mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-11-01 17:08:10 +00:00
3c892a098b
Firstly this patch introduces BVEC_ITER_ALL_INIT for iterating one bio from start to end. As we need to support multipage bvecs, don't access bio->bi_io_vec in copy_to_high_bio_irq(), and just use the standard iterator for that. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
137 lines
3.6 KiB
C
137 lines
3.6 KiB
C
/*
|
|
* 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;
|
|
}
|
|
|
|
#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((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, \
|
|
}
|
|
|
|
#endif /* __LINUX_BVEC_ITER_H */
|