Re: Deleting subvolumes - there be dragons

[Hugo Mills <hugo@carfax.org.uk>]

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On Wed, Jan 29, 2014 at 12:41:57PM +0100, KC wrote:
> I just read this article here: https://lwn.net/Articles/579009/
> which states:
> 
> ---------------------------------
> btrfs subvolume delete path
> 
>  For ordinary subvolumes (as opposed to snapshots, described below),
> the subvolume indicated by path must be empty before it can be
> deleted.
> ---------------------------------

   As you have found, that's not correct. In fact, there's a couple of
potentially misleading things in that article, just from skimming the
first few paragraphs...

> So I gave it a try:
> 
> $ sudo btrfs subvolume create /home2
> $ sudo mkdir /home2/lalala
> < copy a random pdf file into /home2/lalala) >
> $ sudo btrfs subvolume delete /home2
> 
> And boom! It's all gone!
> Even though subvolume was not empty.
> 
> So apart from the fact that it looks like the article is wrong here,
> it seems very dangerous to me that one simple command can nuke an
> entire volume, even if it's full of files and folders.

   You can do the same thing with rm -rf on any filesystem. So yes,
it's a dangerous command, and you need to be sure you want to run it.

> Of course I'm new to btrfs so maybe I'm reading something wrong. If
> so, then please do set me straight.

   No, I think the author of the article is just mistaken.

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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    --- You can't expect a boy to be depraved until he's gone to ---     
                             a good school.                              

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