Merge tag 'afs-fix-rotation-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull afs updates from David Howells:
 "The majority of the patches are aimed at fixing and improving the AFS
  filesystem's rotation over server IP addresses, but there are also
  some fixes from Oleg Nesterov for the use of read_seqbegin_or_lock().

   - Fix fileserver probe handling so that the next round of probes
     doesn't break ongoing server/address rotation by clearing all the
     probe result tracking. This could occasionally cause the rotation
     algorithm to drop straight through, give a 'successful' result
     without actually emitting any RPC calls, leaving the reply buffer
     in an undefined state.

     Instead, detach the probe results into a separate struct and
     allocate a new one each time we start probing and update the
     pointer to it. Probes are also sent in order of address preference
     to try and improve the chance that the preferred one will complete
     first.

   - Fix server rotation so that it uses configurable address
     preferences across on the probes that have completed so far than
     ranking them by RTT as the latter doesn't necessarily give the best
     route. The preference list can be altered by writing into
     /proc/net/afs/addr_prefs.

   - Fix the handling of Read-Only (and Backup) volume callbacks as
     there is one per volume, not one per file, so if someone performs a
     command that, say, offlines the volume but doesn't change it, when
     it comes back online we don't spam the server with a status fetch
     for every vnode we're using. Instead, check the Creation timestamp
     in the VolSync record when prompted by a callback break.

   - Handle volume regression (ie. a RW volume being restored from a
     backup) by scrubbing all cache data for that volume. This is
     detected from the VolSync creation timestamp.

   - Adjust abort handling and abort -> error mapping to match better
     with what other AFS clients do.

   - Fix offline and busy volume state handling as they only apply to
     individual server instances and not entire volumes and the rotation
     algorithm should go and look at other servers if available. Also
     make it sleep briefly before each retry if all the volume instances
     are unavailable"

* tag 'afs-fix-rotation-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: (40 commits)
  afs: trace: Log afs_make_call(), including server address
  afs: Fix offline and busy message emission
  afs: Fix fileserver rotation
  afs: Overhaul invalidation handling to better support RO volumes
  afs: Parse the VolSync record in the reply of a number of RPC ops
  afs: Don't leave DONTUSE/NEWREPSITE servers out of server list
  afs: Fix comment in afs_do_lookup()
  afs: Apply server breaks to mmap'd files in the call processor
  afs: Move the vnode/volume validity checking code into its own file
  afs: Defer volume record destruction to a workqueue
  afs: Make it possible to find the volumes that are using a server
  afs: Combine the endpoint state bools into a bitmask
  afs: Keep a record of the current fileserver endpoint state
  afs: Dispatch vlserver probes in priority order
  afs: Dispatch fileserver probes in priority order
  afs: Mark address lists with configured priorities
  afs: Provide a way to configure address priorities
  afs: Remove the unimplemented afs_cmp_addr_list()
  afs: Add some more info to /proc/net/afs/servers
  rxrpc: Create a procfile to display outstanding client conn bundles
  ...

1 files changed, 186 insertions, 137 deletions

diff --git a/fs/afs/fs_probe.c b/fs/afs/fs_probe.c
index daaf3810cc92..580de4adaaf6 100644
--- a/fs/afs/fs_probe.c
+++ b/fs/afs/fs_probe.c
@@ -15,6 +15,42 @@
 static unsigned int afs_fs_probe_fast_poll_interval = 30 * HZ;
 static unsigned int afs_fs_probe_slow_poll_interval = 5 * 60 * HZ;
 
