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authorDavid Howells <dhowells@redhat.com>2020-10-13 21:51:59 +0200
committerDavid Howells <dhowells@redhat.com>2020-10-16 15:39:21 +0200
commitdca54a7bbb8ca9148ae10d60c66c926e222a9c4b (patch)
tree7a963929b4c3ef79910ef1c56ea1ea45248fcfb7 /fs/afs
parentafs: Fix cell removal (diff)
downloadlinux-dca54a7bbb8ca9148ae10d60c66c926e222a9c4b.tar.xz
linux-dca54a7bbb8ca9148ae10d60c66c926e222a9c4b.zip
afs: Add tracing for cell refcount and active user count
Add a tracepoint to log the cell refcount and active user count and pass in a reason code through various functions that manipulate these counters. Additionally, a helper function, afs_see_cell(), is provided to log interesting places that deal with a cell without actually doing any accounting directly. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/cell.c99
-rw-r--r--fs/afs/dynroot.c4
-rw-r--r--fs/afs/internal.h15
-rw-r--r--fs/afs/mntpt.c4
-rw-r--r--fs/afs/proc.c2
-rw-r--r--fs/afs/super.c16
-rw-r--r--fs/afs/vl_alias.c8
-rw-r--r--fs/afs/vl_rotate.c2
-rw-r--r--fs/afs/volume.c6
9 files changed, 101 insertions, 55 deletions
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index bc7ed46aaca9..52233fa6195f 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -18,6 +18,7 @@
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 *);
@@ -48,7 +49,8 @@ static void afs_set_cell_timer(struct afs_net *net, time64_t delay)
* 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)
+ const char *name, unsigned int namesz,
+ enum afs_cell_trace reason)
{
struct afs_cell *cell = NULL;
struct rb_node *p;
@@ -87,19 +89,20 @@ static struct afs_cell *afs_find_cell_locked(struct afs_net *net,
return ERR_PTR(-ENOENT);
found:
- return afs_use_cell(cell);
+ 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)
+ 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);
+ cell = afs_find_cell_locked(net, name, namesz, reason);
up_read(&net->cells_lock);
return cell;
}
@@ -197,6 +200,8 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
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;
@@ -236,7 +241,7 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
_enter("%s,%s", name, vllist);
if (!excl) {
- cell = afs_find_cell(net, name, namesz);
+ cell = afs_find_cell(net, name, namesz, afs_cell_trace_use_lookup);
if (!IS_ERR(cell))
goto wait_for_cell;
}
@@ -280,13 +285,16 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
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_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,
({
@@ -309,17 +317,17 @@ cell_already_exists:
if (excl) {
ret = -EEXIST;
} else {
- afs_use_cell(cursor);
+ afs_use_cell(cursor, afs_cell_trace_use_lookup);
ret = 0;
}
up_write(&net->cells_lock);
if (candidate)
- afs_put_cell(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_unuse_cell(net, cell, afs_cell_trace_unuse_lookup);
error_noput:
_leave(" = %d [error]", ret);
return ERR_PTR(ret);
@@ -364,15 +372,16 @@ int afs_cell_init(struct afs_net *net, const char *rootcell)
}
if (!test_and_set_bit(AFS_CELL_FL_NO_GC, &new_root->flags))
- afs_use_cell(new_root);
+ 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_unuse_cell(net, old_root, afs_cell_trace_unuse_ws);
_leave(" = 0");
return 0;
}
@@ -485,9 +494,10 @@ static void afs_cell_destroy(struct rcu_head *rcu)
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_unuse_cell(net, cell->alias_of, afs_cell_trace_unuse_alias);
key_put(cell->anonymous_key);
kfree(cell->name);
kfree(cell);
@@ -525,24 +535,30 @@ void afs_cells_timer(struct timer_list *timer)
/*
* Get a reference on a cell record.
*/
-struct afs_cell *afs_get_cell(struct afs_cell *cell)
+struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason)
{
+ int u;
+
if (atomic_read(&cell->ref) <= 0)
BUG();
- atomic_inc(&cell->ref);
+ 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)
+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);
@@ -554,12 +570,16 @@ void afs_put_cell(struct afs_cell *cell)
/*
* Note a cell becoming more active.
