From b95b30940ee46a4d892ca3de3ffb8249c4985b1f Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 19 Aug 2020 15:27:17 +0100 Subject: [PATCH] afs: Don't use VL probe running state to make decisions outside probe code Don't use the running state for VL server probes to make decisions about which server to use as the state is cleared at the start of a probe and intermediate values might also be misleading. Instead, add a separate 'latest known' rtt in the afs_vlserver struct and a flag to indicate if the server is known to be responding and update these as and when we know what to change them to. Fixes: 3bf0fb6f33dd ("afs: Probe multiple fileservers simultaneously") Signed-off-by: David Howells --- fs/afs/internal.h | 4 +++- fs/afs/proc.c | 2 +- fs/afs/vl_list.c | 1 + fs/afs/vl_probe.c | 57 ++++++++++++++++++++++++++++++++++++++---------------- fs/afs/vl_rotate.c | 2 +- 5 files changed, 46 insertions(+), 20 deletions(-) diff --git a/fs/afs/internal.h b/fs/afs/internal.h index b29dfcf..18042b7 100644 --- a/fs/afs/internal.h +++ b/fs/afs/internal.h @@ -401,15 +401,17 @@ struct afs_vlserver { #define AFS_VLSERVER_FL_PROBED 0 /* The VL server has been probed */ #define AFS_VLSERVER_FL_PROBING 1 /* VL server is being probed */ #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; + unsigned int rtt; /* Server's current RTT in uS */ /* Probe state */ wait_queue_head_t probe_wq; atomic_t probe_outstanding; spinlock_t probe_lock; struct { - unsigned int rtt; /* RTT as ktime/64 */ + unsigned int rtt; /* RTT in uS */ u32 abort_code; short error; unsigned short flags; diff --git a/fs/afs/proc.c b/fs/afs/proc.c index 5e83715..e8babb6 100644 --- a/fs/afs/proc.c +++ b/fs/afs/proc.c @@ -310,7 +310,7 @@ static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v) alist->preferred == i ? '>' : '-', &alist->addrs[i].transport); } - seq_printf(m, " info: fl=%lx rtt=%d\n", vlserver->flags, vlserver->probe.rtt); + seq_printf(m, " info: fl=%lx rtt=%d\n", vlserver->flags, vlserver->rtt); seq_printf(m, " probe: fl=%x e=%d ac=%d out=%d\n", vlserver->probe.flags, vlserver->probe.error, vlserver->probe.abort_code, diff --git a/fs/afs/vl_list.c b/fs/afs/vl_list.c index 8fea54e..38b2ba1d 100644 --- a/fs/afs/vl_list.c +++ b/fs/afs/vl_list.c @@ -21,6 +21,7 @@ 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->rtt = UINT_MAX; vlserver->name_len = name_len; vlserver->port = port; memcpy(vlserver->name, name, name_len); diff --git a/fs/afs/vl_probe.c b/fs/afs/vl_probe.c index a6d04b4..d1c7068 100644 --- a/fs/afs/vl_probe.c +++ b/fs/afs/vl_probe.c @@ -11,15 +11,33 @@ #include "internal.h" #include "protocol_yfs.h" -static bool afs_vl_probe_done(struct afs_vlserver *server) + +/* + * Handle the completion of a set of probes. + */ +static void afs_finished_vl_probe(struct afs_vlserver *server) { - if (!atomic_dec_and_test(&server->probe_outstanding)) - return false; + if (!