diff options
Diffstat (limited to 'fs/afs/cell.c')
| -rw-r--r-- | fs/afs/cell.c | 967 |
1 files changed, 967 insertions, 0 deletions
diff --git a/fs/afs/cell.c b/fs/afs/cell.c new file mode 100644 index 000000000..cfd3c4dab --- /dev/null +++ b/fs/afs/cell.c @@ -0,0 +1,967 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* AFS cell and server record management + * + * Copyright (C) 2002, 2017 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/slab.h> +#include <linux/key.h> +#include <linux/ctype.h> +#include <linux/dns_resolver.h> +#include <linux/sched.h> +#include <linux/inet.h> +#include <linux/namei.h> +#include <keys/rxrpc-type.h> +#include "internal.h" + +static unsigned __read_mostly afs_cell_gc_delay = 10; +static unsigned __read_mostly afs_cell_min_ttl = 10 * 60; +static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60; +static atomic_t cell_debug_id; + +static void afs_queue_cell_manager(struct afs_net *); +static void afs_manage_cell_work(struct work_struct *); + +static void afs_dec_cells_outstanding(struct afs_net *net) +{ + if (atomic_dec_and_test(&net->cells_outstanding)) + wake_up_var(&net->cells_outstanding); +} + +/* + * Set the cell timer to fire after a given delay, assuming it's not already + * set for an earlier time. + */ +static void afs_set_cell_timer(struct afs_net *net, time64_t delay) +{ + if (net->live) { + atomic_inc(&net->cells_outstanding); + if (timer_reduce(&net->cells_timer, jiffies + delay * HZ)) + afs_dec_cells_outstanding(net); + } else { + afs_queue_cell_manager(net); + } +} + +/* + * Look up and get an activation reference on a cell record. The caller must + * hold net->cells_lock at least read-locked. + */ +static struct afs_cell *afs_find_cell_locked(struct afs_net *net, + const char *name, unsigned int namesz, + enum afs_cell_trace reason) +{ + struct afs_cell *cell = NULL; + struct rb_node *p; + int n; + + _enter("%*.*s", namesz, namesz, name); + + if (name && namesz == 0) + return ERR_PTR(-EINVAL); + if (namesz > AFS_MAXCELLNAME) + return ERR_PTR(-ENAMETOOLONG); + + if (!name) { + cell = net->ws_cell; + if (!cell) + return ERR_PTR(-EDESTADDRREQ); + goto found; + } + + p = net->cells.rb_node; + while (p) { + cell = rb_entry(p, struct afs_cell, net_node); + + n = strncasecmp(cell->name, name, + min_t(size_t, cell->name_len, namesz)); + if (n == 0) + n = cell->name_len - namesz; + if (n < 0) + p = p->rb_left; + else if (n > 0) + p = p->rb_right; + else + goto found; + } + + return ERR_PTR(-ENOENT); + +found: + return afs_use_cell(cell, reason); +} + +/* + * Look up and get an activation reference on a cell record. + */ +struct afs_cell *afs_find_cell(struct afs_net *net, + const char *name, unsigned int namesz, + enum afs_cell_trace reason) +{ + struct afs_cell *cell; + + down_read(&net->cells_lock); + cell = afs_find_cell_locked(net, name, namesz, reason); + up_read(&net->cells_lock); + return cell; +} + +/* + * Set up a cell record and fill in its name, VL server address list and + * allocate an anonymous key + */ +static struct afs_cell *afs_alloc_cell(struct afs_net *net, + const char *name, unsigned int namelen, + const char *addresses) +{ + struct afs_vlserver_list *vllist; + struct afs_cell *cell; + int i, ret; + + ASSERT(name); + if (namelen == 0) + return ERR_PTR(-EINVAL); + if (namelen > AFS_MAXCELLNAME) { + _leave(" = -ENAMETOOLONG"); + return ERR_PTR(-ENAMETOOLONG); + } + + /* Prohibit cell names that contain unprintable chars, '/' and '@' or + * that begin with a dot. This also precludes "@cell". + */ + if (name[0] == '.') + return ERR_PTR(-EINVAL); + for (i = 0; i < namelen; i++) { + char ch = name[i]; + if (!isprint(ch) || ch == '/' || ch == '@') + return ERR_PTR(-EINVAL); + } + + _enter("%*.