[dm-devel] Is there a way to see updated contents of a DM target's underlying device while the DM target is in use?

[Riches Jr, RobertX M]

Thank you for the wise council to carefully check my code.  I certainly intend to do that.

However, I am able to reproduce the symptom using the standard dm-linear module supplied with the x86_64 kernel that comes with Ubuntu Karmic.  With the attached script, the first 'od' on /dev/vg1/lv1, done before 'dmsetup remove', shows the first part of the file contains 0x00.  A second 'od' after 'dmsetup remove' shows the file contains random data.

I didn't see any queues or caches in dm-linear that would need to be flushed.

Any other suggestions?

Thanks,

Robert Riches
Azad Consultant at Intel
 
-----Original Message-----
From: Alasdair G Kergon [mailto:agk at redhat.com] 
Sent: Wednesday, June 30, 2010 4:08 PM
To: Riches Jr, RobertX M
Cc: Dm-Devel Mailing List Send-To Address (dm-devel at redhat.com)
Subject: Re: [dm-devel] Is there a way to see updated contents of a DM target's underlying device while the DM target is in use?

Sounds like a coding problem you need to debug...check your device stack - and the
code you are using to look for the change - carefully, check where you are
queueing/flushing/caching etc.

Alasdair

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