[PATCH 14/35] monitor: implement handling of fc_udev_device

[mwilck at suse.com]

From: Martin Wilck <mwilck at suse.com>

The reason we fork off discovery tasks is two-fold: Firstly, we'd
otherwise be forced to make all discovery connections sequentially,
which would be slow, as connecting controllers can block on
the order of seconds even in successful cases.

Secondly, this allows us to use the some static variables like
cfg and tracked_ctrls in the discovery code path. Without forking,
we'd have to re-write much more code in fabrics.c. In general,
the alternative to forking would be creating threads, but the
that would probably require a large rewrite of our code base.

A single-threaded server that forks off the actual discovery makes
most sense at this point.

Signed-off-by: Martin Wilck <mwilck at suse.com>
---
 monitor.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 107 insertions(+), 3 deletions(-)

diff --git a/monitor.c b/monitor.c
index 2a906db..6547265 100644
--- a/monitor.c
+++ b/monitor.c
@@ -30,7 +30,9 @@
 
 #include "common.h"
 #include "nvme-status.h"
+#include "nvme.h"
 #include "util/argconfig.h"
+#include "fabrics.h"
 #include "monitor.h"
 #define LOG_FUNCNAME 1
 #include "log.h"
@@ -117,11 +119,113 @@ static int monitor_init_signals(void)
 	return 0;
 }
 
+static int monitor_get_fc_uev_props(struct udev_device *ud,
+				    char *traddr, size_t tra_sz,
+				    char *host_traddr, size_t htra_sz)
+{
+	const char *sysname = udev_device_get_sysname(ud);
+	const char *tra = NULL, *host_tra = NULL;
+	bool fc_event_seen = false;
+	struct udev_list_entry *entry;
+
+	entry = udev_device_get_properties_list_entry(ud);
+	if (!entry) {
+		log(LOG_NOTICE, "%s: emtpy properties list\n", sysname);
+		return -ENOENT;
+	}
+
+	for (; entry; entry = udev_list_entry_get_next(entry)) {
+		const char *name = udev_list_entry_get_name(entry);
+
+		if (!strcmp(name, "FC_EVENT") &&
+		    !strcmp(udev_list_entry_get_value(entry), "nvmediscovery"))
+				fc_event_seen = true;
+		else if (!strcmp(name, "NVMEFC_HOST_TRADDR"))
+			host_tra = udev_list_entry_get_value(entry);
+		else if (!strcmp(name, "NVMEFC_TRADDR"))
+			tra = udev_list_entry_get_value(entry);
+	}
+	if (!fc_event_seen) {
+		log(LOG_DEBUG, "%s: FC_EVENT property missing or unsupported\n",
+		    sysname);
+		return -EINVAL;
+	}
+	if (!tra || !host_tra) {
+		log(LOG_WARNING, "%s: transport properties missing\n", sysname);
+		return -EINVAL;
+	}
+
+	if (!memccpy(traddr, tra, '\0', tra_sz) ||
+	    !memccpy(host_traddr, host_tra, '\0', htra_sz)) {
+		log(LOG_ERR, "traddr (%zu) or host_traddr (%zu) overflow\n",
+		    strlen(traddr), strlen(host_traddr));
+		return -ENAMETOOLONG;
+	}
+
+	return 0;
+}
+
+static int monitor_discovery(char *transport, char *traddr, char *trsvcid,
+			     char *host_traddr)
+{
+	char argstr[BUF_SIZE];
+	pid_t pid;
+	int rc;
+
+	pid = fork();
+	if (pid == -1) {
+		log(LOG_ERR, "failed to fork discovery task: %m");
+		return -errno;
+	} else if (pid > 0)
+		return 0;
+
+	log(LOG_NOTICE, "starting %s discovery for %s==>%s(%s)\n",
+	    transport, host_traddr, traddr, trsvcid ? trsvcid : "none");
+	cfg.nqn = NVME_DISC_SUBSYS_NAME;
+	cfg.transport = transport;
+	cfg.traddr = traddr;
+	cfg.trsvcid = trsvcid;
+	cfg.host_traddr = host_traddr;
+	/* Without the following, the kernel returns EINVAL */
+	cfg.tos = -1;
+
+	rc = build_options(argstr, sizeof(argstr), true);
+	log(LOG_DEBUG, "%s\n", argstr);
+	rc = do_discover(argstr, mon_cfg.autoconnect);
+
+	exit(-rc);
+	/* not reached */
+	return rc;
+}
+
+static void monitor_handle_fc_uev(struct udev_device *ud)
+{
+	const char *action = udev_device_get_action(ud);
+	const char *sysname = udev_device_get_sysname(ud);
+	char traddr[NVMF_TRADDR_SIZE], host_traddr[NVMF_TRADDR_SIZE];
+
+	if (strcmp(action, "change") || strcmp(sysname, "fc_udev_device"))
+		return;
+
+	if (monitor_get_fc_uev_props(ud, traddr, sizeof(traddr),
+				     host_traddr, sizeof(host_traddr)))
+		return;
+
+	monitor_discovery("fc", traddr, NULL, host_traddr);
+}
+
 static void monitor_handle_udevice(struct udev_device *ud)
 {
-	log(LOG_INFO, "uevent: %s %s\n",
-		udev_device_get_action(ud),
-		udev_device_get_sysname(ud));
+	const char *subsys  = udev_device_get_subsystem(ud);
+
+	if (log_level >= LOG_INFO) {
+		const char *action = udev_device_get_action(ud);
+		const char *syspath = udev_device_get_syspath(ud);
+
+		log(LOG_INFO, "%s %s\n", action, syspath);
+	}
+	if (!strcmp(subsys, "fc"))
+		monitor_handle_fc_uev(ud);
 }
 
 static void monitor_handle_uevents(struct udev_monitor *monitor)
-- 
2.29.2