*s,%s", namelen, namelen, name, addresses); + + cell = kzalloc(sizeof(struct afs_cell), GFP_KERNEL); + if (!cell) { + _leave(" = -ENOMEM"); + return ERR_PTR(-ENOMEM); + } + + cell->name = kmalloc(namelen + 1, GFP_KERNEL); + if (!cell->name) { + kfree(cell); + return ERR_PTR(-ENOMEM); + } + + cell->net = net; + cell->name_len = namelen; + for (i = 0; i < namelen; i++) + cell->name[i] = tolower(name[i]); + cell->name[i] = 0; + + atomic_set(&cell->ref, 1); + atomic_set(&cell->active, 0); + INIT_WORK(&cell->manager, afs_manage_cell_work); + cell->volumes = RB_ROOT; + INIT_HLIST_HEAD(&cell->proc_volumes); + seqlock_init(&cell->volume_lock); + cell->fs_servers = RB_ROOT; + seqlock_init(&cell->fs_lock); + rwlock_init(&cell->vl_servers_lock); + cell->flags = (1 << AFS_CELL_FL_CHECK_ALIAS); + + /* Provide a VL server list, filling it in if we were given a list of + * addresses to use. + */ + if (addresses) { + vllist = afs_parse_text_addrs(net, + addresses, strlen(addresses), ':', + VL_SERVICE, AFS_VL_PORT); + if (IS_ERR(vllist)) { + ret = PTR_ERR(vllist); + goto parse_failed; + } + + vllist->source = DNS_RECORD_FROM_CONFIG; + vllist->status = DNS_LOOKUP_NOT_DONE; + cell->dns_expiry = TIME64_MAX; + } else { + ret = -ENOMEM; + vllist = afs_alloc_vlserver_list(0); + if (!vllist) + goto error; + vllist->source = DNS_RECORD_UNAVAILABLE; + vllist->status = DNS_LOOKUP_NOT_DONE; + cell->dns_expiry = ktime_get_real_seconds(); + } + + rcu_assign_pointer(cell->vl_servers, vllist); + + cell->dns_source = vllist->source; + cell->dns_status = vllist->status; + smp_store_release(&cell->dns_lookup_count, 1); /* vs source/status */ + atomic_inc(&net->cells_outstanding); + cell->debug_id = atomic_inc_return(&cell_debug_id); + trace_afs_cell(cell->debug_id, 1, 0, afs_cell_trace_alloc); + + _leave(" = %p", cell); + return cell; + +parse_failed: + if (ret == -EINVAL) + printk(KERN_ERR "kAFS: bad VL server IP address\n"); +error: + kfree(cell->name); + kfree(cell); + _leave(" = %d", ret); + return ERR_PTR(ret); +} + +/* + * afs_lookup_cell - Look up or create a cell record. + * @net: The network namespace + * @name: The name of the cell. + * @namesz: The strlen of the cell name. + * @vllist: A colon/comma separated list of numeric IP addresses or NULL. + * @excl: T if an error should be given if the cell name already exists. + * + * Look up a cell record by name and query the DNS for VL server addresses if + * needed. Note that that actual DNS query is punted off to the manager thread + * so that this function can return immediately if interrupted whilst allowing + * cell records to be shared even if not yet fully constructed. + */ +struct afs_cell *afs_lookup_cell(struct afs_net *net, + const char *name, unsigned int namesz, + const char *vllist, bool excl) +{ + struct afs_cell *cell, *candidate, *cursor; + struct rb_node *parent, **pp; + enum afs_cell_state state; + int ret, n; + + _enter("%s,%s", name, vllist); + + if (!excl) { + cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup); + if (!IS_ERR(cell)) + goto wait_for_cell; + } + + /* Assume we're probably going to create a cell and preallocate and + * mostly set up a candidate record. We can then use this to stash the + * name, the net namespace and VL server addresses. + * + * We also want to do this before we hold any locks