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Date: Tue, 2 Aug 2022 11:27:31 -0300
From: Marc Dionne <marc.dionne@...istor.com>
To: David Howells <dhowells@...hat.com>
Cc: linux-afs@...ts.infradead.org, linux-fsdevel@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] afs: Use refcount_t rather than atomic_t
On Fri, Jul 29, 2022 at 1:40 PM David Howells <dhowells@...hat.com> wrote:
>
> Use refcount_t rather than atomic_t in afs to make use of the count
> checking facilities provided.
>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: Marc Dionne <marc.dionne@...istor.com>
> cc: linux-afs@...ts.infradead.org
> ---
>
> fs/afs/cell.c | 61 +++++++++++++++++++++-----------------------
> fs/afs/cmservice.c | 2 +
> fs/afs/internal.h | 16 ++++++------
> fs/afs/proc.c | 6 ++--
> fs/afs/rxrpc.c | 26 ++++++++++---------
> fs/afs/server.c | 40 +++++++++++++++++------------
> fs/afs/vl_list.c | 19 ++++----------
> fs/afs/volume.c | 21 +++++++++------
> include/trace/events/afs.h | 26 +++++++++----------
> 9 files changed, 110 insertions(+), 107 deletions(-)
>
> diff --git a/fs/afs/cell.c b/fs/afs/cell.c
> index 07ad744eef77..988c2ac7cece 100644
> --- a/fs/afs/cell.c
> +++ b/fs/afs/cell.c
> @@ -158,7 +158,7 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
> cell->name[i] = tolower(name[i]);
> cell->name[i] = 0;
>
> - atomic_set(&cell->ref, 1);
> + refcount_set(&cell->ref, 1);
> atomic_set(&cell->active, 0);
> INIT_WORK(&cell->manager, afs_manage_cell_work);
> cell->volumes = RB_ROOT;
> @@ -287,7 +287,7 @@ 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);
> + 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);
> @@ -295,7 +295,7 @@ struct afs_cell *afs_lookup_cell(struct afs_net *net,
> 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),
> + 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,
> @@ -490,13 +490,13 @@ 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;
> + int r;
>
> _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);
> + 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);
> @@ -539,13 +539,10 @@ void afs_cells_timer(struct timer_list *timer)
> */
> struct afs_cell *afs_get_cell(struct afs_cell *cell, enum afs_cell_trace reason)
> {
> - int u;
> + int r;
>
> - 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);
> + __refcount_inc(&cell->ref, &r);
> + trace_afs_cell(cell->debug_id, r + 1, atomic_read(&cell->active), reason);
> return cell;
> }
>
> @@ -556,12 +553,14 @@ 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;
> + unsigned int a;
> + bool zero;
> + int r;
>
> a = atomic_read(&cell->active);
> - u = atomic_dec_return(&cell->ref);
> - trace_afs_cell(debug_id, u, a, reason);
> - if (u == 0) {
> + 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);
> @@ -574,14 +573,12 @@ void afs_put_cell(struct afs_cell *cell, enum afs_cell_trace reason)
> */
> 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();
> + int r, a;
>
> - u = atomic_read(&cell->ref);
> + r = refcount_read(&cell->ref);
> + WARN_ON(r == 0);
> a = atomic_inc_return(&cell->active);
> - trace_afs_cell(cell->debug_id, u, a, reason);
> + trace_afs_cell(cell->debug_id, r, a, reason);
> return cell;
> }
>
> @@ -593,7 +590,7 @@ void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_tr
> {
> unsigned int debug_id;
> time64_t now, expire_delay;
> - int u, a;
> + int r, a;
>
> if (!cell)
> return;
> @@ -607,9 +604,9 @@ void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_tr
> expire_delay = afs_cell_gc_delay;
>
> debug_id = cell->debug_id;
> - u = atomic_read(&cell->ref);
> + r = refcount_read(&cell->ref);
