[dm-devel] [PATCH 5/6] multipath: Makefile: modules-load.d file for SCSI device handlers

[Benjamin Marzinski]

On Wed, Feb 02, 2022 at 12:40:23AM +0100, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
> 
> The kernel's autoload mechanism for SCSI device handlers doesn't
> work during SCSI device probing. While it's possible to load and
> attach device handlers after probing, it has disadvantages: the
> handlers are useful for error handling even before multipathd has
> started, and at least up to kernel 5.17, the sysfs "access_state" attribute
> will remain invisible for already probed devices.
> 
> Distributions will therefore want to make sure the handlers are either
> built-in in the kernel, or loaded early. Add functionality to
> create and install a modules-load.d file with a list of handlers
> to load. By default, the list is empty, and no file will be generated.
> The list can be specified at install-time like this:
> 
>    make SCSI_DH_MODULES_PRELOAD="scsi_dh_rdac scsi_dh_emc" install
> 
> dracut automatically adds modules-load.d files and the modules they
> reference to the initramfs.
> 
> Note: distributions that compile scsi_mod as a module may rather want
> to use a modprobe.d file with a statement like this:
> 
> softdep scsi_mod post: scsi_dh_alua scsi_dh_rdac
> 

I think you might need a default scsi_dh.conf file with a comment header
or something. install won't install a file that doesn't exist. Or am I
missing something here?

-Ben

> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  Makefile.inc       | 5 +++++
>  multipath/Makefile | 6 ++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/Makefile.inc b/Makefile.inc
> index 5223c96..3342af6 100644
> --- a/Makefile.inc
> +++ b/Makefile.inc
> @@ -9,6 +9,11 @@
>  # Uncomment to disable dmevents polling support
>  # ENABLE_DMEVENTS_POLL = 0
>  
> +# List of scsi device handler modules to load on boot, e.g.
> +# SCSI_DH_MODULES_PRELOAD := scsi_dh_alua scsi_dh_rdac
> +SCSI_DH_MODULES_PRELOAD :=
> +
> +
>  PKGCONFIG	?= pkg-config
>  
>  ifeq ($(TOPDIR),)
> diff --git a/multipath/Makefile b/multipath/Makefile
> index 015f73c..c930499 100644
> --- a/multipath/Makefile
> +++ b/multipath/Makefile
> @@ -29,11 +29,17 @@ install:
>  	$(INSTALL_PROGRAM) -m 644 $(EXEC).8 $(DESTDIR)$(man8dir)
>  	$(INSTALL_PROGRAM) -d $(DESTDIR)$(man5dir)
>  	$(INSTALL_PROGRAM) -m 644 $(EXEC).conf.5 $(DESTDIR)$(man5dir)
> +ifneq ($(SCSI_DH_MODULES_PRELOAD),)
> +	$(INSTALL_PROGRAM) -m 644 scsi_dh.conf $(DESTDIR)$(modulesloaddir)/scsi_dh.conf
> +	for _x in $(SCSI_DH_MODULES_PRELOAD); do echo "$$_x"; done \
> +	    >>$(DESTDIR)$(modulesloaddir)/scsi_dh.conf
> +endif
>  
>  uninstall:
>  	$(RM) $(DESTDIR)$(bindir)/$(EXEC)
>  	$(RM) $(DESTDIR)$(udevrulesdir)/11-dm-mpath.rules
>  	$(RM) $(DESTDIR)$(modulesloaddir)/multipath.conf
> +	$(RM) $(DESTDIR)$(modulesloaddir)/scsi_dh.conf
>  	$(RM) $(DESTDIR)$(libudevdir)/rules.d/56-multipath.rules
>  	$(RM) $(DESTDIR)$(man8dir)/$(EXEC).8
>  	$(RM) $(DESTDIR)$(man5dir)/$(EXEC).conf.5
> -- 
> 2.34.1