as it may involve + * upcalling to userspace to make DNS queries. + */ + candidate = afs_alloc_cell(net, name, namesz, vllist); + if (IS_ERR(candidate)) { + _leave(" = %ld", PTR_ERR(candidate)); + return candidate; + } + + /* Find the insertion point and check to see if someone else added a + * cell whilst we were allocating. + */ + down_write(&net->cells_lock); + + pp = &net->cells.rb_node; + parent = NULL; + while (*pp) { + parent = *pp; + cursor = rb_entry(parent, struct afs_cell, net_node); + + n = strncasecmp(cursor->name, name, + min_t(size_t, cursor->name_len, namesz)); + if (n == 0) + n = cursor->name_len - namesz; + if (n < 0) + pp = &(*pp)->rb_left; + else if (n > 0) + pp = &(*pp)->rb_right; + else + goto cell_already_exists; + } + + cell = candidate; + candidate = NULL; + atomic_set(&cell->active, 2); + trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), 2, afs_cell_trace_insert); + rb_link_node_rcu(&cell->net_node, parent, pp); + rb_insert_color(&cell->net_node, &net->cells); + up_write(&net->cells_lock); + + afs_queue_cell(cell, afs_cell_trace_get_queue_new); + +wait_for_cell: + trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), atomic_read(&cell->active), + afs_cell_trace_wait); + _debug("wait_for_cell"); + wait_var_event(&cell->state, + ({ + state = smp_load_acquire(&cell->state); /* vs error */ + state == AFS_CELL_ACTIVE || state == AFS_CELL_REMOVED; + })); + + /* Check the state obtained from the wait check. */ + if (state == AFS_CELL_REMOVED) { + ret = cell->error; + goto error; + } + + _leave(" = %p [cell]", cell); + return cell; + +cell_already_exists: + _debug("cell exists"); + cell = cursor; + if (excl) { + ret = -EEXIST; + } else { + afs_use_cell(cursor, afs_cell_trace_use_lookup); + ret = 0; + } + up_write(&net->cells_lock); + if (candidate) + afs_put_cell(candidate, afs_cell_trace_put_candidate); + if (ret == 0) + goto wait_for_cell; + goto error_noput; +error: + afs_unuse_cell(net, cell, afs_cell_trace_unuse_lookup); +error_noput: + _leave(" = %d [error]", ret); + return ERR_PTR(ret); +} + +/* + * set the root cell information + * - can be called with a module parameter string + * - can be called from a write to /proc/fs/afs/rootcell + */ +int afs_cell_init(struct afs_net *net, const char *rootcell) +{ + struct afs_cell *old_root, *new_root; + const char *cp, *vllist; + size_t len; + + _enter(""); + + if (!rootcell) { + /* module is loaded with no parameters, or built statically. + * - in the future we might initialize cell DB here. + */ + _leave(" = 0 [no root]"); + return 0; + } + + cp = strchr(rootcell, ':'); + if (!cp) { + _debug("kAFS: no VL server IP addresses specified"); + vllist = NULL; + len = strlen(rootcell); + } else { + vllist = cp + 1; + len = cp - rootcell; + } + + /* allocate a cell record for the root cell */ + new_root = afs_lookup_cell(net, rootcell, len, vllist, false); + if (IS_ERR(new_root)) { + _leave(" = %ld", PTR_ERR(new_root)); + return PTR_ERR(new_root); + } + + if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags)) + afs_use_cell(new_root, afs_cell_trace_use_pin); + + /* install the new cell */ + down_write(&net->cells_lock); + afs_see_cell(new_root, afs_cell_trace_see_ws); + old_root = net->ws_cell; + net->ws_cell = new_root; + up_write(&net->cells_lock); + + afs_unuse_cell(net, old_root, afs_cell_trace_unuse_ws); + _leave(" = 0"); + return 0; +} + +/* + * Update a cell's VL server address list from the DNS. + */ +static int afs_update_cell(struct afs_cell *cell) +{ + struct