> a = atomic_dec_return(&cell->active);
> - trace_afs_cell(debug_id, u, a, reason);
> + trace_afs_cell(debug_id, r, a, reason);
> WARN_ON(a == 0);
> if (a == 1)
> /* 'cell' may now be garbage collected. */
> @@ -621,11 +618,11 @@ void afs_unuse_cell(struct afs_net *net, struct afs_cell *cell, enum afs_cell_tr
> */
> void afs_see_cell(struct afs_cell *cell, enum afs_cell_trace reason)
> {
> - int u, a;
> + int r, a;
>
> - u = atomic_read(&cell->ref);
> + r = refcount_read(&cell->ref);
> a = atomic_read(&cell->active);
> - trace_afs_cell(cell->debug_id, u, a, reason);
> + trace_afs_cell(cell->debug_id, r, a, reason);
> }
>
> /*
> @@ -739,7 +736,7 @@ 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,
> + trace_afs_cell(cell->debug_id, refcount_read(&cell->ref), 0,
> afs_cell_trace_unuse_delete);
> smp_store_release(&cell->state, AFS_CELL_REMOVED);
> }
> @@ -866,7 +863,7 @@ void afs_manage_cells(struct work_struct *work)
> bool sched_cell = false;
>
> active = atomic_read(&cell->active);
> - trace_afs_cell(cell->debug_id, atomic_read(&cell->ref),
> + trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
> active, afs_cell_trace_manage);
>
> ASSERTCMP(active, >=, 1);
> @@ -874,7 +871,7 @@ void afs_manage_cells(struct work_struct *work)
> 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),
> + trace_afs_cell(cell->debug_id, refcount_read(&cell->ref),
> active, afs_cell_trace_unuse_pin);
> }
> }
> diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
> index a3f5de28be79..cedd627e1fae 100644
> --- a/fs/afs/cmservice.c
> +++ b/fs/afs/cmservice.c
> @@ -213,7 +213,7 @@ static void SRXAFSCB_CallBack(struct work_struct *work)
> */
> if (call->server) {
> trace_afs_server(call->server,
> - atomic_read(&call->server->ref),
> + refcount_read(&call->server->ref),
> atomic_read(&call->server->active),
> afs_server_trace_callback);
> afs_break_callbacks(call->server, call->count, call->request);
> diff --git a/fs/afs/internal.h b/fs/afs/internal.h
> index a6f25d9e75b5..64ad55494349 100644
> --- a/fs/afs/internal.h
> +++ b/fs/afs/internal.h
> @@ -122,7 +122,7 @@ struct afs_call {
> };
> struct afs_operation *op;
> unsigned int server_index;
> - atomic_t usage;
> + refcount_t ref;
> enum afs_call_state state;
> spinlock_t state_lock;
> int error; /* error code */
> @@ -365,7 +365,7 @@ struct afs_cell {
> struct hlist_node proc_link; /* /proc cell list link */
> time64_t dns_expiry; /* Time AFSDB/SRV record expires */
> time64_t last_inactive; /* Time of last drop of usage count */
> - atomic_t ref; /* Struct refcount */
> + refcount_t ref; /* Struct refcount */
> atomic_t active; /* Active usage counter */
> unsigned long flags;
> #define AFS_CELL_FL_NO_GC 0 /* The cell was added manually, don't auto-gc */
> @@ -410,7 +410,7 @@ struct afs_vlserver {
> #define AFS_VLSERVER_FL_IS_YFS 2 /* Server is YFS not AFS */
> #define AFS_VLSERVER_FL_RESPONDING 3 /* VL server is responding */
> rwlock_t lock; /* Lock on addresses */
> - atomic_t usage;
> + refcount_t ref;
> unsigned int rtt; /* Server's current RTT in uS */
>
> /* Probe state */
> @@ -446,7 +446,7 @@ struct afs_vlserver_entry {
>
> struct afs_vlserver_list {
> struct rcu_head rcu;
> - atomic_t usage;
> + refcount_t ref;
> u8 nr_servers;
> u8 index; /* Server currently in use */
> u8 preferred; /* Preferred server */
> @@ -517,7 +517,7 @@ struct afs_server {
> #define AFS_SERVER_FL_NO_IBULK 17 /* Fileserver doesn't support FS.InlineBulkStatus */
> #define AFS_SERVER_FL_NO_RM2 18 /* Fileserver doesn't support YFS.RemoveFile2 */
> #define AFS_SERVER_FL_HAS_FS64 19 /* Fileserver supports FS.{Fetch,Store}Data64 */
