All call sites of get_pages_array() are essenitally identical now.
Replace with common helper...
Returns number of slots available in resulting array or 0 on OOM;
it's up to the caller to make sure it doesn't ask to zero-entry
array (i.e. neither maxpages nor size are allowed to be zero).
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
lib/iov_iter.c | 77 +++++++++++++++++++++-----------------------------
1 file changed, 32 insertions(+), 45 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 9280f865fd6a..1c744f0c0b2c 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1187,9 +1187,20 @@ 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 int count = DIV_ROUND_UP(size + start, PAGE_SIZE);
+
+ if (count > maxpages)
+ count = maxpages;
+ WARN_ON(!count); // caller should've prevented that
+ if (!*res) {
+ *res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
+ if (!*res)
+ return 0;
+ }
+ return count;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
@@ -1197,27 +1208,20 @@ static ssize_t pipe_get_pages(struct iov_iter *i,
size_t *start)
{
struct pipe_inode_info *pipe = i->pipe;
- unsigned int npages, off;
+ unsigned int npages, off, count;
struct page **p;
ssize_t left;
- int count;
if (!sanity(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;
+ if (!npages)
+ return -EFAULT;
+ count = want_pages_array(pages, maxsize, off, min(npages, maxpages));
+ if (!count)
+ return -ENOMEM;
p = *pages;
- if (!p) {
- *pages = p = get_pages_array(count);
- if (!p)
- return -ENOMEM;
- }
-
left = maxsize;
npages = 0;
if (off) {
@@ -1280,9 +1284,8 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
struct page ***pages, size_t maxsize,
unsigned maxpages, size_t *_start_offset)
{
- unsigned nr, offset;
- pgoff_t index, count;
- size_t size = maxsize;
+ unsigned nr, offset, count;
+ pgoff_t index;
loff_t pos;
pos = i->xarray_start + i->iov_offset;
@@ -1290,16 +1293,9 @@ 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)
+ return -ENOMEM;
nr = iter_xarray_populate_pages(*pages, i->xarray, index, count);
if (nr == 0)
return 0;
@@ -1348,7 +1344,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
unsigned int maxpages, size_t *start)
{
- int n, res;
+ unsigned int n;
if (maxsize > i->count)
maxsize = i->count;
@@ -1360,6 +1356,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
if (likely(user_backed_iter(i))) {
unsigned int gup_flags = 0;
unsigned long addr;
+ int res;
if (iov_iter_rw(i) != WRITE)
gup_flags |= FOLL_WRITE;
@@ -1369,14 +1366,9 @@ 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)
+ return -ENOMEM;
res = get_user_pages_fast(addr, n, gup_flags, *pages);
if (unlikely(res <= 0))
return res;
@@ -1387,15 +1379,10 @@ 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)
+ return -ENOMEM;
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
