[with braino fixed]
>From 3893e9565ad55a8514f5f819545bf9df5a339c76 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Fri, 10 Jun 2022 22:19:25 -0400
Subject: [PATCH 19/31] iov_iter: massage calling conventions for
first_{iovec,bvec}_segment()
Pass maxsize by reference, return length via the same. And do not
add offset to returned length. Callers adjusted...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
lib/iov_iter.c | 50 +++++++++++++++++++++-----------------------------
1 file changed, 21 insertions(+), 29 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 8f1d63295f37..b789728678d2 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1307,25 +1307,22 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
}
static unsigned long found_ubuf_segment(unsigned long addr,
- size_t len,
- size_t *size, size_t *start)
+ size_t *start)
{
- len += (*start = addr % PAGE_SIZE);
- *size = len;
+ *start = addr % PAGE_SIZE;
return addr & PAGE_MASK;
}
/* must be done on non-empty ITER_UBUF or ITER_IOVEC one */
static unsigned long first_iovec_segment(const struct iov_iter *i,
- size_t *size, size_t *start,
- size_t maxsize)
+ size_t *size, size_t *start)
{
size_t skip;
long k;
if (iter_is_ubuf(i)) {
unsigned long addr = (unsigned long)i->ubuf + i->iov_offset;
- return found_ubuf_segment(addr, maxsize, size, start);
+ return found_ubuf_segment(addr, start);
}
for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
@@ -1334,28 +1331,26 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
if (unlikely(!len))
continue;
- if (len > maxsize)
- len = maxsize;
- return found_ubuf_segment(addr, len, size, start);
+ if (*size > len)
+ *size = len;
+ return found_ubuf_segment(addr, start);
}
BUG(); // if it had been empty, we wouldn't get called
}
/* must be done on non-empty ITER_BVEC one */
static struct page *first_bvec_segment(const struct iov_iter *i,
- size_t *size, size_t *start,
- size_t maxsize)
+ size_t *size, size_t *start)
{
struct page *page;
size_t skip = i->iov_offset, len;
len = i->bvec->bv_len - skip;
- if (len > maxsize)
- len = maxsize;
+ if (*size > len)
+ *size = len;
skip += i->bvec->bv_offset;
page = i->bvec->bv_page + skip / PAGE_SIZE;
- len += (*start = skip % PAGE_SIZE);
- *size = len;
+ *start = skip % PAGE_SIZE;
return page;
}
@@ -1363,7 +1358,6 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
unsigned int maxpages, size_t *start)
{
- size_t len;
int n, res;
if (maxsize > i->count)
@@ -1382,10 +1376,10 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
if (i->nofault)
gup_flags |= FOLL_NOFAULT;
- addr = first_iovec_segment(i, &len, start, maxsize);
- if (len > maxpages * PAGE_SIZE)
- len = maxpages * PAGE_SIZE;
- n = DIV_ROUND_UP(len, PAGE_SIZE);
+ addr = first_iovec_segment(i, &maxsize, start);
+ n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
+ if (n > maxpages)
+ n = maxpages;
if (*pages) {
*pages = get_pages_array(n);
if (!*pages)
@@ -1394,18 +1388,16 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
res = get_user_pages_fast(addr, n, gup_flags, *pages);
if (unlikely(res <= 0))
return res;
- if (res < n)
- len = res * PAGE_SIZE;
- return len - *start;
+ return min_t(size_t, maxsize, res * PAGE_SIZE - *start);
}
if (iov_iter_is_bvec(i)) {
struct page **p;
struct page *page;
- page = first_bvec_segment(i, &len, start, maxsize);
- if (len > maxpages * PAGE_SIZE)
- len = maxpages * PAGE_SIZE;
- n = DIV_ROUND_UP(len, PAGE_SIZE);
+ page = first_bvec_segment(i, &maxsize, start);
+ n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
+ if (n > maxpages)
+ n = maxpages;
p = *pages;
if (!p) {
*pages = p = get_pages_array(n);
@@ -1414,7 +1406,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
}
for (int k = 0; k < n; k++)
get_page(*p++ = page++);
- return len - *start;
+ return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
}
if (iov_iter_is_pipe(i))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
--
2.30.2
