afs: Split the usage count on struct afs_server
Split the usage count on the afs_server struct to have an active count that
registers who's actually using it separately from the reference count on
the object.
This allows a future patch to dispatch polling probes without advancing the
"unuse" time into the future each time we emit a probe, which would
otherwise prevent unused server records from expiring.
Included in this:
(1) The latter part of afs_destroy_server() in which the RCU destruction
of afs_server objects is invoked and the outstanding server count is
decremented is split out into __afs_put_server().
(2) afs_put_server() now calls __afs_put_server() rather then setting the
management timer.
(3) The calls begun by afs_fs_give_up_all_callbacks() and
afs_fs_get_capabilities() can now take a ref on the server record, so
afs_destroy_server() can just drop its ref and needn't wait for the
completion of these calls. They'll put the ref when they're done.
(4) Because of (3), afs_fs_probe_done() no longer needs to wake up
afs_destroy_server() with server->probe_outstanding.
(5) afs_gc_servers can be simplified. It only needs to check if
server->active is 0 rather than playing games with the refcount.
(6) afs_manage_servers() can propose a server for gc if usage == 0 rather
than if ref == 1. The gc is effected by (5).
Signed-off-by: David Howells <dhowells@redhat.com>
This commit is contained in:
David Howells
parent
8100680592
commit
977e5f8ed0
@ -268,7 +268,9 @@ static void SRXAFSCB_CallBack(struct work_struct *work)
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* to maintain cache coherency.
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*/
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if (call->server) {
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trace_afs_server(call->server, atomic_read(&call->server->usage),
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trace_afs_server(call->server,
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atomic_read(&call->server->ref),
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atomic_read(&call->server->active),
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afs_server_trace_callback);
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afs_break_callbacks(call->server, call->count, call->request);
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}
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@ -16,7 +16,6 @@ static bool afs_fs_probe_done(struct afs_server *server)
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if (!atomic_dec_and_test(&server->probe_outstanding))
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return false;
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wake_up_var(&server->probe_outstanding);
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clear_bit_unlock(AFS_SERVER_FL_PROBING, &server->flags);
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wake_up_bit(&server->flags, AFS_SERVER_FL_PROBING);
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return true;
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@ -1842,7 +1842,7 @@ int afs_fs_give_up_all_callbacks(struct afs_net *net,
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bp = call->request;
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*bp++ = htonl(FSGIVEUPALLCALLBACKS);
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/* Can't take a ref on server */
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call->server = afs_use_server(server, afs_server_trace_give_up_cb);
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afs_make_call(ac, call, GFP_NOFS);
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return afs_wait_for_call_to_complete(call, ac);
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}
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@ -1924,7 +1924,7 @@ struct afs_call *afs_fs_get_capabilities(struct afs_net *net,
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return ERR_PTR(-ENOMEM);
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call->key = key;
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call->server = afs_get_server(server, afs_server_trace_get_caps);
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call->server = afs_use_server(server, afs_server_trace_get_caps);
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call->server_index = server_index;
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call->upgrade = true;
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call->async = true;
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@ -1934,7 +1934,6 @@ struct afs_call *afs_fs_get_capabilities(struct afs_net *net,
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bp = call->request;
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*bp++ = htonl(FSGETCAPABILITIES);
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/* Can't take a ref on server */
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trace_afs_make_fs_call(call, NULL);
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afs_make_call(ac, call, GFP_NOFS);
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return call;
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@ -498,7 +498,7 @@ struct afs_server {
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struct hlist_node addr6_link; /* Link in net->fs_addresses6 */
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struct hlist_node proc_link; /* Link in net->fs_proc */
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struct afs_server *gc_next; /* Next server in manager's list */
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time64_t put_time; /* Time at which last put */
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time64_t unuse_time; /* Time at which last unused */
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unsigned long flags;
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#define AFS_SERVER_FL_NOT_READY 1 /* The record is not ready for use */
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#define AFS_SERVER_FL_NOT_FOUND 2 /* VL server says no such server */
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@ -512,7 +512,8 @@ struct afs_server {
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#define AFS_SERVER_FL_NO_RM2 10 /* Fileserver doesn't support YFS.RemoveFile2 */
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#define AFS_SERVER_FL_HAVE_EPOCH 11 /* ->epoch is valid */
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#define AFS_SERVER_FL_NEEDS_UPDATE 12 /* Fileserver address list is out of date */
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atomic_t usage;
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atomic_t ref; /* Object refcount */
