switch xattr_handler->set() to passing dentry and inode separately

preparation for similar switch in ->setxattr() (see the next commit for
rationale).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/xattr.c b/fs/btrfs/xattr.c
index 3bfb252..d1a177a 100644
--- a/fs/btrfs/xattr.c
+++ b/fs/btrfs/xattr.c
@@ -380,23 +380,21 @@
 }
 
 static int btrfs_xattr_handler_set(const struct xattr_handler *handler,
-				   struct dentry *dentry, const char *name,
-				   const void *buffer, size_t size,
-				   int flags)
+				   struct dentry *unused, struct inode *inode,
+				   const char *name, const void *buffer,
+				   size_t size, int flags)
 {
-	struct inode *inode = d_inode(dentry);
-
 	name = xattr_full_name(handler, name);
 	return __btrfs_setxattr(NULL, inode, name, buffer, size, flags);
 }
 
 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler,
-					struct dentry *dentry,
+					struct dentry *unused, struct inode *inode,
 					const char *name, const void *value,
 					size_t size, int flags)
 {
 	name = xattr_full_name(handler, name);
-	return btrfs_set_prop(d_inode(dentry), name, value, size, flags);
+	return btrfs_set_prop(inode, name, value, size, flags);
 }
 
 static const struct xattr_handler btrfs_security_xattr_handler = {