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244 lines
6.2 KiB
244 lines
6.2 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* bvec iterator |
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* |
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* Copyright (C) 2001 Ming Lei <[email protected]> |
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*/ |
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#ifndef __LINUX_BVEC_H |
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#define __LINUX_BVEC_H |
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#include <linux/highmem.h> |
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#include <linux/bug.h> |
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#include <linux/errno.h> |
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#include <linux/limits.h> |
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#include <linux/minmax.h> |
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#include <linux/mm.h> |
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#include <linux/types.h> |
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struct page; |
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/** |
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* struct bio_vec - a contiguous range of physical memory addresses |
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* @bv_page: First page associated with the address range. |
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* @bv_len: Number of bytes in the address range. |
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* @bv_offset: Start of the address range relative to the start of @bv_page. |
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* |
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* The following holds for a bvec if n * PAGE_SIZE < bv_offset + bv_len: |
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* |
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* nth_page(@bv_page, n) == @bv_page + n |
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* |
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* This holds because page_is_mergeable() checks the above property. |
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*/ |
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struct bio_vec { |
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struct page *bv_page; |
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unsigned int bv_len; |
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unsigned int bv_offset; |
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}; |
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struct bvec_iter { |
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sector_t bi_sector; /* device address in 512 byte |
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sectors */ |
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unsigned int bi_size; /* residual I/O count */ |
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unsigned int bi_idx; /* current index into bvl_vec */ |
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unsigned int bi_bvec_done; /* number of bytes completed in |
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current bvec */ |
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} __packed; |
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struct bvec_iter_all { |
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struct bio_vec bv; |
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int idx; |
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unsigned done; |
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}; |
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/* |
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* various member access, note that bio_data should of course not be used |
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* on highmem page vectors |
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*/ |
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#define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) |
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/* multi-page (mp_bvec) helpers */ |
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#define mp_bvec_iter_page(bvec, iter) \ |
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(__bvec_iter_bvec((bvec), (iter))->bv_page) |
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#define mp_bvec_iter_len(bvec, iter) \ |
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min((iter).bi_size, \ |
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__bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done) |
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#define mp_bvec_iter_offset(bvec, iter) \ |
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(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done) |
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#define mp_bvec_iter_page_idx(bvec, iter) \ |
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(mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE) |
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#define mp_bvec_iter_bvec(bvec, iter) \ |
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((struct bio_vec) { \ |
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.bv_page = mp_bvec_iter_page((bvec), (iter)), \ |
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.bv_len = mp_bvec_iter_len((bvec), (iter)), \ |
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.bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ |
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}) |
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/* For building single-page bvec in flight */ |
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#define bvec_iter_offset(bvec, iter) \ |
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(mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) |
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#define bvec_iter_len(bvec, iter) \ |
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min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ |
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PAGE_SIZE - bvec_iter_offset((bvec), (iter))) |
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#define bvec_iter_page(bvec, iter) \ |
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(mp_bvec_iter_page((bvec), (iter)) + \ |
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mp_bvec_iter_page_idx((bvec), (iter))) |
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#define bvec_iter_bvec(bvec, iter) \ |
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((struct bio_vec) { \ |
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.bv_page = bvec_iter_page((bvec), (iter)), \ |
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.bv_len = bvec_iter_len((bvec), (iter)), \ |
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.bv_offset = bvec_iter_offset((bvec), (iter)), \ |
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}) |
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static inline bool bvec_iter_advance(const struct bio_vec *bv, |
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struct bvec_iter *iter, unsigned bytes) |
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{ |
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unsigned int idx = iter->bi_idx; |
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if (WARN_ONCE(bytes > iter->bi_size, |
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"Attempted to advance past end of bvec iter\n")) { |
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iter->bi_size = 0; |
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return false; |
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} |
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iter->bi_size -= bytes; |
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bytes += iter->bi_bvec_done; |
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while (bytes && bytes >= bv[idx].bv_len) { |
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bytes -= bv[idx].bv_len; |
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idx++; |
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} |
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iter->bi_idx = idx; |
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iter->bi_bvec_done = bytes; |
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return true; |
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} |
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/* |
