On Tue, 2022-02-08 at 15:03 -0500, Benjamin Coddington wrote:
> In order to differentiate client state, assign a random uuid to the
> uniquifing portion of the client identifier when a network namespace
> is
> created. Containers may still override this value if they wish to
> maintain
> stable client identifiers by writing to
> /sys/fs/nfs/net/client/identifier,
> either by udev rules or other means.
>
> Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
> ---
> fs/nfs/sysfs.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
> index 8cb70755e3c9..9b811323fd7f 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -167,6 +167,18 @@ static struct nfs_netns_client
> *nfs_netns_client_alloc(struct kobject *parent,
> return NULL;
> }
>
> +static void assign_unique_clientid(struct nfs_netns_client *clp)
> +{
> + unsigned char client_uuid[16];
> + char *uuid_str = kmalloc(UUID_STRING_LEN + 1, GFP_KERNEL);
> +
> + if (uuid_str) {
> + generate_random_uuid(client_uuid);
> + sprintf(uuid_str, "%pU", client_uuid);
> + rcu_assign_pointer(clp->identifier, uuid_str);
> + }
> +}
> +
> void nfs_netns_sysfs_setup(struct nfs_net *netns, struct net *net)
> {
> struct nfs_netns_client *clp;
> @@ -174,6 +186,8 @@ void nfs_netns_sysfs_setup(struct nfs_net *netns,
> struct net *net)
> clp = nfs_netns_client_alloc(nfs_client_kobj, net);
> if (clp) {
> netns->nfs_client = clp;
> + if (net != &init_net)
> + assign_unique_clientid(clp);
Why shouldn't this go in nfs_netns_client_alloc? At this point you've
already published the pointer in netns, so you're prone to races.
Also, why the exclusion of init_net?
> kobject_uevent(&clp->kobject, KOBJ_ADD);
> }
> }
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
