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 A53B73D9044; Wed, 18 Mar 2026 14:58:56 +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=1773845936; cv=none; b=AVjY9O8U4m4bN04O/IzTaktdM3HplfedssmjwENSV+eIqc07htRsouxNgdG1npk7KNwHwrA60J3MKLZYzoieKFIKiKQO81FiipsTG4LstYkkihC3g/BAPcs4WNwy8Xy9Aw3MxEr36Uwl8TBnXsI2ARs7t/YH4s2J0b6Il4ZC9rM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773845936; c=relaxed/simple; bh=aAbnsQVPN1J2BrCXY2H7APqrRX59etxEHRefU+4iVrw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=TIdVBpvT/CXrtDHV3D+9bePQgZtIK4gpwWyFhZvpZRXDorxbcxPBviLp2YjMkvWCqnCWqjSXmJ2POIveGd3F4h0uWivYnKG2BSc32cpcC0uF5dloMVDe0e/OmfWqhunOukw/w9dIz6u8OQo9lNVwRevCt6WlHbF4xEzEY0M8Wvk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WVFWVIdm; 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="WVFWVIdm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC838C19421; Wed, 18 Mar 2026 14:58:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773845936; bh=aAbnsQVPN1J2BrCXY2H7APqrRX59etxEHRefU+4iVrw=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=WVFWVIdmV0DD9MqATiUwDFhXxmKEyj6/rxNROIIJw/7RkCG9dGr6s17VZpogGU6d/ z/qekYo/bP8aKHF11445X639urDIHpI2VCysj5RI3B9OmXmdB47xsc6biND2dirsYm s2CtR0DGy3a88G4ybjf5Zws8QurgfDfh8owZQcsJQ0Q1VRxHwTBotsIwgFNk2I19wW rQWITyt9Gym1YsCELa4xYTjdzlorsVOpa9RVaJpUuxjHpp/4kzwfDCa5V8ch5nd7nB pHXGKZzvB+IdtkDIQG3nIwI67pzGBce5z8yvoUmTOU6qFSzhWEbp2BNqiH6atPS6ts mmQTVspeilqBA== Message-ID: Subject: Re: [PATCH v4 5/6] NFSD: Add export-scoped state revocation 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 Date: Wed, 18 Mar 2026 10:58:53 -0400 In-Reply-To: <202c9697-82cd-409a-8c5c-ea56a3830a8a@kernel.org> References: <20260318-umount-kills-nfsv4-state-v4-0-56aad44ab982@oracle.com> <20260318-umount-kills-nfsv4-state-v4-5-56aad44ab982@oracle.com> <202c9697-82cd-409a-8c5c-ea56a3830a8a@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2026-03-18 at 10:51 -0400, Chuck Lever wrote: > On 3/18/26 10:47 AM, Jeff Layton wrote: > > On Wed, 2026-03-18 at 10:15 -0400, Chuck Lever wrote: > > > From: Chuck Lever > > >=20 > > > nfsd4_revoke_states() revokes all NFSv4 state on an entire > > > superblock, which is too coarse when multiple exports share a > > > filesystem. Add nfsd4_revoke_export_states() to revoke only > > > state associated with files under a specific export root, then > > > convert nfsd4_revoke_states() to a thin wrapper that passes > > > sb->s_root. > > >=20 > > > nfsd4_revoke_export_states() uses find_next_sb_stid() to locate > > > candidate stids, then verifies each against the export root via > > > nfsd_file_inode_is_in_subtree(). That helper is placed in the > > > file cache layer (filecache.c) because it operates on VFS types > > > with no NFSv4 state dependency. It walks all of an inode's > > > dentry aliases rather than calling d_find_any_alias(), because > > > for hard-linked files an arbitrary alias may fall outside the > > > export subtree even when another alias is inside it. > > >=20 > > > When the export root is the filesystem root, the subtree check > > > is elided and every stid matching the superblock is revoked > > > directly. > > >=20 > > > The NFSD_UNLOCK_TYPE_FILESYSTEM handler now calls > > > nfsd4_revoke_export_states() with the resolved path dentry, > > > enabling subtree-scoped revocation through the netlink > > > interface. > > >=20 > > > Signed-off-by: Chuck Lever > > > --- > > > fs/nfsd/filecache.c | 32 +++++++++++++++++++ > > > fs/nfsd/filecache.h | 1 + > > > fs/nfsd/nfs4state.c | 92 +++++++++++++++++++++++++++++++++++++------= ---------- > > > fs/nfsd/nfsctl.c | 3 +- > > > fs/nfsd/state.h | 7 ++++ > > > 5 files changed, 107 insertions(+), 28 deletions(-) > > >=20 > > > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > > > index 1e2b38ed1d35..cd09be0c5465 100644 > > > --- a/fs/nfsd/filecache.c > > > +++ b/fs/nfsd/filecache.c > > > @@ -894,6 +894,38 @@ __nfsd_file_cache_purge(struct net *net) > > > nfsd_file_dispose_list(&dispose); > > > } > > > =20 > > > +/** > > > + * nfsd_file_inode_is_in_subtree - check whether an inode is under a= subtree > > > + * @inode: inode to test > > > + * @root_dentry: dentry of the subtree root > > > + * > > > + * Check whether @inode has any dentry alias that falls within the > > > + * subtree rooted at @root_dentry. Hard-linked files can have alias= es > > > + * in multiple directories, so all aliases must be tested. > > > + * > > > + * Return: %true if any dentry alias of @inode is at or below > > > + * @root_dentry, %false otherwise. > > > + */ > > > +bool nfsd_file_inode_is_in_subtree(struct inode *inode, > > > + struct dentry *root_dentry) > > > +{ > > > + struct dentry *alias; > > > + bool found =3D false; > > > + > > > + /* i_lock stabilizes the alias list; is_subdir() nests > > > + * rename_lock (a seqlock) beneath it but does not sleep. > > > + */ > > > + spin_lock(&inode->i_lock); > > > + hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) { > > > + if (is_subdir(alias, root_dentry)) { > > > + found =3D true; > > > + break; > > > + } > > > + } > > > + spin_unlock(&inode->i_lock); > > > + return found; > > > +} > > > + > > > static struct nfsd_fcache_disposal * > > > nfsd_alloc_fcache_disposal(void) > > > { > > > diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h > > > index b383dbc5b921..36c9a8e388d2 100644 > > > --- a/fs/nfsd/filecache.h > > > +++ b/fs/nfsd/filecache.h > > > @@ -70,6 +70,7 @@ struct net *nfsd_file_put_local(struct nfsd_file __= rcu **nf); > > > struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); > > > struct file *nfsd_file_file(struct nfsd_file *nf); > > > void nfsd_file_close_inode_sync(struct inode *inode); > > > +bool nfsd_file_inode_is_in_subtree(struct inode *inode, struct dentr= y *root_dentry); > > > void nfsd_file_net_dispose(struct nfsd_net *nn); > > > bool nfsd_file_is_cached(struct inode *inode); > > > __be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *f= hp, > > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > > > index 891669b32804..581f38395c42 100644 > > > --- a/fs/nfsd/nfs4state.c > > > +++ b/fs/nfsd/nfs4state.c > > > @@ -1763,15 +1763,6 @@ static struct nfs4_stid *find_next_sb_stid(str= uct nfs4_client *clp, > > > return stid; > > > } > > > =20 > > > -static struct nfs4_stid *find_one_sb_stid(struct nfs4_client *clp, > > > - struct super_block *sb, > > > - unsigned int sc_types) > > > -{ > > > - unsigned long id =3D 0; > > > - > > > - return find_next_sb_stid(clp, sb, sc_types, &id); > > > -} > > > - > > > static void revoke_ol_stid(struct nfs4_client *clp, > > > struct nfs4_ol_stateid *stp) > > > { > > > @@ -1835,20 +1826,19 @@ static void revoke_one_stid(struct nfs4_clien= t *clp, struct nfs4_stid *stid) > > > } > > > =20 > > > /** > > > - * nfsd4_revoke_states - revoke all nfsv4 states associated with giv= en filesystem > > > - * @nn: used to identify instance of nfsd (there is one per net na= mespace) > > > - * @sb: super_block used to identify target filesystem > > > + * nfsd4_revoke_export_states - revoke states associated with a give= n export > > > + * @nn: nfsd_net identifying the nfsd instance (one per ne= t namespace) > > > + * @sb: super_block of the export's filesystem > > > + * @root_dentry: dentry of the export root directory > > > * > > > * All nfs4 states (open, lock, delegation, layout) held by the serv= er instance > > > - * and associated with a file on the given filesystem will be revoke= d resulting > > > - * in any files being closed and so all references from nfsd to the = filesystem > > > - * being released. Thus nfsd will no longer prevent the filesystem = from being > > > - * unmounted. > > > - * > > > - * The clients which own the states will subsequently being notified= that the > > > - * states have been "admin-revoked". > > > + * and associated with files under the given export will be revoked.