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* A simpler version of bvec_iter_advance(), @bytes should not span |
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* across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len |
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*/ |
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static inline void bvec_iter_advance_single(const struct bio_vec *bv, |
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struct bvec_iter *iter, unsigned int bytes) |
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{ |
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unsigned int done = iter->bi_bvec_done + bytes; |
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if (done == bv[iter->bi_idx].bv_len) { |
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done = 0; |
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iter->bi_idx++; |
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} |
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iter->bi_bvec_done = done; |
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iter->bi_size -= bytes; |
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} |
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#define for_each_bvec(bvl, bio_vec, iter, start) \ |
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for (iter = (start); \ |
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(iter).bi_size && \ |
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((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ |
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bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len)) |
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/* for iterating one bio from start to end */ |
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#define BVEC_ITER_ALL_INIT (struct bvec_iter) \ |
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{ \ |
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.bi_sector = 0, \ |
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.bi_size = UINT_MAX, \ |
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.bi_idx = 0, \ |
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.bi_bvec_done = 0, \ |
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} |
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static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all) |
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{ |
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iter_all->done = 0; |
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iter_all->idx = 0; |
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return &iter_all->bv; |
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} |
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static inline void bvec_advance(const struct bio_vec *bvec, |
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struct bvec_iter_all *iter_all) |
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{ |
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struct bio_vec *bv = &iter_all->bv; |
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if (iter_all->done) { |
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bv->bv_page++; |
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bv->bv_offset = 0; |
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} else { |
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bv->bv_page = bvec->bv_page + (bvec->bv_offset >> PAGE_SHIFT); |
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bv->bv_offset = bvec->bv_offset & ~PAGE_MASK; |
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} |
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bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset, |
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bvec->bv_len - iter_all->done); |
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iter_all->done += bv->bv_len; |
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if (iter_all->done == bvec->bv_len) { |
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iter_all->idx++; |
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iter_all->done = 0; |
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} |
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} |
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/** |
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* bvec_kmap_local - map a bvec into the kernel virtual address space |
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* @bvec: bvec to map |
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* |
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* Must be called on single-page bvecs only. Call kunmap_local on the returned |
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* address to unmap. |
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*/ |
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static inline void *bvec_kmap_local(struct bio_vec *bvec) |
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{ |
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return kmap_local_page(bvec->bv_page) + bvec->bv_offset; |
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} |
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/** |
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* memcpy_from_bvec - copy data from a bvec |
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* @bvec: bvec to copy from |
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* |
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* Must be called on single-page bvecs only. |
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*/ |
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static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec) |
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{ |
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memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len); |
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} |
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/** |
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* memcpy_to_bvec - copy data to a bvec |
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* @bvec: bvec to copy to |
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* |
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* Must be called on single-page bvecs only. |
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*/ |
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static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from) |
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{ |
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memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len); |
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} |
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/** |
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* memzero_bvec - zero all data in a bvec |
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* @bvec: bvec to zero |
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* |
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* Must be called on single-page bvecs only. |
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*/ |
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static inline void memzero_bvec(struct bio_vec *bvec) |
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{ |
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memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len); |
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} |
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/** |
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* bvec_virt - return the virtual address for a bvec |
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* @bvec: bvec to return the virtual address for |
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* |
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* Note: the caller must ensure that @bvec->bv_page is not a highmem page. |
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*/ |
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static inline void *bvec_virt(struct bio_vec *bvec) |
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{ |
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WARN_ON_ONCE(PageHighMem(bvec->bv_page)); |
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return page_address(bvec->bv_page) + bvec->bv_offset; |
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} |
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#endif /* __LINUX_BVEC_H */
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