/* 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){	unsigned int idx = iter->bi_idx; 	if (WARN_ONCE(bytes > iter->bi_size,		     "Attempted to advance past end of bvec iter\n")) {		iter->bi_size = 0;		return false;	} 	iter->bi_size -= bytes;	bytes += iter->bi_bvec_done; 	while (bytes && bytes >= bv[idx].bv_len) {		bytes -= bv[idx].bv_len;		idx++;	} 	iter->bi_idx = idx;	iter->bi_bvec_done = bytes;	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 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->bv_page + (bvec->bv_offset >> PAGE_SHIFT);		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;	}} #endif /* __LINUX_BVEC_ITER_H */