[Pvfs2-developers] g_admin_mode

[Phil Carns]

Pete Wyckoff wrote:
> Does anybody know what happened to g_admin_mode?  There are vestiges
> in the tree, but they don't do anything useful.  There is a mgmt
> server call, toggle_admin_mode() that sets it, but nothing that
> looks at it.  Eager to yank all that out if anyone can recall why
> its usage has disappeared.
> 
> 		-- Pete


The idea behind admin mode in general was to be able to put servers into 
a protected mode that prevents modification while tools like fsck run on 
the file system.

There is a problem, however, in that fsck may itself want to modify the 
file system while it is running.  For example, if it finds a stranded 
file, it may want to create a directory entry in /lost+found to be able 
to link to it.

I think the idea with the admin mode hooks on the client side was that a 
utility like fsck could put the client into admin mode when needed, not 
just the server- the idea being that a client with admin mode 
priviledges would be permitted to modify the file system while the 
server is in admin mode.

This never caught on though.  There are a few mgmt operations on the 
client side that are implicitly allowed to bypass admin mode.  For 
remaining functions that fsck uses to change the file system it just 
takes all of the servers in an out of admin mode as it runs.

IMHO it somewhat weakens the purpose of having an admin mode to protect 
the file system if the admin utilities can't/don't keep it in that mode 
during the time frame that they need the file system to stay quiescent, 
but I'm not sure what the right approach is.  We will run into this 
problem soon with the pvfs2-validate tool too.

-Phil