Re: [mdadm PATCH] Create: tell udev md device is not ready when first created.

[Jes Sorensen <jes.sorensen@gmail.com>]

On 04/28/2017 01:05 AM, NeilBrown wrote:
>
> When an array is created the content is not initialized,
> so it could have remnants of an old filesystem or md array
> etc on it.
> udev will see this and might try to activate it, which is almost
> certainly not what is wanted.
>
> So create a mechanism for mdadm to communicate with udev to tell
> it that the device isn't ready.  This mechanism is the existance
> of a file /run/mdadm/created-mdXXX where mdXXX is the md device name.
>
> When creating an array, mdadm will create the file.
> A new udev rule file, 01-md-raid-creating.rules, will detect the
> precense of thst file and set ENV{SYSTEMD_READY}="0".
> This is fairly uniformly used to suppress actions based on the
> contents of the device.
>
> Signed-off-by: NeilBrown <neilb@suse.com>
> ---
>  Assemble.c                  |  2 +-
>  Build.c                     |  2 +-
>  Create.c                    |  9 +++++++-
>  Incremental.c               |  4 ++--
>  Makefile                    |  4 ++--
>  lib.c                       | 29 +++++++++++++++++++++++++
>  mdadm.h                     |  4 +++-
>  mdopen.c                    | 52 ++++++++++++++++++++++++++++-----------------
>  udev-md-raid-creating.rules |  7 ++++++
>  9 files changed, 86 insertions(+), 27 deletions(-)
>  create mode 100644 udev-md-raid-creating.rules

Applied!

I like this solution much better, even though I am not in love with the 
giant usleep() call. Would be nice to find a better way around that.

Sorry it took so long to get back to you on this, last week was a mess.

Thanks,
Jes