RE: [PATCH] [RFC] switch DM tables to readonly automatically

[Christophe Varoqui <christophe.varoqui@free.fr>]

> Hi all,
> 
> this patch switches the device-mapper table to read-only status automatically if one underlying device returns -EROFS.
> 
> Rationale:
> Whenever a SCSI device is switched to read-only a table reload from multipath-tools fails, without any indication about the reason. And it's actually quite tricky to detect the read-only status from userland. And quite pointless, too, as the kernel already knows about it.
> 
> And we now can create tables for CD-ROMs, too, without having to use the '-r' flag to dmsetup ...
> 
> Christophe, this might also fix your problem.
> 
It seems it will solve the map creation error on read-only LU, but what about these LU becoming writable ? ...
as is the case with the Symmetrix R2 upon spliting the synchronisation link.
Will the devmap become writable too automagically or is the multipathd daemon expected to take action the promote the map RW ?

Thanks for caring anyway.

> As usual, comments etc are welcome.
> 
> Cheers,
> 
> Hannes
> --
> Dr. Hannes Reinecke                   zSeries & Storage
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