+struct afs_endpoint_state *afs_get_endpoint_state(struct afs_endpoint_state *estate,
+						  enum afs_estate_trace where)
+{
+	if (estate) {
+		int r;
+
+		__refcount_inc(&estate->ref, &r);
+		trace_afs_estate(estate->server_id, estate->probe_seq, r, where);
+	}
+	return estate;
+}
+
+static void afs_endpoint_state_rcu(struct rcu_head *rcu)
+{
+	struct afs_endpoint_state *estate = container_of(rcu, struct afs_endpoint_state, rcu);
+
+	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
+			 afs_estate_trace_free);
+	afs_put_addrlist(estate->addresses, afs_alist_trace_put_estate);
+	kfree(estate);
+}
+
+void afs_put_endpoint_state(struct afs_endpoint_state *estate, enum afs_estate_trace where)
+{
+	if (estate) {
+		unsigned int server_id = estate->server_id, probe_seq = estate->probe_seq;
+		bool dead;
+		int r;
+
+		dead = __refcount_dec_and_test(&estate->ref, &r);
+		trace_afs_estate(server_id, probe_seq, r, where);
+		if (dead)
+			call_rcu(&estate->rcu, afs_endpoint_state_rcu);
+	}
+}
+
 /*
  * Start the probe polling timer.  We have to supply it with an inc on the
  * outstanding server count.
@@ -38,9 +74,10 @@ static void afs_schedule_fs_probe(struct afs_net *net,
 /*
  * Handle the completion of a set of probes.
  */
-static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server)
+static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server,
+				  struct afs_endpoint_state *estate)
 {
-	bool responded = server->probe.responded;
+	bool responded = test_bit(AFS_ESTATE_RESPONDED, &estate->flags);
 
 	write_seqlock(&net->fs_lock);
 	if (responded) {
@@ -50,6 +87,7 @@ static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server
 		clear_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
 		list_add_tail(&server->probe_link, &net->fs_probe_fast);
 	}
+
 	write_sequnlock(&net->fs_lock);
 
 	afs_schedule_fs_probe(net, server, !responded);
@@ -58,12 +96,13 @@ static void afs_finished_fs_probe(struct afs_net *net, struct afs_server *server
 /*
  * Handle the completion of a probe.
  */
-static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server)
+static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server,
+				  struct afs_endpoint_state *estate)
 {
 	_enter("");
 
-	if (atomic_dec_and_test(&server->probe_outstanding))
-		afs_finished_fs_probe(net, server);
+	if (atomic_dec_and_test(&estate->nr_probing))
+		afs_finished_fs_probe(net, server, estate);
 
 	wake_up_all(&server->probe_wq);
 }
@@ -74,24 +113,22 @@ static void afs_done_one_fs_probe(struct afs_net *net, struct afs_server *server
  */
 static void afs_fs_probe_not_done(struct afs_net *net,
 				  struct afs_server *server,
-				  struct afs_addr_cursor *ac)
+				  struct afs_endpoint_state *estate,
+				  int index)
 {
-	struct afs_addr_list *alist = ac->alist;
-	unsigned int index = ac->index;
-
 	_enter("");
 
 	trace_afs_io_error(0, -ENOMEM, afs_io_error_fs_probe_fail);
 	spin_lock(&server->probe_lock);
 
-	server->probe.local_failure = true;
-	if (server->probe.error == 0)
-		server->probe.error = -ENOMEM;
+	set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
+	if (estate->error == 0)
+		estate->error = -ENOMEM;
 
-	set_bit(index, &alist->failed);
+	set_bit(index, &estate->failed_set);
 
 	spin_unlock(&server->probe_lock);
-	return afs_done_one_fs_probe(net, server);
+	return afs_done_one_fs_probe(net, server, estate);
 }
 
 /*
@@ -100,30 +137,34 @@ static void afs_fs_probe_not_done(struct afs_net *net,
  */
 void afs_fileserver_probe_result(struct afs_call *call)
 {
-	struct afs_addr_list *alist = call->alist;
+	struct afs_endpoint_state *estate = call->probe;
+	struct afs_addr_list *alist = estate->addresses;
+	struct afs_address *addr = &alist->addrs[call->probe_index];
 	struct afs_server *server = call->server;
-	unsigned int index = call->addr_ix;
-	unsigned int rtt_us = 0, cap0;
+	unsigned int index = call->probe_index;
+	unsigned int rtt_us = -1, cap0;
 	int ret = call->error;
 
