Merge tag 'erofs-for-5.16-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs fix from Gao Xiang:
 "Fix an ABBA deadlock introduced by XArray conversion"

* tag 'erofs-for-5.16-rc3-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  erofs: fix deadlock when shrink erofs slab

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c
index 84da2c2800129..ec9a1d780dc14 100644
--- a/fs/erofs/utils.c
+++ b/fs/erofs/utils.c
@@ -150,7 +150,7 @@ 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_erase(&sbi->managed_pslots, grp->index) != grp);
+	DBG_BUGON(__xa_erase(&sbi->managed_pslots, grp->index) != grp);
 
 	/* last refcount should be connected with its managed pslot.  */
 	erofs_workgroup_unfreeze(grp, 0);
@@ -165,15 +165,19 @@ static unsigned long erofs_shrink_workstation(struct erofs_sb_info *sbi,
 	unsigned int freed = 0;
 	unsigned long index;
 
+	xa_lock(&sbi->managed_pslots);
 	xa_for_each(&sbi->managed_pslots, index, grp) {
 		/* try to shrink each valid workgroup */
 		if (!erofs_try_to_release_workgroup(sbi, grp))
 			continue;
+		xa_unlock(&sbi->managed_pslots);
 
 		++freed;
 		if (!--nr_shrink)
-			break;
+			return freed;
+		xa_lock(&sbi->managed_pslots);
 	}
+	xa_unlock(&sbi->managed_pslots);
 	return freed;
 }