linux-stable/fs/afs/cell.c
David Howells acc080d15d afs: Fix tracing deref-before-check
The patch dca54a7bbb: "afs: Add tracing for cell refcount and active user
count" from Oct 13, 2020, leads to the following Smatch complaint:

    fs/afs/cell.c:596 afs_unuse_cell()
    warn: variable dereferenced before check 'cell' (see line 592)

Fix this by moving the retrieval of the cell debug ID to after the check of
the validity of the cell pointer.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: dca54a7bbb ("afs: Add tracing for cell refcount and active user count")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Dan Carpenter <dan.carpenter@oracle.com>
2020-10-27 22:05:56 +00:00

965 lines
24 KiB
C

// 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;
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 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("");
}