Btrfs lockdep and locking cleanups

index 7ab5e0128f0c..6dcb0128ea7f 100644
@@ -216,7 +216,7 @@ int btrfs_delayed_ref_lock(struct btrfs_trans_handle *trans,
 	struct btrfs_delayed_ref_root *delayed_refs;
 
 	delayed_refs = &trans->transaction->delayed_refs;
-	assert_spin_locked(&delayed_refs->lock);
+	lockdep_assert_held(&delayed_refs->lock);
 	if (mutex_trylock(&head->mutex))
 		return 0;
 

@@ -239,7 +239,7 @@ static inline void drop_delayed_ref(struct btrfs_trans_handle *trans,
 				    struct btrfs_delayed_ref_head *head,
 				    struct btrfs_delayed_ref_node *ref)
 {
-	assert_spin_locked(&head->lock);
+	lockdep_assert_held(&head->lock);
 	rb_erase(&ref->ref_node, &head->ref_tree);
 	RB_CLEAR_NODE(&ref->ref_node);
 	if (!list_empty(&ref->add_list))

@@ -307,7 +307,7 @@ void btrfs_merge_delayed_refs(struct btrfs_trans_handle *trans,
 	struct rb_node *node;
 	u64 seq = 0;
 
-	assert_spin_locked(&head->lock);
+	lockdep_assert_held(&head->lock);
 
 	if (RB_EMPTY_ROOT(&head->ref_tree))
 		return;

index aa259d6986e1..ad09845b618c 100644
@@ -1414,7 +1414,7 @@ int btrfs_qgroup_trace_extent_nolock(struct btrfs_fs_info *fs_info,
 	struct btrfs_qgroup_extent_record *entry;
 	u64 bytenr = record->bytenr;
 
-	assert_spin_locked(&delayed_refs->lock);
+	lockdep_assert_held(&delayed_refs->lock);
 	trace_btrfs_qgroup_trace_extent(fs_info, record);
 
 	while (*p) {

index c1618ab9fecf..4116fb20b1af 100644
@@ -4542,7 +4542,7 @@ void check_system_chunk(struct btrfs_trans_handle *trans,
 	 * Needed because we can end up allocating a system chunk and for an
 	 * atomic and race free space reservation in the chunk block reserve.
 	 */
-	ASSERT(mutex_is_locked(&fs_info->chunk_mutex));
+	lockdep_assert_held(&fs_info->chunk_mutex);
 
 	info = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_SYSTEM);
 	spin_lock(&info->lock);

index ec56f33feea9..9cfbccdeacf3 100644
@@ -371,7 +371,7 @@ static struct full_stripe_lock *insert_full_stripe_lock(
 	struct full_stripe_lock *entry;
 	struct full_stripe_lock *ret;
 
-	WARN_ON(!mutex_is_locked(&locks_root->lock));
+	lockdep_assert_held(&locks_root->lock);
 
 	p = &locks_root->root.rb_node;
 	while (*p) {

@@ -413,7 +413,7 @@ static struct full_stripe_lock *search_full_stripe_lock(
 	struct rb_node *node;
 	struct full_stripe_lock *entry;
 
-	WARN_ON(!mutex_is_locked(&locks_root->lock));
+	lockdep_assert_held(&locks_root->lock);
 
 	node = locks_root->root.rb_node;
 	while (node) {

index b2d05c6b1c56..350c12f1f19e 100644
@@ -2047,7 +2047,7 @@ void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_fs_devices *fs_devices;
 
-	WARN_ON(!mutex_is_locked(&fs_info->fs_devices->device_list_mutex));
+	lockdep_assert_held(&fs_info->fs_devices->device_list_mutex);
 
 	/*
 	 * in case of fs with no seed, srcdev->fs_devices will point

@@ -2237,7 +2237,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
 	struct btrfs_device *device;
 	u64 super_flags;
 
-	BUG_ON(!mutex_is_locked(&uuid_mutex));
+	lockdep_assert_held(&uuid_mutex);
 	if (!fs_devices->seeding)
 		return -EINVAL;
 

@@ -2984,7 +2984,7 @@ static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset)
 	 * we release the path used to search the chunk/dev tree and before
 	 * the current task acquires this mutex and calls us.
 	 */
-	ASSERT(mutex_is_locked(&fs_info->delete_unused_bgs_mutex));
+	lockdep_assert_held(&fs_info->delete_unused_bgs_mutex);
 
 	ret = btrfs_can_relocate(fs_info, chunk_offset);
 	if (ret)

@@ -5068,7 +5068,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 {
 	u64 chunk_offset;
 