 	_enter("%pU,%u", &server->uuid, index);
 
+	WRITE_ONCE(addr->last_error, ret);
+
 	spin_lock(&server->probe_lock);
 
 	switch (ret) {
 	case 0:
-		server->probe.error = 0;
+		estate->error = 0;
 		goto responded;
 	case -ECONNABORTED:
-		if (!server->probe.responded) {
-			server->probe.abort_code = call->abort_code;
-			server->probe.error = ret;
+		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags)) {
+			estate->abort_code = call->abort_code;
+			estate->error = ret;
 		}
 		goto responded;
 	case -ENOMEM:
 	case -ENONET:
-		clear_bit(index, &alist->responded);
-		server->probe.local_failure = true;
+		clear_bit(index, &estate->responsive_set);
+		set_bit(AFS_ESTATE_LOCAL_FAILURE, &estate->flags);
 		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
 		goto out;
 	case -ECONNRESET: /* Responded, but call expired. */
@@ -136,29 +177,29 @@ void afs_fileserver_probe_result(struct afs_call *call)
 	case -ETIMEDOUT:
 	case -ETIME:
 	default:
-		clear_bit(index, &alist->responded);
-		set_bit(index, &alist->failed);
-		if (!server->probe.responded &&
-		    (server->probe.error == 0 ||
-		     server->probe.error == -ETIMEDOUT ||
-		     server->probe.error == -ETIME))
-			server->probe.error = ret;
+		clear_bit(index, &estate->responsive_set);
+		set_bit(index, &estate->failed_set);
+		if (!test_bit(AFS_ESTATE_RESPONDED, &estate->flags) &&
+		    (estate->error == 0 ||
+		     estate->error == -ETIMEDOUT ||
+		     estate->error == -ETIME))
+			estate->error = ret;
 		trace_afs_io_error(call->debug_id, ret, afs_io_error_fs_probe_fail);
 		goto out;
 	}
 
 responded:
-	clear_bit(index, &alist->failed);
+	clear_bit(index, &estate->failed_set);
 
 	if (call->service_id == YFS_FS_SERVICE) {
-		server->probe.is_yfs = true;
+		set_bit(AFS_ESTATE_IS_YFS, &estate->flags);
 		set_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
-		alist->addrs[index].srx_service = call->service_id;
+		server->service_id = call->service_id;
 	} else {
-		server->probe.not_yfs = true;
-		if (!server->probe.is_yfs) {
+		set_bit(AFS_ESTATE_NOT_YFS, &estate->flags);
+		if (!test_bit(AFS_ESTATE_IS_YFS, &estate->flags)) {
 			clear_bit(AFS_SERVER_FL_IS_YFS, &server->flags);
-			alist->addrs[index].srx_service = call->service_id;
+			server->service_id = call->service_id;
 		}
 		cap0 = ntohl(call->tmp);
 		if (cap0 & AFS3_VICED_CAPABILITY_64BITFILES)
@@ -167,116 +208,136 @@ responded:
 			clear_bit(AFS_SERVER_FL_HAS_FS64, &server->flags);
 	}
 
-	rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us);
-	if (rtt_us < server->probe.rtt) {
-		server->probe.rtt = rtt_us;
+	rtt_us = rxrpc_kernel_get_srtt(addr->peer);
+	if (rtt_us < estate->rtt) {
+		estate->rtt = rtt_us;
 		server->rtt = rtt_us;
 		alist->preferred = index;
 	}
 
 	smp_wmb(); /* Set rtt before responded. */
-	server->probe.responded = true;
-	set_bit(index, &alist->responded);
+	set_bit(AFS_ESTATE_RESPONDED, &estate->flags);
+	set_bit(index, &estate->responsive_set);
 	set_bit(AFS_SERVER_FL_RESPONDING, &server->flags);
 out:
 	spin_unlock(&server->probe_lock);
 