afs_vlserver_list *vllist, *old = NULL, *p; + unsigned int min_ttl = READ_ONCE(afs_cell_min_ttl); + unsigned int max_ttl = READ_ONCE(afs_cell_max_ttl); + time64_t now, expiry = 0; + int ret = 0; + + _enter("%s", cell->name); + + vllist = afs_dns_query(cell, &expiry); + if (IS_ERR(vllist)) { + ret = PTR_ERR(vllist); + + _debug("%s: fail %d", cell->name, ret); + if (ret == -ENOMEM) + goto out_wake; + + vllist = afs_alloc_vlserver_list(0); + if (!vllist) { + if (ret >= 0) + ret = -ENOMEM; + goto out_wake; + } + + switch (ret) { + case -ENODATA: + case -EDESTADDRREQ: + vllist->status = DNS_LOOKUP_GOT_NOT_FOUND; + break; + case -EAGAIN: + case -ECONNREFUSED: + vllist->status = DNS_LOOKUP_GOT_TEMP_FAILURE; + break; + default: + vllist->status = DNS_LOOKUP_GOT_LOCAL_FAILURE; + break; + } + } + + _debug("%s: got list %d %d", cell->name, vllist->source, vllist->status); + cell->dns_status = vllist->status; + + now = ktime_get_real_seconds(); + if (min_ttl > max_ttl) + max_ttl = min_ttl; + if (expiry < now + min_ttl) + expiry = now + min_ttl; + else if (expiry > now + max_ttl) + expiry = now + max_ttl; + + _debug("%s: status %d", cell->name, vllist->status); + if (vllist->source == DNS_RECORD_UNAVAILABLE) { + switch (vllist->status) { + case DNS_LOOKUP_GOT_NOT_FOUND: + /* The DNS said that the cell does not exist or there + * weren't any addresses to be had. + */ + cell->dns_expiry = expiry; + break; + + case DNS_LOOKUP_BAD: + case DNS_LOOKUP_GOT_LOCAL_FAILURE: + case DNS_LOOKUP_GOT_TEMP_FAILURE: + case DNS_LOOKUP_GOT_NS_FAILURE: + default: + cell->dns_expiry = now + 10; + break; + } + } else { + cell->dns_expiry = expiry; + } + + /* Replace the VL server list if the new record has servers or the old + * record doesn't. + */ + write_lock(&cell->vl_servers_lock); + p = rcu_dereference_protected(cell->vl_servers, true); + if (vllist->nr_servers > 0 || p->nr_servers == 0) { + rcu_assign_pointer(cell->vl_servers, vllist); + cell->dns_source = vllist->source; + old = p; + } + write_unlock(&cell->vl_servers_lock); + afs_put_vlserverlist(cell->net, old); + +out_wake: + smp_store_release(&cell->dns_lookup_count, + cell->dns_lookup_count + 1); /* vs source/status */ + wake_up_var(&cell->dns_lookup_count); + _leave(" = %d", ret); + return ret; +} + +/* + * Destroy a cell record + */ +static void afs_cell_destroy(struct rcu_head *rcu) +{ + struct afs_cell *cell = container_of(rcu, struct afs_cell, rcu); + struct afs_net *net = cell->net; + int u; + + _enter("%p{%s}", cell, cell->name); + + u = atomic_read(&cell->ref); + ASSERTCMP(u, ==, 0); + trace_afs_cell(cell->debug_id, u, atomic_read(&cell->active), afs_cell_trace_free); + + afs_put_vlserverlist(net, rcu_access_pointer(cell->vl_servers)); + afs_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias); + key_put(cell->anonymous_key); + kfree(cell->name); + kfree(cell); + + afs_dec_cells_outstanding(net); + _leave(" [destroyed]"); +} + +/* + * Queue the cell manager. + */ +static void afs_queue_cell_manager(struct afs_net *net) +{ + int outstanding = atomic_inc_return(&net->cells_outstanding); + + _enter("%d", outstanding); + + if (!queue_work(afs_wq, &net->cells_manager)) + afs_dec_cells_outstanding(net); +} + +/* + * Cell management timer. We have an increment on cells_outstanding that we + * need to pass along to the work item. + */ +void afs_cells_timer(struct timer_list *timer) +{ + struct afs_net *net = container_of(timer, struct afs_net, cells_timer); + + _enter(""); + if (!queue_work(afs_wq, &net->cells_manager)) + afs_dec_cells_outstanding(net); +} + +/* + * Get