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fs: dlm: handle sequence numbers as atomic

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Currently seq_next is only be read on the receive side which processed
in an ordered way. The seq_send is being protected by locks. To being
able to read the seq_next value on send side as well we convert it to an
atomic_t value. The atomic_cmpxchg() is probably not necessary, however
the atomic_inc() depends on a if coniditional and this should be handled
in an atomic context.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
This commit is contained in:
Alexander Aring 2023-05-29 17:44:39 -04:00 committed by David Teigland
parent 75a7d60134
commit d00725cab2
1 changed files with 25 additions and 15 deletions
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40
fs/dlm/midcomms.c
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@ -152,8 +152,8 @@
struct midcomms_node {
int nodeid;
uint32_t version;
uint32_t seq_send;
uint32_t seq_next;
atomic_t seq_send;
atomic_t seq_next;
/* These queues are unbound because we cannot drop any message in dlm.
* We could send a fence signal for a specific node to the cluster
* manager if queues hits some maximum value, however this handling
@ -317,8 +317,8 @@ static void midcomms_node_reset(struct midcomms_node *node)
{
pr_debug("reset node %d\n", node->nodeid);
node->seq_next = DLM_SEQ_INIT;
node->seq_send = DLM_SEQ_INIT;
atomic_set(&node->seq_next, DLM_SEQ_INIT);
atomic_set(&node->seq_send, DLM_SEQ_INIT);
node->version = DLM_VERSION_NOT_SET;
node->flags = 0;
@ -492,9 +492,19 @@ static void dlm_midcomms_receive_buffer(union dlm_packet *p,
struct midcomms_node *node,
uint32_t seq)
{
if (seq == node->seq_next) {
node->seq_next++;
bool is_expected_seq;
uint32_t oval, nval;
do {
oval = atomic_read(&node->seq_next);
is_expected_seq = (oval == seq);
if (!is_expected_seq)
break;
nval = oval + 1;
} while (atomic_cmpxchg(&node->seq_next, oval, nval) != oval);
if (is_expected_seq) {
switch (p->header.h_cmd) {
case DLM_FIN:
spin_lock(&node->state_lock);
@ -503,7 +513,7 @@ static void dlm_midcomms_receive_buffer(union dlm_packet *p,
switch (node->state) {
case DLM_ESTABLISHED:
dlm_send_ack(node->nodeid, node->seq_next);
dlm_send_ack(node->nodeid, nval);
/* passive shutdown DLM_LAST_ACK case 1
* additional we check if the node is used by
@ -522,14 +532,14 @@ static void dlm_midcomms_receive_buffer(union dlm_packet *p,
}
break;
case DLM_FIN_WAIT1:
dlm_send_ack(node->nodeid, node->seq_next);
dlm_send_ack(node->nodeid, nval);
node->state = DLM_CLOSING;
set_bit(DLM_NODE_FLAG_STOP_RX, &node->flags);
pr_debug("switch node %d to state %s\n",
node->nodeid, dlm_state_str(node->state));
break;
case DLM_FIN_WAIT2:
dlm_send_ack(node->nodeid, node->seq_next);
dlm_send_ack(node->nodeid, nval);
midcomms_node_reset(node);
pr_debug("switch node %d to state %s\n",
node->nodeid, dlm_state_str(node->state));
@ -557,11 +567,11 @@ static void dlm_midcomms_receive_buffer(union dlm_packet *p,
/* retry to ack message which we already have by sending back
* current node->seq_next number as ack.
*/
if (seq < node->seq_next)
dlm_send_ack(node->nodeid, node->seq_next);
if (seq < oval)
dlm_send_ack(node->nodeid, oval);
log_print_ratelimited("ignore dlm msg because seq mismatch, seq: %u, expected: %u, nodeid: %d",
seq, node->seq_next, node->nodeid);
seq, oval, node->nodeid);
}
}
@ -992,7 +1002,7 @@ void dlm_midcomms_receive_done(int nodeid)
switch (node->state) {
case DLM_ESTABLISHED:
spin_unlock(&node->state_lock);
dlm_send_ack(node->nodeid, node->seq_next);
dlm_send_ack(node->nodeid, atomic_read(&node->seq_next));
break;
default:
spin_unlock(&node->state_lock);
@ -1058,7 +1068,7 @@ static void midcomms_new_msg_cb(void *data)
list_add_tail_rcu(&mh->list, &mh->node->send_queue);
spin_unlock_bh(&mh->node->send_queue_lock);
mh->seq = mh->node->seq_send++;
mh->seq = atomic_fetch_inc(&mh->node->seq_send);
}
static struct dlm_msg *dlm_midcomms_get_msg_3_2(struct dlm_mhandle *mh, int nodeid,
@ -1530,7 +1540,7 @@ static void midcomms_new_rawmsg_cb(void *data)
switch (h->h_cmd) {
case DLM_OPTS:
if (!h->u.h_seq)
h->u.h_seq = cpu_to_le32(rd->node->seq_send++);
h->u.h_seq = cpu_to_le32(atomic_fetch_inc(&rd->node->seq_send));
break;
default:
break;