> - atomic_t ref; /* Object refcount */
> + refcount_t ref; /* Object refcount */
> atomic_t active; /* Active user count */
> u32 addr_version; /* Address list version */
> unsigned int rtt; /* Server's current RTT in uS */
> @@ -571,7 +571,7 @@ struct afs_volume {
> struct rcu_head rcu;
> afs_volid_t vid; /* volume ID */
> };
> - atomic_t usage;
> + refcount_t ref;
> time64_t update_at; /* Time at which to next update */
> struct afs_cell *cell; /* Cell to which belongs (pins ref) */
> struct rb_node cell_node; /* Link in cell->volumes */
> @@ -1493,14 +1493,14 @@ extern int afs_end_vlserver_operation(struct afs_vl_cursor *);
> */
> static inline struct afs_vlserver *afs_get_vlserver(struct afs_vlserver *vlserver)
> {
> - atomic_inc(&vlserver->usage);
> + refcount_inc(&vlserver->ref);
> return vlserver;
> }
>
> static inline struct afs_vlserver_list *afs_get_vlserverlist(struct afs_vlserver_list *vllist)
> {
> if (vllist)
> - atomic_inc(&vllist->usage);
> + refcount_inc(&vllist->ref);
> return vllist;
> }
>
> diff --git a/fs/afs/proc.c b/fs/afs/proc.c
> index e1b863449296..2a0c83d71565 100644
> --- a/fs/afs/proc.c
> +++ b/fs/afs/proc.c
> @@ -47,7 +47,7 @@ static int afs_proc_cells_show(struct seq_file *m, void *v)
>
> /* display one cell per line on subsequent lines */
> seq_printf(m, "%3u %3u %6lld %2u %2u %s\n",
> - atomic_read(&cell->ref),
> + refcount_read(&cell->ref),
> atomic_read(&cell->active),
> cell->dns_expiry - ktime_get_real_seconds(),
> vllist ? vllist->nr_servers : 0,
> @@ -217,7 +217,7 @@ static int afs_proc_cell_volumes_show(struct seq_file *m, void *v)
> }
>
> seq_printf(m, "%3d %08llx %s %s\n",
> - atomic_read(&vol->usage), vol->vid,
> + refcount_read(&vol->ref), vol->vid,
> afs_vol_types[vol->type],
> vol->name);
>
> @@ -388,7 +388,7 @@ static int afs_proc_servers_show(struct seq_file *m, void *v)
> alist = rcu_dereference(server->addresses);
> seq_printf(m, "%pU %3d %3d\n",
> &server->uuid,
> - atomic_read(&server->ref),
> + refcount_read(&server->ref),
> atomic_read(&server->active));
> seq_printf(m, " - info: fl=%lx rtt=%u brk=%x\n",
> server->flags, server->rtt, server->cb_s_break);
> diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
> index a5434f3e57c6..d9acc43cb6f0 100644
> --- a/fs/afs/rxrpc.c
> +++ b/fs/afs/rxrpc.c
> @@ -145,7 +145,7 @@ static struct afs_call *afs_alloc_call(struct afs_net *net,
> call->type = type;
> call->net = net;
> call->debug_id = atomic_inc_return(&rxrpc_debug_id);
> - atomic_set(&call->usage, 1);
> + refcount_set(&call->ref, 1);
> INIT_WORK(&call->async_work, afs_process_async_call);
> init_waitqueue_head(&call->waitq);
> spin_lock_init(&call->state_lock);
> @@ -163,14 +163,15 @@ static struct afs_call *afs_alloc_call(struct afs_net *net,
> void afs_put_call(struct afs_call *call)
> {
> struct afs_net *net = call->net;
> - int n = atomic_dec_return(&call->usage);
> - int o = atomic_read(&net->nr_outstanding_calls);
> + bool zero;
> + int r, o;
>
> - trace_afs_call(call, afs_call_trace_put, n, o,
> + zero = __refcount_dec_and_test(&call->ref, &r);
> + o = atomic_read(&net->nr_outstanding_calls);
> + trace_afs_call(call, afs_call_trace_put, r - 1, o,
> __builtin_return_address(0));
>
> - ASSERTCMP(n, >=, 0);
> - if (n == 0) {
> + if (zero) {
> ASSERT(!work_pending(&call->async_work));
> ASSERT(call->type->name != NULL);
>
> @@ -198,9 +199,11 @@ void afs_put_call(struct afs_call *call)
> static struct afs_call *afs_get_call(struct afs_call *call,
> enum afs_call_trace why)
> {
> - int u = atomic_inc_return(&call->usage);
> + int r;
>
> - trace_afs_call(call, why, u,
> + __refcount_inc(&call->ref, &r);
