Linux 6.13-rc4

[linux.git] / fs / afs / rotate.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* Handle fileserver selection and rotation.
 *
 * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/sched/signal.h>
#include "internal.h"
#include "afs_fs.h"
#include "protocol_uae.h"

void afs_clear_server_states(struct afs_operation *op)
{
        unsigned int i;

        if (op->server_states) {
                for (i = 0; i < op->server_list->nr_servers; i++)
                        afs_put_endpoint_state(op->server_states[i].endpoint_state,
                                               afs_estate_trace_put_server_state);
                kfree(op->server_states);
        }
}

/*
 * Begin iteration through a server list, starting with the vnode's last used
 * server if possible, or the last recorded good server if not.
 */
static bool afs_start_fs_iteration(struct afs_operation *op,
                                   struct afs_vnode *vnode)
{
        struct afs_server *server;
        void *cb_server;
        int i;

        trace_afs_rotate(op, afs_rotate_trace_start, 0);

        read_lock(&op->volume->servers_lock);
        op->server_list = afs_get_serverlist(
                rcu_dereference_protected(op->volume->servers,
                                          lockdep_is_held(&op->volume->servers_lock)));
        read_unlock(&op->volume->servers_lock);

        op->server_states = kcalloc(op->server_list->nr_servers, sizeof(op->server_states[0]),
                                    GFP_KERNEL);
        if (!op->server_states) {
                afs_op_nomem(op);
                trace_afs_rotate(op, afs_rotate_trace_nomem, 0);
                return false;
        }

        rcu_read_lock();
        for (i = 0; i < op->server_list->nr_servers; i++) {
                struct afs_endpoint_state *estate;
                struct afs_server_state *s = &op->server_states[i];

                server = op->server_list->servers[i].server;
                estate = rcu_dereference(server->endpoint_state);
                s->endpoint_state = afs_get_endpoint_state(estate,
                                                           afs_estate_trace_get_server_state);
                s->probe_seq = estate->probe_seq;
                s->untried_addrs = (1UL << estate->addresses->nr_addrs) - 1;
                init_waitqueue_entry(&s->probe_waiter, current);
                afs_get_address_preferences(op->net, estate->addresses);
        }
        rcu_read_unlock();


        op->untried_servers = (1UL << op->server_list->nr_servers) - 1;
        op->server_index = -1;

        cb_server = vnode->cb_server;
        if (cb_server) {
                /* See if the vnode's preferred record is still available */
                for (i = 0; i < op->server_list->nr_servers; i++) {
                        server = op->server_list->servers[i].server;
                        if (server == cb_server) {
                                op->server_index = i;
                                goto found_interest;
                        }
                }

                /* If we have a lock outstanding on a server that's no longer
                 * serving this vnode, then we can't switch to another server
                 * and have to return an error.
                 */
                if (op->flags & AFS_OPERATION_CUR_ONLY) {
                        afs_op_set_error(op, -ESTALE);
                        trace_afs_rotate(op, afs_rotate_trace_stale_lock, 0);
                        return false;
                }

                /* Note that the callback promise is effectively broken */
                write_seqlock(&vnode->cb_lock);
                ASSERTCMP(cb_server, ==, vnode->cb_server);
                vnode->cb_server = NULL;
                if (atomic64_xchg(&vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE)
                        vnode->cb_break++;
                write_sequnlock(&vnode->cb_lock);
        }

found_interest:
        return true;
}

/*
 * Post volume busy note.
 */
static void afs_busy(struct afs_operation *op, u32 abort_code)
{
        const char *m;

        switch (abort_code) {
        case VOFFLINE:          m = "offline";          break;
        case VRESTARTING:       m = "restarting";       break;
        case VSALVAGING:        m = "being salvaged";   break;
        default:                m = "busy";             break;
        }

        pr_notice("kAFS: Volume %llu '%s' on server %pU is %s\n",
                  op->volume->vid, op->volume->name, &op->server->uuid, m);
}

/*
 * Sleep and retry the operation to the same fileserver.
 */
static bool afs_sleep_and_retry(struct afs_operation *op)
{
        trace_afs_rotate(op, afs_rotate_trace_busy_sleep, 0);
        if (!(op->flags & AFS_OPERATION_UNINTR)) {
                msleep_interruptible(1000);
                if (signal_pending(current)) {
                        afs_op_set_error(op, -ERESTARTSYS);
                        return false;
                }
        } else {
                msleep(1000);
        }

        return true;
}

/*
 * Select the fileserver to use.  May be called multiple times to rotate
 * through the fileservers.
 */
bool afs_select_fileserver(struct afs_operation *op)
{
        struct afs_addr_list *alist;
        struct afs_server *server;
        struct afs_vnode *vnode = op->file[0].vnode;
        unsigned long set, failed;
        s32 abort_code = op->call_abort_code;
        int best_prio = 0;
        int error = op->call_error, addr_index, i, j;

        op->nr_iterations++;