-	ASSERT(mutex_is_locked(&fs_info->chunk_mutex));
+	lockdep_assert_held(&fs_info->chunk_mutex);
 	chunk_offset = find_next_chunk(fs_info);
 	return __btrfs_alloc_chunk(trans, chunk_offset, type);
 }

@@ -6618,7 +6618,7 @@ static struct btrfs_fs_devices *open_seed_devices(struct btrfs_fs_info *fs_info,
 	struct btrfs_fs_devices *fs_devices;
 	int ret;
 
-	BUG_ON(!mutex_is_locked(&uuid_mutex));
+	lockdep_assert_held(&uuid_mutex);
 	ASSERT(fsid);
 
 	fs_devices = fs_info->fs_devices->seed;

index b88a79e69ddf..4c75df2eea2e 100644
@@ -1502,8 +1502,8 @@ static inline int should_cow_block(struct btrfs_trans_handle *trans,
 	if (btrfs_is_testing(root->fs_info))
 		return 0;
 
-	/* ensure we can see the force_cow */
-	smp_rmb();
+	/* Ensure we can see the FORCE_COW bit */
+	smp_mb__before_atomic();
 
 	/*
 	 * We do not need to cow a block if

index 4b817947e00f..9c18f05b954d 100644
@@ -2290,11 +2290,18 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
 	struct list_head *head;
 	struct rcu_string *name;
 
-	mutex_lock(&fs_info->fs_devices->device_list_mutex);
+	/*
+	 * Lightweight locking of the devices. We should not need
+	 * device_list_mutex here as we only read the device data and the list
+	 * is protected by RCU.  Even if a device is deleted during the list
+	 * traversals, we'll get valid data, the freeing callback will wait at
+	 * least until until the rcu_read_unlock.
+	 */
+	rcu_read_lock();
 	cur_devices = fs_info->fs_devices;
 	while (cur_devices) {
 		head = &cur_devices->devices;
-		list_for_each_entry(dev, head, dev_list) {
+		list_for_each_entry_rcu(dev, head, dev_list) {
 			if (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state))
 				continue;
 			if (!dev->name)

@@ -2306,14 +2313,12 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
 	}
 
 	if (first_dev) {
-		rcu_read_lock();
 		name = rcu_dereference(first_dev->name);
 		seq_escape(m, name->str, " \t\n\\");
-		rcu_read_unlock();
 	} else {
 		WARN_ON(1);
 	}
-	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
+	rcu_read_unlock();
 	return 0;
 }
 

index 1ba49ebe67da..700a3dfd3129 100644
@@ -65,9 +65,6 @@ struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
 	return acl;
 }
 
-/*
- * Needs to be called with fs_mutex held
- */
 static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
 			 struct inode *inode, struct posix_acl *acl, int type)
 {

@@ -127,11 +124,6 @@ int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 	return ret;
 }
 
-/*
- * btrfs_init_acl is already generally called under fs_mutex, so the locking
- * stuff has been fixed to work with that.  If the locking stuff changes, we
- * need to re-evaluate the acl locking stuff.
- */
 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 		   struct inode *inode, struct inode *dir)
 {

index 7efbc4d1128b..91d0815dd514 100644
@@ -200,13 +200,13 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 	struct btrfs_dev_replace_item *ptr;
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 
-	btrfs_dev_replace_lock(dev_replace, 0);
+	btrfs_dev_replace_read_lock(dev_replace);
 	if (!dev_replace->is_valid ||
 	    !dev_replace->item_needs_writeback) {
-		btrfs_dev_replace_unlock(dev_replace, 0);
+		btrfs_dev_replace_read_unlock(dev_replace);
 		return 0;
 	}
-	btrfs_dev_replace_unlock(dev_replace, 0);
+	btrfs_dev_replace_read_unlock(dev_replace);
 
 	key.objectid = 0;
 	key.type = BTRFS_DEV_REPLACE_KEY;

@@ -264,7 +264,7 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 	ptr = btrfs_item_ptr(eb, path->slots[0],
 			     struct btrfs_dev_replace_item);
 
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	if (dev_replace->srcdev)
 		btrfs_set_dev_replace_src_devid(eb, ptr,
 			dev_replace->srcdev->devid);

@@ -287,7 +287,7 @@ int btrfs_run_dev_replace(struct btrfs_trans_handle *trans,
 	btrfs_set_dev_replace_cursor_right(eb, ptr,
 		dev_replace->cursor_right);
 	dev_replace->item_needs_writeback = 0;
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 
 	btrfs_mark_buffer_dirty(eb);
 

