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Diffstat (limited to 'include/linux/bvec.h')
-rw-r--r-- | include/linux/bvec.h | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/include/linux/bvec.h b/include/linux/bvec.h new file mode 100644 index 000000000..9e3dac51e --- /dev/null +++ b/include/linux/bvec.h @@ -0,0 +1,259 @@ +/* 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/mm.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; +} + +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->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; +} + +/* + * A simpler version of bvec_iter_advance(), @bytes should not span + * across multiple bvec entries, i.e. bytes <= bv[i->bi_idx].bv_len + */ +static inline void bvec_iter_advance_single(const struct bio_vec *bv, + struct bvec_iter *iter, unsigned int bytes) +{ + unsigned int done = iter->bi_bvec_done + bytes; + + if (done == bv[iter->bi_idx].bv_len) { + done = 0; + iter->bi_idx++; + } + iter->bi_bvec_done = done; + iter->bi_size -= bytes; +} + +#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_single((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; + } +} + +/** + * bvec_kmap_local - map a bvec into the kernel virtual address space + * @bvec: bvec to map + * + * Must be called on single-page bvecs only. Call kunmap_local on the returned + * address to unmap. + */ +static inline void *bvec_kmap_local(struct bio_vec *bvec) +{ + return kmap_local_page(bvec->bv_page) + bvec->bv_offset; +} + +/** + * memcpy_from_bvec - copy data from a bvec + * @bvec: bvec to copy from + * + * Must be called on single-page bvecs only. + */ +static inline void memcpy_from_bvec(char *to, struct bio_vec *bvec) +{ + memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, bvec->bv_len); +} + +/** + * memcpy_to_bvec - copy data to a bvec + * @bvec: bvec to copy to + * + * Must be called on single-page bvecs only. + */ +static inline void memcpy_to_bvec(struct bio_vec *bvec, const char *from) +{ + memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, bvec->bv_len); +} + +/** + * memzero_bvec - zero all data in a bvec + * @bvec: bvec to zero + * + * Must be called on single-page bvecs only. + */ +static inline void memzero_bvec(struct bio_vec *bvec) +{ + memzero_page(bvec->bv_page, bvec->bv_offset, bvec->bv_len); +} + +/** + * bvec_virt - return the virtual address for a bvec + * @bvec: bvec to return the virtual address for + * + * Note: the caller must ensure that @bvec->bv_page is not a highmem page. + */ +static inline void *bvec_virt(struct bio_vec *bvec) +{ + WARN_ON_ONCE(PageHighMem(bvec->bv_page)); + return page_address(bvec->bv_page) + bvec->bv_offset; +} + +#endif /* __LINUX_BVEC_H */ |