zed: bump zfs_zevent_len_max if we miss any events

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #11834

diff --git a/cmd/zed/zed_event.c b/cmd/zed/zed_event.c
index 6d746b7b139a8d1ed43d74a95b29b54d4b96bcea..a2753ced0cdc90eb7e0bb39cf592c5d5e3670040 100644 (file)
--- a/cmd/zed/zed_event.c
+++ b/cmd/zed/zed_event.c
@@ -100,6 +100,45 @@ zed_event_fini(struct zed_conf *zcp)
        zed_exec_fini();
 }
 
+static void
+_bump_event_queue_length(void)
+{
+       int zzlm = -1, wr;
+       char qlen_buf[12] = {0}; /* parameter is int => max "-2147483647\n" */
+       long int qlen;
+
+       zzlm = open("/sys/module/zfs/parameters/zfs_zevent_len_max", O_RDWR);
+       if (zzlm < 0)
+               goto done;
+
+       if (read(zzlm, qlen_buf, sizeof (qlen_buf)) < 0)
+               goto done;
+       qlen_buf[sizeof (qlen_buf) - 1] = '\0';
+
+       errno = 0;
+       qlen = strtol(qlen_buf, NULL, 10);
+       if (errno == ERANGE)
+               goto done;
+
+       if (qlen <= 0)
+               qlen = 512; /* default zfs_zevent_len_max value */
+       else
+               qlen *= 2;
+
+       if (qlen > INT_MAX)
+               qlen = INT_MAX;
+       wr = snprintf(qlen_buf, sizeof (qlen_buf), "%ld", qlen);
+
+       if (pwrite(zzlm, qlen_buf, wr, 0) < 0)
+               goto done;
+
+       zed_log_msg(LOG_WARNING, "Bumping queue length to %ld", qlen);
+
+done:
+       if (zzlm > -1)
+               (void) close(zzlm);
+}
+
 /*
  * Seek to the event specified by [saved_eid] and [saved_etime].
  * This protects against processing a given event more than once.
@@ -138,10 +177,7 @@ zed_event_seek(struct zed_conf *zcp, uint64_t saved_eid, int64_t saved_etime[])
 
                if (n_dropped > 0) {
                        zed_log_msg(LOG_WARNING, "Missed %d events", n_dropped);
-                       /*
-                        * FIXME: Increase max size of event nvlist in
-                        *   /sys/module/zfs/parameters/zfs_zevent_len_max ?
-                        */
+                       _bump_event_queue_length();
                }
                if (nvlist_lookup_uint64(nvl, "eid", &eid) != 0) {
                        zed_log_msg(LOG_WARNING, "Failed to lookup zevent eid");
@@ -914,10 +950,7 @@ zed_event_service(struct zed_conf *zcp)
 
        if (n_dropped > 0) {
                zed_log_msg(LOG_WARNING, "Missed %d events", n_dropped);
-               /*
-                * FIXME: Increase max size of event nvlist in
-                * /sys/module/zfs/parameters/zfs_zevent_len_max ?
-                */
+               _bump_event_queue_length();
        }
        if (nvlist_lookup_uint64(nvl, "eid", &eid) != 0) {
                zed_log_msg(LOG_WARNING, "Failed to lookup zevent eid");