        _enter("OP=%x+%x,%llx,%u{%lx},%u{%lx},%d,%d",
               op->debug_id, op->nr_iterations, op->volume->vid,
               op->server_index, op->untried_servers,
               op->addr_index, op->addr_tried,
               error, abort_code);

        if (op->flags & AFS_OPERATION_STOP) {
                trace_afs_rotate(op, afs_rotate_trace_stopped, 0);
                _leave(" = f [stopped]");
                return false;
        }

        if (op->nr_iterations == 0)
                goto start;

        WRITE_ONCE(op->estate->addresses->addrs[op->addr_index].last_error, error);
        trace_afs_rotate(op, afs_rotate_trace_iter, op->call_error);

        /* Evaluate the result of the previous operation, if there was one. */
        switch (op->call_error) {
        case 0:
                clear_bit(AFS_SE_VOLUME_OFFLINE,
                          &op->server_list->servers[op->server_index].flags);
                clear_bit(AFS_SE_VOLUME_BUSY,
                          &op->server_list->servers[op->server_index].flags);
                op->cumul_error.responded = true;

                /* We succeeded, but we may need to redo the op from another
                 * server if we're looking at a set of RO volumes where some of
                 * the servers have not yet been brought up to date lest we
                 * regress the data.  We only switch to the new version once
                 * >=50% of the servers are updated.
                 */
                error = afs_update_volume_state(op);
                if (error != 0) {
                        if (error == 1) {
                                afs_sleep_and_retry(op);
                                goto restart_from_beginning;
                        }
                        afs_op_set_error(op, error);
                        goto failed;
                }
                fallthrough;
        default:
                /* Success or local failure.  Stop. */
                afs_op_set_error(op, error);
                op->flags |= AFS_OPERATION_STOP;
                trace_afs_rotate(op, afs_rotate_trace_stop, error);
                _leave(" = f [okay/local %d]", 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.
                 *
                 * Note that various V* errors should not be sent to a cache manager
                 * by a fileserver as they should be translated to more modern UAE*
                 * errors instead.  IBM AFS and OpenAFS fileservers, however, do leak
                 * these abort codes.
                 */
                trace_afs_rotate(op, afs_rotate_trace_aborted, abort_code);
                op->cumul_error.responded = true;
                switch (abort_code) {
                case VNOVOL:
                        /* This fileserver doesn't know about the volume.
                         * - May indicate that the VL is wrong - retry once and compare
                         *   the results.
                         * - May indicate that the fileserver couldn't attach to the vol.
                         * - The volume might have been temporarily removed so that it can
                         *   be replaced by a volume restore.  "vos" might have ended one
                         *   transaction and has yet to create the next.
                         * - The volume might not be blessed or might not be in-service
                         *   (administrative action).
                         */
                        if (op->flags & AFS_OPERATION_VNOVOL) {
                                afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
                                goto next_server;
                        }

                        write_lock(&op->volume->servers_lock);
                        op->server_list->vnovol_mask |= 1 << op->server_index;
                        write_unlock(&op->volume->servers_lock);

                        set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
                        error = afs_check_volume_status(op->volume, op);
                        if (error < 0) {
                                afs_op_set_error(op, error);
                                goto failed;
                        }

                        if (test_bit(AFS_VOLUME_DELETED, &op->volume->flags)) {
                                afs_op_set_error(op, -ENOMEDIUM);
                                goto failed;
                        }

                        /* If the server list didn't change, then assume that
                         * it's the fileserver having trouble.
                         */
                        if (rcu_access_pointer(op->volume->servers) == op->server_list) {
                                afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
                                goto next_server;
                        }

