[dm-devel] [PATCH v3 2/3] libmultipath: move filter_property() from path_discover() into pathinfo()

[Hannes Reinecke]

On 12/14/2016 03:02 AM, Mauricio Faria de Oliveira wrote:
> The udev property blacklisting is ignored on 'add' uevents
> because uev_add_path() calls pathinfo() directly - but the
> filter_property() check is only performed in path_discover().
>
> So, move the call out from path_discover() into pathinfo().
>
> Since path_discover() always calls pathinfo() to return,
> either directly or via store_pathinfo(), the change is
> equivalent for callers of path_discover(), which turns
> out to be only path_discovery().
>
> Interestingly, multipathd calls path_discovery() without
> DI_BLACKLIST and then calls filter_path() to remove paths,
> so make sure filter_path() also considers filter_property().
>
> Test-case:
>
>   # cat /etc/multipath.conf
>   blacklist {
>       property "ID_SERIAL"
>   }
>
>   # udevadm info --query=property /dev/sdb | grep ID_SERIAL=
>   ID_SERIAL=0QEMU_QEMU_HARDDISK_drive-scsi0-0-0-1
>
>   # multipathd -d -s -v3 &
>
>   # echo add > /sys/block/sdb/uevent
>
> Before:
>
>   uevent 'add' from '/devices/.../block/sdb'
>   Forwarding 1 uevents
>   sdb: add path (uevent)
>   ...
>   0QEMU_QEMU_HARDDISK_drive-scsi0-0-0-1: load table [0 4194304 multipath 1
>   retain_attached_hw_handler 0 1 1 service-time 0 1 1 8:16 1]
>   ...
>   sdb [8:16]: path added to devmap 0QEMU_QEMU_HARDDISK_drive-scsi0-0-0-1
>
> After:
>
>   uevent 'add' from '/devices/.../block/sdb'
>   Forwarding 1 uevents
>   sdb: add path (uevent)
>   sdb: mask = 0x3f
>   sdb: udev property ID_SERIAL blacklisted
>
> Signed-off-by: Mauricio Faria de Oliveira <mauricfo at linux.vnet.ibm.com>
> Reported-by: Benjamin Marzinski <bmarzins at redhat.com>
> ---
>  libmultipath/blacklist.c | 4 ++++
>  libmultipath/discovery.c | 7 ++++---
>  2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/libmultipath/blacklist.c b/libmultipath/blacklist.c
> index 676225f9c2e0..36af28213212 100644
> --- a/libmultipath/blacklist.c
> +++ b/libmultipath/blacklist.c
> @@ -327,6 +327,10 @@ _filter_path (struct config * conf, struct path * pp)
>  {
>  	int r;
>
> +	r = filter_property(conf, pp->udev);
> +	if (r > 0)
> +		return r;
> +
>  	r = _filter_devnode(conf->blist_devnode, conf->elist_devnode,pp->dev);
>  	if (r > 0)
>  		return r;
> diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
> index 3c5c808436b2..52abd4e75c89 100644
> --- a/libmultipath/discovery.c
> +++ b/libmultipath/discovery.c
> @@ -117,9 +117,6 @@ path_discover (vector pathvec, struct config * conf,
>  	if (!devname)
>  		return PATHINFO_FAILED;
>
> -	if (filter_property(conf, udevice) > 0)
> -		return PATHINFO_SKIPPED;
> -
>  	if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
>  			   (char *)devname) > 0)
>  		return PATHINFO_SKIPPED;
> @@ -1747,6 +1744,10 @@ int pathinfo(struct path *pp, struct config *conf, int mask)
>
>  	condlog(3, "%s: mask = 0x%x", pp->dev, mask);
>
> +	if (mask & DI_BLACKLIST && pp->udev)
> +		if (filter_property(conf, pp->udev) > 0)
> +			return PATHINFO_SKIPPED;
> +
>  	/*
>  	 * Sanity check: we need the device number to
>  	 * avoid inconsistent information in
>
Okay, now it's my time for nit-picking:

Why do we remove 'filter_property' from path_discover, but _retain_ 
filter_devnode() there?

In _filter_path we do both.

So wouldn't it make more sense to move filter_devnode() into pathinfo(), 
too, to avoid further inconsistencies between _filter_path() and pathinfo()?

Especially as it looks that if we need to call filter_devnode() in
get_refwwid(), too; starting with line 976 we're just calling 
'store_pathinfo' for the device node, with no check for blacklisted 
devnode at all.
(Which also goes to explain why I have this mysterious bug where 
blacklisting by device node doesn't properly work ...).
So moving filter_devnode() in pathinfo would be more sensible and clean 
up the overall programming model.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare at suse.de			               +49 911 74053 688
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