locking questions (regarding file systems)

R. B. Riddick arne_woerner at yahoo.com
Wed Aug 2 19:34:10 UTC 2006


--- Eric Anderson <anderson at centtech.com> wrote:
> Here's basically what I do:
> in the mount function for the FS, I do something like this:
> 
> DROP_GIANT();
> g_topology_lock();
> error = g_vfs_open(devvp, &cp, "fsname", 0);
> g_topology_unlock();
> PICKUP_GIANT();
> 
> What is needed in my unmount function to release those locks?  I've
> tried some combinations of things, like:
> 
> DROP_GIANT();
> g_topology_lock();
> # wedges here
> g_vfs_close(cp, td);
> g_topology_unlock();
> PICKUP_GIANT();
> vrele(devvp);
> 

So the first un-mount works fine?
And the second un-mount wedges _before_ g_vfs_close?

I cannot find anything really suspicious in ur code...

Just 2 thoughts:

1. Do we really hold GIANT, when we mount and un-mount something?

2. R u sure, that we need vrele()? I mean: Why doesn't g_vfs_close() call
vrele(), if g_vfs_open() increases that use-count variable? Can u print the
use-count variable in the beginning and the end of the mount/un-mount
functions?

-Arne


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