[braino fix]
>From e64d637d648390e4ac0643747ae174c3be15f243 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Date: Fri, 17 Jun 2022 14:45:41 -0400
Subject: [PATCH 22/31] iov_iter: saner helper for page array allocation
All call sites of get_pages_array() are essenitally identical now.
Replace with common helper...
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
lib/iov_iter.c | 64 +++++++++++++++++++-------------------------------
1 file changed, 24 insertions(+), 40 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index a65c766936cc..2ce062f1817d 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1187,9 +1187,19 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
}
EXPORT_SYMBOL(iov_iter_gap_alignment);
-static struct page **get_pages_array(size_t n)
+static int want_pages_array(struct page ***res, size_t size,
+ size_t start, unsigned int maxpages)
{
- return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL);
+ unsigned count = DIV_ROUND_UP(size + start, PAGE_SIZE);
+
+ if (count > maxpages)
+ count = maxpages;
+ if (!*res) {
+ *res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
+ if (!*res)
+ return -ENOMEM;
+ }
+ return count;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
@@ -1206,18 +1216,10 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
return -EFAULT;
*start = off = pipe_npages(i, &npages);
- count = DIV_ROUND_UP(maxsize + off, PAGE_SIZE);
- if (count > npages)
- count = npages;
- if (count > maxpages)
- count = maxpages;
+ count = want_pages_array(pages, maxsize, off, min(npages, maxpages));
+ if (count < 0)
+ return count;
p = *pages;
- if (!p) {
- *pages = p = get_pages_array(count);
- if (!p)
- return -ENOMEM;
- }
-
left = maxsize;
npages = 0;
if (off) {
@@ -1282,7 +1284,6 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
{
unsigned nr, offset;
pgoff_t index, count;
- size_t size = maxsize;
loff_t pos;
pos = i->xarray_start + i->iov_offset;
@@ -1290,16 +1291,9 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
offset = pos & ~PAGE_MASK;
*_start_offset = offset;
- count = DIV_ROUND_UP(size + offset, PAGE_SIZE);
- if (count > maxpages)
- count = maxpages;
-
- if (!*pages) {
- *pages = get_pages_array(count);
- if (!*pages)
- return -ENOMEM;
- }
-
+ count = want_pages_array(pages, maxsize, offset, maxpages);
+ if (count < 0)
+ return count;
nr = iter_xarray_populate_pages(*pages, i->xarray, index, count);
if (nr == 0)
return 0;
@@ -1369,14 +1363,9 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
addr = first_iovec_segment(i, &maxsize);
*start = addr % PAGE_SIZE;
addr &= PAGE_MASK;
- n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
- if (n > maxpages)
- n = maxpages;
- if (*pages) {
- *pages = get_pages_array(n);
- if (!*pages)
- return -ENOMEM;
- }
+ n = want_pages_array(pages, maxsize, *start, maxpages);
+ if (n < 0)
+ return n;
res = get_user_pages_fast(addr, n, gup_flags, *pages);
if (unlikely(res <= 0))
return res;
@@ -1387,15 +1376,10 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
struct page *page;
page = first_bvec_segment(i, &maxsize, start);
- n = DIV_ROUND_UP(maxsize + *start, PAGE_SIZE);
- if (n > maxpages)
- n = maxpages;
+ n = want_pages_array(pages, maxsize, *start, maxpages);
+ if (n < 0)
+ return n;
p = *pages;
- if (!p) {
- *pages = p = get_pages_array(n);
- if (!p)
- return -ENOMEM;
- }
for (int k = 0; k < n; k++)
get_page(*p++ = page++);
return min_t(size_t, maxsize, n * PAGE_SIZE - *start);
--
2.30.2