*/
-struct afs_cell *afs_use_cell(struct afs_cell *cell)
+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();
- atomic_inc(&cell->active);
+ u = atomic_read(&cell->ref);
+ a = atomic_inc_return(&cell->active);
+ trace_afs_cell(cell->debug_id, u, a, reason);
return cell;
}
@@ -567,10 +587,11 @@ struct afs_cell *afs_use_cell(struct afs_cell *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)
+void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_trace reason)
{
+ unsigned int debug_id = cell->debug_id;
time64_t now, expire_delay;
- int a;
+ int u, a;
if (!cell)
return;
@@ -583,7 +604,9 @@ void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell)
if (cell->vl_servers->nr_servers)
expire_delay = afs_cell_gc_delay;
+ 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. */
@@ -591,13 +614,25 @@ void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell)
}
/*
+ * 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)
+void afs_queue_cell(struct afs_cell *cell, enum afs_cell_trace reason)
{
- afs_get_cell(cell);
+ afs_get_cell(cell, reason);
if (!queue_work(afs_wq, &cell->manager))
- afs_put_cell(cell);
+ afs_put_cell(cell, afs_cell_trace_put_queue_fail);
}
/*
@@ -713,6 +748,8 @@ again:
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);
@@ -792,7 +829,7 @@ 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_put_cell(cell, afs_cell_trace_put_destroy);
}
static void afs_manage_cell_work(struct work_struct *work)
@@ -800,7 +837,7 @@ 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_put_cell(cell, afs_cell_trace_put_queue_work);
}
/*
@@ -838,13 +875,17 @@ void afs_manage_cells(struct work_struct *work)
bool sched_cell = false;
active = atomic_read(&cell->active);
- _debug("manage %s %u %u", cell->name, atomic_read(&cell->ref), 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))
- atomic_dec(&cell->active);
+ 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) {
@@ -870,7 +911,7 @@ void afs_manage_cells(struct work_struct *work)
}
if (sched_cell)
- afs_queue_cell(cell);
+ afs_queue_cell(cell, afs_cell_trace_get_queue_manage);
}
up_read(&net->cells_lock);
@@ -907,7 +948,7 @@ void afs_cell_purge(struct afs_net *net)
ws = net->ws_cell;
net->ws_cell = NULL;
up_write(&net->cells_lock);
- afs_unuse_cell(net, ws);
+ afs_unuse_cell(net, ws, afs_cell_trace_unuse_ws);
_debug("del timer");
if (del_timer_sync(&net->cells_timer))
diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c
index da32797dd425..db832cc931c8 100644
--- a/fs/afs/dynroot.c
+++ b/fs/afs/dynroot.c
@@ -123,9 +123,9 @@ static int afs_probe_cell_name(struct dentry *dentry)
len--;
}
- cell = afs_find_cell(net, name, len);
+ cell = afs_find_cell(net, name, len, afs_cell_trace_use_probe);
if (!IS_ERR(cell)) {
- afs_unuse_cell(net, cell);
+ afs_unuse_cell(net, cell, afs_cell_trace_unuse_probe);
return 0;
}
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 06e617ee4cd1..81b0485fd22a 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -375,6 +375,7 @@ struct afs_cell {
enum dns_record_source dns_source:8; /* Latest source of data from lookup */
enum dns_lookup_status dns_status:8; /* Latest status of data from lookup */
unsigned int dns_lookup_count; /* Counter of DNS lookups */
+ unsigned int debug_id;
/* The volumes belonging to this cell */
struct rb_root volumes; /* Tree of volumes on this server */
@@ -919,14 +920,16 @@ static inline bool afs_cb_is_broken(unsigned int cb_break,
* cell.c
*/
extern int afs_cell_init(struct afs_net *, const char *);