(server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) { + server->rtt = UINT_MAX; + clear_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags); + } - wake_up_var(&server->probe_outstanding); clear_bit_unlock(AFS_VLSERVER_FL_PROBING, &server->flags); wake_up_bit(&server->flags, AFS_VLSERVER_FL_PROBING); - return true; +} + +/* + * Handle the completion of a probe RPC call. + */ +static void afs_done_one_vl_probe(struct afs_vlserver *server, bool wake_up) +{ + if (atomic_dec_and_test(&server->probe_outstanding)) { + afs_finished_vl_probe(server); + wake_up = true; + } + + if (wake_up) + wake_up_all(&server->probe_wq); } /* @@ -52,8 +70,13 @@ void afs_vlserver_probe_result(struct afs_call *call) goto responded; case -ENOMEM: case -ENONET: + case -EKEYEXPIRED: + case -EKEYREVOKED: + case -EKEYREJECTED: server->probe.flags |= AFS_VLSERVER_PROBE_LOCAL_FAILURE; - afs_io_error(call, afs_io_error_vl_probe_fail); + if (server->probe.error == 0) + server->probe.error = ret; + trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail); goto out; case -ECONNRESET: /* Responded, but call expired. */ case -ERFKILL: @@ -72,7 +95,7 @@ void afs_vlserver_probe_result(struct afs_call *call) server->probe.error == -ETIMEDOUT || server->probe.error == -ETIME)) server->probe.error = ret; - afs_io_error(call, afs_io_error_vl_probe_fail); + trace_afs_io_error(call->debug_id, ret, afs_io_error_vl_probe_fail); goto out; } @@ -95,22 +118,22 @@ responded: if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) && rtt_us < server->probe.rtt) { server->probe.rtt = rtt_us; + server->rtt = rtt_us; alist->preferred = index; - have_result = true; } smp_wmb(); /* Set rtt before responded. */ server->probe.flags |= AFS_VLSERVER_PROBE_RESPONDED; set_bit(AFS_VLSERVER_FL_PROBED, &server->flags); + set_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags); + have_result = true; out: spin_unlock(&server->probe_lock); _debug("probe [%u][%u] %pISpc rtt=%u ret=%d", server_index, index, &alist->addrs[index].transport, rtt_us, ret); - have_result |= afs_vl_probe_done(server); - if (have_result) - wake_up_all(&server->probe_wq); + afs_done_one_vl_probe(server, have_result); } /* @@ -148,11 +171,10 @@ static bool afs_do_probe_vlserver(struct afs_net *net, in_progress = true; } else { afs_prioritise_error(_e, PTR_ERR(call), ac.abort_code); + afs_done_one_vl_probe(server, false); } } - if (!in_progress) - afs_vl_probe_done(server); return in_progress; } @@ -190,7 +212,7 @@ int afs_wait_for_vl_probes(struct afs_vlserver_list *vllist, { struct wait_queue_entry *waits; struct afs_vlserver *server; - unsigned int rtt = UINT_MAX; + unsigned int rtt = UINT_MAX, rtt_s; bool have_responders = false; int pref = -1, i; @@ -246,10 +268,11 @@ stop: for (i = 0; i < vllist->nr_servers; i++) { if (test_bit(i, &untried)) { server = vllist->servers[i].server; - if ((server->probe.flags & AFS_VLSERVER_PROBE_RESPONDED) && - server->probe.rtt < rtt) { + rtt_s = READ_ONCE(server->rtt); + if (test_bit(AFS_VLSERVER_FL_RESPONDING, &server->flags) && + rtt_s < rtt) { pref = i; - rtt = server->probe.rtt; + rtt = rtt_s; } remove_wait_queue(&server->probe_wq, &waits[i]); diff --git a/fs/afs/vl_rotate.c b/fs/afs/vl_rotate.c index ed2609e..ab2beb4 100644 --- a/fs/afs/vl_rotate.c +++ b/fs/afs/vl_rotate.c @@ -193,7 +193,7 @@ pick_server: struct afs_vlserver *s = vc->server_list->servers[i].server; if (!test_bit(i, &vc->untried) || - !(s->probe.flags & AFS_VLSERVER_PROBE_RESPONDED)) + !test_bit(AFS_VLSERVER_FL_RESPONDING, &s->flags)) continue; if (s->probe.rtt < rtt) { vc->index = i; -- 2.7.4