On Mon, Mar 19, 2018 at 04:01:51PM +0100, Martin Wilck wrote:
> This activates "smart" path detection. This is similar to
> "find_multipaths yes", but doesn't generally ignore single paths
> that are not listed in the WWIDs file. Rather, such paths are
> temporarily treated like multipath members. If no additional paths
> are detected after a certain time, the paths are re-added to the
> system as non-multipath. This needs support by the udev rules, to
> be added in a follow-up patch.
>
> If a multipath map is successfully successfully created, and paths are
> in waiting state, trigger path uevents to update their status.
>
Reviewed-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> ---
> libmultipath/configure.c | 15 ++++++++++++---
> libmultipath/dict.c | 1 +
> multipath/multipath.conf.5 | 13 +++++++++++++
> 3 files changed, 26 insertions(+), 3 deletions(-)
>
> diff --git a/libmultipath/configure.c b/libmultipath/configure.c
> index 98b80337d899..ec1ad9c90f05 100644
> --- a/libmultipath/configure.c
> +++ b/libmultipath/configure.c
> @@ -12,6 +12,7 @@
> #include <string.h>
> #include <sys/file.h>
> #include <errno.h>
> +#include <ctype.h>
> #include <libdevmapper.h>
> #include <libudev.h>
> #include "mpath_cmd.h"
> @@ -474,9 +475,17 @@ trigger_paths_udev_change(struct multipath *mpp, bool is_mpath)
> env = udev_device_get_property_value(
> pp->udev, "DM_MULTIPATH_DEVICE_PATH");
>
> - if (is_mpath && env != NULL && !strcmp(env, "1"))
> - continue;
> - else if (!is_mpath &&
> + if (is_mpath && env != NULL && !strcmp(env, "1")) {
> + /*
> + * If FIND_MULTIPATHS_WAIT_UNTIL is a number,
> + * path is in "maybe" state and timer is running
> + * Send uevent now (see multipath.rules).
> + */
> + env = udev_device_get_property_value(
> + pp->udev, "FIND_MULTIPATHS_WAIT_UNTIL");
> + if (env == NULL || !isdigit(env[0]))
> + continue;
> + } else if (!is_mpath &&
> (env == NULL || !strcmp(env, "0")))
> continue;
>
> diff --git a/libmultipath/dict.c b/libmultipath/dict.c
> index d59fdc85a9cb..1237c23ae7db 100644
> --- a/libmultipath/dict.c
> +++ b/libmultipath/dict.c
> @@ -238,6 +238,7 @@ static const char *find_multipaths_optvals[] = {
> [FIND_MULTIPATHS_ON] = "on",
> [FIND_MULTIPATHS_STRICT] = "strict",
> [FIND_MULTIPATHS_GREEDY] = "greedy",
> + [FIND_MULTIPATHS_SMART] = "smart",
> };
>
> static int
> diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
> index 94c419a078bf..641ba43ad158 100644
> --- a/multipath/multipath.conf.5
> +++ b/multipath/multipath.conf.5
> @@ -978,6 +978,19 @@ with the same WWID have been detected.
> Both multipathd and multipath treat every non-blacklisted device as multipath
> device path.
> .TP
> +.I smart
> +This differs from \fIfind_multipaths yes\fR only in
> +the way it treats new devices for which only one path has been
> +detected yet. When such a device is first encounted in udev rules, it is
> +treated as a multipath device. multipathd waits whether additional paths with
> +the same WWID appears. If that happens, it sets up a multipath map. If it
> +doesn\'t happen until a
> +timeout expires, or if setting up the map fails, a new uevent is triggered for
> +the device; at second encounter in the udev rules, the device will be treated
> +as non-multipath and passed on to upper layers.
> +\fBNote:\fR this may cause delays during device detection if
> +there are single-path devices which aren\'t blacklisted.
> +.TP
> The default is: \fBstrict\fR
> .RE
> .
> --
> 2.16.1
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