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Subject[PATCH 2/4] dlm: delayed reply message warning
Date
Add an option (disabled by default) to print a warning message
when a lock has been waiting a configurable amount of time for
a reply message from another node. This is mainly for debugging.

Signed-off-by: David Teigland <teigland@redhat.com>
---
fs/dlm/config.c | 9 ++++-
fs/dlm/config.h | 1 +
fs/dlm/dlm_internal.h | 2 +
fs/dlm/lock.c | 100 +++++++++++++++++++++++++++++++++++++++++++++---
fs/dlm/lock.h | 1 +
fs/dlm/lockspace.c | 6 +-
6 files changed, 108 insertions(+), 11 deletions(-)

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 0d329ff..9b026ea 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -100,6 +100,7 @@ struct dlm_cluster {
unsigned int cl_log_debug;
unsigned int cl_protocol;
unsigned int cl_timewarn_cs;
+ unsigned int cl_waitwarn_us;
};

enum {
@@ -114,6 +115,7 @@ enum {
CLUSTER_ATTR_LOG_DEBUG,
CLUSTER_ATTR_PROTOCOL,
CLUSTER_ATTR_TIMEWARN_CS,
+ CLUSTER_ATTR_WAITWARN_US,
};

struct cluster_attribute {
@@ -166,6 +168,7 @@ CLUSTER_ATTR(scan_secs, 1);
CLUSTER_ATTR(log_debug, 0);
CLUSTER_ATTR(protocol, 0);
CLUSTER_ATTR(timewarn_cs, 1);
+CLUSTER_ATTR(waitwarn_us, 0);

static struct configfs_attribute *cluster_attrs[] = {
[CLUSTER_ATTR_TCP_PORT] = &cluster_attr_tcp_port.attr,
@@ -179,6 +182,7 @@ static struct configfs_attribute *cluster_attrs[] = {
[CLUSTER_ATTR_LOG_DEBUG] = &cluster_attr_log_debug.attr,
[CLUSTER_ATTR_PROTOCOL] = &cluster_attr_protocol.attr,
[CLUSTER_ATTR_TIMEWARN_CS] = &cluster_attr_timewarn_cs.attr,
+ [CLUSTER_ATTR_WAITWARN_US] = &cluster_attr_waitwarn_us.attr,
NULL,
};

@@ -439,6 +443,7 @@ static struct config_group *make_cluster(struct config_group *g,
cl->cl_log_debug = dlm_config.ci_log_debug;
cl->cl_protocol = dlm_config.ci_protocol;
cl->cl_timewarn_cs = dlm_config.ci_timewarn_cs;
+ cl->cl_waitwarn_us = dlm_config.ci_waitwarn_us;

space_list = &sps->ss_group;
comm_list = &cms->cs_group;
@@ -986,6 +991,7 @@ int dlm_our_addr(struct sockaddr_storage *addr, int num)
#define DEFAULT_LOG_DEBUG 0
#define DEFAULT_PROTOCOL 0
#define DEFAULT_TIMEWARN_CS 500 /* 5 sec = 500 centiseconds */
+#define DEFAULT_WAITWARN_US 0

struct dlm_config_info dlm_config = {
.ci_tcp_port = DEFAULT_TCP_PORT,
@@ -998,6 +1004,7 @@ struct dlm_config_info dlm_config = {
.ci_scan_secs = DEFAULT_SCAN_SECS,
.ci_log_debug = DEFAULT_LOG_DEBUG,
.ci_protocol = DEFAULT_PROTOCOL,
- .ci_timewarn_cs = DEFAULT_TIMEWARN_CS
+ .ci_timewarn_cs = DEFAULT_TIMEWARN_CS,
+ .ci_waitwarn_us = DEFAULT_WAITWARN_US
};

