Remove atomics from zh_refcount

It is protected by z_hold_locks, so we do not need more serialization, simple integer math should be fine. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Richard Yao <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Closes openzfs#14196
amotin · Mar 2, 2023 · 55a0ad2 · 55a0ad2
1 parent c7e17c5
commit 55a0ad2
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Showing 2 changed files with 8 additions and 10 deletions.
diff --git a/include/sys/zfs_znode.h b/include/sys/zfs_znode.h
@@ -217,9 +217,9 @@ typedef struct znode {
 
 typedef struct znode_hold {
 	uint64_t	zh_obj;		/* object id */
-	kmutex_t	zh_lock;	/* lock serializing object access */
 	avl_node_t	zh_node;	/* avl tree linkage */
-	zfs_refcount_t	zh_refcount;	/* active consumer reference count */
+	kmutex_t	zh_lock;	/* lock serializing object access */
+	int		zh_refcount;	/* active consumer reference count */
 } znode_hold_t;
 
 static inline uint64_t

diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
@@ -162,8 +162,7 @@ zfs_znode_hold_cache_constructor(void *buf, void *arg, int kmflags)
 	znode_hold_t *zh = buf;
 
 	mutex_init(&zh->zh_lock, NULL, MUTEX_DEFAULT, NULL);
-	zfs_refcount_create(&zh->zh_refcount);
-	zh->zh_obj = ZFS_NO_OBJECT;
+	zh->zh_refcount = 0;
 
 	return (0);
 }
@@ -174,7 +173,6 @@ zfs_znode_hold_cache_destructor(void *buf, void *arg)
 	znode_hold_t *zh = buf;
 
 	mutex_destroy(&zh->zh_lock);
-	zfs_refcount_destroy(&zh->zh_refcount);
 }
 
 void
@@ -273,26 +271,26 @@ zfs_znode_hold_enter(zfsvfs_t *zfsvfs, uint64_t obj)
 	boolean_t found = B_FALSE;
 
 	zh_new = kmem_cache_alloc(znode_hold_cache, KM_SLEEP);
-	zh_new->zh_obj = obj;
 	search.zh_obj = obj;
 
 	mutex_enter(&zfsvfs->z_hold_locks[i]);
 	zh = avl_find(&zfsvfs->z_hold_trees[i], &search, NULL);
 	if (likely(zh == NULL)) {
 		zh = zh_new;
+		zh->zh_obj = obj;
 		avl_add(&zfsvfs->z_hold_trees[i], zh);
 	} else {
 		ASSERT3U(zh->zh_obj, ==, obj);
 		found = B_TRUE;
 	}
-	zfs_refcount_add(&zh->zh_refcount, NULL);
+	zh->zh_refcount++;
+	ASSERT3S(zh->zh_refcount, >, 0);
 	mutex_exit(&zfsvfs->z_hold_locks[i]);
 
 	if (found == B_TRUE)
 		kmem_cache_free(znode_hold_cache, zh_new);
 
 	ASSERT(MUTEX_NOT_HELD(&zh->zh_lock));
-	ASSERT3S(zfs_refcount_count(&zh->zh_refcount), >, 0);
 	mutex_enter(&zh->zh_lock);
 
 	return (zh);
@@ -305,11 +303,11 @@ zfs_znode_hold_exit(zfsvfs_t *zfsvfs, znode_hold_t *zh)
 	boolean_t remove = B_FALSE;
 
 	ASSERT(zfs_znode_held(zfsvfs, zh->zh_obj));
-	ASSERT3S(zfs_refcount_count(&zh->zh_refcount), >, 0);
 	mutex_exit(&zh->zh_lock);
 
 	mutex_enter(&zfsvfs->z_hold_locks[i]);
-	if (zfs_refcount_remove(&zh->zh_refcount, NULL) == 0) {
+	ASSERT3S(zh->zh_refcount, >, 0);
+	if (--zh->zh_refcount == 0) {
 		avl_remove(&zfsvfs->z_hold_trees[i], zh);
 		remove = B_TRUE;
 	}