= When > > > + * @root_dentry is the filesystem root, all state on @sb is revoked = (equivalent > > > + * to nfsd4_revoke_states). When @root_dentry is a subdirectory, on= ly state on > > > + * files within that subtree is revoked. > > > */ > > > -void nfsd4_revoke_states(struct nfsd_net *nn, struct super_block *sb= ) > > > +void nfsd4_revoke_export_states(struct nfsd_net *nn, struct super_bl= ock *sb, > > > + struct dentry *root_dentry) > > > { > > > unsigned int idhashval; > > > unsigned int sc_types; > > > @@ -1861,18 +1851,53 @@ void nfsd4_revoke_states(struct nfsd_net *nn,= struct super_block *sb) > > > struct nfs4_client *clp; > > > retry: > > > list_for_each_entry(clp, head, cl_idhash) { > > > - struct nfs4_stid *stid =3D find_one_sb_stid(clp, sb, > > > - sc_types); > > > - if (stid) { > > > - spin_unlock(&nn->client_lock); > > > + struct nfs4_stid *stid; > > > + /* Resets to zero on each retry; revocation may > > > + * alter the IDR, so a stale cursor is unsafe. > > > + */ > > > + unsigned long id =3D 0; > > > + > > > + while ((stid =3D find_next_sb_stid(clp, sb, > > > + sc_types, &id)) !=3D NULL) { > > > + if (root_dentry !=3D sb->s_root) { > > > + bool match; > > > + > > > + /* Bare inc to pin clp; get_client_locked() is > > > + * not used because its courtesy-to-active > > > + * transition is unwanted during revocation. > > > + */ > > > + atomic_inc(&clp->cl_rpc_users); > > > + spin_unlock(&nn->client_lock); > > > + match =3D nfsd_file_inode_is_in_subtree( > > > + stid->sc_file->fi_inode, > > > + root_dentry); > >=20 > > Ouch the hardlinked thing makes this hard to reason about. > >=20 > > Ok, so suppose we have two exports on the same superblock. > >=20 > > /export/foo > > /export/bar > >=20 > > One is exported to one client foo and one to another to client bar. > > There is a file hardlinked across those directories: > >=20 > > $ touch /export/foo/baz > > $ ln /export/bar/baz /export/foo/baz > >=20 > > Now, client foo opens /export/foo/baz, and client bar opens > > /export/bar/baz. > >=20 > > /export/bar is unexported and state under it revoked. Won't client > > foo's state end up being revoked too in that case? > >=20 > > Note that the different hardlinks should end up with different > > filehandles since they are exposed to the clients via different > > exports. > >=20 > > I wonder... do we need keep track of the export under which a stateid > > was acquired so we can properly revoke the right ones in this > > situation? >=20 > If I understand your comment correctly, I believe that is what the > earlier patches in this series do -- tie the state IDs to a particular > export. >=20 >=20 I don't think so, not AFAICT.=20 + * Check whether @inode has any dentry alias that falls within the + * subtree rooted at @root_dentry. Hard-linked files can have aliases + * in multiple directories, so all aliases must be tested. In this case, you're calling nfsd_file_inode_is_in_subtree(). In the above example, that's going to return true for foo's state, even though bar's export is the one being revoked. I think to do this properly, you'd have to track an st_export field in struct nfs4_ol_stateid (or maybe in struct nfs4_stid). OTOH, hardlinks are rare so maybe this isn't worth fretting over. --=20 Jeff Layton