9p: move readn meta-function from client to fs layer

There are a couple of methods in the client code which aren't actually
wire operations.  To keep things organized cleaner, these operations are
being moved to the fs layer.

This patch moves the readn meta-function (which executes multiple wire
reads until a buffer is full) to the fs layer.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>




diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c
index b6b85cf..24eb010 100644
--- a/fs/9p/v9fs.c
+++ b/fs/9p/v9fs.c
@@ -234,7 +234,7 @@
 	if (!v9ses->clnt->dotu)
 		v9ses->flags &= ~V9FS_EXTENDED;
 
-	v9ses->maxdata = v9ses->clnt->msize;
+	v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
 
 	/* for legacy mode, fall back to V9FS_ACCESS_ANY */
 	if (!v9fs_extended(v9ses) &&