// 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 (dhowells@redhat.com) */ #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 unsigned afs_server_update_delay = 30; /* Time till VLDB recheck in secs */ static atomic_t afs_server_debug_id; static void afs_inc_servers_outstanding(struct afs_net *net) { atomic_inc(&net->servers_outstanding); } static void afs_dec_servers_outstanding(struct afs_net *net) { if (atomic_dec_and_test(&net->servers_outstanding)) wake_up_var(&net->servers_outstanding); } /* * 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 sockaddr_in6 *a = &srx->transport.sin6, *b; const struct afs_addr_list *alist; struct afs_server *server = NULL; unsigned int i; bool ipv6 = true; int seq = 0, diff; if (srx->transport.sin6.sin6_addr.s6_addr32[0] == 0 || srx->transport.sin6.sin6_addr.s6_addr32[1] == 0 || srx->transport.sin6.sin6_addr.s6_addr32[2] == htonl(0xffff)) ipv6 = false; rcu_read_lock(); do { if (server) afs_put_server(net, server, afs_server_trace_put_find_rsq); server = NULL; read_seqbegin_or_lock(&net->fs_addr_lock, &seq); if (ipv6) { 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 { 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.sin6; diff = ((u16 __force)a->sin6_port - (u16 __force)b->sin6_port); if (diff == 0) diff = ((u32 __force)a->sin6_addr.s6_addr32[3] - (u32 __force)b->sin6_addr.s6_addr32[3]); if (diff == 0) goto found; } } } server = NULL; found: if (server && !atomic_inc_not_zero(&server->usage)) server = NULL; } 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 */ 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_put_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_get_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 */ static struct afs_server *afs_install_server(struct afs_net *net, struct afs_server *candidate) { const struct afs_addr_list *alist; struct afs_server *server; struct rb_node **pp, *p; int ret = -EEXIST, 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 goto exists; } 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); 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); ret = 0; exists: afs_get_server(server, afs_server_trace_get_install); write_sequnlock(&net->fs_lock); return server; } /* * allocate a new server record */ static struct afs_server *afs_alloc_server(struct afs_net *net, const uuid_t *uuid, struct afs_addr_list *alist) { struct afs_server *server; _enter(""); server = kzalloc(sizeof(struct afs_server), GFP_KERNEL); if (!server) goto enomem; atomic_set(&server->usage, 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; server->update_at = ktime_get_real_seconds() + afs_server_update_delay; rwlock_init(&server->fs_lock); INIT_HLIST_HEAD(&server->cb_volumes); rwlock_init(&server->cb_break_lock); init_waitqueue_head(&server->probe_wq); spin_lock_init(&server->probe_lock); afs_inc_servers_outstanding(net); trace_afs_server(server, 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) { 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) return server; alist = afs_vl_lookup_addrs(cell, key, uuid); if (IS_ERR(alist)) return ERR_CAST(alist); candidate = afs_alloc_server(cell->net, uuid, alist); if (!candidate) { afs_put_addrlist(alist); return ERR_PTR(-ENOMEM); } server = afs_install_server(cell->net, candidate); if (server != candidate) { afs_put_addrlist(alist); kfree(candidate); } _leave(" = %p{%d}", server, atomic_read(&server->usage)); 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 u = atomic_inc_return(&server->usage); trace_afs_server(server, u, 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 usage; if (!server) return; server->put_time = ktime_get_real_seconds(); usage = atomic_dec_return(&server->usage); trace_afs_server(server, usage, reason); if (likely(usage > 0)) return; afs_set_server_timer(net, afs_server_gc_delay); } static void afs_server_rcu(struct rcu_head *rcu) { struct afs_server *server = container_of(rcu, struct afs_server, rcu); trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_free); afs_put_addrlist(rcu_access_pointer(server->addresses)); kfree(server); } /* * destroy a dead server */ static void afs_destroy_server(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, }; trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_give_up_cb); if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags)) afs_fs_give_up_all_callbacks(net, server, &ac, NULL); wait_var_event(&server->probe_outstanding, atomic_read(&server->probe_outstanding) == 0); trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_destroy); call_rcu(&server->rcu, afs_server_rcu); afs_dec_servers_outstanding(net); } /* * Garbage collect any expired servers. */ static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list) { struct afs_server *server; bool deleted; int usage; while ((server = gc_list)) { gc_list = server->gc_next; write_seqlock(&net->fs_lock); usage = 1; deleted = atomic_try_cmpxchg(&server->usage, &usage, 0); trace_afs_server(server, usage, afs_server_trace_gc); if (deleted) { rb_erase(&server->uuid_rb, &net->fs_servers); hlist_del_rcu(&server->proc_link); } write_sequnlock(&net->fs_lock); if (deleted) { write_seqlock(&net->fs_addr_lock); 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_addr_lock); 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 usage = atomic_read(&server->usage); _debug("manage %pU %u", &server->uuid, usage); ASSERTCMP(usage, >=, 1); ASSERTIFCMP(purging, usage, ==, 1); if (usage == 1) { time64_t expire_at = server->put_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)) atomic_dec(&net->servers_outstanding); afs_queue_server_manager(net); _debug("wait"); 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_fs_cursor *fc, struct afs_server *server) { struct afs_addr_list *alist, *discard; _enter(""); trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_update); alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key, &server->uuid); if (IS_ERR(alist)) { if ((PTR_ERR(alist) == -ERESTARTSYS || PTR_ERR(alist) == -EINTR) && !(fc->flags & AFS_FS_CURSOR_INTR) && server->addresses) { _leave(" = t [intr]"); return true; } fc->error = PTR_ERR(alist); _leave(" = f [%d]", fc->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); } server->update_at = ktime_get_real_seconds() + afs_server_update_delay; afs_put_addrlist(discard); _leave(" = t"); return true; } /* * See if a server's address list needs updating. */ bool afs_check_server_record(struct afs_fs_cursor *fc, struct afs_server *server) { time64_t now = ktime_get_real_seconds(); long diff; bool success; int ret, retries = 0; _enter(""); ASSERT(server); retry: diff = READ_ONCE(server->update_at) - now; if (diff > 0) { _leave(" = t [not now %ld]", diff); return true; } if (!test_and_set_bit_lock(AFS_SERVER_FL_UPDATING, &server->flags)) { success = afs_update_server_record(fc, server); clear_bit_unlock(AFS_SERVER_FL_UPDATING, &server->flags); wake_up_bit(&server->flags, AFS_SERVER_FL_UPDATING); _leave(" = %d", success); return success; } ret = wait_on_bit(&server->flags, AFS_SERVER_FL_UPDATING, TASK_INTERRUPTIBLE); if (ret == -ERESTARTSYS) { if (!(fc->flags & AFS_FS_CURSOR_INTR) && server->addresses) { _leave(" = t [intr]"); return true; } fc->error = ret; _leave(" = f [intr]"); return false; } retries++; if (retries == 4) { _leave(" = f [stale]"); ret = -ESTALE; return false; } goto retry; }