diff --git a/fs/dlm/config.h b/fs/dlm/config.h
index 4f1d6fc..dd0ce24 100644
--- a/fs/dlm/config.h
+++ b/fs/dlm/config.h
@@ -28,6 +28,7 @@ struct dlm_config_info {
int ci_log_debug;
int ci_protocol;
int ci_timewarn_cs;
+ int ci_waitwarn_us;
};

extern struct dlm_config_info dlm_config;
diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index b942049..6a92478 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -245,6 +245,7 @@ struct dlm_lkb {

int8_t lkb_wait_type; /* type of reply waiting for */
int8_t lkb_wait_count;
+ int lkb_wait_nodeid; /* for debugging */

struct list_head lkb_idtbl_list; /* lockspace lkbtbl */
struct list_head lkb_statequeue; /* rsb g/c/w list */
@@ -254,6 +255,7 @@ struct dlm_lkb {
struct list_head lkb_ownqueue; /* list of locks for a process */
struct list_head lkb_time_list;
ktime_t lkb_timestamp;
+ ktime_t lkb_wait_time;
unsigned long lkb_timeout_cs;

struct dlm_callback lkb_callbacks[DLM_CALLBACKS_SIZE];
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 04b8c44..e3c8641 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -799,10 +799,84 @@ static int msg_reply_type(int mstype)
return -1;
}

+static int nodeid_warned(int nodeid, int num_nodes, int *warned)
+{
+ int i;
+
+ for (i = 0; i < num_nodes; i++) {
+ if (!warned[i]) {
+ warned[i] = nodeid;
+ return 0;
+ }
+ if (warned[i] == nodeid)
+ return 1;
+ }
+ return 0;
+}
+
+void dlm_scan_waiters(struct dlm_ls *ls)
+{
+ struct dlm_lkb *lkb;
+ ktime_t zero = ktime_set(0, 0);
+ s64 us;
+ s64 debug_maxus = 0;
+ u32 debug_scanned = 0;
+ u32 debug_expired = 0;
+ int num_nodes = 0;
+ int *warned = NULL;
+
+ if (!dlm_config.ci_waitwarn_us)
+ return;
+
+ mutex_lock(&ls->ls_waiters_mutex);
+
+ list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
+ if (ktime_equal(lkb->lkb_wait_time, zero))
+ continue;
+
+ debug_scanned++;
+
+ us = ktime_to_us(ktime_sub(ktime_get(), lkb->lkb_wait_time));
+
+ if (us < dlm_config.ci_waitwarn_us)
+ continue;
+
+ lkb->lkb_wait_time = zero;
+
+ debug_expired++;
+ if (us > debug_maxus)
+ debug_maxus = us;
+
+ if (!num_nodes) {
+ num_nodes = ls->ls_num_nodes;
+ warned = kmalloc(GFP_KERNEL, num_nodes * sizeof(int));
+ if (warned)
+ memset(warned, 0, num_nodes * sizeof(int));
+ }
+ if (!warned)
+ continue;
+ if (nodeid_warned(lkb->lkb_wait_nodeid, num_nodes, warned))
+ continue;
+
+ log_error(ls, "waitwarn %x %lld %d us check connection to "
+ "node %d", lkb->lkb_id, (long long)us,
+ dlm_config.ci_waitwarn_us, lkb->lkb_wait_nodeid);
+ }
+ mutex_unlock(&ls->ls_waiters_mutex);
+
+ if (warned)
+ kfree(warned);
+
+ if (debug_expired)
+ log_debug(ls, "scan_waiters %u warn %u over %d us max %lld us",
+ debug_scanned, debug_expired,
+ dlm_config.ci_waitwarn_us, (long long)debug_maxus);
+}
+
/* add/remove lkb from global waiters list of lkb's waiting for
a reply from a remote node */