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atomic_t active; /* Active user count */
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u32 addr_version; /* Address list version */
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u32 cm_epoch; /* Server RxRPC epoch */
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unsigned int debug_id; /* Debugging ID for traces */
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@ -1244,6 +1245,9 @@ extern struct afs_server *afs_find_server(struct afs_net *,
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extern struct afs_server *afs_find_server_by_uuid(struct afs_net *, const uuid_t *);
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extern struct afs_server *afs_lookup_server(struct afs_cell *, struct key *, const uuid_t *, u32);
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extern struct afs_server *afs_get_server(struct afs_server *, enum afs_server_trace);
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extern struct afs_server *afs_use_server(struct afs_server *, enum afs_server_trace);
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extern void afs_unuse_server(struct afs_net *, struct afs_server *, enum afs_server_trace);
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extern void afs_unuse_server_notime(struct afs_net *, struct afs_server *, enum afs_server_trace);
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extern void afs_put_server(struct afs_net *, struct afs_server *, enum afs_server_trace);
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extern void afs_manage_servers(struct work_struct *);
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extern void afs_servers_timer(struct timer_list *);
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@ -378,15 +378,16 @@ static int afs_proc_servers_show(struct seq_file *m, void *v)
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int i;
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if (v == SEQ_START_TOKEN) {
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seq_puts(m, "UUID USE ADDR\n");
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seq_puts(m, "UUID REF ACT ADDR\n");
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return 0;
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}
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server = list_entry(v, struct afs_server, proc_link);
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alist = rcu_dereference(server->addresses);
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seq_printf(m, "%pU %3d %pISpc%s\n",
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seq_printf(m, "%pU %3d %3d %pISpc%s\n",
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&server->uuid,
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atomic_read(&server->usage),
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atomic_read(&server->ref),
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atomic_read(&server->active),
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&alist->addrs[0].transport,
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alist->preferred == 0 ? "*" : "");
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for (i = 1; i < alist->nr_addrs; i++)
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@ -183,7 +183,7 @@ void afs_put_call(struct afs_call *call)
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if (call->type->destructor)
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call->type->destructor(call);
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afs_put_server(call->net, call->server, afs_server_trace_put_call);
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afs_unuse_server_notime(call->net, call->server, afs_server_trace_put_call);
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afs_put_cb_interest(call->net, call->cbi);
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afs_put_addrlist(call->alist);
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kfree(call->request);
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151
fs/afs/server.c
151
fs/afs/server.c
@ -25,6 +25,10 @@ static void afs_dec_servers_outstanding(struct afs_net *net)
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wake_up_var(&net->servers_outstanding);
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}
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static struct afs_server *afs_maybe_use_server(struct afs_server *,
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enum afs_server_trace);
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static void __afs_put_server(struct afs_net *, struct afs_server *);
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/*
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* Find a server by one of its addresses.
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*/
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@ -40,7 +44,7 @@ struct afs_server *afs_find_server(struct afs_net *net,
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do {
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if (server)
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afs_put_server(net, server, afs_server_trace_put_find_rsq);
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afs_unuse_server_notime(net, server, afs_server_trace_put_find_rsq);
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server = NULL;
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read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
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@ -78,9 +82,9 @@ struct afs_server *afs_find_server(struct afs_net *net,
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}
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server = NULL;
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continue;
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found:
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if (server && !atomic_inc_not_zero(&server->usage))
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server = NULL;
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server = afs_maybe_use_server(server, afs_server_trace_get_by_addr);
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} while (need_seqretry(&net->fs_addr_lock, seq));
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@ -91,7 +95,7 @@ struct afs_server *afs_find_server(struct afs_net *net,
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}
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/*
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* Look up a server by its UUID
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* Look up a server by its UUID and mark it active.
