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- // SPDX-License-Identifier: GPL-2.0-or-later
- /* AFS server record management
- *
- * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells ([email protected])
- */
- #include <linux/sched.h>
- #include <linux/slab.h>
- #include "afs_fs.h"
- #include "internal.h"
- #include "protocol_yfs.h"
- static unsigned afs_server_gc_delay = 10; /* Server record timeout in seconds */
- static atomic_t afs_server_debug_id;
- static struct afs_server *afs_maybe_use_server(struct afs_server *,
- enum afs_server_trace);
- static void __afs_put_server(struct afs_net *, struct afs_server *);
- /*
- * Find a server by one of its addresses.
- */
- struct afs_server *afs_find_server(struct afs_net *net,
- const struct sockaddr_rxrpc *srx)
- {
- const struct afs_addr_list *alist;
- struct afs_server *server = NULL;
- unsigned int i;
- int seq = 0, diff;
- rcu_read_lock();
- do {
- if (server)
- afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
- server = NULL;
- read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
- if (srx->transport.family == AF_INET6) {
- const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
- hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
- alist = rcu_dereference(server->addresses);
- for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
- b = &alist->addrs[i].transport.sin6;
- diff = ((u16 __force)a->sin6_port -
- (u16 __force)b->sin6_port);
- if (diff == 0)
- diff = memcmp(&a->sin6_addr,
- &b->sin6_addr,
- sizeof(struct in6_addr));
- if (diff == 0)
- goto found;
- }
- }
- } else {
- const struct sockaddr_in *a = &srx->transport.sin, *b;
- hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
- alist = rcu_dereference(server->addresses);
- for (i = 0; i < alist->nr_ipv4; i++) {
- b = &alist->addrs[i].transport.sin;
- diff = ((u16 __force)a->sin_port -
- (u16 __force)b->sin_port);
- if (diff == 0)
- diff = ((u32 __force)a->sin_addr.s_addr -
- (u32 __force)b->sin_addr.s_addr);
- if (diff == 0)
- goto found;
- }
- }
- }
- server = NULL;
- continue;
- found:
- server = afs_maybe_use_server(server, afs_server_trace_get_by_addr);
- } while (need_seqretry(&net->fs_addr_lock, seq));
- done_seqretry(&net->fs_addr_lock, seq);
- rcu_read_unlock();
- return server;
- }
- /*
- * Look up a server by its UUID and mark it active.
- */
- struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
- {
- struct afs_server *server = NULL;
- struct rb_node *p;
- int diff, seq = 0;
- _enter("%pU", uuid);
- do {
- /* Unfortunately, rbtree walking doesn't give reliable results
- * under just the RCU read lock, so we have to check for
- * changes.
- */
- if (server)
- afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq);
- server = NULL;
- read_seqbegin_or_lock(&net->fs_lock, &seq);
- p = net->fs_servers.rb_node;
- while (p) {
- server = rb_entry(p, struct afs_server, uuid_rb);
- diff = memcmp(uuid, &server->uuid, sizeof(*uuid));
- if (diff < 0) {
- p = p->rb_left;
- } else if (diff > 0) {
- p = p->rb_right;
- } else {
- afs_use_server(server, afs_server_trace_get_by_uuid);
- break;
- }
- server = NULL;
- }
- } while (need_seqretry(&net->fs_lock, seq));
- done_seqretry(&net->fs_lock, seq);
- _leave(" = %p", server);
- return server;
- }
- /*
- * Install a server record in the namespace tree. If there's a clash, we stick
- * it into a list anchored on whichever afs_server struct is actually in the
- * tree.