a reference on a cell record. + */ +struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason) +{ + int u; + + if (atomic_read(&cell->ref) <= 0) + BUG(); + + u = atomic_inc_return(&cell->ref); + trace_afs_cell(cell->debug_id, u, atomic_read(&cell->active), reason); + return cell; +} + +/* + * Drop a reference on a cell record. + */ +void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason) +{ + if (cell) { + unsigned int debug_id = cell->debug_id; + unsigned int u, a; + + a = atomic_read(&cell->active); + u = atomic_dec_return(&cell->ref); + trace_afs_cell(debug_id, u, a, reason); + if (u == 0) { + a = atomic_read(&cell->active); + WARN(a != 0, "Cell active count %u > 0\n", a); + call_rcu(&cell->rcu, afs_cell_destroy); + } + } +} + +/* + * Note a cell becoming more active. + */ +struct afs_cell *afs_use_cell(struct afs_cell *cell, enum afs_cell_trace reason) +{ + int u, a; + + if (atomic_read(&cell->ref) <= 0) + BUG(); + + u = atomic_read(&cell->ref); + a = atomic_inc_return(&cell->active); + trace_afs_cell(cell->debug_id, u, a, reason); + return cell; +} + +/* + * Record a cell becoming less active. When the active counter reaches 1, it + * is scheduled for destruction, but may get reactivated. + */ +void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason) +{ + unsigned int debug_id; + time64_t now, expire_delay; + int u, a; + + if (!cell) + return; + + _enter("%s", cell->name); + + now = ktime_get_real_seconds(); + cell->last_inactive = now; + expire_delay = 0; + if (cell->vl_servers->nr_servers) + expire_delay = afs_cell_gc_delay; + + debug_id = cell->debug_id; + u = atomic_read(&cell->ref); + a = atomic_dec_return(&cell->active); + trace_afs_cell(debug_id, u, a, reason); + WARN_ON(a == 0); + if (a == 1) + /* 'cell' may now be garbage collected. */ + afs_set_cell_timer(net, expire_delay); +} + +/* + * Note that a cell has been seen. + */ +void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason) +{ + int u, a; + + u = atomic_read(&cell->ref); + a = atomic_read(&cell->active); + trace_afs_cell(cell->debug_id, u, a, reason); +} + +/* + * Queue a cell for management, giving the workqueue a ref to hold. + */ +void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason) +{ + afs_get_cell(cell, reason); + if (!queue_work(afs_wq, &cell->manager)) + afs_put_cell(cell, afs_cell_trace_put_queue_fail); +} + +/* + * Allocate a key to use as a placeholder for anonymous user security. + */ +static int afs_alloc_anon_key(struct afs_cell *cell) +{ + struct key *key; + char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp; + + /* Create a key to represent an anonymous user. */ + memcpy(keyname, "afs@", 4); + dp = keyname + 4; + cp = cell->name; + do { + *dp++ = tolower(*cp); + } while (*cp++); + + key = rxrpc_get_null_key(keyname); + if (IS_ERR(key)) + return PTR_ERR(key); + + cell->anonymous_key = key; + + _debug("anon key %p{%x}", + cell->anonymous_key, key_serial(cell->anonymous_key)); + return 0; +} + +/* + * Activate a cell. + */ +static int afs_activate_cell(struct afs_net *net, struct afs_cell *cell) +{ + struct hlist_node **p; + struct afs_cell *pcell; + int ret; + + if (!cell->anonymous_key) { + ret = afs_alloc_anon_key(cell); + if (ret < 0) + return ret; + } + +#ifdef CONFIG_AFS_FSCACHE + cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index, + &afs_cell_cache_index_def, + cell->name, strlen(cell->name), + NULL, 0, + cell, 0, true); +#endif + ret = afs_proc_cell_setup(cell); + if (ret < 