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*/
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struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uuid)
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{
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@ -107,7 +111,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
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* changes.
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*/
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if (server)
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afs_put_server(net, server, afs_server_trace_put_uuid_rsq);
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afs_unuse_server(net, server, afs_server_trace_put_uuid_rsq);
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server = NULL;
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read_seqbegin_or_lock(&net->fs_lock, &seq);
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@ -122,7 +126,7 @@ struct afs_server *afs_find_server_by_uuid(struct afs_net *net, const uuid_t *uu
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} else if (diff > 0) {
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p = p->rb_right;
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} else {
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afs_get_server(server, afs_server_trace_get_by_uuid);
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afs_use_server(server, afs_server_trace_get_by_uuid);
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break;
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}
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@ -198,7 +202,7 @@ exists:
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}
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/*
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* allocate a new server record
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* Allocate a new server record and mark it active.
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*/
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static struct afs_server *afs_alloc_server(struct afs_net *net,
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const uuid_t *uuid,
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@ -212,7 +216,8 @@ static struct afs_server *afs_alloc_server(struct afs_net *net,
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if (!server)
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goto enomem;
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atomic_set(&server->usage, 1);
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atomic_set(&server->ref, 1);
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atomic_set(&server->active, 1);
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server->debug_id = atomic_inc_return(&afs_server_debug_id);
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RCU_INIT_POINTER(server->addresses, alist);
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server->addr_version = alist->version;
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@ -224,7 +229,7 @@ static struct afs_server *afs_alloc_server(struct afs_net *net,
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spin_lock_init(&server->probe_lock);
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afs_inc_servers_outstanding(net);
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trace_afs_server(server, 1, afs_server_trace_alloc);
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trace_afs_server(server, 1, 1, afs_server_trace_alloc);
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_leave(" = %p", server);
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return server;
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@ -292,7 +297,6 @@ struct afs_server *afs_lookup_server(struct afs_cell *cell, struct key *key,
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kfree(candidate);
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}
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_leave(" = %p{%d}", server, atomic_read(&server->usage));
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return server;
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}
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@ -328,9 +332,38 @@ void afs_servers_timer(struct timer_list *timer)
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struct afs_server *afs_get_server(struct afs_server *server,
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enum afs_server_trace reason)
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{
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unsigned int u = atomic_inc_return(&server->usage);
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unsigned int u = atomic_inc_return(&server->ref);
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trace_afs_server(server, u, reason);
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trace_afs_server(server, u, atomic_read(&server->active), reason);
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return server;
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}
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/*
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* Try to get a reference on a server object.
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*/
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static struct afs_server *afs_maybe_use_server(struct afs_server *server,
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enum afs_server_trace reason)
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{
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unsigned int r = atomic_fetch_add_unless(&server->ref, 1, 0);
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unsigned int a;
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if (r == 0)
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return NULL;
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a = atomic_inc_return(&server->active);
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trace_afs_server(server, r, a, reason);
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return server;
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}
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/*
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* Get an active count on a server object.
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*/
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struct afs_server *afs_use_server(struct afs_server *server, enum afs_server_trace reason)
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{
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unsigned int r = atomic_inc_return(&server->ref);
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unsigned int a = atomic_inc_return(&server->active);
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trace_afs_server(server, r, a, reason);
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return server;
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}
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@ -345,28 +378,56 @@ void afs_put_server(struct afs_net *net, struct afs_server *server,
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if (!server)
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return;
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server->put_time = ktime_get_real_seconds();
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usage = atomic_dec_return(&server->ref);
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trace_afs_server(server, usage, atomic_read(&server->active), reason);
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if (unlikely(usage == 0))
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__afs_put_server(net, server);
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}
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usage = atomic_dec_return(&server->usage);
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trace_afs_server(server, usage, reason);
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if (likely(usage > 0))
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return;
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/*
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* Drop an active count on a server object without updating the last-unused
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* time.
