Re: [PATCH v3 3/6] NFS: Shut down the nfs_client only after all the superblocks

[Jeff Layton <jlayton@kernel.org>]

On Tue, 2025-03-25 at 18:35 -0400, trondmy@kernel.org wrote:
> From: Trond Myklebust <trond.myklebust@hammerspace.com>
> 
> The nfs_client manages state for all the superblocks in the
> "cl_superblocks" list, so it must not be shut down until all of them are
> gone.
> 
> Fixes: 7d3e26a054c8 ("NFS: Cancel all existing RPC tasks when shutdown")
> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
> ---
>  fs/nfs/sysfs.c | 22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
> index b30401b2c939..37cb2b776435 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -14,6 +14,7 @@
>  #include <linux/rcupdate.h>
>  #include <linux/lockd/lockd.h>
>  
> +#include "internal.h"
>  #include "nfs4_fs.h"
>  #include "netns.h"
>  #include "sysfs.h"
> @@ -228,6 +229,25 @@ static void shutdown_client(struct rpc_clnt *clnt)
>  	rpc_cancel_tasks(clnt, -EIO, shutdown_match_client, NULL);
>  }
>  
> +/*
> + * Shut down the nfs_client only once all the superblocks
> + * have been shut down.
> + */
> +static void shutdown_nfs_client(struct nfs_client *clp)
> +{
> +	struct nfs_server *server;
> +	rcu_read_lock();
> +	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
> +		if (!(server->flags & NFS_MOUNT_SHUTDOWN)) {
> +			rcu_read_unlock();
> +			return;
> +		}
> +	}
> +	rcu_read_unlock();
> +	nfs_mark_client_ready(clp, -EIO);
> +	shutdown_client(clp->cl_rpcclient);
> +}
> +

Isn't the upshot of this that a mount won't actually get shutdown until
you shutdown all of the mounts to the same server? Personally, I find
that acceptable, but we should note that it is a change in behavior.


>  static ssize_t
>  shutdown_show(struct kobject *kobj, struct kobj_attribute *attr,
>  				char *buf)
> @@ -259,7 +279,6 @@ shutdown_store(struct kobject *kobj, struct kobj_attribute *attr,
>  
>  	server->flags |= NFS_MOUNT_SHUTDOWN;
>  	shutdown_client(server->client);
> -	shutdown_client(server->nfs_client->cl_rpcclient);
>  
>  	if (!IS_ERR(server->client_acl))
>  		shutdown_client(server->client_acl);
> @@ -267,6 +286,7 @@ shutdown_store(struct kobject *kobj, struct kobj_attribute *attr,
>  	if (server->nlm_host)
>  		shutdown_client(server->nlm_host->h_rpcclnt);
>  out:
> +	shutdown_nfs_client(server->nfs_client);
>  	return count;
>  }
>  

-- 
Jeff Layton <jlayton@kernel.org>