Btrfs devel - Mar 2011 - how to know when all space from a snapshot delete is freed?

For some time after I issue a snapshot delete, the space in the volume
is freed.  It starts to free quite fast and then the progress slows and
speeds up again.

Given that the return from the snapshot delete command is immediate and
the space is freed asynchronously, how can I determine absolutely that
the snapshot has been entirely removed and the space freeing operation
is complete?

Cheers,
b.

David worked for some time to a solution to this kind of problem. But I
don''t know if it was merged.

See posts on this ML with subject "PATCH: IOCTL#21 progs"

On 03/02/2011 02:12 PM, Brian J. Murrell wrote:
> For some time after I issue a snapshot delete, the space in the volume
> is freed.  It starts to free quite fast and then the progress slows and
> speeds up again.
> 
> Given that the return from the snapshot delete command is immediate and
> the space is freed asynchronously, how can I determine absolutely that
> the snapshot has been entirely removed and the space freeing operation
> is complete?
> 
> Cheers,
> b.
> 
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the patch has been working in production at the sponsor''s site for
some weeks. It has not been merged, or even built by anyone else, to
my knowledge.

The working kernel patch is at https://patchwork.kernel.org/patch/482721/

The open question, that everyone has more important things to do than
talk about, is, to flesh out the iputs stuff or discard it or put it
in as-is.  That question is orthogonal to the function of the
notification-of-completed-dead-root-removal parts, which are complete
and work as designed.

On Wed, Mar 2, 2011 at 3:14 PM, Goffredo Baroncelli <kreijack@libero.it>
wrote:
> David worked for some time to a solution to this kind of problem. But I
> don''t know if it was merged.
>
> See posts on this ML with subject "PATCH: IOCTL#21 progs"

-- 
"Reasonable, civil, and intelligent people have not left much of a
mark on history." -- T. Herman Zweibel
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On Wed, Mar 2, 2011 at 7:12 AM, Brian J. Murrell <brian@interlinx.bc.ca>
wrote:
> Given that the return from the snapshot delete command is immediate and
> the space is freed asynchronously, how can I determine absolutely that
> the snapshot has been entirely removed and the space freeing operation
> is complete?
>
> Cheers,
> b.
since you just want to determine, and not wait, patch your kernel,
then invoke ioctl#21 with flags of 0x0000 and timeout of 0x0001. you
will have an answer in approximately one millisecond.


-- 
"Reasonable, civil, and intelligent people have not left much of a
mark on history." -- T. Herman Zweibel
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