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[Pádraig Brady <P@xxxxxxxxxxxxxx>]

On 06/21/2012 08:40 AM, Alexey Ababilov wrote:
> Hi!
> 
> On our machines ins Grid Dynamics (HP ProBooks and miscellaneous servers), repeating unmount if it reported "device or resource is busy" while spawning a VM is not acceptable. Very often, unmount is reported as _successful_ during the _first_ attempt, but the filesystem remains _unsynchronized_ and authorized_keys are not updated, so, the VM is not accessible by ssh. That looks strange, but it really happens.
> 
> Could you share your experience in reproducing and fixing this bug, please?
> 
> The same problem will be with sleeping for 4 seconds - the filesystem remains not synchronized.
> 
> Why are you against sync? It's innocent and it constantly fixes the bug.

Well we've just received the info above.
In any case syncing the whole system is not entirely innocent.
Though avoiding is awkward at present:
http://thread.gmane.org/gmane.linux.kernel.cross-arch/9383

I notice in the guestmount man page that it tries to sync before umount by default,
and that must be disabled with the guestmount --no-sync option.
I.E. it's doubly surprising that this is an issue.

Alexey, could you give the version of:
libguestfs-mount libguestfs fuse kernel

Richard what sync method is used.
I didn't see the definition of guestfs_internal_autosync()
in 10s grepping the source.

cheers,
Pádraig.