NFS: Remove bad delegations during open recovery

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@netapp.com>
CC: stable@vger.kernel.org [3.4+]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 755ee162ee7e..471a75f11ea2 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1774,7 +1774,11 @@ 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);
 
+                write_seqlock(&state->seqlock);
+                nfs4_stateid_copy(&state->stateid, &state->open_stateid);
+                write_sequnlock(&state->seqlock);
                 clear_bit(NFS_DELEGATED_STATE, &state->flags);
         }
 }