/* * 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_done;	/* number of bytes completed */ 	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;		iter->bi_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 */