0) + return ret; + + mutex_lock(&net->proc_cells_lock); + for (p = &net->proc_cells.first; *p; p = &(*p)->next) { + pcell = hlist_entry(*p, struct afs_cell, proc_link); + if (strcmp(cell->name, pcell->name) < 0) + break; + } + + cell->proc_link.pprev = p; + cell->proc_link.next = *p; + rcu_assign_pointer(*p, &cell->proc_link.next); + if (cell->proc_link.next) + cell->proc_link.next->pprev = &cell->proc_link.next; + + afs_dynroot_mkdir(net, cell); + mutex_unlock(&net->proc_cells_lock); + return 0; +} + +/* + * Deactivate a cell. + */ +static void afs_deactivate_cell(struct afs_net *net, struct afs_cell *cell) +{ + _enter("%s", cell->name); + + afs_proc_cell_remove(cell); + + mutex_lock(&net->proc_cells_lock); + hlist_del_rcu(&cell->proc_link); + afs_dynroot_rmdir(net, cell); + mutex_unlock(&net->proc_cells_lock); + +#ifdef CONFIG_AFS_FSCACHE + fscache_relinquish_cookie(cell->cache, NULL, false); + cell->cache = NULL; +#endif + + _leave(""); +} + +/* + * Manage a cell record, initialising and destroying it, maintaining its DNS + * records. + */ +static void afs_manage_cell(struct afs_cell *cell) +{ + struct afs_net *net = cell->net; + int ret, active; + + _enter("%s", cell->name); + +again: + _debug("state %u", cell->state); + switch (cell->state) { + case AFS_CELL_INACTIVE: + case AFS_CELL_FAILED: + down_write(&net->cells_lock); + active = 1; + if (atomic_try_cmpxchg_relaxed(&cell->active, &active, 0)) { + rb_erase(&cell->net_node, &net->cells); + trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), 0, + afs_cell_trace_unuse_delete); + smp_store_release(&cell->state, AFS_CELL_REMOVED); + } + up_write(&net->cells_lock); + if (cell->state == AFS_CELL_REMOVED) { + wake_up_var(&cell->state); + goto final_destruction; + } + if (cell->state == AFS_CELL_FAILED) + goto done; + smp_store_release(&cell->state, AFS_CELL_UNSET); + wake_up_var(&cell->state); + goto again; + + case AFS_CELL_UNSET: + smp_store_release(&cell->state, AFS_CELL_ACTIVATING); + wake_up_var(&cell->state); + goto again; + + case AFS_CELL_ACTIVATING: + ret = afs_activate_cell(net, cell); + if (ret < 0) + goto activation_failed; + + smp_store_release(&cell->state, AFS_CELL_ACTIVE); + wake_up_var(&cell->state); + goto again; + + case AFS_CELL_ACTIVE: + if (atomic_read(&cell->active) > 1) { + if (test_and_clear_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) { + ret = afs_update_cell(cell); + if (ret < 0) + cell->error = ret; + } + goto done; + } + smp_store_release(&cell->state, AFS_CELL_DEACTIVATING); + wake_up_var(&cell->state); + goto again; + + case AFS_CELL_DEACTIVATING: + if (atomic_read(&cell->active) > 1) + goto reverse_deactivation; + afs_deactivate_cell(net, cell); + smp_store_release(&cell->state, AFS_CELL_INACTIVE); + wake_up_var(&cell->state); + goto again; + + case AFS_CELL_REMOVED: + goto done; + + default: + break; + } + _debug("bad state %u", cell->state); + BUG(); /* Unhandled state */ + +activation_failed: + cell->error = ret; + afs_deactivate_cell(net, cell); + + smp_store_release(&cell->state, AFS_CELL_FAILED); /* vs error */ + wake_up_var(&cell->state); + goto again; + +reverse_deactivation: + smp_store_release(&cell->state, AFS_CELL_ACTIVE); + wake_up_var(&cell->state); + _leave(" [deact->act]"); + return; + +done: + _leave(" [done %u]", cell->state); + return; + +final_destruction: + /* The root volume is pinning the cell */ + afs_put_volume(cell->net, cell->root_volume, afs_volume_trace_put_cell_root); + cell->root_volume = NULL; + afs_put_cell(cell, afs_cell_trace_put_destroy); +} + +static