-	_debug("probe %pU [%u] %pISpc rtt=%u ret=%d",
-	       &server->uuid, index, &alist->addrs[index].transport,
+	trace_afs_fs_probe(server, false, estate, index, call->error, call->abort_code, rtt_us);
+	_debug("probe[%x] %pU [%u] %pISpc rtt=%d ret=%d",
+	       estate->probe_seq, &server->uuid, index,
+	       rxrpc_kernel_remote_addr(alist->addrs[index].peer),
 	       rtt_us, ret);
 
-	return afs_done_one_fs_probe(call->net, server);
+	return afs_done_one_fs_probe(call->net, server, estate);
 }
 
 /*
- * Probe one or all of a fileserver's addresses to find out the best route and
- * to query its capabilities.
+ * Probe all of a fileserver's addresses to find out the best route and to
+ * query its capabilities.
  */
 void afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
-			     struct key *key, bool all)
+			     struct afs_addr_list *new_alist, struct key *key)
 {
-	struct afs_addr_cursor ac = {
-		.index = 0,
-	};
+	struct afs_endpoint_state *estate, *old;
+	struct afs_addr_list *alist;
+	unsigned long unprobed;
 
 	_enter("%pU", &server->uuid);
 
-	read_lock(&server->fs_lock);
-	ac.alist = rcu_dereference_protected(server->addresses,
-					     lockdep_is_held(&server->fs_lock));
-	afs_get_addrlist(ac.alist);
-	read_unlock(&server->fs_lock);
+	estate = kzalloc(sizeof(*estate), GFP_KERNEL);
+	if (!estate)
+		return;
+
+	refcount_set(&estate->ref, 1);
+	estate->server_id = server->debug_id;
+	estate->rtt = UINT_MAX;
+
+	write_lock(&server->fs_lock);
+
+	old = rcu_dereference_protected(server->endpoint_state,
+					lockdep_is_held(&server->fs_lock));
+	estate->responsive_set = old->responsive_set;
+	estate->addresses = afs_get_addrlist(new_alist ?: old->addresses,
+					     afs_alist_trace_get_estate);
+	alist = estate->addresses;
+	estate->probe_seq = ++server->probe_counter;
+	atomic_set(&estate->nr_probing, alist->nr_addrs);
+
+	rcu_assign_pointer(server->endpoint_state, estate);
+	set_bit(AFS_ESTATE_SUPERSEDED, &old->flags);
+	write_unlock(&server->fs_lock);
+
+	trace_afs_estate(estate->server_id, estate->probe_seq, refcount_read(&estate->ref),
+			 afs_estate_trace_alloc_probe);
+
+	afs_get_address_preferences(net, alist);
 
 	server->probed_at = jiffies;
-	atomic_set(&server->probe_outstanding, all ? ac.alist->nr_addrs : 1);
-	memset(&server->probe, 0, sizeof(server->probe));
-	server->probe.rtt = UINT_MAX;
-
-	ac.index = ac.alist->preferred;
-	if (ac.index < 0 || ac.index >= ac.alist->nr_addrs)
-		all = true;
-
-	if (all) {
-		for (ac.index = 0; ac.index < ac.alist->nr_addrs; ac.index++)
-			if (!afs_fs_get_capabilities(net, server, &ac, key))
-				afs_fs_probe_not_done(net, server, &ac);
-	} else {
-		if (!afs_fs_get_capabilities(net, server, &ac, key))
-			afs_fs_probe_not_done(net, server, &ac);
+	unprobed = (1UL << alist->nr_addrs) - 1;
+	while (unprobed) {
+		unsigned int index = 0, i;
+		int best_prio = -1;
+
+		for (i = 0; i < alist->nr_addrs; i++) {
+			if (test_bit(i, &unprobed) &&
+			    alist->addrs[i].prio > best_prio) {
+				index = i;
+				best_prio = alist->addrs[i].prio;
+			}
+		}
+		__clear_bit(index, &unprobed);
+
+		trace_afs_fs_probe(server, true, estate, index, 0, 0, 0);
+		if (!afs_fs_get_capabilities(net, server, estate, index, key))
+			afs_fs_probe_not_done(net, server, estate, index);
 	}
 
