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     O€РСѓuР?ПБУ     O/* SPDX-License-Identifier: GPL-2.0 */
/*
 * bvec iterator
 *
 * Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
 */
#ifndef __LINUX_BVEC_H
#define __LINUX_BVEC_H

#include <linux/highmem.h>
#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/limits.h>
#include <linux/minmax.h>
#include <linux/types.h>

struct page;

/**
 * struct bio_vec - a contiguous range of physical memory addresses
 * @bv_page:   First page associated with the address range.
 * @bv_len:    Number of bytes in the address range.
 * @bv_offset: Start of the address range relative to the start of @bv_page.
 *
 * The following holds for a bvec if n * PAGE_SIZE < bv_offset + bv_len:
 *
 *   nth_page(@bv_page, n) == @bv_page + n
 *
 * This holds because page_is_mergeable() checks the above property.
 */
struct bio_vec {
	struct page	*bv_page;
	unsigned int	bv_len;
	unsigned int	bv_offset;
};

/**
 * bvec_set_page - initialize a bvec based off a struct page
 * @bv:		bvec to initialize
 * @page:	page the bvec should point to
 * @len:	length of the bvec
 * @offset:	offset into the page
 */
static inline void bvec_set_page(struct bio_vec *bv, struct page *page,
		unsigned int len, unsigned int offset)
{
	bv->bv_page = page;
	bv->bv_len = len;
	bv->bv_offset = offset;
}

/**
 * bvec_set_folio - initialize a bvec based off a struct folio
 * @bv:		bvec to initialize
 * @folio:	folio the bvec should point to
 * @len:	length of the bvec
 * @offset:	offset into the folio
 */
static inline void bvec_set_folio(struct bio_vec *bv, struct folio *folio,
		size_t len, size_t offset)
{
	unsigned long nr = offset / PAGE_SIZE;

	WARN_ON_ONCE(len > UINT_MAX);
	bvec_set_page(bv, folio_page(folio, nr), len, offset % PAGE_SIZE);
}

/**
 * bvec_set_virt - initialize a bvec based on a virtual address
 * @bv:		bvec to initialize
 * @vaddr:	virtual address to set the bvec to
 * @len:	length of the bvec
 */
static inline void bvec_set_virt(struct bio_vec *bv, void *vaddr,
		unsigned int len)
{
	bvec_set_page(bv, virt_to_page(vaddr), len, offset_in_page(vaddr));
}

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 */
} __packed;

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-