                        /* Try again */
                        op->flags |= AFS_OPERATION_VNOVOL;
                        _leave(" = t [vnovol]");
                        return true;

                case VVOLEXISTS:
                case VONLINE:
                        /* These should not be returned from the fileserver. */
                        pr_warn("Fileserver returned unexpected abort %d\n",
                                abort_code);
                        afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
                        goto next_server;

                case VNOSERVICE:
                        /* Prior to AFS 3.2 VNOSERVICE was returned from the fileserver
                         * if the volume was neither in-service nor administratively
                         * blessed.  All usage was replaced by VNOVOL because AFS 3.1 and
                         * earlier cache managers did not handle VNOSERVICE and assumed
                         * it was the client OSes errno 105.
                         *
                         * Starting with OpenAFS 1.4.8 VNOSERVICE was repurposed as the
                         * fileserver idle dead time error which was sent in place of
                         * RX_CALL_TIMEOUT (-3).  The error was intended to be sent if the
                         * fileserver took too long to send a reply to the client.
                         * RX_CALL_TIMEOUT would have caused the cache manager to mark the
                         * server down whereas VNOSERVICE since AFS 3.2 would cause cache
                         * manager to temporarily (up to 15 minutes) mark the volume
                         * instance as unusable.
                         *
                         * The idle dead logic resulted in cache inconsistency since a
                         * state changing call that the cache manager assumed was dead
                         * could still be processed to completion by the fileserver.  This
                         * logic was removed in OpenAFS 1.8.0 and VNOSERVICE is no longer
                         * returned.  However, many 1.4.8 through 1.6.24 fileservers are
                         * still in existence.
                         *
                         * AuriStorFS fileservers have never returned VNOSERVICE.
                         *
                         * VNOSERVICE should be treated as an alias for RX_CALL_TIMEOUT.
                         */
                case RX_CALL_TIMEOUT:
                        afs_op_accumulate_error(op, -ETIMEDOUT, abort_code);
                        goto next_server;

                case VSALVAGING: /* This error should not be leaked to cache managers
                                  * but is from OpenAFS demand attach fileservers.
                                  * It should be treated as an alias for VOFFLINE.
                                  */
                case VSALVAGE: /* VSALVAGE should be treated as a synonym of VOFFLINE */
                case VOFFLINE:
                        /* The volume is in use by the volserver or another volume utility
                         * for an operation that might alter the contents.  The volume is
                         * expected to come back but it might take a long time (could be
                         * days).
                         */
                        if (!test_and_set_bit(AFS_SE_VOLUME_OFFLINE,
                                              &op->server_list->servers[op->server_index].flags)) {
                                afs_busy(op, abort_code);
                                clear_bit(AFS_SE_VOLUME_BUSY,
                                          &op->server_list->servers[op->server_index].flags);
                        }
                        if (op->flags & AFS_OPERATION_NO_VSLEEP) {
                                afs_op_set_error(op, -EADV);
                                goto failed;
                        }
                        goto busy;

                case VRESTARTING: /* The fileserver is either shutting down or starting up. */
                case VBUSY:
                        /* The volume is in use by the volserver or another volume
                         * utility for an operation that is not expected to alter the
                         * contents of the volume.  VBUSY does not need to be returned
                         * for a ROVOL or BACKVOL bound to an ITBusy volserver
                         * transaction.  The fileserver is permitted to continue serving
                         * content from ROVOLs and BACKVOLs during an ITBusy transaction
                         * because the content will not change.  However, many fileserver
                         * releases do return VBUSY for ROVOL and BACKVOL instances under
                         * many circumstances.
                         *
                         * Retry after going round all the servers unless we have a file
                         * lock we need to maintain.
                         */
                        if (op->flags & AFS_OPERATION_NO_VSLEEP) {
                                afs_op_set_error(op, -EBUSY);
                                goto failed;
                        }
                        if (!test_and_set_bit(AFS_SE_VOLUME_BUSY,
                                              &op->server_list->servers[op->server_index].flags)) {
                                afs_busy(op, abort_code);
                                clear_bit(AFS_SE_VOLUME_OFFLINE,
                                          &op->server_list->servers[op->server_index].flags);
                        }
                busy:
                        if (op->flags & AFS_OPERATION_CUR_ONLY) {
                                if (!afs_sleep_and_retry(op))
                                        goto failed;

                                /* Retry with same server & address */
                                _leave(" = t [vbusy]");
                                return true;
                        }

                        op->flags |= AFS_OPERATION_VBUSY;
                        goto next_server;

                case VMOVED:
                        /* The volume migrated to another server.  We consider
                         * consider all locks and callbacks broken and request
                         * an update from the VLDB.
                         *
                         * We also limit the number of VMOVED hops we will
                         * honour, just in case someone sets up a loop.
                         */
                        if (op->flags & AFS_OPERATION_VMOVED) {
                                afs_op_set_error(op, -EREMOTEIO);
                                goto failed;
                        }
                        op->flags |= AFS_OPERATION_VMOVED;

