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, 128 insertions, 87 deletions

diff --git a/fs/afs/vl_rotate.c b/fs/afs/vl_rotate.c
index eb415ce56360..d8f79f6ada3d 100644
--- a/fs/afs/vl_rotate.c
+++ b/fs/afs/vl_rotate.c
@@ -17,18 +17,21 @@
 bool afs_begin_vlserver_operation(struct afs_vl_cursor *vc, struct afs_cell *cell,
 				  struct key *key)
 {
+	static atomic_t debug_ids;
+
 	memset(vc, 0, sizeof(*vc));
 	vc->cell = cell;
 	vc->key = key;
-	vc->error = -EDESTADDRREQ;
-	vc->ac.error = SHRT_MAX;
+	vc->cumul_error.error = -EDESTADDRREQ;
+	vc->nr_iterations = -1;
 
 	if (signal_pending(current)) {
-		vc->error = -EINTR;
+		vc->cumul_error.error = -EINTR;
 		vc->flags |= AFS_VL_CURSOR_STOP;
 		return false;
 	}
 
+	vc->debug_id = atomic_inc_return(&debug_ids);
 	return true;
 }
 
@@ -52,7 +55,7 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
 				    &cell->dns_lookup_count,
 				    smp_load_acquire(&cell->dns_lookup_count)
 				    != dns_lookup_count) < 0) {
-				vc->error = -ERESTARTSYS;
+				vc->cumul_error.error = -ERESTARTSYS;
 				return false;
 			}
 		}
@@ -60,12 +63,12 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
 		/* Status load is ordered after lookup counter load */
 		if (cell->dns_status == DNS_LOOKUP_GOT_NOT_FOUND) {
 			pr_warn("No record of cell %s\n", cell->name);
-			vc->error = -ENOENT;
+			vc->cumul_error.error = -ENOENT;
 			return false;
 		}
 
 		if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
-			vc->error = -EDESTADDRREQ;
+			vc->cumul_error.error = -EDESTADDRREQ;
 			return false;
 		}
 	}
@@ -78,8 +81,8 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
 	if (!vc->server_list->nr_servers)
 		return false;
 
-	vc->untried = (1UL << vc->server_list->nr_servers) - 1;
-	vc->index = -1;
+	vc->untried_servers = (1UL << vc->server_list->nr_servers) - 1;
+	vc->server_index = -1;
 	return true;
 }
 
@@ -89,54 +92,57 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
  */
 bool afs_select_vlserver(struct afs_vl_cursor *vc)
 {
-	struct afs_addr_list *alist;
+	struct afs_addr_list *alist = vc->alist;
 	struct afs_vlserver *vlserver;
-	struct afs_error e;
-	u32 rtt;
-	int error = vc->ac.error, i;
+	unsigned long set, failed;
+	unsigned int rtt;
+	s32 abort_code = vc->call_abort_code;
+	int error = vc->call_error, i;
+
+	vc->nr_iterations++;
 
-	_enter("%lx[%d],%lx[%d],%d,%d",
-	       vc->untried, vc->index,
-	       vc->ac.tried, vc->ac.index,
-	       error, vc->ac.abort_code);
+	_enter("VC=%x+%x,%d{%lx},%d{%lx},%d,%d",
+	       vc->debug_id, vc->nr_iterations, vc->server_index, vc->untried_servers,
+	       vc->addr_index, vc->addr_tried,
+	       error, abort_code);
 
 	if (vc->flags & AFS_VL_CURSOR_STOP) {
 		_leave(" = f [stopped]");
 		return false;
 	}
 
-	vc->nr_iterations++;
+	if (vc->nr_iterations == 0)
+		goto start;
+
+	WRITE_ONCE(alist->addrs[vc->addr_index].last_error, error);
 
