From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
If we're shifting the page data to the right, and this happens to be a
sparse page array, then we may need to allocate new pages in order to
receive the data.
Reported-by: "Mkrtchyan, Tigran" <tigran.mkrtchyan@xxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
---
net/sunrpc/xdr.c | 35 +++++++++++++++++++++++++++++++++--
1 file changed, 33 insertions(+), 2 deletions(-)
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 2e91fbd70f11..60d4442c5273 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -478,16 +478,47 @@ static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
} while ((len -= zero) != 0);
}
+static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
+ unsigned int buflen, gfp_t gfp)
+{
+ unsigned int i, npages, pagelen;
+
+ if (!(buf->flags & XDRBUF_SPARSE_PAGES))
+ return buflen;
+ if (buflen <= buf->head->iov_len)
+ return buflen;
+ pagelen = buflen - buf->head->iov_len;
+ if (pagelen > buf->page_len)
+ pagelen = buf->page_len;
+ npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ for (i = 0; i < npages; i++) {
+ if (!buf->pages[i])
+ continue;
+ buf->pages[i] = alloc_page(gfp);
+ if (likely(buf->pages[i]))
+ continue;
+ buflen -= pagelen;
+ pagelen = i << PAGE_SHIFT;
+ if (pagelen > buf->page_base)
+ buflen += pagelen - buf->page_base;
+ break;
+ }
+ return buflen;
+}
+
static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len)
{
struct kvec *head = buf->head;
struct kvec *tail = buf->tail;
unsigned int sum = head->iov_len + buf->page_len + tail->iov_len;
- unsigned int free_space;
+ unsigned int free_space, newlen;
if (sum > buf->len) {
free_space = min_t(unsigned int, sum - buf->len, len);
- buf->len += free_space;
+ newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
+ GFP_KERNEL);
+ free_space = newlen - buf->len;
+ buf->len = newlen;
len -= free_space;
if (!len)
return;
--
2.29.2
