On Tue, 2017-04-11 at 12:50 -0400, Benjamin Coddington wrote:
> NFS would enjoy the ability to modify the behavior of the NLM client's
> unlock RPC task in order to delay the transmission of the unlock until IO
> that was submitted under that lock has completed. This ability can ensure
> that the NLM client will always complete the transmission of an unlock even
> if the waiting caller has been interrupted with fatal signal.
>
> For this purpose, a pointer to a struct nlmclnt_operations can be assigned
> in a nfs_module's nfs_rpc_ops that will install those nlmclnt_operations on
> the nlm_host. The struct nlmclnt_operations defines three callback
> operations that will be used in a following patch:
>
> nlmclnt_alloc_call - used to call back after a successful allocation of
> a struct nlm_rqst in nlmclnt_proc().
>
> nlmclnt_unlock_prepare - used to call back during NLM unlock's
> rpc_call_prepare. The NLM client defers calling rpc_call_start()
> until this callback returns false.
>
> nlmclnt_release_call - used to call back when the NLM client's struct
> nlm_rqst is freed.
>
> Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
> ---
> fs/lockd/clntlock.c | 1 +
> fs/lockd/clntproc.c | 26 +++++++++++++++++++++++++-
> fs/nfs/client.c | 1 +
> fs/nfs/nfs3proc.c | 2 +-
> fs/nfs/proc.c | 2 +-
> include/linux/lockd/bind.h | 24 ++++++++++++++++++++++--
> include/linux/lockd/lockd.h | 2 ++
> include/linux/nfs_xdr.h | 1 +
> 8 files changed, 54 insertions(+), 5 deletions(-)
>
> diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
> index 41e491b8e5d7..27d577dbe51a 100644
> --- a/fs/lockd/clntlock.c
> +++ b/fs/lockd/clntlock.c
> @@ -69,6 +69,7 @@ struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
> if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
> goto out_nobind;
>
> + host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
> return host;
> out_nobind:
> nlmclnt_release_host(host);
> diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
> index 112952037933..066ac313ae5c 100644
> --- a/fs/lockd/clntproc.c
> +++ b/fs/lockd/clntproc.c
> @@ -150,17 +150,22 @@ static void nlmclnt_release_lockargs(struct nlm_rqst *req)
> * @host: address of a valid nlm_host context representing the NLM server
> * @cmd: fcntl-style file lock operation to perform
> * @fl: address of arguments for the lock operation
> + * @data: address of data to be sent to callback operations
> *
> */
> -int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
> +int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
> {
> struct nlm_rqst *call;
> int status;
> + const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
>
> call = nlm_alloc_call(host);
> if (call == NULL)
> return -ENOMEM;
>
> + if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
> + nlmclnt_ops->nlmclnt_alloc_call(data);
> +
> nlmclnt_locks_init_private(fl, host);
> if (!fl->fl_u.nfs_fl.owner) {
> /* lockowner allocation has failed */
> @@ -169,6 +174,7 @@ int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl)
> }
> /* Set up the argument struct */
> nlmclnt_setlockargs(call, fl);
> + call->a_callback_data = data;
>
> if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
> if (fl->fl_type != F_UNLCK) {
> @@ -214,8 +220,12 @@ struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
>
> void nlmclnt_release_call(struct nlm_rqst *call)
> {
> + const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
> +
> if (!atomic_dec_and_test(&call->a_count))
> return;
> + if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
> + nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
> nlmclnt_release_host(call->a_host);
> nlmclnt_release_lockargs(call);
> kfree(call);
> @@ -687,6 +697,19 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
> return status;
> }
>
> +static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
> +{
> + struct nlm_rqst *req = data;
> + const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
> + bool defer_call = false;
> +
> + if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
> + defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
> +
> + if (!defer_call)
> + rpc_call_start(task);
> +}
> +
> static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
> {
> struct nlm_rqst *req = data;
> @@ -720,6 +743,7 @@ static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
> }
>
> static const struct rpc_call_ops nlmclnt_unlock_ops = {
> + .rpc_call_prepare = nlmclnt_unlock_prepare,
> .rpc_call_done = nlmclnt_unlock_callback,
> .rpc_release = nlmclnt_rpc_release,
> };
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index c335c6dce285..f4c022e57541 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -536,6 +536,7 @@ static int nfs_start_lockd(struct nfs_server *server)
> .noresvport = server->flags & NFS_MOUNT_NORESVPORT ?
