Re: [RFC PATCH 2/3] raid: external and internal metadata support

[Szabolcs Szakacsits <szaka-IyvsvuGDJ8VBDgjK7y7TUQ@public.gmane.org>]

Bill Nottingham <notting@...> writes: 
> OK, so:
> 
> 1) kernel sends write request. If error....
> 2) <some error occurs>
> 3) kernel sends error to userspace
> 4) mdmon wakes up
> 5) mdmon decides where to record this
> 6) mdmon writes to super blocks
> 7) go to step one, hope you don't hit step 2 this time
> 
> This now means that reliable suspend and resume is completely
> impossible on RAID devices, just as it is on FUSE. 

It's not clear from the context but I suppose you mean only FUSE 
root file systems (e.g. what Ubuntu/WUBI has on NTFS via NTFS-3G).

One of the solutions is to apply the same mechanism what swapfiles 
use. That avoids user space completely. The suspend information 
go to a dynamically (userspace involved) and a statically (no 
userspace involved) allocated space on the suspend device.

Regards,  Szaka

--
NTFS-3G: http://ntfs-3g.org

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