On Mon, Mar 16, 2015 at 01:37:05PM +0100, Hannes Reinecke wrote:
> During startup multipathd might race with udev and device discovery.
> During that time any information from libudev might not be fully
> available, leading to spurious multipathd failures during startup.
> So instead of scanning all devices on our own we should just
> re-trigger the existing devices; with that we'll read _all_
> devices via uevents during startup and avoid the race condition.
Should we also be sending change uevents for the dm devices?
-Ben
>
> Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> ---
> libmultipath/discovery.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++
> libmultipath/discovery.h | 1 +
> multipathd/main.c | 36 +++++++++++++++++++++++++++++----
> 3 files changed, 85 insertions(+), 4 deletions(-)
>
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index 4582a20..8762819 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -134,6 +134,58 @@ path_discover (vector pathvec, struct config * conf,
> }
>
> int
> +path_trigger (struct config * conf, int flag)
> +{
> + struct udev_enumerate *udev_iter;
> + struct udev_list_entry *entry;
> + int num_paths = 0;
> +
> + udev_iter = udev_enumerate_new(conf->udev);
> + if (!udev_iter)
> + return -ENOMEM;
> +
> + udev_enumerate_add_match_subsystem(udev_iter, "block");
> + udev_enumerate_scan_devices(udev_iter);
> +
> + udev_list_entry_foreach(entry,
> + udev_enumerate_get_list_entry(udev_iter)) {
> + const char *devpath;
> + char *devname;
> + char filename[PATH_MAX];
> + int fd;
> +
> + devpath = udev_list_entry_get_name(entry);
> + condlog(3, "Trigger device %s", devpath);
> + devname = strrchr(devpath, '/');
> + if (!devname) {
> + condlog(3, "%s: invalid devpath", devpath);
> + continue;
> + }
> + devname++;
> + if (filter_devnode(conf->blist_devnode,
> + conf->elist_devnode, devname) > 0) {
> + condlog(3, "%s: blacklisted", devname);
> + continue;
> + }
> + strncpy(filename, devpath, strlen(devpath) + 1);
> + strncat(filename, "/uevent", 8);
> + fd = open(filename, O_WRONLY | O_CLOEXEC);
> + if (fd < 0)
> + continue;
> + if (write(fd, "add", 3) < 0) {
> + condlog(3, "%s: Failed to trigger 'add' uevent: %m",
> + devpath);
> + } else {
> + num_paths++;
> + }
> + close(fd);
> + }
> + udev_enumerate_unref(udev_iter);
> + condlog(4, "Triggered %d paths", num_paths);
> + return num_paths;
> +}
> +
> +int
> path_discovery (vector pathvec, struct config * conf, int flag)
> {
> struct udev_enumerate *udev_iter;
> diff --git a/libmultipath/discovery.h b/libmultipath/discovery.h
> index da7652c..9ae3d23 100644
> --- a/libmultipath/discovery.h
> +++ b/libmultipath/discovery.h
> @@ -31,6 +31,7 @@
> struct config;
>
> int path_discovery (vector pathvec, struct config * conf, int flag);
> +int path_trigger (struct config * conf, int flag);
>
> int do_tur (char *);
> int path_offline (struct path *);
> diff --git a/multipathd/main.c b/multipathd/main.c
> index d9f2435..480b10d 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -1581,6 +1581,24 @@ configure (struct vectors * vecs, int start_waiters)
> }
>
> int
> +trigger_devices (struct vectors * vecs)
> +{
> +
> + if (!vecs->pathvec && !(vecs->pathvec = vector_alloc()))
> + return 1;
> +
> + if (!vecs->mpvec && !(vecs->mpvec = vector_alloc()))
> + return 1;
> +
> + /*
> + * Trigger all non-blacklisted block devices
> + */
> + path_trigger(conf, DI_ALL);
> +
> + return 0;
> +}
> +
> +int
> reconfigure (struct vectors * vecs)
> {
> struct config * old = conf;
> @@ -1902,15 +1920,21 @@ child (void * param)
> condlog(0, "failed to create cli listener: %d", rc);
> goto failed;
> }
> - /*
> - * fetch and configure both paths and multipaths
> - */
> #ifdef USE_SYSTEMD
> sd_notify(0, "STATUS=configure");
> #endif
> post_config_state(DAEMON_CONFIGURE);
>
> /*
> + * Trigger all paths to force reconfiguration
> + */
> + pthread_cleanup_push(cleanup_lock, &vecs->lock);
> + lock(vecs->lock);
> + pthread_testcancel();
> + trigger_devices(vecs);
> + lock_cleanup_pop(vecs->lock);
> +
> + /*
> * start threads
> */
> if ((rc = pthread_create(&check_thr, &misc_attr, checkerloop, vecs))) {
> @@ -1927,6 +1951,8 @@ child (void * param)
> pid_rc = pidfile_create(DEFAULT_PIDFILE, daemon_pid);
> /* Ignore errors, we can live without */
>
> + post_config_state(DAEMON_RUNNING);
> +
> #ifdef USE_SYSTEMD
> sd_notify(0, "READY=1\nSTATUS=running");
> #endif
> @@ -2129,7 +2155,9 @@ main (int argc, char *argv[])
> conf->bindings_read_only = 1;
> break;
> default:
> - ;
> + fprintf(stderr, "Invalid argument '-%c'\n",
> + optopt);
> + exit(1);
> }
> }
> if (optind < argc) {
> --
> 1.8.4.5
--
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