9p: Reduce object size with CONFIG_NET_9P_DEBUG

Reduce object size by deduplicating formats.

Use vsprintf extension %pV.
Rename P9_DPRINTK uses to p9_debug, align arguments.
Add function for _p9_debug and macro to add __func__.
Add missing "\n"s to p9_debug uses.
Remove embedded function names as p9_debug adds it.
Remove P9_EPRINTK macro and convert use to pr_<level>.
Add and use pr_fmt and pr_<level>.

$ size fs/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  62133	    984	  16000	  79117	  1350d	fs/9p/built-in.o.new
  67342	    984	  16928	  85254	  14d06	fs/9p/built-in.o.old
$ size net/9p/built-in.o*
   text	   data	    bss	    dec	    hex	filename
  88792	   4148	  22024	 114964	  1c114	net/9p/built-in.o.new
  94072	   4148	  23232	 121452	  1da6c	net/9p/built-in.o.old

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
index d288773..29653b7 100644
--- a/fs/9p/xattr.c
+++ b/fs/9p/xattr.c
@@ -32,8 +32,8 @@
 	attr_fid = p9_client_xattrwalk(fid, name, &attr_size);
 	if (IS_ERR(attr_fid)) {
 		retval = PTR_ERR(attr_fid);
-		P9_DPRINTK(P9_DEBUG_VFS,
-			"p9_client_attrwalk failed %zd\n", retval);
+		p9_debug(P9_DEBUG_VFS, "p9_client_attrwalk failed %zd\n",
+			 retval);
 		attr_fid = NULL;
 		goto error;
 	}
@@ -87,8 +87,8 @@
 {
 	struct p9_fid *fid;
 
-	P9_DPRINTK(P9_DEBUG_VFS, "%s: name = %s value_len = %zu\n",
-		__func__, name, buffer_size);
+	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu\n",
+		 name, buffer_size);
 	fid = v9fs_fid_lookup(dentry);
 	if (IS_ERR(fid))
 		return PTR_ERR(fid);
@@ -115,8 +115,8 @@
 	int retval, msize, write_count;
 	struct p9_fid *fid = NULL;
 
-	P9_DPRINTK(P9_DEBUG_VFS, "%s: name = %s value_len = %zu flags = %d\n",
-		__func__, name, value_len, flags);
+	p9_debug(P9_DEBUG_VFS, "name = %s value_len = %zu flags = %d\n",
+		 name, value_len, flags);
 
 	fid = v9fs_fid_clone(dentry);
 	if (IS_ERR(fid)) {
@@ -129,8 +129,8 @@
 	 */
 	retval = p9_client_xattrcreate(fid, name, value_len, flags);
 	if (retval < 0) {
-		P9_DPRINTK(P9_DEBUG_VFS,
-			"p9_client_xattrcreate failed %d\n", retval);
+		p9_debug(P9_DEBUG_VFS, "p9_client_xattrcreate failed %d\n",
+			 retval);
 		goto error;
 	}
 	msize = fid->clnt->msize;