@@ -352,7 +352,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 		return PTR_ERR(trans);
 	}
 
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	switch (dev_replace->replace_state) {
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:

@@ -390,7 +390,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	dev_replace->item_needs_writeback = 1;
 	atomic64_set(&dev_replace->num_write_errors, 0);
 	atomic64_set(&dev_replace->num_uncorrectable_read_errors, 0);
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 
 	ret = btrfs_sysfs_add_device_link(tgt_device->fs_devices, tgt_device);
 	if (ret)

@@ -402,7 +402,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 	trans = btrfs_start_transaction(root, 0);
 	if (IS_ERR(trans)) {
 		ret = PTR_ERR(trans);
-		btrfs_dev_replace_lock(dev_replace, 1);
+		btrfs_dev_replace_write_lock(dev_replace);
 		goto leave;
 	}
 

@@ -426,7 +426,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
 leave:
 	dev_replace->srcdev = NULL;
 	dev_replace->tgtdev = NULL;
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 	btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 	return ret;
 }

@@ -493,18 +493,18 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	/* don't allow cancel or unmount to disturb the finishing procedure */
 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
 
-	btrfs_dev_replace_lock(dev_replace, 0);
+	btrfs_dev_replace_read_lock(dev_replace);
 	/* was the operation canceled, or is it finished? */
 	if (dev_replace->replace_state !=
 	    BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED) {
-		btrfs_dev_replace_unlock(dev_replace, 0);
+		btrfs_dev_replace_read_unlock(dev_replace);
 		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 		return 0;
 	}
 
 	tgt_device = dev_replace->tgtdev;
 	src_device = dev_replace->srcdev;
-	btrfs_dev_replace_unlock(dev_replace, 0);
+	btrfs_dev_replace_read_unlock(dev_replace);
 
 	/*
 	 * flush all outstanding I/O and inode extent mappings before the

@@ -529,7 +529,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	/* keep away write_all_supers() during the finishing procedure */
 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
 	mutex_lock(&fs_info->chunk_mutex);
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	dev_replace->replace_state =
 		scrub_ret ? BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED
 			  : BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED;

@@ -549,7 +549,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 				 btrfs_dev_name(src_device),
 				 src_device->devid,
 				 rcu_str_deref(tgt_device->name), scrub_ret);
-		btrfs_dev_replace_unlock(dev_replace, 1);
+		btrfs_dev_replace_write_unlock(dev_replace);
 		mutex_unlock(&fs_info->chunk_mutex);
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		mutex_unlock(&uuid_mutex);

@@ -586,7 +586,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 	list_add(&tgt_device->dev_alloc_list, &fs_info->fs_devices->alloc_list);
 	fs_info->fs_devices->rw_devices++;
 
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 
 	btrfs_rm_dev_replace_blocked(fs_info);
 

@@ -679,7 +679,7 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 {
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 
-	btrfs_dev_replace_lock(dev_replace, 0);
+	btrfs_dev_replace_read_lock(dev_replace);
 	/* even if !dev_replace_is_valid, the values are good enough for
 	 * the replace_status ioctl */
 	args->result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;

@@ -691,7 +691,7 @@ void btrfs_dev_replace_status(struct btrfs_fs_info *fs_info,
 	args->status.num_uncorrectable_read_errors =
 		atomic64_read(&dev_replace->num_uncorrectable_read_errors);
 	args->status.progress_1000 = btrfs_dev_replace_progress(fs_info);
-	btrfs_dev_replace_unlock(dev_replace, 0);
+	btrfs_dev_replace_read_unlock(dev_replace);
 }
 
 int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,

@@ -714,13 +714,13 @@ static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 		return -EROFS;
 
 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	switch (dev_replace->replace_state) {
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
-		btrfs_dev_replace_unlock(dev_replace, 1);
+		btrfs_dev_replace_write_unlock(dev_replace);
 		goto leave;
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:

@@ -733,7 +733,7 @@ static u64 __btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 	dev_replace->replace_state = BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED;
 	dev_replace->time_stopped = get_seconds();
 	dev_replace->item_needs_writeback = 1;
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 	btrfs_scrub_cancel(fs_info);
 
 	trans = btrfs_start_transaction(root, 0);

@@ -756,7 +756,7 @@ void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 
 	mutex_lock(&dev_replace->lock_finishing_cancel_unmount);
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	switch (dev_replace->replace_state) {
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:

@@ -772,7 +772,7 @@ void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info)
 		break;
 	}
 
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 	mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
 }
 

