From: Steven Whitehouse <swhiteho@redhat.com>
To: cluster-devel.redhat.com
Subject: [Cluster-devel] [PATCH 1/2] GFS2: use schedule timeout in find insert glock
Date: Mon, 8 Oct 2018 14:13:10 +0100 [thread overview]
Message-ID: <2d468838-ea79-9c89-ae02-89b18f4bda37@redhat.com> (raw)
In-Reply-To: <2889867.YGlmsYasr8@dhcp-3-135.uk.xensource.com>
Hi,
On 08/10/18 14:10, Tim Smith wrote:
> On Monday, 8 October 2018 14:03:24 BST Steven Whitehouse wrote:
>> On 08/10/18 13:59, Mark Syms wrote:
>>> That sounds entirely reasonable so long as you are absolutely sure that
>>> nothing is ever going to mess with that glock, we erred on the side of
>>> more caution not knowing whether it would be guaranteed safe or not.
>>>
>>> Thanks,
>>>
>>> Mark
>> We should have a look at the history to see how that wait got added.
>> However the "dead" flag here means "don't touch this glock" and is there
>> so that we can separate the marking dead from the actual removal from
>> the list (which simplifies the locking during the scanning procedures)
> You beat me to it :-)
>
> I think there might be a bit of a problem inserting a new entry with the same
> name before the old entry has been fully destroyed (or at least removed),
> which would be why the schedule() is there.
>
If the old entry is marked dead, all future lookups should ignore it. We
should only have a single non-dead entry at a time, but that doesn't
seem like it should need us to wait for it.
If we do discover that the wait is really required, then it sounds like
as you mentioned above there is a lost wakeup, and that must presumably
be on a code path that sets the dead flag and then fails to send a wake
up later on. If we can drop the wait in the first place, that seems like
a better plan,
Steve.
next prev parent reply other threads:[~2018-10-08 13:13 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-08 12:36 [Cluster-devel] [PATCH 0/2] GFS2 locking patches Mark Syms
2018-10-08 12:36 ` [Cluster-devel] [PATCH 1/2] GFS2: use schedule timeout in find insert glock Mark Syms
2018-10-08 12:56 ` Steven Whitehouse
2018-10-08 12:59 ` Mark Syms
2018-10-08 13:03 ` Steven Whitehouse
2018-10-08 13:10 ` Tim Smith
2018-10-08 13:13 ` Steven Whitehouse [this message]
2018-10-08 13:26 ` Tim Smith
2018-10-09 8:13 ` Mark Syms
2018-10-09 8:41 ` Steven Whitehouse
2018-10-09 8:50 ` Mark Syms
2018-10-09 12:34 ` Andreas Gruenbacher
2018-10-09 14:00 ` Tim Smith
2018-10-09 14:47 ` Andreas Gruenbacher
2018-10-09 15:34 ` Tim Smith
2018-10-08 13:25 ` Bob Peterson
2018-10-08 12:36 ` [Cluster-devel] [PATCH 2/2] GFS2: Flush the GFS2 delete workqueue before stopping the kernel threads Mark Syms
2018-10-08 12:57 ` Steven Whitehouse
2018-10-08 20:10 ` Bob Peterson
2018-10-08 20:53 ` Mark Syms
[not found] ` <1603192.QCZcUHDx0E@dhcp-3-135.uk.xensource.com>
[not found] ` <CAHc6FU7AyDQ=yEj9WtN+aqtf7jfWs0TGh=Og0fQFVHyYMKHacA@mail.gmail.com>
2018-10-09 15:08 ` [Cluster-devel] [PATCH 1/2] GFS2: use schedule timeout in find insert glock Tim Smith
2018-10-10 8:22 ` Tim Smith
2018-10-11 8:14 ` Mark Syms
2018-10-11 19:28 ` Mark Syms
[not found] ` <5bbfa461.1c69fb81.1242f.59a7SMTPIN_ADDED_BROKEN@mx.google.com>
2019-03-06 16:14 ` Andreas Gruenbacher
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