Re: [PATCH v3 00/10] multipath-tools: avoid I/O during uevent processing

[Benjamin Marzinski <bmarzins@redhat.com>]

On Mon, Mar 18, 2019 at 12:24:35PM +0100, Martin Wilck wrote:
> Hi Christophe, hi Ben,
> 
> the bulk of this series attempts to avoid unnecessary I/O for "multipath -u"
> calls from udev rules. I came up with it in a recent attempt to debug
> avoid "multipath -u" hangups during boot. I found that the detect_alua()
> call in the get_refwwid->pathinfo->scsi_ioctl_pathinfo call sequence would
> cause an sg ioctl to be sent for every "multipath -u" invocation. That's
> obvious nonsense, we don't need to detect ALUA capabilities to find out
> if a device is a potential multipath member.
> 
> So, rather than setting pp->tpgs in pathinfo, I resorted to a "lazy"
> approach where ALUA capabilities are probed when they are needed, no
> sooner. I also cleaned up the ALUA code a bit (still some more to go),
> and made it attempt to read INQUIRY data from sysfs.
> 
> Regards,
> Martin

Reviewed-by: Benjamin Marzinski <bmarzins@redhat.com>

for the set.
 
> Changes v2->v3:
> 
>  - added 8/10 "tidy up do_set_from_hwe() with statement expression"
>    (Hannes), renumber subsequent patches accordingly.
>  - 9/10: cleanup ugly macro usage; do retrieve VPD for "unknown"
>    SCSI storage devices
>  
> Changes v1->v2:
> 
>  - 6/9: remove one remaining direct access to pp->tpgs
>  - 9/9: use non-personal email address for maintainer
> 
> Martin Wilck (10):
>   libmultipath: add sysfs_get_inquiry()
>   libmultipath: alua: make API more consistent
>   libmultipath: alua: try to retrieve inquiry data from sysfs
>   libmultipath: constify sysfs_get_timeout()
>   libmultipath: detect_alua(): use system timeout
>   libmultipath: lazy tpgs probing
>   libmultipath: don't link alua_rtpg.o twice
>   libmultipath: tidy up do_set_from_hwe() with statement expression
>   libmultipath: check_rdac(): pre-check in hwtable
>   libmultipath: hwtable: add Lenovo DE series
> 
>  libmultipath/discovery.c              | 46 +++++++++++++++++-------
>  libmultipath/discovery.h              | 10 +++---
>  libmultipath/hwtable.c                | 20 +++++++++++
>  libmultipath/prioritizers/Makefile    |  3 --
>  libmultipath/prioritizers/alua.c      |  4 +--
>  libmultipath/prioritizers/alua_rtpg.c | 45 +++++++++++++++++------
>  libmultipath/prioritizers/alua_rtpg.h |  7 ++--
>  libmultipath/propsel.c                | 52 ++++++++++++++++++---------
>  multipathd/main.c                     |  7 ++--
>  9 files changed, 139 insertions(+), 55 deletions(-)
> 
> -- 
> 2.21.0