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*/
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void afs_unuse_server_notime(struct afs_net *net, struct afs_server *server,
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enum afs_server_trace reason)
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{
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if (server) {
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unsigned int active = atomic_dec_return(&server->active);
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if (active == 0)
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afs_set_server_timer(net, afs_server_gc_delay);
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afs_put_server(net, server, reason);
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}
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}
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/*
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* Drop an active count on a server object.
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*/
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void afs_unuse_server(struct afs_net *net, struct afs_server *server,
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enum afs_server_trace reason)
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{
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if (server) {
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server->unuse_time = ktime_get_real_seconds();
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afs_unuse_server_notime(net, server, reason);
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}
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}
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static void afs_server_rcu(struct rcu_head *rcu)
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{
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struct afs_server *server = container_of(rcu, struct afs_server, rcu);
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trace_afs_server(server, atomic_read(&server->usage),
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afs_server_trace_free);
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trace_afs_server(server, atomic_read(&server->ref),
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atomic_read(&server->active), afs_server_trace_free);
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afs_put_addrlist(rcu_access_pointer(server->addresses));
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kfree(server);
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}
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static void __afs_put_server(struct afs_net *net, struct afs_server *server)
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{
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call_rcu(&server->rcu, afs_server_rcu);
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afs_dec_servers_outstanding(net);
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}
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/*
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* destroy a dead server
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*/
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@ -379,19 +440,10 @@ static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
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.error = 0,
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};
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trace_afs_server(server, atomic_read(&server->usage),
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afs_server_trace_give_up_cb);
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if (test_bit(AFS_SERVER_FL_MAY_HAVE_CB, &server->flags))
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afs_fs_give_up_all_callbacks(net, server, &ac, NULL);
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wait_var_event(&server->probe_outstanding,
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atomic_read(&server->probe_outstanding) == 0);
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trace_afs_server(server, atomic_read(&server->usage),
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afs_server_trace_destroy);
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call_rcu(&server->rcu, afs_server_rcu);
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afs_dec_servers_outstanding(net);
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afs_put_server(net, server, afs_server_trace_destroy);
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}
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/*
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@ -400,31 +452,28 @@ static void afs_destroy_server(struct afs_net *net, struct afs_server *server)
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static void afs_gc_servers(struct afs_net *net, struct afs_server *gc_list)
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{
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struct afs_server *server;
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bool deleted;
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int usage;
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int active;
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while ((server = gc_list)) {
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gc_list = server->gc_next;
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write_seqlock(&net->fs_lock);
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usage = 1;
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deleted = atomic_try_cmpxchg(&server->usage, &usage, 0);
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trace_afs_server(server, usage, afs_server_trace_gc);
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if (deleted) {
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active = atomic_read(&server->active);
