Re: [PATCH v3 2/2] mdadm: Introduce new array state 'broken' for raid0/linear

[Song Liu <songliubraving@fb.com>]

> On Aug 22, 2019, at 9:13 AM, Guilherme G. Piccoli <gpiccoli@canonical.com> wrote:
> 
> Currently if a md raid0/linear array gets one or more members removed while
> being mounted, kernel keeps showing state 'clean' in the 'array_state'
> sysfs attribute. Despite udev signaling the member device is gone, 'mdadm'
> cannot issue the STOP_ARRAY ioctl successfully, given the array is mounted.
> 
> Nothing else hints that something is wrong (except that the removed devices
> don't show properly in the output of mdadm 'detail' command). There is no
> other property to be checked, and if user is not performing reads/writes
> to the array, even kernel log is quiet and doesn't give a clue about the
> missing member.
> 
> This patch is the mdadm counterpart of kernel new array state 'broken'.
> The 'broken' state mimics the state 'clean' in every aspect, being useful
> only to distinguish if an array has some member missing. All necessary
> paths in mdadm were changed to deal with 'broken' state, and in case the
> tool runs in a kernel that is not updated, it'll work normally, i.e., it
> doesn't require the 'broken' state in order to work.
> Also, this patch changes the way the array state is showed in the 'detail'
> command (for raid0/linear only) - now it takes the 'array_state' sysfs
> attribute into account instead of only rely in the MD_SB_CLEAN flag.
> 
> Cc: NeilBrown <neilb@suse.com>
> Cc: Song Liu <songliubraving@fb.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com>

CC Jes, who maintains mdadm.