29.02.2012 23:45, Jeff Layton пишет:
On Wed, 29 Feb 2012 22:39:01 +0400
Stanislav Kinsbursky<skinsbursky@xxxxxxxxxxxxx> wrote:
Hi, Jeff.
I'll try to explain, how all this namespaces-aware SUNRPC PipeFS works.
The main idea is, that today we have 2 types of independently created and
destroyed but linked objects:
1) pipe data itself. This object is created whenever kernel requires (on mount,
module install, whatever)
2) dentry/inode for this pipe. This object is created on PipeFS superblock creation.
This means, any kernel user of SUNRPC pipes have to provide two mechanisms:
1) Safe call (in per-net operations, if the object is global your case) for
PipeFS dentry/inode pair. This is done this in nfsd4_init_cld_pipe().
2) Notifier callback for PipeFS mount/umount operations. Note: this callback is
done from SUNRPC module (i.e. you have to get nfsd module); this callback is
safe - i.e you can be sure, that superblock is valid.
This is the part I'm having a hard time with. IIUC, the existing
examples are fairly clear since you have a 1:1 ratio of objects: a
per-net object (the pipe data) that is hooked up to a dentry/inode in a
per-net sb.
Here though, we don't really have that. We have a global pipe object
and I don't see how you can hook that up to multiple dentries/inodes.
One possibility is to completely "namespacify" this code -- don't use a
global rpc_pipe object and make it per-net instead. If I do that though,
then I suppose I'll also need to make all of the
nfsd4_client_tracking_ops take a struct net arg as well?
Thanks for the help so far...
There is no problem at all.
Would be great (for me - eventially I'll update it to namespace aware code) if
you'll convert you code into something like this:
1) Safe and unsafe dentry creation routines, parametrized by net. Don't use
per-net data - hard-code your global pointer.
2) Pipe data creation routine, parametrized by net. Call this one only for
"init_net" for far - no per-net ops required. Also call safe dentry creation
routine here.
3) Notifier callback - just ignore any callbacks from not init_net. Otherwise
call unsafe dentry creation routine.
If you'll do so, then it will be very easy to convert this feature to network
namespace aware.
--
Best regards,
Stanislav Kinsbursky
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