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if (active == 0) {
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trace_afs_server(server, atomic_read(&server->ref),
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active, afs_server_trace_gc);
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rb_erase(&server->uuid_rb, &net->fs_servers);
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hlist_del_rcu(&server->proc_link);
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}
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write_sequnlock(&net->fs_lock);
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if (deleted) {
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write_seqlock(&net->fs_addr_lock);
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if (!hlist_unhashed(&server->addr4_link))
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hlist_del_rcu(&server->addr4_link);
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if (!hlist_unhashed(&server->addr6_link))
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hlist_del_rcu(&server->addr6_link);
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write_sequnlock(&net->fs_addr_lock);
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afs_destroy_server(net, server);
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}
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write_sequnlock(&net->fs_lock);
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if (active == 0)
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afs_destroy_server(net, server);
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}
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}
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@ -453,15 +502,14 @@ void afs_manage_servers(struct work_struct *work)
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for (cursor = rb_first(&net->fs_servers); cursor; cursor = rb_next(cursor)) {
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struct afs_server *server =
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rb_entry(cursor, struct afs_server, uuid_rb);
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int usage = atomic_read(&server->usage);
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int active = atomic_read(&server->active);
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_debug("manage %pU %u", &server->uuid, usage);
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_debug("manage %pU %u", &server->uuid, active);
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ASSERTCMP(usage, >=, 1);
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ASSERTIFCMP(purging, usage, ==, 1);
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ASSERTIFCMP(purging, active, ==, 0);
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if (usage == 1) {
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time64_t expire_at = server->put_time;
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if (active == 0) {
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time64_t expire_at = server->unuse_time;
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if (!test_bit(AFS_SERVER_FL_VL_FAIL, &server->flags) &&
|
||||
!test_bit(AFS_SERVER_FL_NOT_FOUND, &server->flags))
|
||||
@ -532,7 +580,8 @@ static noinline bool afs_update_server_record(struct afs_fs_cursor *fc, struct a
|
||||
|
||||
_enter("");
|
||||
|
||||
trace_afs_server(server, atomic_read(&server->usage), afs_server_trace_update);
|
||||
trace_afs_server(server, atomic_read(&server->ref), atomic_read(&server->active),
|
||||
afs_server_trace_update);
|
||||
|
||||
alist = afs_vl_lookup_addrs(fc->vnode->volume->cell, fc->key,
|
||||
&server->uuid);
|
||||
|
||||
@ -16,7 +16,7 @@ void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
|
||||
if (slist && refcount_dec_and_test(&slist->usage)) {
|
||||
for (i = 0; i < slist->nr_servers; i++) {
|
||||
afs_put_cb_interest(net, slist->servers[i].cb_interest);
|
||||
afs_put_server(net, slist->servers[i].server,
|
||||
afs_unuse_server(net, slist->servers[i].server,
|
||||
afs_server_trace_put_slist);
|
||||
}
|
||||
kfree(slist);
|
||||
|
||||
@ -33,6 +33,7 @@ enum afs_server_trace {
|
||||
afs_server_trace_destroy,
|
||||
afs_server_trace_free,
|
||||
afs_server_trace_gc,
|
||||
afs_server_trace_get_by_addr,
|
||||
afs_server_trace_get_by_uuid,
|
||||
afs_server_trace_get_caps,
|
||||
afs_server_trace_get_install,
|
||||
@ -241,6 +242,7 @@ enum afs_cb_break_reason {
|
||||
EM(afs_server_trace_destroy, "DESTROY ") \
|
||||
EM(afs_server_trace_free, "FREE ") \
|
||||
EM(afs_server_trace_gc, "GC ") \
|
||||
EM(afs_server_trace_get_by_addr, "GET addr ") \
|
||||
EM(afs_server_trace_get_by_uuid, "GET uuid ") \
|
||||
EM(afs_server_trace_get_caps, "GET caps ") \
|
||||
EM(afs_server_trace_get_install, "GET inst ") \
|
||||
@ -1271,26 +1273,30 @@ TRACE_EVENT(afs_cb_miss,
|
||||
);
|
||||
|
||||
TRACE_EVENT(afs_server,
|
||||
TP_PROTO(struct afs_server *server, int usage, enum afs_server_trace reason),
|
||||
TP_PROTO(struct afs_server *server, int ref, int active,
|
||||
enum afs_server_trace reason),
|
||||
|
||||
TP_ARGS(server, usage, reason),
|
||||
TP_ARGS(server, ref, active, reason),
|
||||
|
||||
TP_STRUCT__entry(
|
||||
__field(unsigned int, server )
|
||||
__field(int, usage )
|
||||
__field(int, ref )
|
||||
__field(int, active )
|
||||
__field(int, reason )
|
||||
),
|
||||
|
||||
TP_fast_assign(
|
||||
__entry->server = server->debug_id;
|
||||
__entry->usage = usage;
|
||||
__entry->ref = ref;
|
||||
__entry->active = active;
|
||||
__entry->reason = reason;
|
||||
),
|
||||
|
||||
TP_printk("s=%08x %s u=%d",
|
||||
TP_printk("s=%08x %s u=%d a=%d",
|
||||
__entry->server,
|
||||
__print_symbolic(__entry->reason, afs_server_traces),
|
||||
__entry->usage)
|
||||
__entry->ref,
|
||||
__entry->active)
|
||||
);
|
||||
|
||||
#endif /* _TRACE_AFS_H */
|
||||
|
||||
Loading…
Reference in New Issue
Block a user