Re: [PATCH 2/2] We should clear NFS_DELEGATED_STATE after return delegation

[Bian Naimeng <biannm@cn.fujitsu.com>]

> On Mon, 2010-08-16 at 15:50 +0800, Bian Naimeng wrote:
>>>>>>>> We should clear NFS_DELEGATED_STATE bit for inode->open_states after return delegation.

... snip ...

>>    A open state can be found at nfsi->open_states and owner->so_states always, but
>>   it not be found at nfsi->open_files until we call nfs4_intent_set_file.
>>
>>    At _nfs4_do_open, we will invoke nfs4_return_incompatible_delegation to return a 
>>   delegation,  a open stateid which set NFS_DELEGATED_STATE bit may not be found at
>>   nfsi->open_files, but it still at nfsi->open_states, so we do not clear 
>>   NFS_DELEGATED_STATE bit for it.
>>
>>    Then _nfs4_do_open will find it by nfs4_get_open_state, and we still use it
>>   as a delegation, some error will occur.
>>
> 
> OK. I see agree that is a race, but AFAICS, your fix means that we end
> up with an nfs_state structure that has cleared NFS_DELEGATED_STATE, but
> that did not recover its open stateid.
> 

Hi trond, what do you think about this one?

Best Regards
 Bian

-------------------------------------------------------------------------
If there are not any delegation at this inode, we should clear stateid's
NFS_DELEGATED_STATE when update it.

Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>

---
 fs/nfs/delegation.c |    1 +
 fs/nfs/nfs4proc.c   |   12 +++++++++++-
 2 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
index 83bb16f..3a7a19d 100644
--- a/fs/nfs/delegation.c
+++ b/fs/nfs/delegation.c
@@ -109,6 +109,7 @@ again:
 			continue;
 		if (memcmp(state->stateid.data, stateid->data, sizeof(state->stateid.data)) != 0)
 			continue;
+		clear_bit(NFS_DELEGATED_STATE, &state->flags);
 		get_nfs_open_context(ctx);
 		spin_unlock(&inode->i_lock);
 		err = nfs4_open_delegation_recall(ctx, state, stateid);
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 36400d3..c0c0320 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -900,8 +900,18 @@ static int update_open_stateid(struct nfs4_state *state, nfs4_stateid *open_stat
 
 	rcu_read_lock();
 	deleg_cur = rcu_dereference(nfsi->delegation);
-	if (deleg_cur == NULL)
+	if (deleg_cur == NULL) {
+		if (delegation == NULL &&
+		    test_bit(NFS_DELEGATED_STATE, &state->flags)) {
+			/*FIXME: If the state has NFS_DELEGATED_STATE bit, 
+			 * we catch a race. Maybe should recover its open
+			 * stateid, here we just clear the NFS_DELEGATED_STATE
+			 * bit.
+			 */
+			clear_bit(NFS_DELEGATED_STATE, &state->flags);
+		}
 		goto no_delegation;
+	}
 
 	spin_lock(&deleg_cur->lock);
 	if (nfsi->delegation != deleg_cur ||
-- 
1.6.5.2