 	/* Evaluate the result of the previous operation, if there was one. */
 	switch (error) {
-	case SHRT_MAX:
-		goto start;
-
 	default:
 	case 0:
 		/* Success or local failure.  Stop. */
-		vc->error = error;
+		vc->cumul_error.error = error;
 		vc->flags |= AFS_VL_CURSOR_STOP;
-		_leave(" = f [okay/local %d]", vc->ac.error);
+		_leave(" = f [okay/local %d]", vc->cumul_error.error);
 		return false;
 
 	case -ECONNABORTED:
 		/* The far side rejected the operation on some grounds.  This
 		 * might involve the server being busy or the volume having been moved.
 		 */
-		switch (vc->ac.abort_code) {
+		switch (abort_code) {
 		case AFSVL_IO:
 		case AFSVL_BADVOLOPER:
 		case AFSVL_NOMEM:
 			/* The server went weird. */
-			vc->error = -EREMOTEIO;
+			afs_prioritise_error(&vc->cumul_error, -EREMOTEIO, abort_code);
 			//write_lock(&vc->cell->vl_servers_lock);
-			//vc->server_list->weird_mask |= 1 << vc->index;
+			//vc->server_list->weird_mask |= 1 << vc->server_index;
 			//write_unlock(&vc->cell->vl_servers_lock);
 			goto next_server;
 
 		default:
-			vc->error = afs_abort_to_error(vc->ac.abort_code);
+			afs_prioritise_error(&vc->cumul_error, error, abort_code);
 			goto failed;
 		}
 
@@ -149,12 +155,12 @@ bool afs_select_vlserver(struct afs_vl_cursor *vc)
 	case -ETIMEDOUT:
 	case -ETIME:
 		_debug("no conn %d", error);
-		vc->error = error;
+		afs_prioritise_error(&vc->cumul_error, error, 0);
 		goto iterate_address;
 
 	case -ECONNRESET:
 		_debug("call reset");
-		vc->error = error;
+		afs_prioritise_error(&vc->cumul_error, error, 0);
 		vc->flags |= AFS_VL_CURSOR_RETRY;
 		goto next_server;
 
@@ -165,7 +171,13 @@ bool afs_select_vlserver(struct afs_vl_cursor *vc)
 
 restart_from_beginning:
 	_debug("restart");
-	afs_end_cursor(&vc->ac);
+	if (vc->call_responded &&
+	    vc->addr_index != vc->alist->preferred &&
+	    test_bit(alist->preferred, &vc->addr_tried))
+		WRITE_ONCE(alist->preferred, vc->addr_index);
+	afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_restart);
+	alist = vc->alist = NULL;
+
 	afs_put_vlserverlist(vc->cell->net, vc->server_list);
 	vc->server_list = NULL;
 	if (vc->flags & AFS_VL_CURSOR_RETRIED)
@@ -173,53 +185,58 @@ restart_from_beginning:
 	vc->flags |= AFS_VL_CURSOR_RETRIED;
 start:
 	_debug("start");
+	ASSERTCMP(alist, ==, NULL);
 
 	if (!afs_start_vl_iteration(vc))
 		goto failed;
 
 	error = afs_send_vl_probes(vc->cell->net, vc->key, vc->server_list);
-	if (error < 0)
-		goto failed_set_error;
+	if (error < 0) {
+		afs_prioritise_error(&vc->cumul_error, error, 0);
+		goto failed;
+	}
 
 pick_server:
-	_debug("pick [%lx]", vc->untried);
+	_debug("pick [%lx]", vc->untried_servers);
+	ASSERTCMP(alist, ==, NULL);
 
-	error = afs_wait_for_vl_probes(vc->server_list, vc->untried);
-	if (error < 0)
-		goto failed_set_error;
+	error = afs_wait_for_vl_probes(vc->server_list, vc->untried_servers);
+	if (error < 0) {
+		afs_prioritise_error(&vc->cumul_error, error, 0);
+		goto failed;
+	}
 
 	/* Pick the untried server with the lowest RTT. */
-	vc->index = vc->server_list->preferred;
-	if (test_bit(vc->index, &vc->untried))
+	vc->server_index = vc->server_list->preferred;
+	if (test_bit(vc->server_index, &vc->untried_servers))
 		goto selected_server;
 
-	vc->index = -1;
-	rtt = U32_MAX;
+	vc->server_index = -1;
+	rtt = UINT_MAX;
 	for (i = 0; i < vc->server_list->nr_servers; i++) {
 		struct afs_vlserver *s = vc->server_list->servers[i].server;
 
