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CA-388210: use unique datapaths for concurrent VDI copies #5920

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Testing on a box shows that the new unique arguments for 'domain' work, but opening as a draft PR, because this needs wider testing in XenRT.

This parameter was passed through unchanged.
However VDI.epoch_begin/epoch_end doesn't actually need it, so drop it.

We intend to change how we compute the 'domain' parameter, and VDI.epoch_begin/end wouldn't have
sufficient information to compute it anymore.

No functional change.

Signed-off-by: Edwin Török <[email protected]>
We are going to change how we compute it, so factor it out into a function.

No functional change.

Signed-off-by: Edwin Török <[email protected]>
…ument as domain for Dom0

Dom0 allows multiple attaches of RO disks, used e.g. for VDI.copy.
Send a unique value to SMAPIv3 plugins to avoid bugs to the lack of reference counting in those plugins.

XAPI already sends a unique value here, either vbd/domid/device, or a fresh UUID (for storage migration).

Signed-off-by: Edwin Török <[email protected]>
It is believed that the deadlocks in SMAPIv3 were caused by VDI.copy operations that attach
the same disk RO multiple times in Dom0.
With the previous commits we now use a unique identifier and spawn a separate qemu-dp process
in the SMAPIv3 plugins, which should prevent the deadlocks and IO errors due to lack of refcounting.

Signed-off-by: Edwin Török <[email protected]>
or vbd/domid/device.
For regular guests keep the domain as passed by XAPI (an integer).
*)
let domain_of ~dp ~vm' =
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Requiring a prime in named label is a bit awkward - is there a reason this is not just ~vm?

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2 participants