SUNRPC: Optimise away unnecessary data moves in xdr_align_pages
We only have to call xdr_shrink_pagelen() if the remaining RPC message does not fit in the page buffer length that we supplied to xdr_align_pages(). Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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					 1 changed files with 13 additions and 10 deletions
				
			
		|  | @ -730,21 +730,24 @@ static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len) | |||
| 
 | ||||
| 	if (xdr->nwords == 0) | ||||
| 		return 0; | ||||
| 	/* Realign pages to current pointer position */ | ||||
| 	iov  = buf->head; | ||||
| 	if (iov->iov_len > cur) { | ||||
| 		xdr_shrink_bufhead(buf, iov->iov_len - cur); | ||||
| 		xdr->nwords = XDR_QUADLEN(buf->len - cur); | ||||
| 	} | ||||
| 
 | ||||
| 	if (nwords > xdr->nwords) { | ||||
| 		nwords = xdr->nwords; | ||||
| 		len = nwords << 2; | ||||
| 	} | ||||
| 	/* Realign pages to current pointer position */ | ||||
| 	iov  = buf->head; | ||||
| 	if (iov->iov_len > cur) | ||||
| 		xdr_shrink_bufhead(buf, iov->iov_len - cur); | ||||
| 
 | ||||
| 	/* Truncate page data and move it into the tail */ | ||||
| 	if (buf->page_len > len) | ||||
| 		xdr_shrink_pagelen(buf, buf->page_len - len); | ||||
| 	else | ||||
| 	if (buf->page_len <= len) | ||||
| 		len = buf->page_len; | ||||
| 	xdr->nwords = XDR_QUADLEN(buf->len - cur); | ||||
| 	else if (nwords < xdr->nwords) { | ||||
| 		/* Truncate page data and move it into the tail */ | ||||
| 		xdr_shrink_pagelen(buf, buf->page_len - len); | ||||
| 		xdr->nwords = XDR_QUADLEN(buf->len - cur); | ||||
| 	} | ||||
| 	return len; | ||||
| } | ||||
| 
 | ||||
|  |  | |||
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	 Trond Myklebust
				Trond Myklebust