[PATCH v2 26/40] afs: Dispatch fileserver probes in priority order

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

When probing all the addresses for a fileserver, 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/fs_probe.c | 25 +++++++++++++++++++++++--
include/trace/events/afs.h | 33 +++++++++++++++++++++++++++++++++
2 files changed, 56 insertions(+), 2 deletions(-)

diff --git a/fs/afs/fs_probe.c b/fs/afs/fs_probe.c
index 8008d3ecabab..c5702698b18b 100644
--- a/fs/afs/fs_probe.c
+++ b/fs/afs/fs_probe.c
@@ -102,7 +102,7 @@ void afs_fileserver_probe_result(struct afs_call *call)
struct afs_address *addr = &alist->addrs[call->probe_index];
struct afs_server *server = call->server;
unsigned int index = call->probe_index;
- unsigned int rtt_us = 0, cap0;
+ unsigned int rtt_us = -1, cap0;
int ret = call->error;

_enter("%pU,%u", &server->uuid, index);
@@ -182,6 +182,7 @@ void afs_fileserver_probe_result(struct afs_call *call)
out:
spin_unlock(&server->probe_lock);

+ trace_afs_fs_probe(server, false, alist, index, call->error, call->abort_code, rtt_us);
_debug("probe %pU [%u] %pISpc rtt=%d ret=%d",
&server->uuid, index, rxrpc_kernel_remote_addr(alist->addrs[index].peer),
rtt_us, ret);
@@ -207,6 +208,8 @@ void afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
afs_get_addrlist(alist, afs_alist_trace_get_probe);
read_unlock(&server->fs_lock);

+ afs_get_address_preferences(net, alist);
+
server->probed_at = jiffies;
atomic_set(&server->probe_outstanding, all ? alist->nr_addrs : 1);
memset(&server->probe, 0, sizeof(server->probe));
@@ -217,10 +220,28 @@ void afs_fs_probe_fileserver(struct afs_net *net, struct afs_server *server,
all = true;

if (all) {
- for (index = 0; index < alist->nr_addrs; index++)
+ unsigned long unprobed = (1UL << alist->nr_addrs) - 1;
+ unsigned int i;
+ int best_prio;
+
+ 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_fs_probe(server, true, alist, index, 0, 0, 0);
if (!afs_fs_get_capabilities(net, server, alist, index, key))
afs_fs_probe_not_done(net, server, alist, index);
+ }
} else {
+ trace_afs_fs_probe(server, true, alist, index, 0, 0, 0);
if (!afs_fs_get_capabilities(net, server, alist, index, key))
afs_fs_probe_not_done(net, server, alist, index);
}
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 0f68d67f52c8..81eb87fbcfa7 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -1387,6 +1387,39 @@ TRACE_EVENT(afs_alist,
__entry->ref)
);

+TRACE_EVENT(afs_fs_probe,
+ TP_PROTO(struct afs_server *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(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("s=%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 */