@@ -782,12 +782,12 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 	struct task_struct *task;
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 
-	btrfs_dev_replace_lock(dev_replace, 1);
+	btrfs_dev_replace_write_lock(dev_replace);
 	switch (dev_replace->replace_state) {
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_NEVER_STARTED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_FINISHED:
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_CANCELED:
-		btrfs_dev_replace_unlock(dev_replace, 1);
+		btrfs_dev_replace_write_unlock(dev_replace);
 		return 0;
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
 		break;

@@ -801,10 +801,10 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
 			   "cannot continue dev_replace, tgtdev is missing");
 		btrfs_info(fs_info,
 			   "you may cancel the operation after 'mount -o degraded'");
-		btrfs_dev_replace_unlock(dev_replace, 1);
+		btrfs_dev_replace_write_unlock(dev_replace);
 		return 0;
 	}
-	btrfs_dev_replace_unlock(dev_replace, 1);
+	btrfs_dev_replace_write_unlock(dev_replace);
 
 	WARN_ON(test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags));
 	task = kthread_run(btrfs_dev_replace_kthread, fs_info, "btrfs-devrepl");

@@ -873,37 +873,37 @@ int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace)
 	return 1;
 }
 
-void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw)
+void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace)
 {
-	if (rw == 1) {
-		/* write */
-again:
-		wait_event(dev_replace->read_lock_wq,
-			   atomic_read(&dev_replace->blocking_readers) == 0);
-		write_lock(&dev_replace->lock);
-		if (atomic_read(&dev_replace->blocking_readers)) {
-			write_unlock(&dev_replace->lock);
-			goto again;
-		}
-	} else {
-		read_lock(&dev_replace->lock);
-		atomic_inc(&dev_replace->read_locks);
-	}
+	read_lock(&dev_replace->lock);
+	atomic_inc(&dev_replace->read_locks);
 }
 
-void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw)
+void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace)
 {
-	if (rw == 1) {
-		/* write */
-		ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
+	ASSERT(atomic_read(&dev_replace->read_locks) > 0);
+	atomic_dec(&dev_replace->read_locks);
+	read_unlock(&dev_replace->lock);
+}
+
+void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace)
+{
+again:
+	wait_event(dev_replace->read_lock_wq,
+		   atomic_read(&dev_replace->blocking_readers) == 0);
+	write_lock(&dev_replace->lock);
+	if (atomic_read(&dev_replace->blocking_readers)) {
 		write_unlock(&dev_replace->lock);
-	} else {
-		ASSERT(atomic_read(&dev_replace->read_locks) > 0);
-		atomic_dec(&dev_replace->read_locks);
-		read_unlock(&dev_replace->lock);
+		goto again;
 	}
 }
 
+void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace)
+{
+	ASSERT(atomic_read(&dev_replace->blocking_readers) == 0);
+	write_unlock(&dev_replace->lock);
+}
+
 /* inc blocking cnt and release read lock */
 void btrfs_dev_replace_set_lock_blocking(
 					struct btrfs_dev_replace *dev_replace)

index f94a76844ae7..6629ff432a1d 100644
@@ -37,8 +37,10 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info,
 void btrfs_dev_replace_suspend_for_unmount(struct btrfs_fs_info *fs_info);
 int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info);
 int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace);
-void btrfs_dev_replace_lock(struct btrfs_dev_replace *dev_replace, int rw);
-void btrfs_dev_replace_unlock(struct btrfs_dev_replace *dev_replace, int rw);
+void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace);
+void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace);
+void btrfs_dev_replace_write_lock(struct btrfs_dev_replace *dev_replace);
+void btrfs_dev_replace_write_unlock(struct btrfs_dev_replace *dev_replace);
 void btrfs_dev_replace_set_lock_blocking(struct btrfs_dev_replace *dev_replace);
 void btrfs_dev_replace_clear_lock_blocking(
 					struct btrfs_dev_replace *dev_replace);

index ab852b8e3e37..a52dd12af648 100644
@@ -395,20 +395,20 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 		goto error;
 
 	/* insert extent in reada_tree + all per-device trees, all or nothing */
-	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	spin_lock(&fs_info->reada_lock);
 	ret = radix_tree_insert(&fs_info->reada_tree, index, re);
 	if (ret == -EEXIST) {
 		re_exist = radix_tree_lookup(&fs_info->reada_tree, index);
 		re_exist->refcnt++;
 		spin_unlock(&fs_info->reada_lock);
-		btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+		btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 		radix_tree_preload_end();
 		goto error;
 	}
 	if (ret) {
 		spin_unlock(&fs_info->reada_lock);
-		btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+		btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 		radix_tree_preload_end();
 		goto error;
 	}

