From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E3EC62E7F11; Sun, 1 Mar 2026 18:19:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772389165; cv=none; b=T4X9bbc2SIAv0pibAjLU0XxRCWEQdL2HuUwHbfYsFXea4UzQYaJwpIRDj//nhXk9dIdZ3Mtc+BT8c+4hdQlW7X00AXMmaoHIbBLTjvwSzaWFULaZAtgttUCJoZ9gjIKCkMol3ZNmgfBgnUEqHVY5ZH9iNGyj26knZBDutx+gdRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772389165; c=relaxed/simple; bh=nuBGqJp9wHKEQIFVaF8YscjzAS45MPN091edCGD91Pc=; h=MIME-Version:Date:From:To:Cc:Message-Id:In-Reply-To:References: Subject:Content-Type; b=H/1a0rRb8BkHXTFtEBo4yVRCfuht5bnHrg6BMfaMqkGhX12uyYmkJYtfI5DDB5+qrol+dz9Tmv2wtAkuDuQl6NiYa0so0tGuOF0mwZzO/gnteWptFdAK6bB3vS93EtOGpV59MEkVMEUo3QuQ6+8fXKzqIeJHxSdbI69liCBcZts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a67ysH+K; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="a67ysH+K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 18A0FC2BC86; Sun, 1 Mar 2026 18:19:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772389164; bh=nuBGqJp9wHKEQIFVaF8YscjzAS45MPN091edCGD91Pc=; h=Date:From:To:Cc:In-Reply-To:References:Subject:From; b=a67ysH+KFsrmvVX9NW9WMKrKle0oDA8YO3N1osFkQC76lUwf956JCcSNZYZkoHCYq yx/XwOFvIhcw5gXG6IvBJkyGZBQSV6e2mlcUbRqMp3iJRFXNbaH/f//E/I+lHvHAHj CBg1JnxW/0RHkulMImBtIijkj92kCyoPf7WGOr40WNl6VnNFKqy0W+flqo1vVexGHb F5HGkWRidzYqExm5n/YBda3MVQaNlhcuENLaY3/ThtETcZsu0CUiCAIq3rDT1Rzuuy +hXuZz+UxV8F/+1I5RrLELG97yV8sw7VTsh7xMBBgQmnDXnXsoT+1G0mtrd9ghDjrq J+BZVwUMBBVlg== Received: from phl-compute-10.internal (phl-compute-10.internal [10.202.2.50]) by mailfauth.phl.internal (Postfix) with ESMTP id 0FFE0F40090; Sun, 1 Mar 2026 13:19:23 -0500 (EST) Received: from phl-imap-15 ([10.202.2.104]) by phl-compute-10.internal (MEProxy); Sun, 01 Mar 2026 13:19:23 -0500 X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddvheehgeelucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepofggfffhvfevkfgjfhfutgfgsehtqhertdertdejnecuhfhrohhmpedfvehhuhgt khcunfgvvhgvrhdfuceotggvlheskhgvrhhnvghlrdhorhhgqeenucggtffrrghtthgvrh hnpefghfeguedtieeiveeugfevtdejfedukeevgfeggfeugfetgfeltdetueelleelteen ucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegthhhutg hklhgvvhgvrhdomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqudeifeegleel leehledqfedvleekgeegvdefqdgtvghlpeepkhgvrhhnvghlrdhorhhgsehfrghsthhmrg hilhdrtghomhdpnhgspghrtghpthhtohepuddvpdhmohguvgepshhmthhpohhuthdprhgt phhtthhopegrmhhirhejfehilhesghhmrghilhdrtghomhdprhgtphhtthhopegsrhgruh hnvghrsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehjlhgrhihtohhnsehkvghrnhgv lhdrohhrghdprhgtphhtthhopegthhhutghkrdhlvghvvghrsehorhgrtghlvgdrtghomh dprhgtphhtthhopegurghirdhnghhosehorhgrtghlvgdrtghomhdprhgtphhtthhopehn vghilhgssehofihnmhgrihhlrdhnvghtpdhrtghpthhtohepohhkohhrnhhivghvsehrvg guhhgrthdrtghomhdprhgtphhtthhopehjrggtkhesshhushgvrdgtohhmpdhrtghpthht ohepjhgrtghksehsuhhsvgdrtgii X-ME-Proxy: Feedback-ID: ifa6e4810:Fastmail Received: by mailuser.phl.internal (Postfix, from userid 501) id DADFD780070; Sun, 1 Mar 2026 13:19:22 -0500 (EST) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AVsRjBM015Tw Date: Sun, 01 Mar 2026 13:19:02 -0500 From: "Chuck Lever" To: "Amir Goldstein" Cc: "Jan Kara" , "Christian Brauner" , "Jan Kara" , NeilBrown , "Jeff Layton" , "Olga Kornievskaia" , "Dai Ngo" , "Tom Talpey" , linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, "Chuck Lever" Message-Id: <07a2af61-6737-4e47-ad69-652af18eb47b@app.fastmail.com> In-Reply-To: References: <20260224163908.44060-1-cel@kernel.org> <20260224163908.44060-2-cel@kernel.org> <20260226-alimente-kunst-fb9eae636deb@brauner> <1165a90b-acbf-4c0d-a7e3-3972eba0d35a@kernel.org> <3cff098e-74a8-4111-babb-9c13c7ba2344@kernel.org> Subject: Re: [PATCH v3 1/3] fs: add umount notifier chain for filesystem unmount notification Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Sun, Mar 1, 2026, at 1:09 PM, Amir Goldstein wrote: > On Sun, Mar 1, 2026 at 6:21=E2=80=AFPM Chuck Lever wr= ote: >> Perhaps that description nails down too much implementation detail, >> and it might be stale. A broader description is this user story: >> >> "As a system administrator, I'd like to be able to unexport an NFSD > > Doesn't "unexporting" involve communicating to nfsd? > Meaning calling to svc_export_put() to path_put() the > share root path? > >> share that is being accessed by NFSv4 clients, and then unmount it, >> reliably (for example, via automation). Currently the umount step >> hangs if there are still outstanding delegations granted to the NFSv4 >> clients." > > Can't svc_export_put() be the trigger for nfsd to release all resources > associated with this share? Currently unexport does not revoke NFSv4 state. So, that would be a user-visible behavior change. I suggested that approach a few months ago to linux-nfs@ and there was push-back. >> The discussion here has added some interesting corner cases: NFSD >> can export bind mounts (portions of a local physical file system); >> unprivileged users can create and umount file systems using "share". > > The basic question is whether nfsd is exporting a mount, a filesystem > or something in between (i.e. a subtree of a filesystem). > > AFAIK, the current implementation is that nfsd is actually exporting > one specific mount, so changing the properties of this mount > (e.g. readonly) would affect the exported share. AIUI NFSD can export starting at any arbitrary directory that appears in the mount namespace. It does not have to start at the local file system's root directory. But even so, outstanding NFSv4 delegations on a narrow portion of a mounted file system will still pin that mount. --=20 Chuck Lever