                        set_bit(AFS_VOLUME_WAIT, &op->volume->flags);
                        set_bit(AFS_VOLUME_NEEDS_UPDATE, &op->volume->flags);
                        error = afs_check_volume_status(op->volume, op);
                        if (error < 0) {
                                afs_op_set_error(op, error);
                                goto failed;
                        }

                        /* If the server list didn't change, then the VLDB is
                         * out of sync with the fileservers.  This is hopefully
                         * a temporary condition, however, so we don't want to
                         * permanently block access to the file.
                         *
                         * TODO: Try other fileservers if we can.
                         *
                         * TODO: Retry a few times with sleeps.
                         */
                        if (rcu_access_pointer(op->volume->servers) == op->server_list) {
                                afs_op_accumulate_error(op, -ENOMEDIUM, abort_code);
                                goto failed;
                        }

                        goto restart_from_beginning;

                case UAEIO:
                case VIO:
                        afs_op_accumulate_error(op, -EREMOTEIO, abort_code);
                        if (op->volume->type != AFSVL_RWVOL)
                                goto next_server;
                        goto failed;

                case VDISKFULL:
                case UAENOSPC:
                        /* The partition is full.  Only applies to RWVOLs.
                         * Translate locally and return ENOSPC.
                         * No replicas to failover to.
                         */
                        afs_op_set_error(op, -ENOSPC);
                        goto failed_but_online;

                case VOVERQUOTA:
                case UAEDQUOT:
                        /* Volume is full.  Only applies to RWVOLs.
                         * Translate locally and return EDQUOT.
                         * No replicas to failover to.
                         */
                        afs_op_set_error(op, -EDQUOT);
                        goto failed_but_online;

                default:
                        afs_op_accumulate_error(op, error, abort_code);
                failed_but_online:
                        clear_bit(AFS_SE_VOLUME_OFFLINE,
                                  &op->server_list->servers[op->server_index].flags);
                        clear_bit(AFS_SE_VOLUME_BUSY,
                                  &op->server_list->servers[op->server_index].flags);
                        goto failed;
                }

        case -ETIMEDOUT:
        case -ETIME:
                if (afs_op_error(op) != -EDESTADDRREQ)
                        goto iterate_address;
                fallthrough;
        case -ERFKILL:
        case -EADDRNOTAVAIL:
        case -ENETUNREACH:
        case -EHOSTUNREACH:
        case -EHOSTDOWN:
        case -ECONNREFUSED:
                _debug("no conn");
                afs_op_accumulate_error(op, error, 0);
                goto iterate_address;

        case -ENETRESET:
                pr_warn("kAFS: Peer reset %s (op=%x)\n",
                        op->type ? op->type->name : "???", op->debug_id);
                fallthrough;
        case -ECONNRESET:
                _debug("call reset");
                afs_op_set_error(op, error);
                goto failed;
        }

restart_from_beginning:
        trace_afs_rotate(op, afs_rotate_trace_restart, 0);
        _debug("restart");
        op->estate = NULL;
        op->server = NULL;
        afs_clear_server_states(op);
        op->server_states = NULL;
        afs_put_serverlist(op->net, op->server_list);
        op->server_list = NULL;
start:
        _debug("start");
        ASSERTCMP(op->estate, ==, NULL);
        /* See if we need to do an update of the volume record.  Note that the
         * volume may have moved or even have been deleted.
         */
        error = afs_check_volume_status(op->volume, op);
        trace_afs_rotate(op, afs_rotate_trace_check_vol_status, error);
        if (error < 0) {
                afs_op_set_error(op, error);
                goto failed;
        }

        if (!afs_start_fs_iteration(op, vnode))
                goto failed;

        _debug("__ VOL %llx __", op->volume->vid);

pick_server:
        _debug("pick [%lx]", op->untried_servers);
        ASSERTCMP(op->estate, ==, NULL);

        error = afs_wait_for_fs_probes(op, op->server_states,
                                       !(op->flags & AFS_OPERATION_UNINTR));
        switch (error) {
        case 0: /* No untried responsive servers and no outstanding probes */
                trace_afs_rotate(op, afs_rotate_trace_probe_none, 0);
                goto no_more_servers;
        case 1: /* Got a response */
                trace_afs_rotate(op, afs_rotate_trace_probe_response, 0);
                break;
        case 2: /* Probe data superseded */
                trace_afs_rotate(op, afs_rotate_trace_probe_superseded, 0);
                goto restart_from_beginning;
        default:
                trace_afs_rotate(op, afs_rotate_trace_probe_error, error);
                afs_op_set_error(op, error);
                goto failed;
        }

