Re: [bug report] raid0 array mkfs.xfs hang

[John Garry <john.g.garry@oracle.com>]

On 14/08/2024 15:52, Martin K. Petersen wrote:
> 
> Keith,
> 
>> Your change looks fine, though it sounds odd that md raid is changing
>> queue_limit values outside the limits_lock. The stacking limits should
>> have set the md device to 0 if one of the member drives doesn't
>> support write_zeroes, right?
> 

And even if we had used the limits lock to synchronize the update, that 
only synchronizes writers but not readers (of the limits).

> SCSI can't reliably detect ahead of time whether a device supports WRITE
> SAME. So we'll issue a WRITE SAME command and if that fails we'll set
> the queue limit to 0. So it is "normal" that the limit changes at
> runtime.
> 
> I'm debugging a couple of other regressions from the queue limits
> shuffle so I haven't looked into this one yet. But I assume that's
> what's happening.
>