-		if (!test_bit(i, &vc->untried) ||
+		if (!test_bit(i, &vc->untried_servers) ||
 		    !test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
 			continue;
-		if (s->probe.rtt < rtt) {
-			vc->index = i;
+		if (s->probe.rtt <= rtt) {
+			vc->server_index = i;
 			rtt = s->probe.rtt;
 		}
 	}
 
-	if (vc->index == -1)
+	if (vc->server_index == -1)
 		goto no_more_servers;
 
 selected_server:
-	_debug("use %d", vc->index);
-	__clear_bit(vc->index, &vc->untried);
+	_debug("use %d", vc->server_index);
+	__clear_bit(vc->server_index, &vc->untried_servers);
 
 	/* We're starting on a different vlserver from the list.  We need to
 	 * check it, find its address list and probe its capabilities before we
 	 * use it.
 	 */
-	ASSERTCMP(vc->ac.alist, ==, NULL);
-	vlserver = vc->server_list->servers[vc->index].server;
+	vlserver = vc->server_list->servers[vc->server_index].server;
 	vc->server = vlserver;
 
 	_debug("USING VLSERVER: %s", vlserver->name);
@@ -227,34 +244,48 @@ selected_server:
 	read_lock(&vlserver->lock);
 	alist = rcu_dereference_protected(vlserver->addresses,
 					  lockdep_is_held(&vlserver->lock));
-	afs_get_addrlist(alist);
+	vc->alist = afs_get_addrlist(alist, afs_alist_trace_get_vlrotate_set);
 	read_unlock(&vlserver->lock);
 
-	memset(&vc->ac, 0, sizeof(vc->ac));
-
-	if (!vc->ac.alist)
-		vc->ac.alist = alist;
-	else
-		afs_put_addrlist(alist);
-
-	vc->ac.index = -1;
+	vc->addr_tried = 0;
+	vc->addr_index = -1;
 
 iterate_address:
-	ASSERT(vc->ac.alist);
 	/* Iterate over the current server's address list to try and find an
 	 * address on which it will respond to us.
 	 */
-	if (!afs_iterate_addresses(&vc->ac))
+	set = READ_ONCE(alist->responded);
+	failed = READ_ONCE(alist->probe_failed);
+	vc->addr_index = READ_ONCE(alist->preferred);
+
+	_debug("%lx-%lx-%lx,%d", set, failed, vc->addr_tried, vc->addr_index);
+
+	set &= ~(failed | vc->addr_tried);
+
+	if (!set)
 		goto next_server;
 
-	_debug("VL address %d/%d", vc->ac.index, vc->ac.alist->nr_addrs);
+	if (!test_bit(vc->addr_index, &set))
+		vc->addr_index = __ffs(set);
+
+	set_bit(vc->addr_index, &vc->addr_tried);
+	vc->alist = alist;
 
-	_leave(" = t %pISpc", &vc->ac.alist->addrs[vc->ac.index].transport);
+	_debug("VL address %d/%d", vc->addr_index, alist->nr_addrs);
+
+	vc->call_responded = false;
+	_leave(" = t %pISpc", rxrpc_kernel_remote_addr(alist->addrs[vc->addr_index].peer));
 	return true;
 
 next_server:
 	_debug("next");
-	afs_end_cursor(&vc->ac);
+	ASSERT(alist);
+	if (vc->call_responded &&
+	    vc->addr_index != alist->preferred &&
+	    test_bit(alist->preferred, &vc->addr_tried))
+		WRITE_ONCE(alist->preferred, vc->addr_index);
+	afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_next);
+	alist = vc->alist = NULL;
 	goto pick_server;
 
 no_more_servers:
@@ -264,25 +295,26 @@ no_more_servers:
 	if (vc->flags & AFS_VL_CURSOR_RETRY)
 		goto restart_from_beginning;
 
-	e.error = -EDESTADDRREQ;
-	e.responded = false;
 	for (i = 0; i < vc->server_list->nr_servers; i++) {
 		struct afs_vlserver *s = vc->server_list->servers[i].server;
 
 		if (test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags))
-			e.responded = true;
-		afs_prioritise_error(&e, READ_ONCE(s->probe.error),
+			vc->cumul_error.responded = true;
+		afs_prioritise_error(&vc->cumul_error, READ_ONCE(s->probe.error),
 				     s->probe.abort_code);
 	}
 
