erofs: remove void tagging/untagging of workgroup pointers

Because workgroup pointers inserted to a radix tree are always tagged with
a single value of 0, it is possible to remove tagging and untagging of the
pointers completely.
Signed-off-by: Vladimir Zapolskiy <vladimir@tuxera.com>
Link: https://lore.kernel.org/r/20200102120118.14979-4-vladimir@tuxera.comReviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>

fs/erofs/utils.c

@@ -68,8 +68,6 @@ struct erofs_workgroup *erofs_find_workgroup(struct super_block *sb,
 	rcu_read_lock();
 	grp = radix_tree_lookup(&sbi->workstn_tree, index);
 	if (grp) {
-		grp = xa_untag_pointer(grp);
-
 		if (erofs_workgroup_get(grp)) {
 			/* prefer to relax rcu read side */
 			rcu_read_unlock();
@@ -101,8 +99,6 @@ int erofs_register_workgroup(struct super_block *sb,
 	sbi = EROFS_SB(sb);
 	xa_lock(&sbi->workstn_tree);
 
-	grp = xa_tag_pointer(grp, 0);
-
 	/*
 	 * Bump up reference count before making this workgroup
 	 * visible to other users in order to avoid potential UAF
@@ -173,8 +169,7 @@ static bool erofs_try_to_release_workgroup(struct erofs_sb_info *sbi,
 	 * however in order to avoid some race conditions, add a
 	 * DBG_BUGON to observe this in advance.
 	 */
-	DBG_BUGON(xa_untag_pointer(radix_tree_delete(&sbi->workstn_tree,
-						     grp->index)) != grp);
+	DBG_BUGON(radix_tree_delete(&sbi->workstn_tree, grp->index) != grp);
 
 	/*
 	 * If managed cache is on, last refcount should indicate
@@ -199,7 +194,7 @@ static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
 				       batch, first_index, PAGEVEC_SIZE);
 
 	for (i = 0; i < found; ++i) {
-		struct erofs_workgroup *grp = xa_untag_pointer(batch[i]);
+		struct erofs_workgroup *grp = batch[i];
 
 		first_index = grp->index + 1;