On 2018年08月02日 15:19, Misono Tomohiro wrote:
> Cleanup patch and no functional changes.
> 
> Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

Looks good to me.

Reviewed-by: Qu Wenruo <wqu@suse.com>

Thanks,
Qu

> ---
>  fs/btrfs/ioctl.c   |  6 ++----
>  fs/btrfs/scrub.c   |  8 ++------
>  fs/btrfs/super.c   |  9 +++------
>  fs/btrfs/volumes.c | 21 ++++++---------------
>  4 files changed, 13 insertions(+), 31 deletions(-)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index b077544b5232..2becabe2aaf4 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3165,10 +3165,8 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info,
>  	di_args->total_bytes = btrfs_device_get_total_bytes(dev);
>  	memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid));
>  	if (dev->name) {
> -		struct rcu_string *name;
> -
> -		name = rcu_dereference(dev->name);
> -		strncpy(di_args->path, name->str, sizeof(di_args->path) - 1);
> +		strncpy(di_args->path, rcu_str_deref(dev->name),
> +				sizeof(di_args->path) - 1);
>  		di_args->path[sizeof(di_args->path) - 1] = 0;
>  	} else {
>  		di_args->path[0] = '\0';
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index 6702896cdb8f..5a282268deee 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -4113,7 +4113,6 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
>  	struct scrub_ctx *sctx;
>  	int ret;
>  	struct btrfs_device *dev;
> -	struct rcu_string *name;
>  
>  	if (btrfs_fs_closing(fs_info))
>  		return -EINVAL;
> @@ -4167,11 +4166,8 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
>  	if (!is_dev_replace && !readonly &&
>  	    !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) {
>  		mutex_unlock(&fs_info->fs_devices->device_list_mutex);
> -		rcu_read_lock();
> -		name = rcu_dereference(dev->name);
> -		btrfs_err(fs_info, "scrub: device %s is not writable",
> -			  name->str);
> -		rcu_read_unlock();
> +		btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable",
> +			  rcu_str_deref(dev->name));
>  		return -EROFS;
>  	}
>  
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 81107ad49f3a..d9f00704f4aa 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -2290,7 +2290,6 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
>  	struct btrfs_fs_devices *cur_devices;
>  	struct btrfs_device *dev, *first_dev = NULL;
>  	struct list_head *head;
> -	struct rcu_string *name;
>  
>  	/*
>  	 * Lightweight locking of the devices. We should not need
> @@ -2314,12 +2313,10 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
>  		cur_devices = cur_devices->seed;
>  	}
>  
> -	if (first_dev) {
> -		name = rcu_dereference(first_dev->name);
> -		seq_escape(m, name->str, " \t\n\\");
> -	} else {
> +	if (first_dev)
> +		seq_escape(m, rcu_str_deref(first_dev->name), " \t\n\\");
> +	else
>  		WARN_ON(1);
> -	}
>  	rcu_read_unlock();
>  	return 0;
>  }
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 1da162928d1a..d30bbc3cf921 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -6187,21 +6187,12 @@ static void submit_stripe_bio(struct btrfs_bio *bbio, struct bio *bio,
>  	btrfs_io_bio(bio)->stripe_index = dev_nr;
>  	bio->bi_end_io = btrfs_end_bio;
>  	bio->bi_iter.bi_sector = physical >> 9;
> -#ifdef DEBUG
> -	{
> -		struct rcu_string *name;
> -
> -		rcu_read_lock();
> -		name = rcu_dereference(dev->name);
> -		btrfs_debug(fs_info,
> -			"btrfs_map_bio: rw %d 0x%x, sector=%llu, dev=%lu (%s id %llu), size=%u",
> -			bio_op(bio), bio->bi_opf,
> -			(u64)bio->bi_iter.bi_sector,
> -			(u_long)dev->bdev->bd_dev, name->str, dev->devid,
> -			bio->bi_iter.bi_size);
> -		rcu_read_unlock();
> -	}
> -#endif
> +	btrfs_debug_in_rcu(fs_info,
> +		"btrfs_map_bio: rw %d 0x%x, sector=%llu, dev=%lu (%s id %llu), size=%u",
> +		bio_op(bio), bio->bi_opf,
> +		(u64)bio->bi_iter.bi_sector,
> +		(u_long)dev->bdev->bd_dev, rcu_str_deref(dev->name), dev->devid,
> +		bio->bi_iter.bi_size);
>  	bio_set_dev(bio, dev->bdev);
>  
>  	btrfs_bio_counter_inc_noblocked(fs_info);
>