-	afs_put_addrlist(ac.alist);
+	afs_put_endpoint_state(old, afs_estate_trace_put_probe);
 }
 
 /*
- * Wait for the first as-yet untried fileserver to respond.
+ * Wait for the first as-yet untried fileserver to respond, for the probe state
+ * to be superseded or for all probes to finish.
  */
-int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
+int afs_wait_for_fs_probes(struct afs_operation *op, struct afs_server_state *states, bool intr)
 {
-	struct wait_queue_entry *waits;
-	struct afs_server *server;
-	unsigned int rtt = UINT_MAX, rtt_s;
-	bool have_responders = false;
-	int pref = -1, i;
+	struct afs_endpoint_state *estate;
+	struct afs_server_list *slist = op->server_list;
+	bool still_probing = true;
+	int ret = 0, i;
 
-	_enter("%u,%lx", slist->nr_servers, untried);
+	_enter("%u", slist->nr_servers);
 
-	/* Only wait for servers that have a probe outstanding. */
 	for (i = 0; i < slist->nr_servers; i++) {
-		if (test_bit(i, &untried)) {
-			server = slist->servers[i].server;
-			if (!atomic_read(&server->probe_outstanding))
-				__clear_bit(i, &untried);
-			if (server->probe.responded)
-				have_responders = true;
-		}
+		estate = states[i].endpoint_state;
+		if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
+			return 2;
+		if (atomic_read(&estate->nr_probing))
+			still_probing = true;
+		if (estate->responsive_set & states[i].untried_addrs)
+			return 1;
 	}
-	if (have_responders || !untried)
+	if (!still_probing)
 		return 0;
 
-	waits = kmalloc(array_size(slist->nr_servers, sizeof(*waits)), GFP_KERNEL);
-	if (!waits)
-		return -ENOMEM;
-
-	for (i = 0; i < slist->nr_servers; i++) {
-		if (test_bit(i, &untried)) {
-			server = slist->servers[i].server;
-			init_waitqueue_entry(&waits[i], current);
-			add_wait_queue(&server->probe_wq, &waits[i]);
-		}
-	}
+	for (i = 0; i < slist->nr_servers; i++)
+		add_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
 
 	for (;;) {
-		bool still_probing = false;
+		still_probing = false;
 
-		set_current_state(TASK_INTERRUPTIBLE);
+		set_current_state(intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 		for (i = 0; i < slist->nr_servers; i++) {
-			if (test_bit(i, &untried)) {
-				server = slist->servers[i].server;
-				if (server->probe.responded)
-					goto stop;
-				if (atomic_read(&server->probe_outstanding))
-					still_probing = true;
+			estate = states[i].endpoint_state;
+			if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags)) {
+				ret = 2;
+				goto stop;
+			}
+			if (atomic_read(&estate->nr_probing))
+				still_probing = true;
+			if (estate->responsive_set & states[i].untried_addrs) {
+				ret = 1;
+				goto stop;
 			}
 		}
 
@@ -288,28 +349,12 @@ int afs_wait_for_fs_probes(struct afs_server_list *slist, unsigned long untried)
 stop:
 	set_current_state(TASK_RUNNING);
 
