911a8ce8d4
There is no need to only iterate in chunks of PAGE_SIZE or less in bvec_iter_advance, given that the callers pass in the chunk length that they are operating on - either that already is less than PAGE_SIZE because they do classic page-based iteration, or it is larger because the caller operates on multi-page bvecs. This should help shaving off a few cycles of the I/O hot path. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: UtsavisGreat <utsavbalar1231@gmail.com>
139 lines
3.6 KiB
C
139 lines
3.6 KiB
C
/*
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* bvec iterator
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*
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* Copyright (C) 2001 Ming Lei <ming.lei@canonical.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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*
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public Licens
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
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*/
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#ifndef __LINUX_BVEC_ITER_H
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#define __LINUX_BVEC_ITER_H
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#include <linux/kernel.h>
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#include <linux/bug.h>
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#include <linux/errno.h>
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/*
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* was unsigned short, but we might as well be ready for > 64kB I/O pages
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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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#ifdef CONFIG_PFK
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u64 bi_dun; /* DUN setting for bio */
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#endif
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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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#define bvec_iter_page(bvec, iter) \
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(__bvec_iter_bvec((bvec), (iter))->bv_page)
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#define 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 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 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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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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while (bytes) {
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const struct bio_vec *cur = bv + iter->bi_idx;
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unsigned len = min3(bytes, iter->bi_size,
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cur->bv_len - iter->bi_bvec_done);
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bytes -= len;
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iter->bi_size -= len;
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iter->bi_bvec_done += len;
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if (iter->bi_bvec_done == cur->bv_len) {
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iter->bi_bvec_done = 0;
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iter->bi_idx++;
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}
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}
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return true;
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}
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static inline bool bvec_iter_rewind(const struct bio_vec *bv,
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struct bvec_iter *iter,
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unsigned int bytes)
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{
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while (bytes) {
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unsigned len = min(bytes, iter->bi_bvec_done);
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if (iter->bi_bvec_done == 0) {
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if (WARN_ONCE(iter->bi_idx == 0,
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"Attempted to rewind iter beyond "
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"bvec's boundaries\n")) {
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return false;
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}
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iter->bi_idx--;
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iter->bi_bvec_done = __bvec_iter_bvec(bv, *iter)->bv_len;
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continue;
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}
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bytes -= len;
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iter->bi_size += len;
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iter->bi_bvec_done -= len;
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}
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return true;
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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((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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#endif /* __LINUX_BVEC_ITER_H */
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