Commit dca54a7b authored by David Howells's avatar David Howells
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
parent 1d0e850a

fs/afs/cell.c

+70 −29
Original line number Diff line number Diff line
@@ -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 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net, 
	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;
@@ -583,21 +604,35 @@ 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. */

		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)

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 @@ static void afs_manage_cell(struct afs_cell *cell) 
		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 @@ static void afs_manage_cell(struct afs_cell *cell) 
	/* 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))

fs/afs/dynroot.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

	}

fs/afs/internal.h

+9 −6
Original line number Diff line number Diff line
@@ -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 *);

fs/afs/mntpt.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

fs/afs/proc.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}