erofs: code cleanup by removing ifdef macro surrounding

Define erofs_listxattr and erofs_xattr_handlers to NULL when
CONFIG_EROFS_FS_XATTR is not enabled, then we can remove many
ugly ifdef macros in the code.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Link: https://lore.kernel.org/r/20200526090343.22794-1-cgxu519@mykernel.netSigned-off-by: Gao Xiang <hsiangkao@redhat.com>

fs/erofs/inode.c

@@ -311,27 +311,21 @@ int erofs_getattr(const struct path *path, struct kstat *stat,
 
 const struct inode_operations erofs_generic_iops = {
 	.getattr = erofs_getattr,
-#ifdef CONFIG_EROFS_FS_XATTR
 	.listxattr = erofs_listxattr,
-#endif
 	.get_acl = erofs_get_acl,
 };
 
 const struct inode_operations erofs_symlink_iops = {
 	.get_link = page_get_link,
 	.getattr = erofs_getattr,
-#ifdef CONFIG_EROFS_FS_XATTR
 	.listxattr = erofs_listxattr,
-#endif
 	.get_acl = erofs_get_acl,
 };
 
 const struct inode_operations erofs_fast_symlink_iops = {
 	.get_link = simple_get_link,
 	.getattr = erofs_getattr,
-#ifdef CONFIG_EROFS_FS_XATTR
 	.listxattr = erofs_listxattr,
-#endif
 	.get_acl = erofs_get_acl,
 };
 

fs/erofs/namei.c

@@ -244,9 +244,7 @@ static struct dentry *erofs_lookup(struct inode *dir,
 const struct inode_operations erofs_dir_iops = {
 	.lookup = erofs_lookup,
 	.getattr = erofs_getattr,
-#ifdef CONFIG_EROFS_FS_XATTR
 	.listxattr = erofs_listxattr,
-#endif
 	.get_acl = erofs_get_acl,
 };
 

fs/erofs/super.c

@@ -408,10 +408,8 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_time_gran = 1;
 
 	sb->s_op = &erofs_sops;
-
-#ifdef CONFIG_EROFS_FS_XATTR
 	sb->s_xattr = erofs_xattr_handlers;
-#endif
+
 	/* set erofs default mount options */
 	erofs_default_options(sbi);
 

fs/erofs/xattr.h

@@ -76,11 +76,8 @@ static inline int erofs_getxattr(struct inode *inode, int index,
 	return -EOPNOTSUPP;
 }
 
-static inline ssize_t erofs_listxattr(struct dentry *dentry,
-				      char *buffer, size_t buffer_size)
-{
-	return -EOPNOTSUPP;
-}
+#define erofs_listxattr (NULL)
+#define erofs_xattr_handlers (NULL)
 #endif	/* !CONFIG_EROFS_FS_XATTR */
 
 #ifdef CONFIG_EROFS_FS_POSIX_ACL