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 E78F927A904; Fri, 9 Jan 2026 16:25:32 +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=1767975933; cv=none; b=fFol2EKTRGOZVXKYSMh7IY/l6ug0cEL0StsIT2v3MzSnM3YGkR02xclynREWR/GmVRivhG1sbKGaJoECgEAFamKB0MqD7RDco3w8SEfHD4wuSS4OvEuFaiRSmWaqYn42POYDCaFMn6A0cs+HW985noMtITw3ChrVS2o3FbdnEuI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767975933; c=relaxed/simple; bh=FhiNykbiBss1/KxwHOY92IhGt6Pi7ObKBHR7HRP4rhI=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=rxVXvmTLW020ktdhmAehr0SMqK4Y5HPUehYIYL9QfkNKhnRTp3O8g3oKSdSsVS29R/Z9UVSMA+SB9WiEbu95VxX5hgm7Rtm6wj4MLHjYkxy9lkAvKmF62oJztR1guXxBnHGdzFYrZgrob81eE7wV8PCxGexDJwjOFqsxybiznnY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=STfxoSlb; 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="STfxoSlb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 917C9C4CEF1; Fri, 9 Jan 2026 16:25:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767975932; bh=FhiNykbiBss1/KxwHOY92IhGt6Pi7ObKBHR7HRP4rhI=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=STfxoSlbQMlu7HhmiWYvIrsXTnvyGlDCVa7VOP9Nw/A9k+1FYy7royV3REWQ8eH6v 2O5VZwDNpvX3uIBXaEDljGWdQcqGmGe81qtaSPhuYZompnKEXYDoGfbRqR5sJ9H6CE zonj4OdVZPJST1t26o2ARC4g+TuKON0CWPOddH9JUCueFbCrTHzZqxlQCM0mSGCIxS yy5iEYChmX+m3lILxLH8tpMF8/05DmsFXYtG40J9B2ThLXQvUjCzREohxqIOkSzRp4 h2RBI0RGUeS4Xa0osWBBWoZOsIazUD8QihXuHr0qRxVHA8xNNiZBouMGOVx2UgWKjq 6nCwgmUuYqT3w== Message-ID: <206cb47d470bb06b26175755adec013cfac759d7.camel@kernel.org> Subject: Re: [PATCH v2 0/6] Automatic NFSv4 state revocation on filesystem unmount From: Jeff Layton To: Chuck Lever , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Chuck Lever , Christian Brauner , Jan Kara , Al Viro Date: Fri, 09 Jan 2026 11:25:30 -0500 In-Reply-To: <20260108004016.3907158-1-cel@kernel.org> References: <20260108004016.3907158-1-cel@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2026-01-07 at 19:40 -0500, Chuck Lever wrote: > From: Chuck Lever >=20 > When an NFS server exports a filesystem and clients hold NFSv4 state > (opens, locks, delegations), unmounting the underlying filesystem > fails with EBUSY. The /proc/fs/nfsd/unlock_fs interface exists for > administrators to manually revoke state before retrying the unmount, > but this approach has significant operational drawbacks. >=20 > Manual intervention breaks automation workflows. Containerized NFS > servers, orchestration systems, and unattended maintenance scripts > cannot reliably unmount exported filesystems without implementing > custom logic to detect the failure and invoke unlock_fs. System > administrators managing many exports face tedious, error-prone > procedures when decommissioning storage. >=20 > This series enables the NFS server to detect filesystem unmount > events and automatically revoke associated state. The mechanism > uses the kernel's existing fs_pin infrastructure, which provides > callbacks during mount lifecycle transitions. >=20 (cc'ing the vfs maintainers) One thing I want to point out here is that the only user of fs_pin is the BSD process accounting subsystem, which would be really nice to get rid of at some point: https://lore.kernel.org/linux-fsdevel/20260106-bsd-acct-v1-1-d15564b52c83@k= ernel.org/ I suspect the VFS maintainers might want you to use something different here so fs_pin can eventually go away too. An alternate idea might be to plumb an srcu notifier chain into the umount codepath, similar to the lease_notifier_chain in fs/locks.c. Then nfsd could register to be notified when there is a umount attempt and do the right thing to tear down state. > When a filesystem > is unmounted, all NFSv4 opens, locks, and delegations referencing > it are revoked, async COPY operations are cancelled with > NFS4ERR_ADMIN_REVOKED sent to clients, NLM locks are released, > and cached file handles are closed. >=20 > With automatic revocation, unmount operations complete without > administrator intervention once the brief state cleanup finishes. > Clients receive immediate notification of state loss through > standard NFSv4 error codes, allowing applications to handle the > situation appropriately rather than encountering silent failures. >=20 > Based on the nfsd-testing branch of: >=20 > https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/ >=20 > Changes since v1: > - Explain why drop_client() is being renamed > - Finish implementing revocation on umount > - Rename pin_insert_group > - Clarified log output and code comments > - Hold nfsd_mutex while closing nfsd_files >=20 > Chuck Lever (6): > nfsd: cancel async COPY operations when admin revokes filesystem state > fs: export pin_insert and pin_remove for modular filesystems > fs: add pin_insert_sb() for superblock-only pins > fs: invoke group_pin_kill() during mount teardown > nfsd: revoke NFSv4 state when filesystem is unmounted > nfsd: close cached files on filesystem unmount >=20 > fs/fs_pin.c | 50 ++++++++ > fs/namespace.c | 2 + > fs/nfsd/Makefile | 2 +- > fs/nfsd/filecache.c | 44 +++++++ > fs/nfsd/filecache.h | 1 + > fs/nfsd/netns.h | 4 + > fs/nfsd/nfs4proc.c | 124 +++++++++++++++++-- > fs/nfsd/nfs4state.c | 46 +++++-- > fs/nfsd/nfsctl.c | 11 +- > fs/nfsd/pin.c | 274 +++++++++++++++++++++++++++++++++++++++++ > fs/nfsd/state.h | 9 ++ > fs/nfsd/xdr4.h | 1 + > include/linux/fs_pin.h | 1 + > 13 files changed, 548 insertions(+), 21 deletions(-) > create mode 100644 fs/nfsd/pin.c --=20 Jeff Layton