void afs_manage_cell_work(struct work_struct *work) +{ + struct afs_cell *cell = container_of(work, struct afs_cell, manager); + + afs_manage_cell(cell); + afs_put_cell(cell, afs_cell_trace_put_queue_work); +} + +/* + * Manage the records of cells known to a network namespace. This includes + * updating the DNS records and garbage collecting unused cells that were + * automatically added. + * + * Note that constructed cell records may only be removed from net->cells by + * this work item, so it is safe for this work item to stash a cursor pointing + * into the tree and then return to caller (provided it skips cells that are + * still under construction). + * + * Note also that we were given an increment on net->cells_outstanding by + * whoever queued us that we need to deal with before returning. + */ +void afs_manage_cells(struct work_struct *work) +{ + struct afs_net *net = container_of(work, struct afs_net, cells_manager); + struct rb_node *cursor; + time64_t now = ktime_get_real_seconds(), next_manage = TIME64_MAX; + bool purging = !net->live; + + _enter(""); + + /* Trawl the cell database looking for cells that have expired from + * lack of use and cells whose DNS results have expired and dispatch + * their managers. + */ + down_read(&net->cells_lock); + + for (cursor = rb_first(&net->cells); cursor; cursor = rb_next(cursor)) { + struct afs_cell *cell = + rb_entry(cursor, struct afs_cell, net_node); + unsigned active; + bool sched_cell = false; + + active = atomic_read(&cell->active); + trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), + active, afs_cell_trace_manage); + + ASSERTCMP(active, >=, 1); + + if (purging) { + if (test_and_clear_bit(AFS_CELL_FL_NO_GC, &cell->flags)) { + active = atomic_dec_return(&cell->active); + trace_afs_cell(cell->debug_id, atomic_read(&cell->ref), + active, afs_cell_trace_unuse_pin); + } + } + + if (active == 1) { + struct afs_vlserver_list *vllist; + time64_t expire_at = cell->last_inactive; + + read_lock(&cell->vl_servers_lock); + vllist = rcu_dereference_protected( + cell->vl_servers, + lockdep_is_held(&cell->vl_servers_lock)); + if (vllist->nr_servers > 0) + expire_at += afs_cell_gc_delay; + read_unlock(&cell->vl_servers_lock); + if (purging || expire_at <= now) + sched_cell = true; + else if (expire_at < next_manage) + next_manage = expire_at; + } + + if (!purging) { + if (test_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags)) + sched_cell = true; + } + + if (sched_cell) + afs_queue_cell(cell, afs_cell_trace_get_queue_manage); + } + + up_read(&net->cells_lock); + + /* Update the timer on the way out. We have to pass an increment on + * cells_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->cells_manager)) + atomic_inc(&net->cells_outstanding); + } else { + afs_set_cell_timer(net, next_manage - now); + } + } + + afs_dec_cells_outstanding(net); + _leave(" [%d]", atomic_read(&net->cells_outstanding)); +} + +/* + * Purge in-memory cell database. + */ +void afs_cell_purge(struct afs_net *net) +{ + struct afs_cell *ws; + + _enter(""); + + down_write(&net->cells_lock); + ws = net->ws_cell; + net->ws_cell = NULL; + up_write(&net->cells_lock); + afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws); + + _debug("del timer"); + if (del_timer_sync(&net->cells_timer)) + atomic_dec(&net->cells_outstanding); + + _debug("kick mgr"); + afs_queue_cell_manager(net); + + _debug("wait"); + wait_var_event(&net->cells_outstanding, + !atomic_read(&net->cells_outstanding)); + _leave(""); +} |