> +
> + trace_afs_call(call, why, r + 1,
> atomic_read(&call->net->nr_outstanding_calls),
> __builtin_return_address(0));
> return call;
> @@ -668,14 +671,13 @@ static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
> unsigned long call_user_ID)
> {
> struct afs_call *call = (struct afs_call *)call_user_ID;
> - int u;
> + int r;
>
> trace_afs_notify_call(rxcall, call);
> call->need_attention = true;
>
> - u = atomic_fetch_add_unless(&call->usage, 1, 0);
> - if (u != 0) {
> - trace_afs_call(call, afs_call_trace_wake, u + 1,
> + if (__refcount_inc_not_zero(&call->ref, &r)) {
> + trace_afs_call(call, afs_call_trace_wake, r + 1,
> atomic_read(&call->net->nr_outstanding_calls),
> __builtin_return_address(0));
>
> diff --git a/fs/afs/server.c b/fs/afs/server.c
> index 6e5b9a19b234..ffed828622b6 100644
> --- a/fs/afs/server.c
> +++ b/fs/afs/server.c
> @@ -228,7 +228,7 @@ static struct afs_server *afs_alloc_server(struct afs_cell *cell,
> if (!server)
> goto enomem;
>
> - atomic_set(&server->ref, 1);
> + refcount_set(&server->ref, 1);
> atomic_set(&server->active, 1);
> server->debug_id = atomic_inc_return(&afs_server_debug_id);
> RCU_INIT_POINTER(server->addresses, alist);
> @@ -352,9 +352,10 @@ void afs_servers_timer(struct timer_list *timer)
> struct afs_server *afs_get_server(struct afs_server *server,
> enum afs_server_trace reason)
> {
> - unsigned int u = atomic_inc_return(&server->ref);
> + int r;
>
> - trace_afs_server(server, u, atomic_read(&server->active), reason);
> + __refcount_inc(&server->ref, &r);
> + trace_afs_server(server, r + 1, atomic_read(&server->active), reason);
> return server;
> }
>
> @@ -364,14 +365,14 @@ struct afs_server *afs_get_server(struct afs_server *server,
> static struct afs_server *afs_maybe_use_server(struct afs_server *server,
> enum afs_server_trace reason)
> {
> - unsigned int r = atomic_fetch_add_unless(&server->ref, 1, 0);
> unsigned int a;
> + int r;
>
> - if (r == 0)
> + if (!__refcount_inc_not_zero(&server->ref, &r))
> return NULL;
>
> a = atomic_inc_return(&server->active);
> - trace_afs_server(server, r, a, reason);
> + trace_afs_server(server, r + 1, a, reason);
> return server;
> }
>
> @@ -380,10 +381,13 @@ static struct afs_server *afs_maybe_use_server(struct afs_server *server,
> */
> struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason)
> {
> - unsigned int r = atomic_inc_return(&server->ref);
> - unsigned int a = atomic_inc_return(&server->active);
> + unsigned int a;
> + int r;
> +
> + __refcount_inc(&server->ref, &r);
> + a = atomic_inc_return(&server->active);
>
> - trace_afs_server(server, r, a, reason);
> + trace_afs_server(server, r + 1, a, reason);
> return server;
> }
>
> @@ -393,14 +397,15 @@ struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_tra
> void afs_put_server(struct afs_net *net, struct afs_server *server,
> enum afs_server_trace reason)
> {
> - unsigned int usage;
> + bool zero;
> + int r;
>
> if (!server)
> return;
>
> - usage = atomic_dec_return(&server->ref);
> - trace_afs_server(server, usage, atomic_read(&server->active), reason);
> - if (unlikely(usage == 0))
> + zero = __refcount_dec_and_test(&server->ref, &r);
> + trace_afs_server(server, r - 1, atomic_read(&server->active), reason);
> + if (unlikely(zero))
> __afs_put_server(net, server);
> }
>
> @@ -436,7 +441,7 @@ static void afs_server_rcu(struct rcu_head *rcu)
> {
> struct afs_server *server = container_of(rcu, struct afs_server, rcu);
>
> - trace_afs_server(server, atomic_read(&server->ref),
> + trace_afs_server(server, refcount_read(&server->ref),
> atomic_read(&server->active), afs_server_trace_free);
