Re: [PATCH v8 5/6] nfsd: add the infrastructure to handle the cld upcall

[Stanislav Kinsbursky <skinsbursky@parallels.com>]

05.03.2012 18:39, Jeff Layton пишет:
>
> Ok, I've started looking at the existing examples to try and ease the
> eventual containerization of this. Am I correct that the existing
> blocklayout pipe containerization is not yet complete?
>
> AIUI, you have a rpc_pipe per nfs_net struct, and those structs are
> allocated on a per-net basis. bl_pipe_downcall does this however:
>
>          if (copy_from_user(&bl_mount_reply, src, mlen) != 0)
>                  return -EFAULT;
>
> ...but bl_mount_reply is global:
>
>      static struct bl_dev_msg bl_mount_reply;
>
> So, if you're getting downcalls in two different network namespaces at
> the same time this could end up corrupt. It seems like bl_mount_reply
> needs to be part of nfs_net as well.

Thanks for this catch, Jeff!
I need to fix this.

>
> When you get a downcall, you have a filp pointer. Is there any way to
> determine the "correct" nfs_net object for a particular filp?
>

Yes, sure.
This nfs_net object will be, obviously, in the same network namespace, as PipeFS 
superblock. Network namespace is stored on PipeFS sb->s_fs_info.
IOW, code below should works:

struct nfs_net *nn = net_generic(file->f_dentry->d_sb->s_fs_info, nfs_net_id);

-- 
Best regards,
Stanislav Kinsbursky