- */
- static struct afs_server *afs_install_server(struct afs_cell *cell,
- struct afs_server *candidate)
- {
- const struct afs_addr_list *alist;
- struct afs_server *server, *next;
- struct afs_net *net = cell->net;
- struct rb_node **pp, *p;
- int diff;
- _enter("%p", candidate);
- write_seqlock(&net->fs_lock);
- /* Firstly install the server in the UUID lookup tree */
- pp = &net->fs_servers.rb_node;
- p = NULL;
- while (*pp) {
- p = *pp;
- _debug("- consider %p", p);
- server = rb_entry(p, struct afs_server, uuid_rb);
- diff = memcmp(&candidate->uuid, &server->uuid, sizeof(uuid_t));
- if (diff < 0) {
- pp = &(*pp)->rb_left;
- } else if (diff > 0) {
- pp = &(*pp)->rb_right;
- } else {
- if (server->cell == cell)
- goto exists;
- /* We have the same UUID representing servers in
- * different cells. Append the new server to the list.
- */
- for (;;) {
- next = rcu_dereference_protected(
- server->uuid_next,
- lockdep_is_held(&net->fs_lock.lock));
- if (!next)
- break;
- server = next;
- }
- rcu_assign_pointer(server->uuid_next, candidate);
- candidate->uuid_prev = server;
- server = candidate;
- goto added_dup;
- }
- }
- server = candidate;
- rb_link_node(&server->uuid_rb, p, pp);
- rb_insert_color(&server->uuid_rb, &net->fs_servers);
- hlist_add_head_rcu(&server->proc_link, &net->fs_proc);
- added_dup:
- write_seqlock(&net->fs_addr_lock);
- alist = rcu_dereference_protected(server->addresses,
- lockdep_is_held(&net->fs_addr_lock.lock));
- /* Secondly, if the server has any IPv4 and/or IPv6 addresses, install
- * it in the IPv4 and/or IPv6 reverse-map lists.
- *
- * TODO: For speed we want to use something other than a flat list
- * here; even sorting the list in terms of lowest address would help a
- * bit, but anything we might want to do gets messy and memory
- * intensive.
- */
- if (alist->nr_ipv4 > 0)
- hlist_add_head_rcu(&server->addr4_link, &net->fs_addresses4);
- if (alist->nr_addrs > alist->nr_ipv4)
- hlist_add_head_rcu(&server->addr6_link, &net->fs_addresses6);
- write_sequnlock(&net->fs_addr_lock);
- exists:
- afs_get_server(server, afs_server_trace_get_install);
- write_sequnlock(&net->fs_lock);
- return server;
- }
- /*
- * Allocate a new server record and mark it active.
- */
- static struct afs_server *afs_alloc_server(struct afs_cell *cell,
- const uuid_t *uuid,
- struct afs_addr_list *alist)
- {
- struct afs_server *server;
- struct afs_net *net = cell->net;
- _enter("");
- server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
- if (!server)
- goto enomem;
- refcount_set(&server->ref, 1);
- atomic_set(&server->active, 1);
- server->debug_id = atomic_inc_return(&afs_server_debug_id);
- RCU_INIT_POINTER(server->addresses, alist);
- server->addr_version = alist->version;
- server->uuid = *uuid;
- rwlock_init(&server->fs_lock);
- INIT_WORK(&server->initcb_work, afs_server_init_callback_work);
- init_waitqueue_head(&server->probe_wq);
- INIT_LIST_HEAD(&server->probe_link);
- spin_lock_init(&server->probe_lock);
- server->cell = cell;
- server->rtt = UINT_MAX;
- afs_inc_servers_outstanding(net);
- trace_afs_server(server->debug_id, 1, 1, afs_server_trace_alloc);
- _leave(" = %p", server);
- return server;
- enomem:
- _leave(" = NULL [nomem]");
- return NULL;
- }
- /*
- * Look up an address record for a server
- */
- static struct afs_addr_list *afs_vl_lookup_addrs(struct afs_cell *cell,
- struct key *key, const uuid_t *uuid)
- {
- struct afs_vl_cursor vc;
- struct afs_addr_list *alist = NULL;
- int ret;
- ret = -ERESTARTSYS;
- if (afs_begin_vlserver_operation(&vc, cell, key)) {
- while (afs_select_vlserver(&vc)) {
- if (test_bit(AFS_VLSERVER_FL_IS_YFS, &vc.server->flags))
- alist = afs_yfsvl_get_endpoints(&vc, uuid);
- else
- alist = afs_vl_get_addrs_u(&vc, uuid);
- }
- ret = afs_end_vlserver_operation(&vc);
- }
- return ret < 0 ? ERR_PTR(ret) : alist;
- }
- /*
- * Get or create a fileserver record.
