[ ssic-linux-Bugs-983095 ] Can't mount below /dev on multiple nodes

Bugs item #983095, was opened at 2004-06-30 19:43
Message generated for change (Comment added) made by rogertsang
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Category: Filesystem
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: David Zafman (dzafman)
Assigned to: Nobody/Anonymous (nobody)
Summary: Can't mount below /dev on multiple nodes

Initial Comment:

This was seen when attempting to do profiling on
multiple nodes.

The opcontrol command does the following:

mount -t oprofilefs nodev /dev/oprofile >/dev/null

Since this adds the entry to /etc/mtab, a subsequent
node can't do another mount even though /dev is unique
for each node.

While we could simply add a "-n" to the opcontrol
script, this doesn't solve the general problem.  We
could change the mount command to replace /dev
directory specification to /cluster/nodeX/dev.  This
would allow every node to mount below /dev, because the
mount command would fix things to reflect the SSI
kernel notion of what /dev is.

I believe that this change would improve our
application compatibility.


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>Comment By: Roger Tsang (rogertsang)
Date: 2008-01-01 20:00

Message:
Logged In: YES 
user_id=1246761
Originator: NO

This bug is resolved in SSI-1.9.  In SSI-1.9 /dev/X resolves to
/cluster/nodeX/dev.  mtab /dev/X entries are unique for each node.

----------------------------------------------------------------------

Comment By: David Zafman (dzafman)
Date: 2004-06-30 21:30

Message:
Logged In: YES 
user_id=297844


The fix for this is harder than I first thought.  First if
we get mount to mount on /cluster/nodeX/dev instead of /dev,
the mount point won't be seen below /dev and vice versa. 
This is due to the bind mount nature of /dev.

Also, since /dev is controlled by the node context, the
mount system call currently only works for local node, even
though we might want to function ship to the node context node.

It is critical that the translation /dev ->
/cluster/nodeX/dev at user level matches the results of the
mount() system call in terms of which /dev has the mount
actually on.

----------------------------------------------------------------------

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