        /* Pick the untried server with the highest priority untried endpoint.
         * If we have outstanding callbacks, we stick with the server we're
         * already using if we can.
         */
        if (op->server) {
                _debug("server %u", op->server_index);
                if (test_bit(op->server_index, &op->untried_servers))
                        goto selected_server;
                op->server = NULL;
                _debug("no server");
        }

        rcu_read_lock();
        op->server_index = -1;
        best_prio = -1;
        for (i = 0; i < op->server_list->nr_servers; i++) {
                struct afs_endpoint_state *es;
                struct afs_server_entry *se = &op->server_list->servers[i];
                struct afs_addr_list *sal;
                struct afs_server *s = se->server;

                if (!test_bit(i, &op->untried_servers) ||
                    test_bit(AFS_SE_EXCLUDED, &se->flags) ||
                    !test_bit(AFS_SERVER_FL_RESPONDING, &s->flags))
                        continue;
                es = op->server_states[i].endpoint_state;
                sal = es->addresses;

                afs_get_address_preferences_rcu(op->net, sal);
                for (j = 0; j < sal->nr_addrs; j++) {
                        if (es->failed_set & (1 << j))
                                continue;
                        if (!sal->addrs[j].peer)
                                continue;
                        if (sal->addrs[j].prio > best_prio) {
                                op->server_index = i;
                                best_prio = sal->addrs[j].prio;
                        }
                }
        }
        rcu_read_unlock();

        if (op->server_index == -1)
                goto no_more_servers;

selected_server:
        trace_afs_rotate(op, afs_rotate_trace_selected_server, best_prio);
        _debug("use %d prio %u", op->server_index, best_prio);
        __clear_bit(op->server_index, &op->untried_servers);

        /* We're starting on a different fileserver from the list.  We need to
         * check it, create a callback intercept, find its address list and
         * probe its capabilities before we use it.
         */
        ASSERTCMP(op->estate, ==, NULL);
        server = op->server_list->servers[op->server_index].server;

        if (!afs_check_server_record(op, server, op->key))
                goto failed;

        _debug("USING SERVER: %pU", &server->uuid);

        op->flags |= AFS_OPERATION_RETRY_SERVER;
        op->server = server;
        if (vnode->cb_server != server) {
                vnode->cb_server = server;
                vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
                atomic64_set(&vnode->cb_expires_at, AFS_NO_CB_PROMISE);
        }

retry_server:
        op->addr_tried = 0;
        op->addr_index = -1;

iterate_address:
        /* Iterate over the current server's address list to try and find an
         * address on which it will respond to us.
         */
        op->estate = op->server_states[op->server_index].endpoint_state;
        set = READ_ONCE(op->estate->responsive_set);
        failed = READ_ONCE(op->estate->failed_set);
        _debug("iterate ES=%x rs=%lx fs=%lx", op->estate->probe_seq, set, failed);
        set &= ~(failed | op->addr_tried);
        trace_afs_rotate(op, afs_rotate_trace_iterate_addr, set);
        if (!set)
                goto wait_for_more_probe_results;

        alist = op->estate->addresses;
        best_prio = -1;
        addr_index = 0;
        for (i = 0; i < alist->nr_addrs; i++) {
                if (!(set & (1 << i)))
                        continue;
                if (alist->addrs[i].prio > best_prio) {
                        addr_index = i;
                        best_prio = alist->addrs[i].prio;
                }
        }

        alist->preferred = addr_index;

        op->addr_index = addr_index;
        set_bit(addr_index, &op->addr_tried);

        op->volsync.creation = TIME64_MIN;
        op->volsync.update = TIME64_MIN;
        op->call_responded = false;
        _debug("address [%u] %u/%u %pISp",
               op->server_index, addr_index, alist->nr_addrs,
               rxrpc_kernel_remote_addr(alist->addrs[op->addr_index].peer));
        _leave(" = t");
        return true;

wait_for_more_probe_results:
        error = afs_wait_for_one_fs_probe(op->server, op->estate, op->addr_tried,
                                          !(op->flags & AFS_OPERATION_UNINTR));
        if (error == 1)
                goto iterate_address;
        if (!error)
                goto restart_from_beginning;

