xfs
[Top] [All Lists]

Re: DMAPI implementation about undeliverable event messages

To: Aurelien Degremont - Stagiaire <degremont@xxxxxxxxxxx>
Subject: Re: DMAPI implementation about undeliverable event messages
From: Dean Roehrich <roehrich@xxxxxxx>
Date: Mon, 07 Mar 2005 10:45:29 -0600
Cc: linux-xfs@xxxxxxxxxxx
Sender: linux-xfs-bounce@xxxxxxxxxxx
>From:  Aurelien Degremont - Stagiaire <degremont@xxxxxxxxxxx>
>Dean Roehrich a écrit :
>> These are often blocked, but interruptible.  Otherwise they're stuck until t
>he
>> HSM application is restarted so it can continue processing events.
>
>Yes, i saw this, no other solutions ?
>
>There's an issue with the DM_EVENT_UNMOUNT event.
>If the HSM application is unavailable, you try to unmount a managed 
>filesystem, the filesystem will start to be unmount, the event msg will 
>be sent, but not received, so the unmount call will be blocked.
>Unfortunately, the HSM application will never be able to re-register for 
>the UNMOUNT event for this filesystem, because this filesystem is no 
>longer available as a "loaded and dmapi-compliant" filesystem (we cannot 
>get the filesystem handle anymore), but it's also not unloaded. The 
>system is quite broken for this FS and i see no solution to solve the 
>situation...
>
>Am i clear ? :)

Yes.

There's a comment header for dm_send_unmount_event() that talks about some
issues with this being a synchronous event.  The spec still says it
is synchronous:

http://www.opengroup.org/onlinepubs/9657099/toc.htm

This looks like another case where the spec can cause a headache.

Dean


<Prev in Thread] Current Thread [Next in Thread>