-	for (i = 0; i < slist->nr_servers; i++) {
-		if (test_bit(i, &untried)) {
-			server = slist->servers[i].server;
-			rtt_s = READ_ONCE(server->rtt);
-			if (test_bit(AFS_SERVER_FL_RESPONDING, &server->flags) &&
-			    rtt_s < rtt) {
-				pref = i;
-				rtt = rtt_s;
-			}
-
-			remove_wait_queue(&server->probe_wq, &waits[i]);
-		}
-	}
-
-	kfree(waits);
-
-	if (pref == -1 && signal_pending(current))
-		return -ERESTARTSYS;
+	for (i = 0; i < slist->nr_servers; i++)
+		remove_wait_queue(&slist->servers[i].server->probe_wq, &states[i].probe_waiter);
 
-	if (pref >= 0)
-		slist->preferred = pref;
-	return 0;
+	if (!ret && signal_pending(current))
+		ret = -ERESTARTSYS;
+	return ret;
 }
 
 /*
@@ -327,7 +372,7 @@ void afs_fs_probe_timer(struct timer_list *timer)
 /*
  * Dispatch a probe to a server.
  */
-static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server, bool all)
+static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server)
 	__releases(&net->fs_lock)
 {
 	struct key *key = NULL;
@@ -340,7 +385,7 @@ static void afs_dispatch_fs_probe(struct afs_net *net, struct afs_server *server
 	afs_get_server(server, afs_server_trace_get_probe);
 	write_sequnlock(&net->fs_lock);
 
-	afs_fs_probe_fileserver(net, server, key, all);
+	afs_fs_probe_fileserver(net, server, NULL, key);
 	afs_put_server(net, server, afs_server_trace_put_probe);
 }
 
@@ -352,7 +397,7 @@ void afs_probe_fileserver(struct afs_net *net, struct afs_server *server)
 {
 	write_seqlock(&net->fs_lock);
 	if (!list_empty(&server->probe_link))
-		return afs_dispatch_fs_probe(net, server, true);
+		return afs_dispatch_fs_probe(net, server);
 	write_sequnlock(&net->fs_lock);
 }
 
@@ -412,7 +457,7 @@ again:
 		_debug("probe %pU", &server->uuid);
 
 	if (server && (first_pass || !need_resched())) {
-		afs_dispatch_fs_probe(net, server, server == fast);
+		afs_dispatch_fs_probe(net, server);
 		first_pass = false;
 		goto again;
 	}
@@ -436,12 +481,13 @@ again:
 /*
  * Wait for a probe on a particular fileserver to complete for 2s.
  */
-int afs_wait_for_one_fs_probe(struct afs_server *server, bool is_intr)
+int afs_wait_for_one_fs_probe(struct afs_server *server, struct afs_endpoint_state *estate,
+			      unsigned long exclude, bool is_intr)
 {
 	struct wait_queue_entry wait;
 	unsigned long timo = 2 * HZ;
 
-	if (atomic_read(&server->probe_outstanding) == 0)
+	if (atomic_read(&estate->nr_probing) == 0)
 		goto dont_wait;
 
 	init_wait_entry(&wait, 0);
@@ -449,8 +495,9 @@ int afs_wait_for_one_fs_probe(struct afs_server *server, bool is_intr)
 		prepare_to_wait_event(&server->probe_wq, &wait,
 				      is_intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 		if (timo == 0 ||
-		    server->probe.responded ||
-		    atomic_read(&server->probe_outstanding) == 0 ||
+		    test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags) ||
+		    (estate->responsive_set & ~exclude) ||
+		    atomic_read(&estate->nr_probing) == 0 ||
 		    (is_intr && signal_pending(current)))
 			break;
 		timo = schedule_timeout(timo);
@@ -459,7 +506,9 @@ int afs_wait_for_one_fs_probe(struct afs_server *server, bool is_intr)
 	finish_wait(&server->probe_wq, &wait);
 
 dont_wait:
-	if (server->probe.responded)
+	if (estate->responsive_set & ~exclude)
+		return 1;
+	if (test_bit(AFS_ESTATE_SUPERSEDED, &estate->flags))
 		return 0;
 	if (is_intr && signal_pending(current))
 		return -ERESTARTSYS;