Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 954 insertions, 0 deletions

diff --git a/fs/afs/cell.c b/fs/afs/cell.c
new file mode 100644
index 000000000..926cb1188
--- /dev/null
+++ b/fs/afs/cell.c
@@ -0,0 +1,954 @@
+// 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;
+
+		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 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("");
+}