> 1 : 0,
> .net = clp->cl_net,
> + .nlmclnt_ops = clp->cl_nfs_mod->rpc_ops->nlmclnt_ops,
> };
>
> if (nlm_init.nfs_version > 3)
> diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
> index dc925b531f32..03b3c3de28f1 100644
> --- a/fs/nfs/nfs3proc.c
> +++ b/fs/nfs/nfs3proc.c
> @@ -870,7 +870,7 @@ nfs3_proc_lock(struct file *filp, int cmd, struct file_lock *fl)
> {
> struct inode *inode = file_inode(filp);
>
> - return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl);
> + return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl, NULL);
> }
>
> static int nfs3_have_delegation(struct inode *inode, fmode_t flags)
> diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
> index b7bca8303989..9872cf676a50 100644
> --- a/fs/nfs/proc.c
> +++ b/fs/nfs/proc.c
> @@ -638,7 +638,7 @@ nfs_proc_lock(struct file *filp, int cmd, struct file_lock *fl)
> {
> struct inode *inode = file_inode(filp);
>
> - return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl);
> + return nlmclnt_proc(NFS_SERVER(inode)->nlm_host, cmd, fl, NULL);
> }
>
> /* Helper functions for NFS lock bounds checking */
> diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
> index 140edab64446..05728396a1a1 100644
> --- a/include/linux/lockd/bind.h
> +++ b/include/linux/lockd/bind.h
> @@ -18,6 +18,7 @@
>
> /* Dummy declarations */
> struct svc_rqst;
> +struct rpc_task;
>
> /*
> * This is the set of functions for lockd->nfsd communication
> @@ -43,6 +44,7 @@ struct nlmclnt_initdata {
> u32 nfs_version;
> int noresvport;
> struct net *net;
> + const struct nlmclnt_operations *nlmclnt_ops;
> };
>
> /*
> @@ -52,8 +54,26 @@ struct nlmclnt_initdata {
> extern struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init);
> extern void nlmclnt_done(struct nlm_host *host);
>
> -extern int nlmclnt_proc(struct nlm_host *host, int cmd,
> - struct file_lock *fl);
> +/*
> + * NLM client operations provide a means to modify RPC processing of NLM
> + * requests. Callbacks receive a pointer to data passed into the call to
> + * nlmclnt_proc().
> + */
> +struct nlmclnt_operations {
> + /* Called on successful allocation of nlm_rqst, use for allocation or
> + * reference counting. */
> + void (*nlmclnt_alloc_call)(void *);
> +
> + /* Called in rpc_task_prepare for unlock. A return value of true
> + * indicates the callback has put the task to sleep on a waitqueue
> + * and NLM should not call rpc_call_start(). */
> + bool (*nlmclnt_unlock_prepare)(struct rpc_task*, void *);
> +
> + /* Called when the nlm_rqst is freed, callbacks should clean up here */
> + void (*nlmclnt_release_call)(void *);
> +};
> +
> +extern int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data);
> extern int lockd_up(struct net *net);
> extern void lockd_down(struct net *net);
>
> diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
> index c15373894a42..01c38992150d 100644
> --- a/include/linux/lockd/lockd.h
> +++ b/include/linux/lockd/lockd.h
> @@ -69,6 +69,7 @@ struct nlm_host {
> char *h_addrbuf; /* address eyecatcher */
> struct net *net; /* host net */
> char nodename[UNX_MAXNODENAME + 1];
> + const struct nlmclnt_operations *h_nlmclnt_ops; /* Callback ops for NLM users */
> };
>
> /*
> @@ -142,6 +143,7 @@ struct nlm_rqst {
> struct nlm_block * a_block;
> unsigned int a_retries; /* Retry count */
> u8 a_owner[NLMCLNT_OHSIZE];
> + void * a_callback_data; /* sent to nlmclnt_operations callbacks */
> };
>
> /*
> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
> index 348f7c158084..3279ab2e1fee 100644
> --- a/include/linux/nfs_xdr.h
> +++ b/include/linux/nfs_xdr.h
> @@ -1550,6 +1550,7 @@ struct nfs_rpc_ops {
> const struct inode_operations *dir_inode_ops;
> const struct inode_operations *file_inode_ops;
> const struct file_operations *file_ops;
> + const struct nlmclnt_operations *nlmclnt_ops;
>
> int (*getroot) (struct nfs_server *, struct nfs_fh *,
> struct nfs_fsinfo *);
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