        /* We've now had a failure to respond on all of a server's addresses -
         * immediately probe them again and consider retrying the server.
         */
        trace_afs_rotate(op, afs_rotate_trace_probe_fileserver, 0);
        afs_probe_fileserver(op->net, op->server);
        if (op->flags & AFS_OPERATION_RETRY_SERVER) {
                error = afs_wait_for_one_fs_probe(op->server, op->estate, op->addr_tried,
                                                  !(op->flags & AFS_OPERATION_UNINTR));
                switch (error) {
                case 1:
                        op->flags &= ~AFS_OPERATION_RETRY_SERVER;
                        trace_afs_rotate(op, afs_rotate_trace_retry_server, 1);
                        goto retry_server;
                case 0:
                        trace_afs_rotate(op, afs_rotate_trace_retry_server, 0);
                        goto restart_from_beginning;
                case -ERESTARTSYS:
                        afs_op_set_error(op, error);
                        goto failed;
                case -ETIME:
                case -EDESTADDRREQ:
                        goto next_server;
                }
        }

next_server:
        trace_afs_rotate(op, afs_rotate_trace_next_server, 0);
        _debug("next");
        op->estate = NULL;
        goto pick_server;

no_more_servers:
        /* That's all the servers poked to no good effect.  Try again if some
         * of them were busy.
         */
        trace_afs_rotate(op, afs_rotate_trace_no_more_servers, 0);
        if (op->flags & AFS_OPERATION_VBUSY) {
                afs_sleep_and_retry(op);
                op->flags &= ~AFS_OPERATION_VBUSY;
                goto restart_from_beginning;
        }

        rcu_read_lock();
        for (i = 0; i < op->server_list->nr_servers; i++) {
                struct afs_endpoint_state *estate;

                estate = op->server_states[i].endpoint_state;
                error = READ_ONCE(estate->error);
                if (error < 0)
                        afs_op_accumulate_error(op, error, estate->abort_code);
        }
        rcu_read_unlock();

failed:
        trace_afs_rotate(op, afs_rotate_trace_failed, 0);
        op->flags |= AFS_OPERATION_STOP;
        op->estate = NULL;
        _leave(" = f [failed %d]", afs_op_error(op));
        return false;
}

/*
 * Dump cursor state in the case of the error being EDESTADDRREQ.
 */
void afs_dump_edestaddrreq(const struct afs_operation *op)
{
        static int count;
        int i;

        if (!IS_ENABLED(CONFIG_AFS_DEBUG_CURSOR) || count > 3)
                return;
        count++;

        rcu_read_lock();

        pr_notice("EDESTADDR occurred\n");
        pr_notice("OP: cbb=%x cbb2=%x fl=%x err=%hd\n",
                  op->file[0].cb_break_before,
                  op->file[1].cb_break_before, op->flags, op->cumul_error.error);
        pr_notice("OP: ut=%lx ix=%d ni=%u\n",
                  op->untried_servers, op->server_index, op->nr_iterations);
        pr_notice("OP: call  er=%d ac=%d r=%u\n",
                  op->call_error, op->call_abort_code, op->call_responded);

        if (op->server_list) {
                const struct afs_server_list *sl = op->server_list;

                pr_notice("FC: SL nr=%u vnov=%hx\n",
                          sl->nr_servers, sl->vnovol_mask);
                for (i = 0; i < sl->nr_servers; i++) {
                        const struct afs_server *s = sl->servers[i].server;
                        const struct afs_endpoint_state *e =
                                rcu_dereference(s->endpoint_state);
                        const struct afs_addr_list *a = e->addresses;

                        pr_notice("FC: server fl=%lx av=%u %pU\n",
                                  s->flags, s->addr_version, &s->uuid);
                        pr_notice("FC:  - pq=%x R=%lx F=%lx\n",
                                  e->probe_seq, e->responsive_set, e->failed_set);
                        if (a) {
                                pr_notice("FC:  - av=%u nr=%u/%u/%u pr=%u\n",
                                          a->version,
                                          a->nr_ipv4, a->nr_addrs, a->max_addrs,
                                          a->preferred);
                                if (a == e->addresses)
                                        pr_notice("FC:  - current\n");
                        }
                }
        }

        pr_notice("AC: t=%lx ax=%d\n", op->addr_tried, op->addr_index);
        rcu_read_unlock();
}