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/vfs_addr.c b/fs/9p/vfs_addr.c
index 2524e4c..0ad61c6 100644
--- a/fs/9p/vfs_addr.c
+++ b/fs/9p/vfs_addr.c
@@ -56,7 +56,7 @@
 	struct inode *inode;
 
 	inode = page->mapping->host;
-	P9_DPRINTK(P9_DEBUG_VFS, "\n");
+	p9_debug(P9_DEBUG_VFS, "\n");
 
 	BUG_ON(!PageLocked(page));
 
@@ -116,14 +116,14 @@
 	struct inode *inode;
 
 	inode = mapping->host;
-	P9_DPRINTK(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
+	p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
 
 	ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
 	if (ret == 0)
 		return ret;
 
 	ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
-	P9_DPRINTK(P9_DEBUG_VFS, "  = %d\n", ret);
+	p9_debug(P9_DEBUG_VFS, "  = %d\n", ret);
 	return ret;
 }
 
@@ -263,10 +263,9 @@
 	 * Now that we do caching with cache mode enabled, We need
 	 * to support direct IO
 	 */
-	P9_DPRINTK(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) "
-			"off/no(%lld/%lu) EINVAL\n",
-			iocb->ki_filp->f_path.dentry->d_name.name,
-			(long long) pos, nr_segs);
+	p9_debug(P9_DEBUG_VFS, "v9fs_direct_IO: v9fs_direct_IO (%s) off/no(%lld/%lu) EINVAL\n",
+		 iocb->ki_filp->f_path.dentry->d_name.name,
+		 (long long)pos, nr_segs);
 
 	return -EINVAL;
 }