> afs_put_addrlist(rcu_access_pointer(server->addresses));
> kfree(server);
> @@ -487,7 +492,7 @@ static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
>
> active = atomic_read(&server->active);
> if (active == 0) {
> - trace_afs_server(server, atomic_read(&server->ref),
> + trace_afs_server(server, refcount_read(&server->ref),
> active, afs_server_trace_gc);
> next = rcu_dereference_protected(
> server->uuid_next, lockdep_is_held(&net->fs_lock.lock));
> @@ -553,7 +558,7 @@ void afs_manage_servers(struct work_struct *work)
> _debug("manage %pU %u", &server->uuid, active);
>
> if (purging) {
> - trace_afs_server(server, atomic_read(&server->ref),
> + trace_afs_server(server, refcount_read(&server->ref),
> active, afs_server_trace_purging);
> if (active != 0)
> pr_notice("Can't purge s=%08x\n", server->debug_id);
> @@ -633,7 +638,8 @@ static noinline bool afs_update_server_record(struct afs_operation *op,
>
> _enter("");
>
> - trace_afs_server(server, atomic_read(&server->ref), atomic_read(&server->active),
> + trace_afs_server(server, refcount_read(&server->ref),
> + atomic_read(&server->active),
> afs_server_trace_update);
>
> alist = afs_vl_lookup_addrs(op->volume->cell, op->key, &server->uuid);
> diff --git a/fs/afs/vl_list.c b/fs/afs/vl_list.c
> index 38b2ba1d9ec0..acc48216136a 100644
> --- a/fs/afs/vl_list.c
> +++ b/fs/afs/vl_list.c
> @@ -17,7 +17,7 @@ struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
> vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
> GFP_KERNEL);
> if (vlserver) {
> - atomic_set(&vlserver->usage, 1);
> + refcount_set(&vlserver->ref, 1);
> rwlock_init(&vlserver->lock);
> init_waitqueue_head(&vlserver->probe_wq);
> spin_lock_init(&vlserver->probe_lock);
> @@ -39,13 +39,9 @@ static void afs_vlserver_rcu(struct rcu_head *rcu)
>
> void afs_put_vlserver(struct afs_net *net, struct afs_vlserver *vlserver)
> {
> - if (vlserver) {
> - unsigned int u = atomic_dec_return(&vlserver->usage);
> - //_debug("VL PUT %p{%u}", vlserver, u);
> -
> - if (u == 0)
> - call_rcu(&vlserver->rcu, afs_vlserver_rcu);
> - }
> + if (vlserver &&
> + refcount_dec_and_test(&vlserver->ref))
> + call_rcu(&vlserver->rcu, afs_vlserver_rcu);
> }
>
> struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
> @@ -54,7 +50,7 @@ struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
>
> vllist = kzalloc(struct_size(vllist, servers, nr_servers), GFP_KERNEL);
> if (vllist) {
> - atomic_set(&vllist->usage, 1);
> + refcount_set(&vllist->ref, 1);
> rwlock_init(&vllist->lock);
> }
>
> @@ -64,10 +60,7 @@ struct afs_vlserver_list *afs_alloc_vlserver_list(unsigned int nr_servers)
> void afs_put_vlserverlist(struct afs_net *net, struct afs_vlserver_list *vllist)
> {
> if (vllist) {
> - unsigned int u = atomic_dec_return(&vllist->usage);
> -
> - //_debug("VLLS PUT %p{%u}", vllist, u);
> - if (u == 0) {
> + if (refcount_dec_and_test(&vllist->ref)) {
> int i;
>
> for (i = 0; i < vllist->nr_servers; i++) {
> diff --git a/fs/afs/volume.c b/fs/afs/volume.c
> index cc665cef0abe..f4937029dcd7 100644
> --- a/fs/afs/volume.c
> +++ b/fs/afs/volume.c
> @@ -52,7 +52,7 @@ static void afs_remove_volume_from_cell(struct afs_volume *volume)
> struct afs_cell *cell = volume->cell;
>
> if (!hlist_unhashed(&volume->proc_link)) {
> - trace_afs_volume(volume->vid, atomic_read(&volume->usage),
> + trace_afs_volume(volume->vid, refcount_read(&cell->ref),
> afs_volume_trace_remove);
> write_seqlock(&cell->volume_lock);
> hlist_del_rcu(&volume->proc_link);
> @@ -87,7 +87,7 @@ static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
> volume->type_force = params->force;
