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Diffstat (limited to '')
| -rw-r--r-- | include/linux/bvec.h | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/include/linux/bvec.h b/include/linux/bvec.h new file mode 100644 index 000000000..bc1f16e9f --- /dev/null +++ b/include/linux/bvec.h @@ -0,0 +1,144 @@ +/* + * 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; +} + +static inline void bvec_iter_skip_zero_bvec(struct bvec_iter *iter) +{ + iter->bi_bvec_done = 0; + iter->bi_idx++; +} + +#define for_each_bvec(bvl, bio_vec, iter, start) \ + for (iter = (start); \ + (iter).bi_size && \ + ((bvl = bvec_iter_bvec((bio_vec), (iter))), 1); \ + (bvl).bv_len ? (void)bvec_iter_advance((bio_vec), &(iter), \ + (bvl).bv_len) : bvec_iter_skip_zero_bvec(&(iter))) + +/* 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 */ |