1 files changed, 164 insertions, 28 deletions

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index a1f82a87d34d..679cd674b81d 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);
@@ -530,6 +552,74 @@ void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int b
 }
 EXPORT_SYMBOL_GPL(xdr_write_pages);
 
+static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
+		__be32 *p, unsigned int len)
+{
+	if (len > iov->iov_len)
+		len = iov->iov_len;
+	if (p == NULL)
+		p = (__be32*)iov->iov_base;
+	xdr->p = p;
+	xdr->end = (__be32*)(iov->iov_base + len);
+	xdr->iov = iov;
+	xdr->page_ptr = NULL;
+}
+
+static int xdr_set_page_base(struct xdr_stream *xdr,
+		unsigned int base, unsigned int len)
+{
+	unsigned int pgnr;
+	unsigned int maxlen;
+	unsigned int pgoff;
+	unsigned int pgend;
+	void *kaddr;
+
+	maxlen = xdr->buf->page_len;
+	if (base >= maxlen)
+		return -EINVAL;
+	maxlen -= base;
+	if (len > maxlen)
+		len = maxlen;
+
+	base += xdr->buf->page_base;
+
+	pgnr = base >> PAGE_SHIFT;
+	xdr->page_ptr = &xdr->buf->pages[pgnr];
+	kaddr = page_address(*xdr->page_ptr);
+
+	pgoff = base & ~PAGE_MASK;
+	xdr->p = (__be32*)(kaddr + pgoff);
+
+	pgend = pgoff + len;
+	if (pgend > PAGE_SIZE)
+		pgend = PAGE_SIZE;
+	xdr->end = (__be32*)(kaddr + pgend);
+	xdr->iov = NULL;
+	return 0;
+}
+
+static void xdr_set_next_page(struct xdr_stream *xdr)
+{
+	unsigned int newbase;
+
+	newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
+	newbase -= xdr->buf->page_base;
+
+	if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
+		xdr_set_iov(xdr, xdr->buf->tail, NULL, xdr->buf->len);
+}
+
+static bool xdr_set_next_buffer(struct xdr_stream *xdr)
+{
+	if (xdr->page_ptr != NULL)
+		xdr_set_next_page(xdr);
+	else if (xdr->iov == xdr->buf->head) {
+		if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
+			xdr_set_iov(xdr, xdr->buf->tail, NULL, xdr->buf->len);
+	}
+	return xdr->p != xdr->end;
+}
+
 /**
  * xdr_init_decode - Initialize an xdr_stream for decoding data.
  * @xdr: pointer to xdr_stream struct
@@ -538,20 +628,67 @@ EXPORT_SYMBOL_GPL(xdr_write_pages);
  */
 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 {
-	struct kvec *iov = buf->head;
-	unsigned int len = iov->iov_len;
-
-	if (len > buf->len)
-		len = buf->len;
 	xdr->buf = buf;
-	xdr->iov = iov;
-	xdr->p = p;
-	xdr->end = (__be32 *)((char *)iov->iov_base + len);
+	xdr->scratch.iov_base = NULL;
+	xdr->scratch.iov_len = 0;
+	if (buf->head[0].iov_len != 0)
+		xdr_set_iov(xdr, buf->head, p, buf->len);
+	else if (buf->page_len != 0)
+		xdr_set_page_base(xdr, 0, buf->len);
 }
 EXPORT_SYMBOL_GPL(xdr_init_decode);
 
+static __be32 * __xdr_inline_decode(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;
+	xdr->p = q;
+	return p;
+}
+
 /**
- * xdr_inline_decode - Retrieve non-page XDR data to decode
+ * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
+ * @xdr: pointer to xdr_stream struct
+ * @buf: pointer to an empty buffer
+ * @buflen: size of 'buf'
+ *
+ * The scratch buffer is used when decoding from an array of pages.
+ * If an xdr_inline_decode() call spans across page boundaries, then
+ * we copy the data into the scratch buffer in order to allow linear
+ * access.
+ */
+void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
+{
+	xdr->scratch.iov_base = buf;
+	xdr->scratch.iov_len = buflen;
+}
+EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
+
+static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
+{
+	__be32 *p;
+	void *cpdest = xdr->scratch.iov_base;
+	size_t cplen = (char *)xdr->end - (char *)xdr->p;
+
+	if (nbytes > xdr->scratch.iov_len)
+		return NULL;
+	memcpy(cpdest, xdr->p, cplen);
+	cpdest += cplen;
+	nbytes -= cplen;
+	if (!xdr_set_next_buffer(xdr))
+		return NULL;
+	p = __xdr_inline_decode(xdr, nbytes);
+	if (p == NULL)
+		return NULL;
+	memcpy(cpdest, p, nbytes);
+	return xdr->scratch.iov_base;
+}
+
+/**
+ * xdr_inline_decode - Retrieve XDR data to decode
  * @xdr: pointer to xdr_stream struct
  * @nbytes: number of bytes of data to decode
  *
@@ -562,13 +699,16 @@ EXPORT_SYMBOL_GPL(xdr_init_decode);
  */
 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 {
-	__be32 *p = xdr->p;
-	__be32 *q = p + XDR_QUADLEN(nbytes);
+	__be32 *p;
 
-	if (unlikely(q > xdr->end || q < p))
+	if (nbytes == 0)
+		return xdr->p;
+	if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
 		return NULL;
-	xdr->p = q;
-	return p;
+	p = __xdr_inline_decode(xdr, nbytes);
+	if (p != NULL)
+		return p;
+	return xdr_copy_to_scratch(xdr, nbytes);
 }
 EXPORT_SYMBOL_GPL(xdr_inline_decode);
 
@@ -628,16 +768,12 @@ EXPORT_SYMBOL_GPL(xdr_read_pages);
  */
 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
 {
-	char * kaddr = page_address(xdr->buf->pages[0]);
 	xdr_read_pages(xdr, len);
 	/*
 	 * Position current pointer at beginning of tail, and
 	 * set remaining message length.
 	 */
-	if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
-		len = PAGE_CACHE_SIZE - xdr->buf->page_base;
-	xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
-	xdr->end = (__be32 *)((char *)xdr->p + len);
+	xdr_set_page_base(xdr, 0, len);
 }
 EXPORT_SYMBOL_GPL(xdr_enter_page);