-extern struct afs_cell *afs_find_cell(struct afs_net *, const char *, unsigned);
+extern struct afs_cell *afs_find_cell(struct afs_net *, const char *, unsigned,
+ enum afs_cell_trace);
extern struct afs_cell *afs_lookup_cell(struct afs_net *, const char *, unsigned,
const char *, bool);
-extern struct afs_cell *afs_use_cell(struct afs_cell *);
-extern void afs_unuse_cell(struct afs_net *, struct afs_cell *);
-extern struct afs_cell *afs_get_cell(struct afs_cell *);
-extern void afs_put_cell(struct afs_cell *);
-extern void afs_queue_cell(struct afs_cell *);
+extern struct afs_cell *afs_use_cell(struct afs_cell *, enum afs_cell_trace);
+extern void afs_unuse_cell(struct afs_net *, struct afs_cell *, enum afs_cell_trace);
+extern struct afs_cell *afs_get_cell(struct afs_cell *, enum afs_cell_trace);
+extern void afs_see_cell(struct afs_cell *, enum afs_cell_trace);
+extern void afs_put_cell(struct afs_cell *, enum afs_cell_trace);
+extern void afs_queue_cell(struct afs_cell *, enum afs_cell_trace);
extern void afs_manage_cells(struct work_struct *);
extern void afs_cells_timer(struct timer_list *);
extern void __net_exit afs_cell_purge(struct afs_net *);
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index c69a0282960c..052dab2f5c03 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -88,7 +88,7 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
ctx->force = true;
}
if (ctx->cell) {
- afs_unuse_cell(ctx->net, ctx->cell);
+ afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt);
ctx->cell = NULL;
}
if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) {
@@ -124,7 +124,7 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
char *buf;
if (src_as->cell)
- ctx->cell = afs_use_cell(src_as->cell);
+ ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt);
if (size < 2 || size > PAGE_SIZE - 1)
return -EINVAL;
diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 76fbe0560cfb..065a28bfa3f1 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -129,7 +129,7 @@ static int afs_proc_cells_write(struct file *file, char *buf, size_t size)
}
if (test_and_set_bit(AFS_CELL_FL_NO_GC, &cell->flags))
- afs_unuse_cell(net, cell);
+ afs_unuse_cell(net, cell, afs_cell_trace_unuse_no_pin);
} else {
goto inval;
}
diff --git a/fs/afs/super.c b/fs/afs/super.c
index e72c223f831d..ac4e3ed4e9bd 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -294,7 +294,8 @@ static int afs_parse_source(struct fs_context *fc, struct fs_parameter *param)
cellnamesz, cellnamesz, cellname ?: "");
return PTR_ERR(cell);
}
- afs_unuse_cell(ctx->net, ctx->cell);
+ afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_parse);
+ afs_see_cell(cell, afs_cell_trace_see_source);
ctx->cell = cell;
}
@@ -389,8 +390,9 @@ static int afs_validate_fc(struct fs_context *fc)
_debug("switch to alias");
key_put(ctx->key);
ctx->key = NULL;
- cell = afs_use_cell(ctx->cell->alias_of);
- afs_unuse_cell(ctx->net, ctx->cell);
+ cell = afs_use_cell(ctx->cell->alias_of,
+ afs_cell_trace_use_fc_alias);
+ afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
ctx->cell = cell;
goto reget_key;
}
@@ -508,7 +510,7 @@ static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
if (ctx->dyn_root) {
as->dyn_root = true;
} else {
- as->cell = afs_use_cell(ctx->cell);
+ as->cell = afs_use_cell(ctx->cell, afs_cell_trace_use_sbi);
as->volume = afs_get_volume(ctx->volume,
afs_volume_trace_get_alloc_sbi);
}
@@ -521,7 +523,7 @@ static void afs_destroy_sbi(struct afs_super_info *as)
if (as) {
