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bio_map_user_iov(): switch to iov_iter_get_pages()/iov_iter_advance()

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... and to hell with iov_for_each() nonsense

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-09-23 16:08:57 -04:00
parent 1cfd0ddd82
commit 076098e51b
1 changed files with 23 additions and 32 deletions
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55
block/bio.c
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@ -1328,7 +1328,7 @@ struct bio *bio_map_user_iov(struct request_queue *q,
struct page **pages;
struct bio *bio;
int cur_page = 0;
int ret, offset;
int ret;
struct iov_iter i;
struct iovec iov;
struct bio_vec *bvec;
@ -1365,43 +1365,32 @@ struct bio *bio_map_user_iov(struct request_queue *q,
if (!pages)
goto out;
iov_for_each(iov, i, *iter) {
unsigned long uaddr = (unsigned long) iov.iov_base;
unsigned long len = iov.iov_len;
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
const int local_nr_pages = end - start;
const int page_limit = cur_page + local_nr_pages;
i = *iter;
while (iov_iter_count(&i)) {
ssize_t bytes;
size_t offs, added = 0;
int npages;
ret = get_user_pages_fast(uaddr, local_nr_pages,
(iter->type & WRITE) != WRITE,
&pages[cur_page]);
if (unlikely(ret < local_nr_pages)) {
for (j = cur_page; j < page_limit; j++) {
if (!pages[j])
break;
put_page(pages[j]);
}
ret = -EFAULT;
bytes = iov_iter_get_pages(&i, pages + cur_page, LONG_MAX,
nr_pages - cur_page, &offs);
if (unlikely(bytes <= 0)) {
ret = bytes ? bytes : -EFAULT;
goto out_unmap;
}
offset = offset_in_page(uaddr);
for (j = cur_page; j < page_limit; j++) {
unsigned int bytes = PAGE_SIZE - offset;
npages = DIV_ROUND_UP(offs + bytes, PAGE_SIZE);
for (j = cur_page; j < cur_page + npages; j++) {
unsigned int n = PAGE_SIZE - offs;
unsigned short prev_bi_vcnt = bio->bi_vcnt;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
if (n > bytes)
n = bytes;
/*
* sorry...
*/
if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
bytes)
if (bio_add_pc_page(q, bio, pages[j], n, offs) < n)
break;
/*
@ -1411,16 +1400,18 @@ struct bio *bio_map_user_iov(struct request_queue *q,
if (bio->bi_vcnt == prev_bi_vcnt)
put_page(pages[j]);
len -= bytes;
offset = 0;
added += n;
bytes -= n;
offs = 0;
}
iov_iter_advance(&i, added);
cur_page = j;
/*
* release the pages we didn't map into the bio, if any
*/
while (j < page_limit)
while (j < cur_page + npages)
put_page(pages[j++]);
cur_page = j;
}
kfree(pages);