- */
- struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
- const uuid_t *uuid, u32 addr_version)
- {
- struct afs_addr_list *alist;
- struct afs_server *server, *candidate;
- _enter("%p,%pU", cell->net, uuid);
- server = afs_find_server_by_uuid(cell->net, uuid);
- if (server) {
- if (server->addr_version != addr_version)
- set_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
- return server;
- }
- alist = afs_vl_lookup_addrs(cell, key, uuid);
- if (IS_ERR(alist))
- return ERR_CAST(alist);
- candidate = afs_alloc_server(cell, uuid, alist);
- if (!candidate) {
- afs_put_addrlist(alist);
- return ERR_PTR(-ENOMEM);
- }
- server = afs_install_server(cell, candidate);
- if (server != candidate) {
- afs_put_addrlist(alist);
- kfree(candidate);
- } else {
- /* Immediately dispatch an asynchronous probe to each interface
- * on the fileserver. This will make sure the repeat-probing
- * service is started.
- */
- afs_fs_probe_fileserver(cell->net, server, key, true);
- }
- return server;
- }
- /*
- * Set the server timer to fire after a given delay, assuming it's not already
- * set for an earlier time.
- */
- static void afs_set_server_timer(struct afs_net *net, time64_t delay)
- {
- if (net->live) {
- afs_inc_servers_outstanding(net);
- if (timer_reduce(&net->fs_timer, jiffies + delay * HZ))
- afs_dec_servers_outstanding(net);
- }
- }
- /*
- * Server management timer. We have an increment on fs_outstanding that we
- * need to pass along to the work item.
- */
- void afs_servers_timer(struct timer_list *timer)
- {
- struct afs_net *net = container_of(timer, struct afs_net, fs_timer);
- _enter("");
- if (!queue_work(afs_wq, &net->fs_manager))
- afs_dec_servers_outstanding(net);
- }
- /*
- * Get a reference on a server object.
- */
- struct afs_server *afs_get_server(struct afs_server *server,
- enum afs_server_trace reason)
- {
- unsigned int a;
- int r;
- __refcount_inc(&server->ref, &r);
- a = atomic_read(&server->active);
- trace_afs_server(server->debug_id, r + 1, a, reason);
- return server;
- }
- /*
- * Try to get a reference on a server object.
- */
- static struct afs_server *afs_maybe_use_server(struct afs_server *server,
- enum afs_server_trace reason)
- {
- unsigned int a;
- int r;
- if (!__refcount_inc_not_zero(&server->ref, &r))
- return NULL;
- a = atomic_inc_return(&server->active);
- trace_afs_server(server->debug_id, r + 1, a, reason);
- return server;
- }
- /*
- * Get an active count on a server object.
- */
- struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason)
- {
- unsigned int a;
- int r;
- __refcount_inc(&server->ref, &r);
- a = atomic_inc_return(&server->active);
- trace_afs_server(server->debug_id, r + 1, a, reason);
- return server;
- }
- /*
- * Release a reference on a server record.
- */
- void afs_put_server(struct afs_net *net, struct afs_server *server,
- enum afs_server_trace reason)
- {
- unsigned int a, debug_id = server->debug_id;
- bool zero;
- int r;
- if (!server)
- return;
- a = atomic_read(&server->active);
- zero = __refcount_dec_and_test(&server->ref, &r);
- trace_afs_server(debug_id, r - 1, a, reason);
- if (unlikely(zero))
- __afs_put_server(net, server);
- }
- /*
- * Drop an active count on a server object without updating the last-unused
- * time.
- */
- void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server,
- enum afs_server_trace reason)
- {
- if (server) {
- unsigned int active = atomic_dec_return(&server->active);
- if (active == 0)
- afs_set_server_timer(net, afs_server_gc_delay);
- afs_put_server(net, server, reason);
- }
- }
- /*
- * Drop an active count on a server object.
