On Thu, Jun 22, 2017 at 04:59:11PM +0200, Martin Wilck wrote:
> Kernels 4.3 and newer (commit 1bab0de0 "dm-mpath, scsi_dh: don't
> let dm detach device handlers") imply "retain_attached_hw_handler yes".
>
> Clarify this in the propsel code, log messages, and documentation.
ACK
-Ben
>
> Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
> Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
> ---
> libmultipath/configure.c | 3 ++-
> libmultipath/dmparser.c | 3 ++-
> libmultipath/propsel.c | 7 ++++++-
> libmultipath/util.c | 36 ++++++++++++++++++++++++++++++++++++
> libmultipath/util.h | 2 ++
> multipath/multipath.conf.5 | 15 +++++++++++----
> 6 files changed, 59 insertions(+), 7 deletions(-)
>
> diff --git a/libmultipath/configure.c b/libmultipath/configure.c
> index a7f2b443..74b6f52a 100644
> --- a/libmultipath/configure.c
> +++ b/libmultipath/configure.c
> @@ -572,7 +572,8 @@ select_action (struct multipath * mpp, vector curmp, int force_reload)
> }
>
> if (mpp->retain_hwhandler != RETAIN_HWHANDLER_UNDEF &&
> - mpp->retain_hwhandler != cmpp->retain_hwhandler) {
> + mpp->retain_hwhandler != cmpp->retain_hwhandler &&
> + get_linux_version_code() < KERNEL_VERSION(4, 3, 0)) {
> mpp->action = ACT_RELOAD;
> condlog(3, "%s: set ACT_RELOAD (retain_hwhandler change)",
> mpp->alias);
> diff --git a/libmultipath/dmparser.c b/libmultipath/dmparser.c
> index 1121c715..b647c256 100644
> --- a/libmultipath/dmparser.c
> +++ b/libmultipath/dmparser.c
> @@ -97,7 +97,8 @@ assemble_map (struct multipath * mp, char * params, int len)
> } else if (mp->no_path_retry != NO_PATH_RETRY_UNDEF) {
> add_feature(&f, no_path_retry);
> }
> - if (mp->retain_hwhandler == RETAIN_HWHANDLER_ON)
> + if (mp->retain_hwhandler == RETAIN_HWHANDLER_ON &&
> + get_linux_version_code() < KERNEL_VERSION(4, 3, 0))
> add_feature(&f, retain_hwhandler);
>
> APPEND(p, end, "%s %s %i %i", f, mp->hwhandler, nr_priority_groups,
> diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
> index e885a845..d609394e 100644
> --- a/libmultipath/propsel.c
> +++ b/libmultipath/propsel.c
> @@ -628,7 +628,12 @@ int select_retain_hwhandler(struct config *conf, struct multipath *mp)
>
> if (!VERSION_GE(conf->version, minv_dm_retain)) {
> mp->retain_hwhandler = RETAIN_HWHANDLER_OFF;
> - origin = "(setting: WARNING, requires kernel version >= 1.5.0)";
> + origin = "(setting: WARNING, requires kernel dm-mpath version >= 1.5.0)";
> + goto out;
> + }
> + if (get_linux_version_code() >= KERNEL_VERSION(4, 3, 0)) {
> + mp->retain_hwhandler = RETAIN_HWHANDLER_ON;
> + origin = "(setting: implied in kernel >= 4.3.0)";
> goto out;
> }
> mp_set_ovr(retain_hwhandler);
> diff --git a/libmultipath/util.c b/libmultipath/util.c
> index b90cd8b0..dff2ed3c 100644
> --- a/libmultipath/util.c
> +++ b/libmultipath/util.c
> @@ -6,6 +6,7 @@
> #include <sys/stat.h>
> #include <sys/sysmacros.h>
> #include <sys/types.h>
> +#include <sys/utsname.h>
> #include <dirent.h>
> #include <unistd.h>
> #include <errno.h>
> @@ -380,3 +381,38 @@ int systemd_service_enabled(const char *dev)
> found = systemd_service_enabled_in(dev, "/run");
> return found;
> }
> +
> +static int _linux_version_code;
> +static pthread_once_t _lvc_initialized = PTHREAD_ONCE_INIT;
> +
> +/* Returns current kernel version encoded as major*65536 + minor*256 + patch,
> + * so, for example, to check if the kernel is greater than 2.2.11:
> + *
> + * if (get_linux_version_code() > KERNEL_VERSION(2,2,11)) { <stuff> }
> + *
> + * Copyright (C) 1999-2004 by Erik Andersen <andersen@xxxxxxxxxxxx>
> + * Code copied from busybox (GPLv2 or later)
> + */
> +static void
> +_set_linux_version_code(void)
> +{
> + struct utsname name;
> + char *t;
> + int i, r;
> +
> + uname(&name); /* never fails */
> + t = name.release;
> + r = 0;
> + for (i = 0; i < 3; i++) {
> + t = strtok(t, ".");
> + r = r * 256 + (t ? atoi(t) : 0);
> + t = NULL;
> + }
> + _linux_version_code = r;
> +}
> +
> +int get_linux_version_code(void)
> +{
> + pthread_once(&_lvc_initialized, _set_linux_version_code);
> + return _linux_version_code;
> +}
> diff --git a/libmultipath/util.h b/libmultipath/util.h
> index b087e32e..45291be8 100644
> --- a/libmultipath/util.h
> +++ b/libmultipath/util.h
> @@ -15,6 +15,8 @@ char *convert_dev(char *dev, int is_path_device);
> char *parse_uid_attribute_by_attrs(char *uid_attrs, char *path_dev);
> void setup_thread_attr(pthread_attr_t *attr, size_t stacksize, int detached);
> int systemd_service_enabled(const char *dev);
> +int get_linux_version_code(void);
> +#define KERNEL_VERSION(maj, min, ptc) ((((maj) * 256) + (min)) * 256 + (ptc))
>
> #define safe_sprintf(var, format, args...) \
> snprintf(var, sizeof(var), format, ##args) >= sizeof(var)
> diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
> index b32d0383..3b4e5187 100644
> --- a/multipath/multipath.conf.5
> +++ b/multipath/multipath.conf.5
> @@ -698,15 +698,16 @@ The default is: \fB<unset>\fR
> .
> .TP
> .B retain_attached_hw_handler
> -If set to
> +(Obsolete for kernels >= 4.3) If set to
> .I yes
> and the SCSI layer has already attached a hardware_handler to the device,
> multipath will not force the device to use the hardware_handler specified by
> mutipath.conf. If the SCSI layer has not attached a hardware handler,
> multipath will continue to use its configured hardware handler.
> .RS
> -.TP
> -The default is: \fByes\fR
> +.PP
> +The default is: \fByes\fR. Linux kernel 4.3 or newer always behaves as if
> +\fB"retain_attached_hw_handler yes"\fR was set.
> .RE
> .
> .
> @@ -1182,8 +1183,14 @@ Active/Standby mode exclusively.
> .I 1 alua
> (Hardware-dependent)
> Hardware handler for SCSI-3 ALUA compatible arrays.
> -.TP
> +.PP
> The default is: \fB<unset>\fR
> +.PP
> +\fBImportant Note:\fR Linux kernels 4.3 and newer automatically attach a device
> +handler to known devices (which includes all devices supporting SCSI-3 ALUA)
> +and disallow changing the handler
> +afterwards. Setting \fBhardware_handler\fR for such devices on these kernels
> +has no effect.
> .RE
> .
> .
> --
> 2.13.1
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
