_bvec((bvec), (iter))->bv_page)
8fc55455 ML	50
3d75ca0a	51	#define mp_bvec_iter_len(bvec, iter) \
8fc55455 ML	52	min((iter).bi_size, \
	53	__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
	54
3d75ca0a	55	#define mp_bvec_iter_offset(bvec, iter) \
8fc55455 ML	56	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
8fc55455 ML	57
3d75ca0a ML	58	#define mp_bvec_iter_page_idx(bvec, iter) \
	59	(mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
	60
	61	#define mp_bvec_iter_bvec(bvec, iter) \
	62	((struct bio_vec) { \
	63	.bv_page = mp_bvec_iter_page((bvec), (iter)), \
	64	.bv_len = mp_bvec_iter_len((bvec), (iter)), \
	65	.bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
	66	})
	67
	68	/* For building single-page bvec in flight */
	69	#define bvec_iter_offset(bvec, iter) \
	70	(mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
	71
	72	#define bvec_iter_len(bvec, iter) \
	73	min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \
	74	PAGE_SIZE - bvec_iter_offset((bvec), (iter)))
	75
	76	#define bvec_iter_page(bvec, iter) \
52d52d1c CH	77	(mp_bvec_iter_page((bvec), (iter)) + \
52d52d1c CH	78	mp_bvec_iter_page_idx((bvec), (iter)))
3d75ca0a	79
8fc55455 ML	80	#define bvec_iter_bvec(bvec, iter) \
	81	((struct bio_vec) { \
	82	.bv_page = bvec_iter_page((bvec), (iter)), \
	83	.bv_len = bvec_iter_len((bvec), (iter)), \
	84	.bv_offset = bvec_iter_offset((bvec), (iter)), \
	85	})
	86
b1fb2c52 DM	87	static inline bool bvec_iter_advance(const struct bio_vec *bv,
b1fb2c52 DM	88	struct bvec_iter *iter, unsigned bytes)
8fc55455	89	{
b1fb2c52 DM	90	if (WARN_ONCE(bytes > iter->bi_size,
	91	"Attempted to advance past end of bvec iter\n")) {
	92	iter->bi_size = 0;
	93	return false;
	94	}
8fc55455 ML	95
8fc55455 ML	96	while (bytes) {
5b88a17c CH	97	const struct bio_vec *cur = bv + iter->bi_idx;
	98	unsigned len = min3(bytes, iter->bi_size,
	99	cur->bv_len - iter->bi_bvec_done);
8fc55455 ML	100
	101	bytes -= len;
	102	iter->bi_size -= len;
	103	iter->bi_bvec_done += len;
	104
5b88a17c	105	if (iter->bi_bvec_done == cur->bv_len) {
8fc55455 ML	106	iter->bi_bvec_done = 0;
	107	iter->bi_idx++;
	108	}
	109	}
b1fb2c52	110	return true;
8fc55455 ML	111	}
	112
	113	#define for_each_bvec(bvl, bio_vec, iter, start) \
	114	for (iter = (start); \
	115	(iter).bi_size && \
	116	((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \
	117	bvec_iter_advance((bio_vec), &(iter), (bvl).bv_len))
	118
3c892a09 ML	119	/* for iterating one bio from start to end */
	120	#define BVEC_ITER_ALL_INIT (struct bvec_iter) \
	121	{ \
	122	.bi_sector = 0, \
	123	.bi_size = UINT_MAX, \
	124	.bi_idx = 0, \
	125	.bi_bvec_done = 0, \
	126	}
	127
6dc4f100 ML	128	static inline struct bio_vec bvec_init_iter_all(struct bvec_iter_all iter_all)
6dc4f100 ML	129	{
6dc4f100	130	iter_all->done = 0;
1200e07f	131	iter_all->idx = 0;
6dc4f100 ML	132
	133	return &iter_all->bv;
	134	}
	135
5c61ee2c JA	136	static inline struct page bvec_nth_page(struct page page, int idx)
	137	{
	138	return idx == 0 ? page : nth_page(page, idx);
	139	}
	140
1200e07f ML	141	static inline void bvec_advance(const struct bio_vec *bvec,
1200e07f ML	142	struct bvec_iter_all *iter_all)
6dc4f100 ML	143	{
	144	struct bio_vec *bv = &iter_all->bv;
	145
1200e07f	146	if (iter_all->done) {
52d52d1c	147	bv->bv_page++;
6dc4f100 ML	148	bv->bv_offset = 0;
6dc4f100 ML	149	} else {
6bedf00e ML	150	bv->bv_page = bvec_nth_page(bvec->bv_page, bvec->bv_offset /
	151	PAGE_SIZE);
	152	bv->bv_offset = bvec->bv_offset & ~PAGE_MASK;
6dc4f100 ML	153	}
	154	bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
	155	bvec->bv_len - iter_all->done);
1200e07f ML	156	iter_all->done += bv->bv_len;
	157
	158	if (iter_all->done == bvec->bv_len) {
	159	iter_all->idx++;
	160	iter_all->done = 0;
	161	}
6dc4f100 ML	162	}
6dc4f100 ML	163
45a3fb95 ML	164	/*
	165	* Get the last single-page segment from the multi-page bvec and store it
	166	* in @seg
	167	*/
	168	static inline void mp_bvec_last_segment(const struct bio_vec *bvec,
	169	struct bio_vec *seg)
	170	{
	171	unsigned total = bvec->bv_offset + bvec->bv_len;
	172	unsigned last_page = (total - 1) / PAGE_SIZE;
	173
52d52d1c	174	seg->bv_page = bvec->bv_page + last_page;
45a3fb95 ML	175
	176	/* the whole segment is inside the last page */
	177	if (bvec->bv_offset >= last_page * PAGE_SIZE) {
	178	seg->bv_offset = bvec->bv_offset % PAGE_SIZE;
	179	seg->bv_len = bvec->bv_len;
	180	} else {
	181	seg->bv_offset = 0;
	182	seg->bv_len = total - last_page * PAGE_SIZE;
	183	}
	184	}
	185
8fc55455	186	#endif /* __LINUX_BVEC_ITER_H */