Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c9513edb authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Chris Mason
Browse files

Btrfs: fix the race between reading and updating devices 



On btrfs_congested_fn and __unplug_io_fn paths, we should hold
device_list_mutex to avoid remove/add device path to
update fs_devices->devices

On __btrfs_close_devices and btrfs_prepare_sprout paths, the devices in
fs_devices->devices or fs_devices->devices is updated, so we should hold
the mutex to avoid the reader side to reach them

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4f6c9328

fs/btrfs/disk-io.c

+2 −0
Original line number Diff line number Diff line
@@ -1410,6 +1410,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits) 
	struct btrfs_device *device;

	struct backing_dev_info *bdi;



	mutex_lock(&info->fs_devices->device_list_mutex);

	list_for_each_entry(device, &info->fs_devices->devices, dev_list) {

		if (!device->bdev)

			continue;
@@ -1419,6 +1420,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits) 
			break;

		}

	}

	mutex_unlock(&info->fs_devices->device_list_mutex);

	return ret;

}

fs/btrfs/volumes.c

+7 −0
Original line number Diff line number Diff line
@@ -481,6 +481,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices) 
	if (--fs_devices->opened > 0)

		return 0;



	mutex_lock(&fs_devices->device_list_mutex);

	list_for_each_entry(device, &fs_devices->devices, dev_list) {

		if (device->bdev) {

			blkdev_put(device->bdev, device->mode);
@@ -495,6 +496,8 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices) 
		device->writeable = 0;

		device->in_fs_metadata = 0;

	}

	mutex_unlock(&fs_devices->device_list_mutex);



	WARN_ON(fs_devices->open_devices);

	WARN_ON(fs_devices->rw_devices);

	fs_devices->opened = 0;
@@ -1415,7 +1418,11 @@ static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans, 
	INIT_LIST_HEAD(&seed_devices->devices);

	INIT_LIST_HEAD(&seed_devices->alloc_list);

	mutex_init(&seed_devices->device_list_mutex);



	mutex_lock(&root->fs_info->fs_devices->device_list_mutex);

	list_splice_init(&fs_devices->devices, &seed_devices->devices);

	mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);



	list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);

	list_for_each_entry(device, &seed_devices->devices, dev_list) {

		device->fs_devices = seed_devices;