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WSL2-Linux-Kernel
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iov_iter: first_{iovec,bvec}_segment() - simplify a bit 

We return length + offset in page via *size.  Don't bother - the caller
can do that arithmetics just as well; just report the length to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2022-06-21 15:55:19 -04:00
Родитель 599a0bdd72
Коммит dda8e5d17c
1 изменённых файлов: 16 добавлений и 16 удалений
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32
lib/iov_iter.c
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@ -1308,7 +1308,7 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
continue; continue;
if (len > maxsize) if (len > maxsize)
len = maxsize; len = maxsize;
len += (*start = addr % PAGE_SIZE); *start = addr % PAGE_SIZE;
*size = len; *size = len;
return addr & PAGE_MASK; return addr & PAGE_MASK;
} }
@ -1328,7 +1328,7 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
len = maxsize; len = maxsize;
skip += i->bvec->bv_offset; skip += i->bvec->bv_offset;
page = i->bvec->bv_page + skip / PAGE_SIZE; page = i->bvec->bv_page + skip / PAGE_SIZE;
len += (*start = skip % PAGE_SIZE); *start = skip % PAGE_SIZE;
*size = len; *size = len;
return page; return page;
} }
@ -1357,24 +1357,24 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
gup_flags |= FOLL_NOFAULT; gup_flags |= FOLL_NOFAULT;
addr = first_iovec_segment(i, &len, start, maxsize); addr = first_iovec_segment(i, &len, start, maxsize);
if (len > maxpages * PAGE_SIZE) n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
len = maxpages * PAGE_SIZE; if (n > maxpages)
n = DIV_ROUND_UP(len, PAGE_SIZE); n = maxpages;
res = get_user_pages_fast(addr, n, gup_flags, pages); res = get_user_pages_fast(addr, n, gup_flags, pages);
if (unlikely(res <= 0)) if (unlikely(res <= 0))
return res; return res;
return (res == n ? len : res * PAGE_SIZE) - *start; return min_t(size_t, len, res * PAGE_SIZE - *start);
} }
if (iov_iter_is_bvec(i)) { if (iov_iter_is_bvec(i)) {
struct page *page; struct page *page;
page = first_bvec_segment(i, &len, start, maxsize); page = first_bvec_segment(i, &len, start, maxsize);
if (len > maxpages * PAGE_SIZE) n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
len = maxpages * PAGE_SIZE; if (n > maxpages)
n = DIV_ROUND_UP(len, PAGE_SIZE); n = maxpages;
while (n--) for (int k = 0; k < n; k++)
get_page(*pages++ = page++); get_page(*pages++ = page++);
return len - *start; return min_t(size_t, len, n * PAGE_SIZE - *start);
} }
if (iov_iter_is_pipe(i)) if (iov_iter_is_pipe(i))
return pipe_get_pages(i, pages, maxsize, maxpages, start); return pipe_get_pages(i, pages, maxsize, maxpages, start);
@ -1489,7 +1489,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
gup_flags |= FOLL_NOFAULT; gup_flags |= FOLL_NOFAULT;
addr = first_iovec_segment(i, &len, start, maxsize); addr = first_iovec_segment(i, &len, start, maxsize);
n = DIV_ROUND_UP(len, PAGE_SIZE); n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
p = get_pages_array(n); p = get_pages_array(n);
if (!p) if (!p)
return -ENOMEM; return -ENOMEM;
@ -1500,19 +1500,19 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
return res; return res;
} }
*pages = p; *pages = p;
return (res == n ? len : res * PAGE_SIZE) - *start; return min_t(size_t, len, res * PAGE_SIZE - *start);
} }
if (iov_iter_is_bvec(i)) { if (iov_iter_is_bvec(i)) {
struct page *page; struct page *page;
page = first_bvec_segment(i, &len, start, maxsize); page = first_bvec_segment(i, &len, start, maxsize);
n = DIV_ROUND_UP(len, PAGE_SIZE); n = DIV_ROUND_UP(len + *start, PAGE_SIZE);
*pages = p = get_pages_array(n); *pages = p = get_pages_array(n);
if (!p) if (!p)
return -ENOMEM; return -ENOMEM;
while (n--) for (int k = 0; k < n; k++)
get_page(*p++ = page++); get_page(*p++ = page++);
return len - *start; return min_t(size_t, len, n * PAGE_SIZE - *start);
} }
if (iov_iter_is_pipe(i)) if (iov_iter_is_pipe(i))
return pipe_get_pages_alloc(i, pages, maxsize, start); return pipe_get_pages_alloc(i, pages, maxsize, start);