[v2,09/10] nfs: add code to allow client to wait on lock callbacks
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Message ID 1473446870-1831-10-git-send-email-jlayton@redhat.com
State New
Headers show

Commit Message

Jeff Layton Sept. 9, 2016, 6:47 p.m. UTC
Add a waitqueue head to the client structure. Have clients set a wait
on that queue prior to requesting a lock from the server. If the lock
is blocked, then we can use that to wait for wakeups.

Note that we do need to do this "manually" since we need to set the
wait on the waitqueue prior to requesting the lock, but requesting a
lock can involve activities that can block.

However, only do that for NFSv4.1 locks, either by compiling out
all of the waitqueue handling when CONFIG_NFS_V4_1 is disabled, or
at runtime if we're dealing with v4.0 locks.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/nfs/callback_proc.c    |  7 ++++
 fs/nfs/nfs4client.c       |  3 ++
 fs/nfs/nfs4proc.c         | 88 ++++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/nfs_fs_sb.h |  3 ++
 4 files changed, 100 insertions(+), 1 deletion(-)

Patch
diff mbox

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index dc3b8ee5827a..590ed26232cc 100644
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -632,12 +632,19 @@  out:
 __be32 nfs4_callback_notify_lock(struct cb_notify_lock_args *args, void *dummy,
 				 struct cb_process_state *cps)
 {
+	struct nfs_lowner	*lowner = &args->cbnl_owner;
+
 	if (!cps->clp) /* set in cb_sequence */
 		return htonl(NFS4ERR_OP_NOT_IN_SESSION);
 
 	dprintk_rcu("NFS: CB_RECALL_NOTIFY_LOCK request from %s\n",
 		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR));
 
+	/* Don't wake anybody if the string looked bogus */
+	if (lowner->id || lowner->s_dev)
+		__wake_up(&cps->clp->cl_lock_waitq, TASK_NORMAL, 0,
+			  &args->cbnl_owner);
+
 	return htonl(NFS4_OK);
 }
 #endif /* CONFIG_NFS_V4_1 */
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index cd3b7cfdde16..9f62df5feb7d 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -199,6 +199,9 @@  struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *cl_init)
 	clp->cl_minorversion = cl_init->minorversion;
 	clp->cl_mvops = nfs_v4_minor_ops[cl_init->minorversion];
 	clp->cl_mig_gen = 1;
+#if IS_ENABLED(CONFIG_NFS_V4_1)
+	init_waitqueue_head(&clp->cl_lock_waitq);
+#endif
 	return clp;
 
 error:
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 66fa2af03b33..2271c44aff32 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6166,7 +6166,8 @@  static int nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *
 #define NFS4_LOCK_MAXTIMEOUT (30 * HZ)
 
 static int
-nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
+nfs4_retry_setlk_simple(struct nfs4_state *state, int cmd,
+			struct file_lock *request)
 {
 	int status;
 	unsigned long timeout = NFS4_LOCK_MINTIMEOUT;
@@ -6185,6 +6186,91 @@  nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
 	return status;
 }
 
+#ifdef CONFIG_NFS_V4_1
+struct nfs4_lock_waiter {
+	struct task_struct	*task;
+	struct nfs_lowner	*owner;
+	bool			notified;
+};
+
+static int
+nfs4_wake_lock_waiter(wait_queue_t *wait, unsigned int mode, int flags, void *key)
+{
+	int ret;
+	struct nfs4_lock_waiter	*waiter	= wait->private;
+	struct nfs_lowner	*lowner = key, *wowner = waiter->owner;
+
+	/* Only wake if the callback was for the same owner */
+	if (lowner->clientid != wowner->clientid ||
+	    lowner->id != wowner->id		 ||
+	    lowner->s_dev != wowner->s_dev)
+		return 0;
+
+	waiter->notified = true;
+
+	/* override "private" so we can use default_wake_function */
+	wait->private = waiter->task;
+	ret = autoremove_wake_function(wait, mode, flags, key);
+	wait->private = waiter;
+	return ret;
+}
+
+static int
+nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
+{
+	int status;
+	unsigned long flags;
+	struct nfs4_lock_state *lsp = request->fl_u.nfs4_fl.owner;
+	struct nfs_server *server = NFS_SERVER(state->inode);
+	struct nfs_client *clp = server->nfs_client;
+	wait_queue_head_t *q = &clp->cl_lock_waitq;
+	struct nfs_lowner owner = { .clientid = clp->cl_clientid,
+				    .id = lsp->ls_seqid.owner_id,
+				    .s_dev = server->s_dev };
+	struct nfs4_lock_waiter waiter = { .task  = current,
+					   .owner = &owner,
+					   .notified = false };
+	wait_queue_t wait;
+
+	/* Don't bother with waitqueue if we don't expect a callback */
+	if (!test_bit(NFS_STATE_MAY_NOTIFY_LOCK, &state->flags))
+		return nfs4_retry_setlk_simple(state, cmd, request);
+
+	init_wait(&wait);
+	wait.private = &waiter;
+	wait.func = nfs4_wake_lock_waiter;
+	add_wait_queue(q, &wait);
+
+	do {
+		status = nfs4_proc_setlk(state, cmd, request);
+		if ((status != -EAGAIN) || IS_SETLK(cmd))
+			break;
+
+		spin_lock_irqsave(&q->lock, flags);
+		if (waiter.notified) {
+			spin_unlock_irqrestore(&q->lock, flags);
+			continue;
+		}
+		set_current_state(TASK_INTERRUPTIBLE);
+		spin_unlock_irqrestore(&q->lock, flags);
+
+		freezable_schedule_timeout_interruptible(NFS4_LOCK_MAXTIMEOUT);
+		status = -ERESTARTSYS;
+		if (signalled())
+			break;
+	} while(status < 0);
+
+	finish_wait(q, &wait);
+	return status;
+}
+#else /* !CONFIG_NFS_V4_1 */
+static inline int
+nfs4_retry_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
+{
+	return nfs4_retry_setlk_simple(state, cmd, request);
+}
+#endif
+
 static int
 nfs4_proc_lock(struct file *filp, int cmd, struct file_lock *request)
 {
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 14a762d2734d..b34097c67848 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -103,6 +103,9 @@  struct nfs_client {
 #define NFS_SP4_MACH_CRED_WRITE    5	/* WRITE */
 #define NFS_SP4_MACH_CRED_COMMIT   6	/* COMMIT */
 #define NFS_SP4_MACH_CRED_PNFS_CLEANUP  7 /* LAYOUTRETURN */
+#if IS_ENABLED(CONFIG_NFS_V4_1)
+	wait_queue_head_t	cl_lock_waitq;
+#endif /* CONFIG_NFS_V4_1 */
 #endif /* CONFIG_NFS_V4 */
 
 	/* Our own IP address, as a null-terminated string.