1 files changed, 52 insertions, 9 deletions

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index a1f82a87d34d..cd9e841e7492 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -111,6 +111,23 @@ xdr_decode_string_inplace(__be32 *p, char **sp,
 }
 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
 
+/**
+ * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
+ * @buf: XDR buffer where string resides
+ * @len: length of string, in bytes
+ *
+ */
+void
+xdr_terminate_string(struct xdr_buf *buf, const u32 len)
+{
+        char *kaddr;
+
+        kaddr = kmap_atomic(buf->pages[0], KM_USER0);
+        kaddr[buf->page_base + len] = '\0';
+        kunmap_atomic(kaddr, KM_USER0);
+}
+EXPORT_SYMBOL(xdr_terminate_string);
+
 void
 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
                  unsigned int len)
@@ -395,24 +412,29 @@ xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 {
         struct kvec *tail;
         size_t copy;
-        char *p;
         unsigned int pglen = buf->page_len;
+        unsigned int tailbuf_len;
 
         tail = buf->tail;
         BUG_ON (len > pglen);
 
+        tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
+
         /* Shift the tail first */
-        if (tail->iov_len != 0) {
-                p = (char *)tail->iov_base + len;
+        if (tailbuf_len != 0) {
+                unsigned int free_space = tailbuf_len - tail->iov_len;
+
+                if (len < free_space)
+                        free_space = len;
+                tail->iov_len += free_space;
+
+                copy = len;
                 if (tail->iov_len > len) {
-                        copy = tail->iov_len - len;
-                        memmove(p, tail->iov_base, copy);
+                        char *p = (char *)tail->iov_base + len;
+                        memmove(p, tail->iov_base, tail->iov_len - len);
                 } else
-                        buf->buflen -= len;
-                /* Copy from the inlined pages into the tail */
-                copy = len;
-                if (copy > tail->iov_len)
                         copy = tail->iov_len;
+                /* Copy from the inlined pages into the tail */
                 _copy_from_pages((char *)tail->iov_base,
                                 buf->pages, buf->page_base + pglen - len,
                                 copy);
@@ -551,6 +573,27 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 EXPORT_SYMBOL_GPL(xdr_init_decode);
 
 /**
+ * xdr_inline_peek - Allow read-ahead in the XDR data stream
+ * @xdr: pointer to xdr_stream struct
+ * @nbytes: number of bytes of data to decode
+ *
+ * Check if the input buffer is long enough to enable us to decode
+ * 'nbytes' more bytes of data starting at the current position.
+ * If so return the current pointer without updating the current
+ * pointer position.
+ */
+__be32 * xdr_inline_peek(struct xdr_stream *xdr, size_t nbytes)
+{
+        __be32 *p = xdr->p;
+        __be32 *q = p + XDR_QUADLEN(nbytes);
+
+        if (unlikely(q > xdr->end || q < p))
+                return NULL;
+        return p;
+}
+EXPORT_SYMBOL_GPL(xdr_inline_peek);
+
+/**
  * xdr_inline_decode - Retrieve non-page XDR data to decode
  * @xdr: pointer to xdr_stream struct
  * @nbytes: number of bytes of data to decode