struct afs_net *net = afs_net(as->net_ns);
afs_put_volume(net, as->volume, afs_volume_trace_put_destroy_sbi);
- afs_unuse_cell(net, as->cell);
+ afs_unuse_cell(net, as->cell, afs_cell_trace_unuse_sbi);
put_net(as->net_ns);
kfree(as);
}
@@ -607,7 +609,7 @@ static void afs_free_fc(struct fs_context *fc)
afs_destroy_sbi(fc->s_fs_info);
afs_put_volume(ctx->net, ctx->volume, afs_volume_trace_put_free_fc);
- afs_unuse_cell(ctx->net, ctx->cell);
+ afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_fc);
key_put(ctx->key);
kfree(ctx);
}
@@ -634,7 +636,7 @@ static int afs_init_fs_context(struct fs_context *fc)
ctx->net = afs_net(fc->net_ns);
/* Default to the workstation cell. */
- cell = afs_find_cell(ctx->net, NULL, 0);
+ cell = afs_find_cell(ctx->net, NULL, 0, afs_cell_trace_use_fc);
if (IS_ERR(cell))
cell = NULL;
ctx->cell = cell;
diff --git a/fs/afs/vl_alias.c b/fs/afs/vl_alias.c
index ddb4cb67d0fd..f04a80e4f5c3 100644
--- a/fs/afs/vl_alias.c
+++ b/fs/afs/vl_alias.c
@@ -177,7 +177,7 @@ static int afs_compare_cell_roots(struct afs_cell *cell)
is_alias:
rcu_read_unlock();
- cell->alias_of = afs_use_cell(p);
+ cell->alias_of = afs_use_cell(p, afs_cell_trace_use_alias);
return 1;
}
@@ -247,18 +247,18 @@ static int afs_query_for_alias(struct afs_cell *cell, struct key *key)
continue;
if (p->root_volume)
continue; /* Ignore cells that have a root.cell volume. */
- afs_use_cell(p);
+ afs_use_cell(p, afs_cell_trace_use_check_alias);
mutex_unlock(&cell->net->proc_cells_lock);
if (afs_query_for_alias_one(cell, key, p) != 0)
goto is_alias;
if (mutex_lock_interruptible(&cell->net->proc_cells_lock) < 0) {
- afs_unuse_cell(cell->net, p);
+ afs_unuse_cell(cell->net, p, afs_cell_trace_unuse_check_alias);
return -ERESTARTSYS;
}
- afs_unuse_cell(cell->net, p);
+ afs_unuse_cell(cell->net, p, afs_cell_trace_unuse_check_alias);
}
mutex_unlock(&cell->net->proc_cells_lock);
diff --git a/fs/afs/vl_rotate.c b/fs/afs/vl_rotate.c
index da3b072d4d63..488e58490b16 100644
--- a/fs/afs/vl_rotate.c
+++ b/fs/afs/vl_rotate.c
@@ -45,7 +45,7 @@ static bool afs_start_vl_iteration(struct afs_vl_cursor *vc)
cell->dns_expiry <= ktime_get_real_seconds()) {
dns_lookup_count = smp_load_acquire(&cell->dns_lookup_count);
set_bit(AFS_CELL_FL_DO_LOOKUP, &cell->flags);
- afs_queue_cell(cell);
+ afs_queue_cell(cell, afs_cell_trace_get_queue_dns);
if (cell->dns_source == DNS_RECORD_UNAVAILABLE) {
if (wait_var_event_interruptible(
diff --git a/fs/afs/volume.c b/fs/afs/volume.c
index a838030e9563..f84194b791d3 100644
--- a/fs/afs/volume.c
+++ b/fs/afs/volume.c
@@ -83,7 +83,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
volume->vid = vldb->vid[params->type];
volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
- volume->cell = afs_get_cell(params->cell);
+ volume->cell = afs_get_cell(params->cell, afs_cell_trace_get_vol);
volume->type = params->type;
volume->type_force = params->force;
volume->name_len = vldb->name_len;
@@ -106,7 +106,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
return volume;
error_1:
- afs_put_cell(volume->cell);
+ afs_put_cell(volume->cell, afs_cell_trace_put_vol);
kfree(volume);
error_0:
return ERR_PTR(ret);
@@ -228,7 +228,7 @@ static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
afs_remove_volume_from_cell(volume);
afs_put_serverlist(net, rcu_access_pointer(volume->servers));
- afs_put_cell(volume->cell);
+ afs_put_cell(volume->cell, afs_cell_trace_put_vol);
trace_afs_volume(volume->vid, atomic_read(&volume->usage),
afs_volume_trace_free);
kfree_rcu(volume, rcu);