Need to force sync(2) before umounting UFS1 filesystems?

[Attilio Rao]

2011/9/29 Kirk McKusick <mckusick at mckusick.com>:
> Hi Attilio,
>
> I have been looking into the problem described below and since you
> appear to be the person that put in the change in question, I would
> like to get you opinion on what (if anything) should be changed here.

Kirk,
please note that I didn't add/change anything wrt. that codepath.

In the old code it was present a lockmgr() acquisition with LK_DRAIN
and LK_NOWAIT. This means that if the lockmgr() lock on the struct
mount was already held by any other consumer it was going to fallback
in the codepath you outlined in the patch immediately, rather than
just sleeping (and note that LK_NOWAIT was just passed in the case of
a non-forced unmount).

Said that, I don't really have an objection with making the forced
unmount case as the default, but I still didn't go through the whole
thread you outlined and I don't have any context on it, thus I'm not
sure if this is the right approach or not.

If you want to share more context on the problem you are trying to
solve by switching that policy we may discuss this too, but in general
I don't have a problem about adopting forced unmount policy on unmount
for all the cases.

Attilio


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