lockd: Introduce nlmclnt_operations

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@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
index 41e491b8e5d7e40164e0e51d90534c9d8660a94e..27d577dbe51a48f21950a63758e76783fed67eca 100644 (file)
--- 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 112952037933b79fa36dbea67579c576ee19be58..066ac313ae5c0fff15188d3123079acd9a7180f3 100644 (file)
--- 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 @@ out:
        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 @@ die:
 }
 
 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 3e7b2e6a7cfbef02398359d741e9536550ad9b66..e0302101e18afd93471fa810014f9a16d8b14513 100644 (file)
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -546,6 +546,7 @@ 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 dc925b531f32632bb708c3f8490d0d00c7315495..03b3c3de28f18c37050f4e0463e9c645b559276d 100644 (file)
--- 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 b7bca83039895b5692163d2a119f29c126ea5d83..9872cf676a50a7cfe945bfc5294602b4f67b5673 100644 (file)
--- 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 140edab644462051f23d813514fe9a60404aa0e7..05728396a1a18f701f5bba8075be5301e6a89e4e 100644 (file)
--- 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 b37dee3acaba4c152fc2c0c928f4f312c74cc778..41f7b6a04d6914841a155d4734d308f6b4cc8d00 100644 (file)
--- 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 51e27f9746eee922ba09aaf30b366d5a72e5899a..677c6b91dfcd7234645c52e2ee22abf3fa53cee7 100644 (file)
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1551,6 +1551,7 @@ 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 *);