Re: [PATCH v4 3/6] NFSD: Add filesystem scope to NFSD_CMD_UNLOCK

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2026-03-18 at 10:15 -0400, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Add NFSD_UNLOCK_TYPE_FILESYSTEM to the NFSD_CMD_UNLOCK netlink
> command, providing a netlink equivalent of /proc/fs/nfsd/unlock_fs.
> 
> The filesystem scope requires a "path" string attribute containing
> the filesystem path whose state should be released. The handler
> resolves the path to its superblock, then cancels async copies,
> releases NLM locks, and revokes NFSv4 state on that superblock --
> the same operations performed by write_unlock_fs().
> 
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  Documentation/netlink/specs/nfsd.yaml | 11 ++++++++--
>  fs/nfsd/netlink.c                     |  7 +++---
>  fs/nfsd/nfsctl.c                      | 41 ++++++++++++++++++++++++++++++++++-
>  include/uapi/linux/nfsd_netlink.h     |  2 ++
>  4 files changed, 55 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml
> index 02fadfca22ba..1083ef60cac3 100644
> --- a/Documentation/netlink/specs/nfsd.yaml
> +++ b/Documentation/netlink/specs/nfsd.yaml
> @@ -11,7 +11,7 @@ definitions:
>      type: enum
>      name: unlock-type
>      render-max: true
> -    entries: [ip]
> +    entries: [ip, filesystem]
>  
>  attribute-sets:
>    -
> @@ -149,6 +149,12 @@ attribute-sets:
>            Required when type is ip.
>          checks:
>            min-len: 16
> +      -
> +        name: path
> +        type: string
> +        doc: >-
> +          Filesystem path whose state should be released.
> +          Required when type is filesystem.
>  
>  operations:
>    list:
> @@ -251,7 +257,7 @@ operations:
>              - npools
>      -
>        name: unlock
> -      doc: release NLM locks by scope
> +      doc: release locks or revoke NFS state by scope
>        attribute-set: unlock
>        flags: [admin-perm]
>        do:
> @@ -259,3 +265,4 @@ operations:
>            attributes:
>              - type
>              - address
> +            - path
> diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
> index 9ec0d56eaa21..8367d4e3fe4f 100644
> --- a/fs/nfsd/netlink.c
> +++ b/fs/nfsd/netlink.c
> @@ -48,9 +48,10 @@ static const struct nla_policy nfsd_pool_mode_set_nl_policy[NFSD_A_POOL_MODE_MOD
>  };
>  
>  /* NFSD_CMD_UNLOCK - do */
> -static const struct nla_policy nfsd_unlock_nl_policy[NFSD_A_UNLOCK_ADDRESS + 1] = {
> -	[NFSD_A_UNLOCK_TYPE] = NLA_POLICY_MAX(NLA_U32, 0),
> +static const struct nla_policy nfsd_unlock_nl_policy[NFSD_A_UNLOCK_PATH + 1] = {
> +	[NFSD_A_UNLOCK_TYPE] = NLA_POLICY_MAX(NLA_U32, NFSD_UNLOCK_TYPE_MAX),
>  	[NFSD_A_UNLOCK_ADDRESS] = NLA_POLICY_MIN_LEN(16),
> +	[NFSD_A_UNLOCK_PATH] = { .type = NLA_NUL_STRING, .len = PATH_MAX - 1, },
>  };
>  
>  /* Ops table for nfsd */
> @@ -112,7 +113,7 @@ static const struct genl_split_ops nfsd_nl_ops[] = {
>  		.cmd		= NFSD_CMD_UNLOCK,
>  		.doit		= nfsd_nl_unlock_doit,
>  		.policy		= nfsd_unlock_nl_policy,
> -		.maxattr	= NFSD_A_UNLOCK_ADDRESS,
> +		.maxattr	= NFSD_A_UNLOCK_PATH,
>  		.flags		= GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
>  	},
>  };
> diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
> index 858f3803c490..d3ed343699bd 100644
> --- a/fs/nfsd/nfsctl.c
> +++ b/fs/nfsd/nfsctl.c
> @@ -2180,7 +2180,44 @@ static int nfsd_nl_unlock_by_ip(struct genl_info *info)
>  }
>  
>  /**
> - * nfsd_nl_unlock_doit - release NLM locks by scope
> + * nfsd_nl_unlock_by_filesystem - release locks and state on a filesystem
> + * @info: netlink metadata and command arguments
> + *
> + * Return: 0 on success or a negative errno.
> + */
> +static int nfsd_nl_unlock_by_filesystem(struct genl_info *info)
> +{
> +	struct net *net = genl_info_net(info);
> +	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> +	struct path path;
> +	int error;
> +
> +	if (GENL_REQ_ATTR_CHECK(info, NFSD_A_UNLOCK_PATH))
> +		return -EINVAL;
> +
> +	trace_nfsd_ctl_unlock_fs(net,
> +				 nla_data(info->attrs[NFSD_A_UNLOCK_PATH]));
> +	error = kern_path(nla_data(info->attrs[NFSD_A_UNLOCK_PATH]),
> +			  0, &path);
> +	if (error)
> +		return error;
> +
> +	nfsd4_cancel_copy_by_sb(net, path.dentry->d_sb);
> +	error = nlmsvc_unlock_all_by_sb(path.dentry->d_sb);
> +
> +	mutex_lock(&nfsd_mutex);
> +	if (nn->nfsd_serv)
> +		nfsd4_revoke_states(nn, path.dentry->d_sb);
> +	else
> +		error = -EINVAL;
> +	mutex_unlock(&nfsd_mutex);
> +
> +	path_put(&path);
> +	return error;
> +}
> +
> +/**
> + * nfsd_nl_unlock_doit - release locks or revoke NFS state
>   * @skb: reply buffer
>   * @info: netlink metadata and command arguments
>   *
> @@ -2198,6 +2235,8 @@ int nfsd_nl_unlock_doit(struct sk_buff *skb, struct genl_info *info)
>  	switch (type) {
>  	case NFSD_UNLOCK_TYPE_IP:
>  		return nfsd_nl_unlock_by_ip(info);
> +	case NFSD_UNLOCK_TYPE_FILESYSTEM:
> +		return nfsd_nl_unlock_by_filesystem(info);
>  	default:
>  		return -EINVAL;
>  	}
> diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_netlink.h
> index 8edd75590f31..340ad36080fe 100644
> --- a/include/uapi/linux/nfsd_netlink.h
> +++ b/include/uapi/linux/nfsd_netlink.h
> @@ -12,6 +12,7 @@
>  
>  enum nfsd_unlock_type {
>  	NFSD_UNLOCK_TYPE_IP,
> +	NFSD_UNLOCK_TYPE_FILESYSTEM,
>  
>  	/* private: */
>  	__NFSD_UNLOCK_TYPE_MAX,
> @@ -91,6 +92,7 @@ enum {
>  enum {
>  	NFSD_A_UNLOCK_TYPE = 1,
>  	NFSD_A_UNLOCK_ADDRESS,
> +	NFSD_A_UNLOCK_PATH,
>  
>  	__NFSD_A_UNLOCK_MAX,
>  	NFSD_A_UNLOCK_MAX = (__NFSD_A_UNLOCK_MAX - 1)

Yeah, following up on my last mail. I think it would be cleaner to just
implement a new UNLOCK_FILESYSTEM command instead of overloading the
one that unlocks by IP.

-- 
Jeff Layton <jlayton@kernel.org>