Commit ad3d24c5 authored by Chuck Lever's avatar Chuck Lever Committed by Chuck Lever
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SUNRPC: Clean up xdr_write_pages() 



Make it more evident how xdr_write_pages() updates the tail buffer
by using the convention of naming the iov pointer variable "tail".
I spent more than a couple of hours chasing through code to
understand this, so someone is likely to find this useful later.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
parent da522b5f

net/sunrpc/xdr.c

+13 −9
Original line number Diff line number Diff line
@@ -1224,30 +1224,34 @@ EXPORT_SYMBOL(xdr_restrict_buflen); 
/**

 * xdr_write_pages - Insert a list of pages into an XDR buffer for sending

 * @xdr: pointer to xdr_stream

 * @pages: list of pages

 * @base: offset of first byte

 * @len: length of data in bytes

 * @pages: array of pages to insert

 * @base: starting offset of first data byte in @pages

 * @len: number of data bytes in @pages to insert

 *

 * After the @pages are added, the tail iovec is instantiated pointing to

 * end of the head buffer, and the stream is set up to encode subsequent

 * items into the tail.

 */

void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,

		 unsigned int len)

{

	struct xdr_buf *buf = xdr->buf;

	struct kvec *iov = buf->tail;

	struct kvec *tail = buf->tail;



	buf->pages = pages;

	buf->page_base = base;

	buf->page_len = len;



	iov->iov_base = (char *)xdr->p;

	iov->iov_len  = 0;

	xdr->iov = iov;

	tail->iov_base = xdr->p;

	tail->iov_len = 0;

	xdr->iov = tail;



	if (len & 3) {

		unsigned int pad = 4 - (len & 3);



		BUG_ON(xdr->p >= xdr->end);

		iov->iov_base = (char *)xdr->p + (len & 3);

		iov->iov_len  += pad;

		tail->iov_base = (char *)xdr->p + (len & 3);

		tail->iov_len += pad;

		len += pad;

		*xdr->p++ = 0;

	}