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Unverified Commit 2b968c0f authored by Vladimir Zapolskiy's avatar Vladimir Zapolskiy Committed by Michael Bestas
Browse files

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.

Change-Id: I148904fa4ad13d0de593a5cf5b308638253da446
Signed-off-by: default avatarVladimir Zapolskiy <vladimir@tuxera.com>
Link: https://lore.kernel.org/r/20200102120118.14979-4-vladimir@tuxera.com


Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarGao Xiang <gaoxiang25@huawei.com>
parent 795dc2d9

fs/erofs/utils.c

+2 −7
Original line number Diff line number Diff line
@@ -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;