On Wed, 2012-09-26 at 13:12 -0400, bjschuma@xxxxxxxxxx wrote:
> From: Bryan Schumaker <bjschuma@xxxxxxxxxx>
>
> I put the client into an open recovery loop by:
> Client: Open file
> read half
> Server: Expire client (echo 0 > /sys/kernel/debug/nfsd/forget_clients)
> Client: Drop vm cache (echo 3 > /proc/sys/vm/drop_caches)
> finish reading file
>
> This causes a loop because the client never updates the nfs4_state after
> discovering that the delegation is invalid. This means it will keep
> trying to read using the bad delegation rather than attempting to re-open
> the file.
>
> Signed-off-by: Bryan Schumaker <bjschuma@xxxxxxxxxx>
> ---
> fs/nfs/nfs4proc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
> index 1e50326..e47ec55 100644
> --- a/fs/nfs/nfs4proc.c
> +++ b/fs/nfs/nfs4proc.c
> @@ -1774,7 +1774,9 @@ static void nfs41_clear_delegation_stateid(struct nfs4_state *state)
> * informs us the stateid is unrecognized. */
> if (status != -NFS4ERR_BAD_STATEID)
> nfs41_free_stateid(server, stateid);
> + nfs_remove_bad_delegation(state->inode);
>
> + nfs4_stateid_copy(&state->stateid, &state->open_stateid);
nfs4_stateid_copy needs to be write-protected by the state->seqlock
here.
> clear_bit(NFS_DELEGATED_STATE, &state->flags);
> }
> }
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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