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_vfs.h b/fs/9p/v9fs_vfs.h
index 57997fa..046cff3 100644
--- a/fs/9p/v9fs_vfs.h
+++ b/fs/9p/v9fs_vfs.h
@@ -52,3 +52,5 @@
 void v9fs_inode2stat(struct inode *inode, struct p9_stat *stat);
 void v9fs_dentry_release(struct dentry *);
 int v9fs_uflags2omode(int uflags, int extended);
+
+ssize_t v9fs_file_readn(struct file *, char *, char __user *, u32, u64);