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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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;
 
     refcount_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);
     INIT_LIST_HEAD(&cell->fs_open_mmaps);
     init_rwsem(&cell->fs_open_mmaps_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, refcount_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, refcount_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;
 
         ret = -ENOMEM;
         vllist = afs_alloc_vlserver_list(0);
         if (!vllist)
             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 r;
 
     _enter("%p{%s}", cell, cell->name);
 
     r = refcount_read(&cell->ref);
     ASSERTCMP(r, ==, 0);
     trace_afs_cell(cell->debug_id, r, 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 r;
 
     __refcount_inc(&cell->ref, &r);
     trace_afs_cell(cell->debug_id, r + 1, 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 a;
         bool zero;
         int r;
 
         a = atomic_read(&cell->active);
         zero = __refcount_dec_and_test(&cell->ref, &r);
         trace_afs_cell(debug_id, r - 1, a, reason);
         if (zero) {
             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 r, a;
 
     r = refcount_read(&cell->ref);
     WARN_ON(r == 0);
     a = atomic_inc_return(&cell->active);
     trace_afs_cell(cell->debug_id, r, 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 r, 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;
     r = refcount_read(&cell->ref);
     a = atomic_dec_return(&cell->active);
     trace_afs_cell(debug_id, r, 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 r, a;
 
     r = refcount_read(&cell->ref);
     a = atomic_read(&cell->active);
     trace_afs_cell(cell->debug_id, r, 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;
     }
 
     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);
 
     _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, refcount_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, refcount_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, refcount_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("");
 }

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