-static int add_to_waiters(struct dlm_lkb *lkb, int mstype)
+static int add_to_waiters(struct dlm_lkb *lkb, int mstype, int to_nodeid)
{
struct dlm_ls *ls = lkb->lkb_resource->res_ls;
int error = 0;
@@ -842,6 +916,8 @@ static int add_to_waiters(struct dlm_lkb *lkb, int mstype)

lkb->lkb_wait_count++;
lkb->lkb_wait_type = mstype;
+ lkb->lkb_wait_time = ktime_get();
+ lkb->lkb_wait_nodeid = to_nodeid; /* for debugging */
hold_lkb(lkb);
list_add(&lkb->lkb_wait_reply, &ls->ls_waiters);
out:
@@ -1157,6 +1233,16 @@ void dlm_adjust_timeouts(struct dlm_ls *ls)
list_for_each_entry(lkb, &ls->ls_timeout, lkb_time_list)
lkb->lkb_timestamp = ktime_add_us(lkb->lkb_timestamp, adj_us);
mutex_unlock(&ls->ls_timeout_mutex);
+
+ if (!dlm_config.ci_waitwarn_us)
+ return;
+
+ mutex_lock(&ls->ls_waiters_mutex);
+ list_for_each_entry(lkb, &ls->ls_waiters, lkb_wait_reply) {
+ if (ktime_to_us(lkb->lkb_wait_time))
+ lkb->lkb_wait_time = ktime_get();
+ }
+ mutex_unlock(&ls->ls_waiters_mutex);
}

/* lkb is master or local copy */
@@ -2844,12 +2930,12 @@ static int send_common(struct dlm_rsb *r, struct dlm_lkb *lkb, int mstype)
struct dlm_mhandle *mh;
int to_nodeid, error;

- error = add_to_waiters(lkb, mstype);
+ to_nodeid = r->res_nodeid;
+
+ error = add_to_waiters(lkb, mstype, to_nodeid);
if (error)
return error;

- to_nodeid = r->res_nodeid;
-
error = create_message(r, lkb, to_nodeid, mstype, &ms, &mh);
if (error)
goto fail;
@@ -2951,12 +3037,12 @@ static int send_lookup(struct dlm_rsb *r, struct dlm_lkb *lkb)
struct dlm_mhandle *mh;
int to_nodeid, error;

- error = add_to_waiters(lkb, DLM_MSG_LOOKUP);
+ to_nodeid = dlm_dir_nodeid(r);
+
+ error = add_to_waiters(lkb, DLM_MSG_LOOKUP, to_nodeid);
if (error)
return error;

- to_nodeid = dlm_dir_nodeid(r);
-
error = create_message(r, NULL, to_nodeid, DLM_MSG_LOOKUP, &ms, &mh);
if (error)
goto fail;
diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index 88e93c8..265017a 100644
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -24,6 +24,7 @@ int dlm_put_lkb(struct dlm_lkb *lkb);
void dlm_scan_rsbs(struct dlm_ls *ls);
int dlm_lock_recovery_try(struct dlm_ls *ls);
void dlm_unlock_recovery(struct dlm_ls *ls);
+void dlm_scan_waiters(struct dlm_ls *ls);
void dlm_scan_timeout(struct dlm_ls *ls);
void dlm_adjust_timeouts(struct dlm_ls *ls);

diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index f994a7d..14cbf40 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -243,7 +243,6 @@ static struct dlm_ls *find_ls_to_scan(void)
static int dlm_scand(void *data)
{
struct dlm_ls *ls;
- int timeout_jiffies = dlm_config.ci_scan_secs * HZ;

while (!kthread_should_stop()) {
ls = find_ls_to_scan();
@@ -252,13 +251,14 @@ static int dlm_scand(void *data)
ls->ls_scan_time = jiffies;
dlm_scan_rsbs(ls);
dlm_scan_timeout(ls);
+ dlm_scan_waiters(ls);
dlm_unlock_recovery(ls);
} else {
ls->ls_scan_time += HZ;
}
- } else {
- schedule_timeout_interruptible(timeout_jiffies);
+ continue;
}
+ schedule_timeout_interruptible(dlm_config.ci_scan_secs * HZ);
}
return 0;
}
--
1.7.1.1


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