@@ -451,13 +451,13 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 			}
 			radix_tree_delete(&fs_info->reada_tree, index);
 			spin_unlock(&fs_info->reada_lock);
-			btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+			btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 			goto error;
 		}
 		have_zone = 1;
 	}
 	spin_unlock(&fs_info->reada_lock);
-	btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 
 	if (!have_zone)
 		goto error;

index 9cfbccdeacf3..f500b37f3f00 100644
@@ -3885,11 +3885,11 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 			break;
 		}
 
-		btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
+		btrfs_dev_replace_write_lock(&fs_info->dev_replace);
 		dev_replace->cursor_right = found_key.offset + length;
 		dev_replace->cursor_left = found_key.offset;
 		dev_replace->item_needs_writeback = 1;
-		btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
+		btrfs_dev_replace_write_unlock(&fs_info->dev_replace);
 		ret = scrub_chunk(sctx, scrub_dev, chunk_offset, length,
 				  found_key.offset, cache, is_dev_replace);
 

@@ -3925,10 +3925,10 @@ int scrub_enumerate_chunks(struct scrub_ctx *sctx,
 
 		scrub_pause_off(fs_info);
 
-		btrfs_dev_replace_lock(&fs_info->dev_replace, 1);
+		btrfs_dev_replace_write_lock(&fs_info->dev_replace);
 		dev_replace->cursor_left = dev_replace->cursor_right;
 		dev_replace->item_needs_writeback = 1;
-		btrfs_dev_replace_unlock(&fs_info->dev_replace, 1);
+		btrfs_dev_replace_write_unlock(&fs_info->dev_replace);
 
 		if (ro_set)
 			btrfs_dec_block_group_ro(cache);

@@ -4144,16 +4144,16 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 		return -EIO;
 	}
 
-	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	if (dev->scrub_ctx ||
 	    (!is_dev_replace &&
 	     btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) {
-		btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+		btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 		mutex_unlock(&fs_info->scrub_lock);
 		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
 		return -EINPROGRESS;
 	}
-	btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 
 	ret = scrub_workers_get(fs_info, is_dev_replace);
 	if (ret) {

index 350c12f1f19e..991e62a48090 100644
@@ -1916,12 +1916,12 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	mutex_lock(&uuid_mutex);
 
 	num_devices = fs_info->fs_devices->num_devices;
-	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
 		WARN_ON(num_devices < 1);
 		num_devices--;
 	}
-	btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 
 	ret = btrfs_check_raid_min_devices(fs_info, num_devices - 1);
 	if (ret)

@@ -3892,12 +3892,12 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
 	}
 
 	num_devices = fs_info->fs_devices->num_devices;
-	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace)) {
 		BUG_ON(num_devices < 1);
 		num_devices--;
 	}
-	btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 	allowed = BTRFS_AVAIL_ALLOC_BIT_SINGLE | BTRFS_BLOCK_GROUP_DUP;
 	if (num_devices > 1)
 		allowed |= (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1);

@@ -5209,11 +5209,11 @@ int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len)
 		ret = 1;
 	free_extent_map(em);
 
-	btrfs_dev_replace_lock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_lock(&fs_info->dev_replace);
 	if (btrfs_dev_replace_is_ongoing(&fs_info->dev_replace) &&
 	    fs_info->dev_replace.tgtdev)
 		ret++;
-	btrfs_dev_replace_unlock(&fs_info->dev_replace, 0);
+	btrfs_dev_replace_read_unlock(&fs_info->dev_replace);
 
 	return ret;
 }

@@ -5779,10 +5779,10 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 	if (!bbio_ret)
 		goto out;
 
-	btrfs_dev_replace_lock(dev_replace, 0);
+	btrfs_dev_replace_read_lock(dev_replace);
 	dev_replace_is_ongoing = btrfs_dev_replace_is_ongoing(dev_replace);
 	if (!dev_replace_is_ongoing)
-		btrfs_dev_replace_unlock(dev_replace, 0);
+		btrfs_dev_replace_read_unlock(dev_replace);
 	else
 		btrfs_dev_replace_set_lock_blocking(dev_replace);
 

@@ -5984,7 +5984,7 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 out:
 	if (dev_replace_is_ongoing) {
 		btrfs_dev_replace_clear_lock_blocking(dev_replace);
-		btrfs_dev_replace_unlock(dev_replace, 0);
+		btrfs_dev_replace_read_unlock(dev_replace);
 	}
 	free_extent_map(em);
 	return ret;