-	error = e.error;
-
-failed_set_error:
-	vc->error = error;
 failed:
+	if (alist) {
+		if (vc->call_responded &&
+		    vc->addr_index != alist->preferred &&
+		    test_bit(alist->preferred, &vc->addr_tried))
+			WRITE_ONCE(alist->preferred, vc->addr_index);
+		afs_put_addrlist(alist, afs_alist_trace_put_vlrotate_fail);
+		alist = vc->alist = NULL;
+	}
 	vc->flags |= AFS_VL_CURSOR_STOP;
-	afs_end_cursor(&vc->ac);
-	_leave(" = f [failed %d]", vc->error);
+	_leave(" = f [failed %d]", vc->cumul_error.error);
 	return false;
 }
 
@@ -305,7 +337,10 @@ static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 	pr_notice("DNS: src=%u st=%u lc=%x\n",
 		  cell->dns_source, cell->dns_status, cell->dns_lookup_count);
 	pr_notice("VC: ut=%lx ix=%u ni=%hu fl=%hx err=%hd\n",
-		  vc->untried, vc->index, vc->nr_iterations, vc->flags, vc->error);
+		  vc->untried_servers, vc->server_index, vc->nr_iterations,
+		  vc->flags, vc->cumul_error.error);
+	pr_notice("VC: call  er=%d ac=%d r=%u\n",
+		  vc->call_error, vc->call_abort_code, vc->call_responded);
 
 	if (vc->server_list) {
 		const struct afs_vlserver_list *sl = vc->server_list;
@@ -322,16 +357,14 @@ static void afs_vl_dump_edestaddrreq(const struct afs_vl_cursor *vc)
 					  a->nr_ipv4, a->nr_addrs, a->max_addrs,
 					  a->preferred);
 				pr_notice("VC:  - R=%lx F=%lx\n",
-					  a->responded, a->failed);
-				if (a == vc->ac.alist)
+					  a->responded, a->probe_failed);
+				if (a == vc->alist)
 					pr_notice("VC:  - current\n");
 			}
 		}
 	}
 
-	pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
-		  vc->ac.tried, vc->ac.index, vc->ac.abort_code, vc->ac.error,
-		  vc->ac.responded, vc->ac.nr_iterations);
+	pr_notice("AC: t=%lx ax=%u\n", vc->addr_tried, vc->addr_index);
 	rcu_read_unlock();
 }
 
@@ -342,17 +375,25 @@ int afs_end_vlserver_operation(struct afs_vl_cursor *vc)
 {
 	struct afs_net *net = vc->cell->net;
 
-	if (vc->error == -EDESTADDRREQ ||
-	    vc->error == -EADDRNOTAVAIL ||
-	    vc->error == -ENETUNREACH ||
-	    vc->error == -EHOSTUNREACH)
+	_enter("VC=%x+%x", vc->debug_id, vc->nr_iterations);
+
+	switch (vc->cumul_error.error) {
+	case -EDESTADDRREQ:
+	case -EADDRNOTAVAIL:
+	case -ENETUNREACH:
+	case -EHOSTUNREACH:
 		afs_vl_dump_edestaddrreq(vc);
+		break;
+	}
 
-	afs_end_cursor(&vc->ac);
+	if (vc->alist) {
+		if (vc->call_responded &&
+		    vc->addr_index != vc->alist->preferred &&
+		    test_bit(vc->alist->preferred, &vc->addr_tried))
+			WRITE_ONCE(vc->alist->preferred, vc->addr_index);
+		afs_put_addrlist(vc->alist, afs_alist_trace_put_vlrotate_end);
+		vc->alist = NULL;
+	}
 	afs_put_vlserverlist(net, vc->server_list);
-
-	if (vc->error == -ECONNABORTED)
-		vc->error = afs_abort_to_error(vc->ac.abort_code);
-
-	return vc->error;
+	return vc->cumul_error.error;
 }