On Thu, 2008-10-16 at 09:28 +1100, Neil Brown wrote:
> Hi Trond,
> I wonder if you would consider including the following patch which
> makes nfs_file_cred a little more robust.
>
> It isn't strictly needed with current mainline. However we have a patch
> set which (among other things) passes a 'struct file' down (via
> ATTR_FILE) for a chmod call.
> If chmod is called on e.g. a device special file, this will cause
> nfs3_proc_setattr to call nfs_file_cred on a 'struct file' which does
> not have an associated open context or credential. That goes Oops.
>
> Thanks for your consideration,
> NeilBrown
Hi Neil,
Won't this still end up exploding in nfs4_proc_setattr?
Cheers
Trond
> --------------
>
> From: NeilBrown <neilb@xxxxxxx>
>
> As not all files have an associated open_context (e.g. device special
> files), it is safest to test for the existence of the open context
> before de-referencing it.
>
> Signed-off-by: NeilBrown <neilb@xxxxxxx>
>
>
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 78a5922..63bf8f0 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -372,8 +372,12 @@ static inline struct nfs_open_context *nfs_file_open_context(struct file *filp)
>
> static inline struct rpc_cred *nfs_file_cred(struct file *file)
> {
> - if (file != NULL)
> - return nfs_file_open_context(file)->cred;
> + if (file != NULL) {
> + struct nfs_open_context *ctx =
> + nfs_file_open_context(file);
> + if (ctx)
> + return ctx->cred;
> + }
> return NULL;
> }
>
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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