tools/rbd-ggate: close log before running postfork

[wjwithagen]

Otherwise the assert in Log:open() will trigger since
all data is kept during the fork and also the is_started flag

Fixes: https://tracker.ceph.com/issues/41592

Checklist

• References tracker ticket
• Updates documentation if necessary
• Includes tests for new functionality or reproducer for bug

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[trociny]

@wjwithagen I wonder isn't a350c80 fixed the similar issue in rbd-nbd? Could you please try? (Right now I don't have an evironment with freshly built ceph to try it myself).

[trociny]

Also, don't you want to backport the fix to the stable releases? Then it would be good to create a tracker ticket for this issue.

[wjwithagen]

Also, don't you want to backport the fix to the stable releases? Then it would be good to create a tracker ticket for this issue.

I think this needs to go for backport, once I has the correct fix.

Usually I first fix master, and see what comes of it. Sometimes it is a totally different problem from what I first thought.
If it then requires backporting, I make a tracker, and ask for back-ports.
I'm rather clumsy at creating back-ports, so unless I have to, I avoid them.
I also cheat, because I can add patches to the FreeBSD ports (and my jenkins tests) , in case they did not (yet) make it in the Ceph tree.

[wjwithagen]

@wjwithagen I wonder isn't a350c80 fixed the similar issue in rbd-nbd? Could you please try? (Right now I don't have an evironment with freshly built ceph to try it myself).

I tried looking in what nbd-stuff did, but overlooked the more interresting stuff.
Will try also this aproach.

[wjwithagen]

@trociny
The rbd-ndb example works....
I'll redo this PR that way.

[trociny]

@wjwithagen Excellent! So, could you please create a tracker ticket, squash your commits into one and add 'Fixes: ...' to the commit log message?

[wjwithagen]

@trociny
https://tracker.ceph.com/issues/41592

[trociny]

nit: s/fixes:/Fixes:/

otherwise LGTM