> volume->name_len = vldb->name_len;
>
> - atomic_set(&volume->usage, 1);
> + refcount_set(&volume->ref, 1);
> INIT_HLIST_NODE(&volume->proc_link);
> rwlock_init(&volume->servers_lock);
> rwlock_init(&volume->cb_v_break_lock);
> @@ -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_cell_trace_put_vol);
> - trace_afs_volume(volume->vid, atomic_read(&volume->usage),
> + trace_afs_volume(volume->vid, refcount_read(&volume->ref),
> afs_volume_trace_free);
> kfree_rcu(volume, rcu);
>
> @@ -242,8 +242,10 @@ struct afs_volume *afs_get_volume(struct afs_volume *volume,
> enum afs_volume_trace reason)
> {
> if (volume) {
> - int u = atomic_inc_return(&volume->usage);
> - trace_afs_volume(volume->vid, u, reason);
> + int r;
> +
> + __refcount_inc(&volume->ref, &r);
> + trace_afs_volume(volume->vid, r + 1, reason);
> }
> return volume;
> }
> @@ -257,9 +259,12 @@ void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
> {
> if (volume) {
> afs_volid_t vid = volume->vid;
> - int u = atomic_dec_return(&volume->usage);
> - trace_afs_volume(vid, u, reason);
> - if (u == 0)
> + bool zero;
> + int r;
> +
> + zero = __refcount_dec_and_test(&volume->ref, &r);
> + trace_afs_volume(vid, r - 1, reason);
> + if (zero)
> afs_destroy_volume(net, volume);
> }
> }
> diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
> index 499f5fabd20f..aa60f42a9763 100644
> --- a/include/trace/events/afs.h
> +++ b/include/trace/events/afs.h
> @@ -728,14 +728,14 @@ TRACE_EVENT(afs_cb_call,
>
> TRACE_EVENT(afs_call,
> TP_PROTO(struct afs_call *call, enum afs_call_trace op,
> - int usage, int outstanding, const void *where),
> + int ref, int outstanding, const void *where),
>
> - TP_ARGS(call, op, usage, outstanding, where),
> + TP_ARGS(call, op, ref, outstanding, where),
>
> TP_STRUCT__entry(
> __field(unsigned int, call )
> __field(int, op )
> - __field(int, usage )
> + __field(int, ref )
> __field(int, outstanding )
> __field(const void *, where )
> ),
> @@ -743,15 +743,15 @@ TRACE_EVENT(afs_call,
> TP_fast_assign(
> __entry->call = call->debug_id;
> __entry->op = op;
> - __entry->usage = usage;
> + __entry->ref = ref;
> __entry->outstanding = outstanding;
> __entry->where = where;
> ),
>
> - TP_printk("c=%08x %s u=%d o=%d sp=%pSR",
> + TP_printk("c=%08x %s r=%d o=%d sp=%pSR",
> __entry->call,
> __print_symbolic(__entry->op, afs_call_traces),
> - __entry->usage,
> + __entry->ref,
> __entry->outstanding,
> __entry->where)
> );
> @@ -1476,36 +1476,36 @@ TRACE_EVENT(afs_volume,
> __entry->reason = reason;
> ),
>
> - TP_printk("V=%llx %s u=%d",
> + TP_printk("V=%llx %s ur=%d",
> __entry->vid,
> __print_symbolic(__entry->reason, afs_volume_traces),
> __entry->ref)
> );
>
> TRACE_EVENT(afs_cell,
> - TP_PROTO(unsigned int cell_debug_id, int usage, int active,
> + TP_PROTO(unsigned int cell_debug_id, int ref, int active,
> enum afs_cell_trace reason),
>
> - TP_ARGS(cell_debug_id, usage, active, reason),
> + TP_ARGS(cell_debug_id, ref, active, reason),
>
> TP_STRUCT__entry(
> __field(unsigned int, cell )
> - __field(int, usage )
> + __field(int, ref )
> __field(int, active )
> __field(int, reason )
> ),
>
> TP_fast_assign(
> __entry->cell = cell_debug_id;
> - __entry->usage = usage;
> + __entry->ref = ref;
> __entry->active = active;
> __entry->reason = reason;
> ),
>
> - TP_printk("L=%08x %s u=%d a=%d",
> + TP_printk("L=%08x %s r=%d a=%d",
> __entry->cell,
> __print_symbolic(__entry->reason, afs_cell_traces),
> - __entry->usage,
> + __entry->ref,
> __entry->active)
> );
Reviewed-by: Marc Dionne <marc.dionne@...istor.com>
Marc
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