Re: [PATCH 1/2] btrfs: drop never met condition of disk_total_bytes == 0

[Nikolay Borisov <nborisov@suse.com>]

On 24.09.20 г. 13:11 ч., Anand Jain wrote:
> btrfs_device::disk_total_bytes is set even for a seed device (the
> comment is wrong).
> 
> The function fill_device_from_item() does the job of reading it from the
> item and updating btrfs_device::disk_total_bytes. So both the missing
> device and the seed devices do have their disk_total_bytes updated.
> 
> So this patch removes the check dev->disk_total_bytes == 0 in the
> function verify_one_dev_extent()
> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/volumes.c | 15 ---------------
>  1 file changed, 15 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 7f43ed88fffc..9be40eece8ed 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -7578,21 +7578,6 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
>  		goto out;
>  	}
>  
> -	/* It's possible this device is a dummy for seed device */
> -	if (dev->disk_total_bytes == 0) {
> -		struct btrfs_fs_devices *devs;
> -
> -		devs = list_first_entry(&fs_info->fs_devices->seed_list,
> -					struct btrfs_fs_devices, seed_list);
> -		dev = btrfs_find_device(devs, devid, NULL, NULL, false);
> -		if (!dev) {
> -			btrfs_err(fs_info, "failed to find seed devid %llu",
> -				  devid);
> -			ret = -EUCLEAN;
> -			goto out;
> -		}
> -	}

The commit which introduced this check states that the device with a
disk_total_bytes = 0 occurs from clone_fs_devices called from open_seed.
It seems the check is legit and your changelog doesn't account for that
if it's safe you should provide description why is that.

> -
>  	if (physical_offset + physical_len > dev->disk_total_bytes) {
>  		btrfs_err(fs_info,
>  "dev extent devid %llu physical offset %llu len %llu is beyond device boundary %llu",
>