Re: Moving an entire subvol?

[Shriramana Sharma <samjnaa@gmail.com>]

On Tue, Dec 2, 2014 at 2:04 PM, Hugo Mills <hugo@carfax.org.uk> wrote:
>
>> Is that correct: what btr sub list shows as "top level" is indeed the
>> parent subvolume?
>
>    No, it's the top-level subvolume. (See my earlier mail about
> nomenclature). "Parent subvolume" has a number of meanings, none of
> which should be "the subvolume with subvolid 5".

Um I searched my inbox but didn't find a specific definition from you
for "top-level". You only said it's better to avoid calling it "root"
to avoid confounding it with the subvol that may be mounted at root
i.e. /.

IIUC the "top-level subvolume" can only be subvolid 5 which accords
with your later comment:

> that putting files in the top-level subvol can't do what most people
> want to do with it. Hence the recommended subvol management layout at
> [1] https://btrfs.wiki.kernel.org/index.php/SysadminGuide#Subvolumes

... which means that I am not able to understand the output of btr sub
list which gives the subvolid of whichever subvol is currently the
"parent" (as in outer nesting) subvol. Observe:

$ btr sub list .
ID 257 gen 10 top level 5 path test1
ID 258 gen 10 top level 5 path test2
ID 259 gen 9 top level 258 path test2/foo
$ sudo mv test2/foo test1/
$ btr sub list .
ID 257 gen 10 top level 5 path test1
ID 258 gen 10 top level 5 path test2
ID 259 gen 9 top level 257 path test1/foo
$

So now what is the meaning of "top level"?

-- 
Shriramana Sharma ஶ்ரீரமணஶர்மா श्रीरमणशर्मा