btrfs: unlinked 34 orphans

btrfs: unlinked 34 orphans

[David Arendt]

Hi,

I received the message: btrfs: unlinked 34 orphans

Just out of couriosity: what does it mean ?

Thanks in advance
Bye,
David Arendt

Re: btrfs: unlinked 34 orphans

[Oystein Viggen]

* [David Arendt]=20

> I received the message: btrfs: unlinked 34 orphans
>
> Just out of couriosity: what does it mean ?

Ooh, ooh!  I think I know this one :)

When a file is unlinked/deleted while an application has it open, it is
kept around allocated on disk so that the app has access to the data in
the file.  When the file is closed or the app exits, it is deallocated
(disk space is freed).  This is a quite normal way of handling temporar=
y
files.

Now, if there is an unclean shutdown while a file is in this "deleted,
but not freed" state, you get an orphaned file or inode -- that is,
allocated data with no directory entry pointing to it.  When btrfs
unlinks these orphans during mount, it's just completing what would hav=
e
happened once the unlinked files were closed.  If this happened after a=
n
unclean shutdown (crash or power loss), the message is just btrfs
bragging about working properly.

None of this is actually specific to btrfs.  I believe posix filesystem=
s
are more or less required (or at least expected) to behave like this.

(interestingly, Microsoft Windows has a different take on this issue by
simply not letting you delete open files).

=D8ystein
--=20
This message was generated by a horde of attack elephants armed with PR=
NGs.

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