[PATCH v2 27/40] afs: Dispatch vlserver probes in priority order

David Howells
2023-12-13T13:50:52Z

When probing all the addresses for a volume location server, dispatch them
in order of descending priority to try and get back highest priority one
first.

Also add a tracepoint to show the transmission and completion of the
probes.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
---
fs/afs/internal.h | 1 +
fs/afs/vl_list.c | 2 ++
fs/afs/vl_probe.c | 20 ++++++++++++++++++--
include/trace/events/afs.h | 34 ++++++++++++++++++++++++++++++++++
4 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 9a1e151e77e7..88db04220773 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -447,6 +447,7 @@ struct afs_vlserver {
rwlock_t lock; /* Lock on addresses */
refcount_t ref;
unsigned int rtt; /* Server's current RTT in uS */
+ unsigned int debug_id;

/* Probe state */
wait_queue_head_t probe_wq;
diff --git a/fs/afs/vl_list.c b/fs/afs/vl_list.c
index 5c4cd71caccf..9b1c20daac53 100644
--- a/fs/afs/vl_list.c
+++ b/fs/afs/vl_list.c
@@ -13,6 +13,7 @@ struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
unsigned short port)
{
struct afs_vlserver *vlserver;
+ static atomic_t debug_ids;

vlserver = kzalloc(struct_size(vlserver, name, name_len + 1),
GFP_KERNEL);
@@ -21,6 +22,7 @@ struct afs_vlserver *afs_alloc_vlserver(const char *name, size_t name_len,
rwlock_init(&vlserver->lock);
init_waitqueue_head(&vlserver->probe_wq);
spin_lock_init(&vlserver->probe_lock);
+ vlserver->debug_id = atomic_inc_return(&debug_ids);
vlserver->rtt = UINT_MAX;
vlserver->name_len = name_len;
vlserver->service_id = VL_SERVICE;
diff --git a/fs/afs/vl_probe.c b/fs/afs/vl_probe.c
index f868ae5d40e5..b128dc3d8af7 100644
--- a/fs/afs/vl_probe.c
+++ b/fs/afs/vl_probe.c
@@ -131,6 +131,7 @@ void afs_vlserver_probe_result(struct afs_call *call)
out:
spin_unlock(&server->probe_lock);

+ trace_afs_vl_probe(server, false, alist, index, call->error, call->abort_code, rtt_us);
_debug("probe [%u][%u] %pISpc rtt=%d ret=%d",
server_index, index, rxrpc_kernel_remote_addr(addr->peer),
rtt_us, ret);
@@ -150,8 +151,10 @@ static bool afs_do_probe_vlserver(struct afs_net *net,
{
struct afs_addr_list *alist;
struct afs_call *call;
- unsigned int index;
+ unsigned long unprobed;
+ unsigned int index, i;
bool in_progress = false;
+ int best_prio;

_enter("%s", server->name);

@@ -165,7 +168,20 @@ static bool afs_do_probe_vlserver(struct afs_net *net,
memset(&server->probe, 0, sizeof(server->probe));
server->probe.rtt = UINT_MAX;

- for (index = 0; index < alist->nr_addrs; index++) {
+ unprobed = (1UL << alist->nr_addrs) - 1;
+ while (unprobed) {
+ best_prio = -1;
+ index = 0;
+ for (i = 0; i < alist->nr_addrs; i++) {
+ if (test_bit(i, &unprobed) &&
+ alist->addrs[i].prio > best_prio) {
+ index = i;
+ best_prio = alist->addrs[i].prio;
+ }
+ }
+ __clear_bit(index, &unprobed);
+
+ trace_afs_vl_probe(server, true, alist, index, 0, 0, 0);
call = afs_vl_get_capabilities(net, alist, index, key, server,
server_index);
if (!IS_ERR(call)) {
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 81eb87fbcfa7..f1815b3dafb0 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -1420,6 +1420,40 @@ TRACE_EVENT(afs_fs_probe,
&__entry->srx.transport)
);

+TRACE_EVENT(afs_vl_probe,
+ TP_PROTO(struct afs_vlserver *server, bool tx, struct afs_addr_list *alist,
+ unsigned int addr_index, int error, s32 abort_code, unsigned int rtt_us),
+
+ TP_ARGS(server, tx, alist, addr_index, error, abort_code, rtt_us),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, server)
+ __field(bool, tx)
+ __field(unsigned short, flags)
+ __field(u16, addr_index)
+ __field(short, error)
+ __field(s32, abort_code)
+ __field(unsigned int, rtt_us)
+ __field_struct(struct sockaddr_rxrpc, srx)
+ ),
+
+ TP_fast_assign(
+ __entry->server = server->debug_id;
+ __entry->tx = tx;
+ __entry->addr_index = addr_index;
+ __entry->error = error;
+ __entry->abort_code = abort_code;
+ __entry->rtt_us = rtt_us;
+ memcpy(&__entry->srx, rxrpc_kernel_remote_srx(alist->addrs[addr_index].peer),
+ sizeof(__entry->srx));
+ ),
+
+ TP_printk("vl=%08x %s ax=%u e=%d ac=%d rtt=%d %pISpc",
+ __entry->server, __entry->tx ? "tx" : "rx", __entry->addr_index,
+ __entry->error, __entry->abort_code, __entry->rtt_us,
+ &__entry->srx.transport)
+ );
+
#endif /* _TRACE_AFS_H */

/* This part must be outside protection */