diff options
Diffstat (limited to 'fs/afs/server.c')
| -rw-r--r-- | fs/afs/server.c | 692 |
1 files changed, 692 insertions, 0 deletions
diff --git a/fs/afs/server.c b/fs/afs/server.c new file mode 100644 index 000000000..2c7f6211c --- /dev/null +++ b/fs/afs/server.c @@ -0,0 +1,692 @@ +/* AFS server record management + * + * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/sched.h> +#include <linux/slab.h> +#include "afs_fs.h" +#include "internal.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 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 afs_addr_list *alist; + struct afs_server *server = NULL; + unsigned int i; + int seq = 0, diff; + + rcu_read_lock(); + + do { + if (server) + afs_put_server(net, server); + 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; + 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); + 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); + 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); + 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); + RCU_INIT_POINTER(server->addresses, alist); + server->addr_version = alist->version; + server->uuid = *uuid; + server->flags = (1UL << AFS_SERVER_FL_NEW); + 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); + + afs_inc_servers_outstanding(net); + _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_addr_cursor ac; + struct afs_addr_list *alist; + int ret; + + ret = afs_set_vl_cursor(&ac, cell); + if (ret < 0) + return ERR_PTR(ret); + + while (afs_iterate_addresses(&ac)) { + if (test_bit(ac.index, &ac.alist->yfs)) + alist = afs_yfsvl_get_endpoints(cell->net, &ac, key, uuid); + else + alist = afs_vl_get_addrs_u(cell->net, &ac, key, uuid); + switch (ac.error) { + case 0: + afs_end_cursor(&ac); + return alist; + case -ECONNABORTED: + ac.error = afs_abort_to_error(ac.abort_code); + goto error; + case -ENOMEM: + case -ENONET: + goto error; + case -ENETUNREACH: + case -EHOSTUNREACH: + case -ECONNREFUSED: + break; + default: + ac.error = -EIO; + goto error; + } + } + +error: + return ERR_PTR(afs_end_cursor(&ac)); +} + +/* + * 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); +} + +/* + * Release a reference on a server record. + */ +void afs_put_server(struct afs_net *net, struct afs_server *server) +{ + unsigned int usage; + + if (!server) + return; + + server->put_time = ktime_get_real_seconds(); + + usage = atomic_dec_return(&server->usage); + + _enter("{%u}", usage); + + 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); + + 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, + .start = alist->index, + .index = 0, + .addr = &alist->addrs[alist->index], + .error = 0, + }; + _enter("%p", server); + + if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags)) + afs_fs_give_up_all_callbacks(net, server, &ac, NULL); + + 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); + 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(""); +} + +/* + * Probe a fileserver to find its capabilities. + * + * TODO: Try service upgrade. + */ +static bool afs_do_probe_fileserver(struct afs_fs_cursor *fc) +{ + _enter(""); + + fc->ac.addr = NULL; + fc->ac.start = READ_ONCE(fc->ac.alist->index); + fc->ac.index = fc->ac.start; + fc->ac.error = 0; + fc->ac.begun = false; + + while (afs_iterate_addresses(&fc->ac)) { + afs_fs_get_capabilities(afs_v2net(fc->vnode), fc->cbi->server, + &fc->ac, fc->key); + switch (fc->ac.error) { + case 0: + afs_end_cursor(&fc->ac); + set_bit(AFS_SERVER_FL_PROBED, &fc->cbi->server->flags); + return true; + case -ECONNABORTED: + fc->ac.error = afs_abort_to_error(fc->ac.abort_code); + goto error; + case -ENOMEM: + case -ENONET: + goto error; + case -ENETUNREACH: + case -EHOSTUNREACH: + case -ECONNREFUSED: + case -ETIMEDOUT: + case -ETIME: + break; + default: + fc->ac.error = -EIO; + goto error; + } + } + +error: + afs_end_cursor(&fc->ac); + return false; +} + +/* + * If we haven't already, try probing the fileserver to get its capabilities. + * We try not to instigate parallel probes, but it's possible that the parallel + * probes will fail due to authentication failure when ours would succeed. + * + * TODO: Try sending an anonymous probe if an authenticated probe fails. + */ +bool afs_probe_fileserver(struct afs_fs_cursor *fc) +{ + bool success; + int ret, retries = 0; + + _enter(""); + +retry: + if (test_bit(AFS_SERVER_FL_PROBED, &fc->cbi->server->flags)) { + _leave(" = t"); + return true; + } + + if (!test_and_set_bit_lock(AFS_SERVER_FL_PROBING, &fc->cbi->server->flags)) { + success = afs_do_probe_fileserver(fc); + clear_bit_unlock(AFS_SERVER_FL_PROBING, &fc->cbi->server->flags); + wake_up_bit(&fc->cbi->server->flags, AFS_SERVER_FL_PROBING); + _leave(" = t"); + return success; + } + + _debug("wait"); + ret = wait_on_bit(&fc->cbi->server->flags, AFS_SERVER_FL_PROBING, + TASK_INTERRUPTIBLE); + if (ret == -ERESTARTSYS) { + fc->ac.error = ret; + _leave(" = f [%d]", ret); + return false; + } + + retries++; + if (retries == 4) { + fc->ac.error = -ESTALE; + _leave(" = f [stale]"); + return false; + } + _debug("retry"); + goto retry; +} + +/* + * 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(""); + + alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key, + &server->uuid); + if (IS_ERR(alist)) { + fc->ac.error = PTR_ERR(alist); + _leave(" = f [%d]", fc->ac.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) { + fc->ac.error = ret; + _leave(" = f [intr]"); + return false; + } + + retries++; + if (retries == 4) { + _leave(" = f [stale]"); + ret = -ESTALE; + return false; + } + goto retry; +} |