- */
- void afs_unuse_server(struct afs_net *net, struct afs_server *server,
- enum afs_server_trace reason)
- {
- if (server) {
- server->unuse_time = ktime_get_real_seconds();
- afs_unuse_server_notime(net, server, reason);
- }
- }
- static void afs_server_rcu(struct rcu_head *rcu)
- {
- struct afs_server *server = container_of(rcu, struct afs_server, rcu);
- trace_afs_server(server->debug_id, refcount_read(&server->ref),
- atomic_read(&server->active), afs_server_trace_free);
- afs_put_addrlist(rcu_access_pointer(server->addresses));
- kfree(server);
- }
- static void __afs_put_server(struct afs_net *net, struct afs_server *server)
- {
- call_rcu(&server->rcu, afs_server_rcu);
- afs_dec_servers_outstanding(net);
- }
- static void afs_give_up_callbacks(struct afs_net *net, struct afs_server *server)
- {
- struct afs_addr_list *alist = rcu_access_pointer(server->addresses);
- struct afs_addr_cursor ac = {
- .alist = alist,
- .index = alist->preferred,
- .error = 0,
- };
- afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
- }
- /*
- * destroy a dead server
- */
- static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
- {
- if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
- afs_give_up_callbacks(net, server);
- flush_work(&server->initcb_work);
- afs_put_server(net, server, afs_server_trace_destroy);
- }
- /*
- * Garbage collect any expired servers.
- */
- static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
- {
- struct afs_server *server, *next, *prev;
- int active;
- while ((server = gc_list)) {
- gc_list = server->gc_next;
- write_seqlock(&net->fs_lock);
- active = atomic_read(&server->active);
- if (active == 0) {
- trace_afs_server(server->debug_id, refcount_read(&server->ref),
- active, afs_server_trace_gc);
- next = rcu_dereference_protected(
- server->uuid_next, lockdep_is_held(&net->fs_lock.lock));
- prev = server->uuid_prev;
- if (!prev) {
- /* The one at the front is in the tree */
- if (!next) {
- rb_erase(&server->uuid_rb, &net->fs_servers);
- } else {
- rb_replace_node_rcu(&server->uuid_rb,
- &next->uuid_rb,
- &net->fs_servers);
- next->uuid_prev = NULL;
- }
- } else {
- /* This server is not at the front */
- rcu_assign_pointer(prev->uuid_next, next);
- if (next)
- next->uuid_prev = prev;
- }
- list_del(&server->probe_link);
- hlist_del_rcu(&server->proc_link);
- if (!hlist_unhashed(&server->addr4_link))
- hlist_del_rcu(&server->addr4_link);
- if (!hlist_unhashed(&server->addr6_link))
- hlist_del_rcu(&server->addr6_link);
- }
- write_sequnlock(&net->fs_lock);
- if (active == 0)
- afs_destroy_server(net, server);
- }
- }
- /*
- * Manage the records of servers known to be within a network namespace. This
- * includes garbage collecting unused servers.
- *
- * Note also that we were given an increment on net->servers_outstanding by
- * whoever queued us that we need to deal with before returning.
- */
- void afs_manage_servers(struct work_struct *work)
- {
- struct afs_net *net = container_of(work, struct afs_net, fs_manager);
- struct afs_server *gc_list = NULL;
- struct rb_node *cursor;
- time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX;
- bool purging = !net->live;
- _enter("");
- /* Trawl the server list looking for servers that have expired from
- * lack of use.
- */
- read_seqlock_excl(&net->fs_lock);
- for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
- struct afs_server *server =
- rb_entry(cursor, struct afs_server, uuid_rb);
- int active = atomic_read(&server->active);
- _debug("manage %pU %u", &server->uuid, active);
- if (purging) {
- trace_afs_server(server->debug_id, refcount_read(&server->ref),
- active, afs_server_trace_purging);
- if (active != 0)
- pr_notice("Can't purge s=%08x\n", server->debug_id);
- }
- if (active == 0) {
- time64_t expire_at = server->unuse_time;
- if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
- !test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
- expire_at += afs_server_gc_delay;
- if (purging || expire_at <= now) {
- server->gc_next = gc_list;
- gc_list = server;
- } else if (expire_at < next_manage) {
- next_manage = expire_at;
- }
- }
- }
- read_sequnlock_excl(&net->fs_lock);
- /* Update the timer on the way out. We have to pass an increment on
- * servers_outstanding in the namespace that we are in to the timer or
- * the work scheduler.
