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fix the copy vs. map logics in blk_rq_map_user_iov()

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-04-08 19:05:19 -04:00
parent 03cc0789a6
commit 357f435d8a
3 changed files with 28 additions and 39 deletions
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47
block/blk-map.c
View file

@ -9,24 +9,6 @@
#include "blk.h"
static bool iovec_gap_to_prv(struct request_queue *q,
struct iovec *prv, struct iovec *cur)
{
unsigned long prev_end;
if (!queue_virt_boundary(q))
return false;
if (prv->iov_base == NULL && prv->iov_len == 0)
/* prv is not set - don't check */
return false;
prev_end = (unsigned long)(prv->iov_base + prv->iov_len);
return (((unsigned long)cur->iov_base & queue_virt_boundary(q)) ||
prev_end & queue_virt_boundary(q));
}
int blk_rq_append_bio(struct request_queue *q, struct request *rq,
struct bio *bio)
{
@ -125,31 +107,18 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
struct rq_map_data *map_data,
const struct iov_iter *iter, gfp_t gfp_mask)
{
struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0};
bool copy = (q->dma_pad_mask & iter->count) || map_data;
bool copy = false;
unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
struct bio *bio = NULL;
struct iov_iter i;
int ret;
if (!iter || !iter->count)
return -EINVAL;
iov_for_each(iov, i, *iter) {
unsigned long uaddr = (unsigned long) iov.iov_base;
if (!iov.iov_len)
return -EINVAL;
/*
* Keep going so we check length of all segments
*/
if ((uaddr & queue_dma_alignment(q)) ||
iovec_gap_to_prv(q, &prv, &iov))
copy = true;
prv.iov_base = iov.iov_base;
prv.iov_len = iov.iov_len;
}
if (map_data)
copy = true;
else if (iov_iter_alignment(iter) & align)
copy = true;
else if (queue_virt_boundary(q))
copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
i = *iter;
do {

1
include/linux/uio.h
View file

@ -87,6 +87,7 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
size_t iov_iter_zero(size_t bytes, struct iov_iter *);
unsigned long iov_iter_alignment(const struct iov_iter *i);
unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
unsigned long nr_segs, size_t count);
void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,

19
lib/iov_iter.c
View file

@ -569,6 +569,25 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
}
EXPORT_SYMBOL(iov_iter_alignment);
unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
{
unsigned long res = 0;
size_t size = i->count;
if (!size)
return 0;
iterate_all_kinds(i, size, v,
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0), 0),
(res |= (!res ? 0 : (unsigned long)v.bv_offset) |
(size != v.bv_len ? size : 0)),
(res |= (!res ? 0 : (unsigned long)v.iov_base) |
(size != v.iov_len ? size : 0))
);
return res;
}
EXPORT_SYMBOL(iov_iter_gap_alignment);
ssize_t iov_iter_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)