btrfs progs always assume devid 1?

From: Roman Mamedov <rm@romanrm.net>
To: linux-btrfs@vger.kernel.org
Subject: btrfs progs always assume devid 1?
Date: Thu, 6 Dec 2018 00:50:49 +0500	[thread overview]
Message-ID: <20181206005049.3642ebd0@natsu> (raw)

Hello,

To migrate my FS to a different physical disk, I have added a new empty device
to the FS, then ran the remove operation on the original one.

Now my FS has only devid 2:

Label: 'p1'  uuid: d886c190-b383-45ba-9272-9f00c6a10c50
	Total devices 1 FS bytes used 36.63GiB
	devid    2 size 50.00GiB used 45.06GiB path /dev/mapper/vg-p1

And all the operations of btrfs-progs now fail to work in their default
invocation, such as:

# btrfs fi resize max .
Resize '.' of 'max'
ERROR: unable to resize '.': No such device

[768813.414821] BTRFS info (device dm-5): resizer unable to find device 1

Of course this works:

# btrfs fi resize 2:max .
Resize '.' of '2:max'

But this is inconvenient and seems to be a rather simple oversight. If what I
got is normal (the device staying as ID 2 after such operation), then count
that as a suggestion that btrfs-progs should use the first existing devid,
rather than always looking for hard-coded devid 1.

-- 
With respect,
Roman