nfs: allow blocking locks to be awoken by lock callbacks

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
skipping all of it at runtime if we're dealing with v4.0, or v4.1
servers that don't send lock callbacks.

Note too that even when we expect to get a lock callback, RFC5661
section 20.11.4 is pretty clear that we still need to poll for them,
so we do still sleep on a timeout. We do however always poll at the
longest interval in that case.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
[Anna: nfs4_retry_setlk() "status" should default to -ERESTARTSYS]
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
index 97488182441439c4f656dfd8770a15b7a99554f7..e9aa235e9d10197d8b138f1d0e657dd6449c578f 100644 (file)
--- a/fs/nfs/callback_proc.c
+++ b/fs/nfs/callback_proc.c
@@ -638,6 +638,10 @@ __be32 nfs4_callback_notify_lock(struct cb_notify_lock_args *args, void *dummy,
        dprintk_rcu("NFS: CB_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 (args->cbnl_valid)
+               __wake_up(&cps->clp->cl_lock_waitq, TASK_NORMAL, 0, args);
+
        return htonl(NFS4_OK);
 }
 #endif /* CONFIG_NFS_V4_1 */

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index a2c9654d018f3c115ce3b821576aea9cd850faeb..074ac7131459ebc378ef3a1cf50244ff758f2a88 100644 (file)
--- 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 a74c4167b5b08a9882009f2fce6ab15f50dde8dc..5ec333f3a19be21d25d189129fe881db3489f418 100644 (file)
--- 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 = -ERESTARTSYS;
        unsigned long   timeout = NFS4_LOCK_MINTIMEOUT;
@@ -6183,6 +6184,97 @@ 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 inode            *inode;
+       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 cb_notify_lock_args *cbnl = key;
+       struct nfs4_lock_waiter *waiter = wait->private;
+       struct nfs_lowner       *lowner = &cbnl->cbnl_owner,
+                               *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;
+
+       /* Make sure it's for the right inode */
+       if (nfs_compare_fh(NFS_FH(waiter->inode), &cbnl->cbnl_fh))
+               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 = -ERESTARTSYS;
+       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,
+                                          .inode = state->inode,
+                                          .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);
+
+       while(!signalled()) {
+               status = nfs4_proc_setlk(state, cmd, request);
+               if ((status != -EAGAIN) || IS_SETLK(cmd))
+                       break;
+
+               status = -ERESTARTSYS;
+               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);
+       }
+
+       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 14a762d2734d91fff13fd17ebcf76978eb9feb2a..b34097c6784864193e67053f8fa8e5bbbc092071 100644 (file)
--- 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.