From: no-reply@sashiko.virtuozzo.com
To: Konstantin Khorenko <khorenko@virtuozzo.com>,
Liu Kui <kui.liu@virtuozzo.com>
Cc: devel@openvz.org, azaitsev@virtuozzo.com
Subject: Re: [Devel] [PATCH hci-8.1 3/3] fs/fuse: use wait_var_event to wait for fuse file references
Date: Wed, 30 Sep 2026 05:51:54 +0000 [thread overview]
Message-ID: <010701a0f0de952e-d3ea2dd4-834d-48fe-aad5-e063b184afce-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20260930-close-wait-rework-v2-v1-3-f8062178544a@virtuozzo.com>
> On close_wait mounts, fuse_release_close_wait() needs to wait for all
> asynchronous references to the fuse file to be dropped before sending
> FUSE_RELEASE. This wait on fi->page_waitq was inherited from the past
> implementation and is no longer appropriate as the wait condition
> evolved:
>
> - fi->page_waitq is meant to serve page-under-writeback waiters and
> fuse_set_nowrite()'s writectr waiters; now it also has to serve the
> ff reference waiter, so every wakeup can wake unrelated waiters.
>
> - the wake is decoupled from the decrement, so every path dropping an
> ff reference must remember to wake fi->page_waitq, and because of
> this we grew two variants of the stock fuse_file_put():
> __fuse_file_put() and fuse_release_ff(). This is bug prone, and a
> misuse can leave the releaser blocked forever.
>
> Instead of waiting on fi->page_waitq, a simple wait_var_event() on
> &ff->count serves the purpose best: the matching wake_up_var() uses
> the address purely as a hash key and never dereferences it, so the
> wakeup can be folded into fuse_file_put() itself. With that, both
> __fuse_file_put() and fuse_release_ff() become redundant and are
> removed. This cleanup also makes the code less divergent from
> mainline.
>
> https://virtuozzo.atlassian.net/browse/VSTOR-147878
>
> Signed-off-by: Liu Kui <kui.liu@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20260930-close-wait-rework-v2-v1-0-f8062178544a@virtuozzo.com?part=3
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next prev parent reply other threads:[~2026-09-30 5:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 5:44 [Devel] [PATCH hci-8.1 0/3] fs/fuse: rework close_wait handling Liu Kui
2026-09-30 5:44 ` [Devel] [PATCH hci-8.1 1/3] fs/fuse: give num_openers and i_size_unstable each a single role Liu Kui
2026-09-30 5:50 ` no-reply
2026-09-30 5:44 ` [Devel] [PATCH hci-8.1 2/3] fs/fuse: move the close_wait handling of fuse_release() into a helper Liu Kui
2026-09-30 5:49 ` no-reply
2026-09-30 5:44 ` [Devel] [PATCH hci-8.1 3/3] fs/fuse: use wait_var_event to wait for fuse file references Liu Kui
2026-09-30 5:51 ` no-reply [this message]
2026-09-30 15:39 ` [Devel] [PATCH hci-8.1 0/3] fs/fuse: rework close_wait handling Konstantin Khorenko
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