- */
- if (!purging && next_manage < TIME64_MAX) {
- now = ktime_get_real_seconds();
- if (next_manage - now <= 0) {
- if (queue_work(afs_wq, &net->fs_manager))
- afs_inc_servers_outstanding(net);
- } else {
- afs_set_server_timer(net, next_manage - now);
- }
- }
- afs_gc_servers(net, gc_list);
- afs_dec_servers_outstanding(net);
- _leave(" [%d]", atomic_read(&net->servers_outstanding));
- }
- static void afs_queue_server_manager(struct afs_net *net)
- {
- afs_inc_servers_outstanding(net);
- if (!queue_work(afs_wq, &net->fs_manager))
- afs_dec_servers_outstanding(net);
- }
- /*
- * Purge list of servers.
- */
- void afs_purge_servers(struct afs_net *net)
- {
- _enter("");
- if (del_timer_sync(&net->fs_timer))
- afs_dec_servers_outstanding(net);
- afs_queue_server_manager(net);
- _debug("wait");
- atomic_dec(&net->servers_outstanding);
- wait_var_event(&net->servers_outstanding,
- !atomic_read(&net->servers_outstanding));
- _leave("");
- }
- /*
- * Get an update for a server's address list.
- */
- static noinline bool afs_update_server_record(struct afs_operation *op,
- struct afs_server *server)
- {
- struct afs_addr_list *alist, *discard;
- _enter("");
- trace_afs_server(server->debug_id, refcount_read(&server->ref),
- atomic_read(&server->active),
- afs_server_trace_update);
- alist = afs_vl_lookup_addrs(op->volume->cell, op->key, &server->uuid);
- if (IS_ERR(alist)) {
- if ((PTR_ERR(alist) == -ERESTARTSYS ||
- PTR_ERR(alist) == -EINTR) &&
- (op->flags & AFS_OPERATION_UNINTR) &&
- server->addresses) {
- _leave(" = t [intr]");
- return true;
- }
- op->error = PTR_ERR(alist);
- _leave(" = f [%d]", op->error);
- return false;
- }
- discard = alist;
- if (server->addr_version != alist->version) {
- write_lock(&server->fs_lock);
- discard = rcu_dereference_protected(server->addresses,
- lockdep_is_held(&server->fs_lock));
- rcu_assign_pointer(server->addresses, alist);
- server->addr_version = alist->version;
- write_unlock(&server->fs_lock);
- }
- afs_put_addrlist(discard);
- _leave(" = t");
- return true;
- }
- /*
- * See if a server's address list needs updating.
- */
- bool afs_check_server_record(struct afs_operation *op, struct afs_server *server)
- {
- bool success;
- int ret, retries = 0;
- _enter("");
- ASSERT(server);
- retry:
- if (test_bit(AFS_SERVER_FL_UPDATING, &server->flags))
- goto wait;
- if (test_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags))
- goto update;
- _leave(" = t [good]");
- return true;
- update:
- if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) {
- clear_bit(AFS_SERVER_FL_NEEDS_UPDATE, &server->flags);
- success = afs_update_server_record(op, server);
- clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags);
- wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING);
- _leave(" = %d", success);
- return success;
- }
- wait:
- ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING,
- (op->flags & AFS_OPERATION_UNINTR) ?
- TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
- if (ret == -ERESTARTSYS) {
- op->error = ret;
- _leave(" = f [intr]");
- return false;
- }
- retries++;
- if (retries == 4) {
- _leave(" = f [stale]");
- ret = -ESTALE;
- return false;
- }
- goto retry;
- }
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