v9fs: fixup for inode_setattr being removed

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index d97c34a..c7c23ea 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -1263,10 +1263,19 @@
 		return PTR_ERR(fid);
 
 	retval = p9_client_setattr(fid, &p9attr);
-	if (retval >= 0)
-		retval = inode_setattr(dentry->d_inode, iattr);
+	if (retval < 0)
+		return retval;
 
-	return retval;
+	if ((iattr->ia_valid & ATTR_SIZE) &&
+	    iattr->ia_size != i_size_read(dentry->d_inode)) {
+		retval = vmtruncate(dentry->d_inode, iattr->ia_size);
+		if (retval)
+			return retval;
+	}
+
+	setattr_copy(dentry->d_inode, iattr);
+	mark_inode_dirty(dentry->d_inode);
+	return 0;
 }
 
 /**