Re: [PATCH v2 1/2] NFSv4: Fix problems with close in the presence of a delegation

[Anna Schumaker <Anna.Schumaker@netapp.com>]

On 08/26/2014 04:15 PM, Trond Myklebust wrote:
> On Tue, Aug 26, 2014 at 4:11 PM, Anna Schumaker
> <Anna.Schumaker@netapp.com> wrote:
>> On 08/26/2014 02:30 PM, Trond Myklebust wrote:
>>> In the presence of delegations, we can no longer assume that the
>>> state->n_rdwr, state->n_rdonly, state->n_wronly reflect the open
>>> stateid share mode, and so we need to need to calculate the initial
>> Nit:  Remove the duplicate "need to" (above).
>>
>>> value for calldata->arg.fmode using the state->flags.
>>>
>>> Reported-by: James Drews <drews@engr.wisc.edu>
>>> Fixes: 88069f77e1ac5 (NFSv41: Fix a potential state leakage when...)
>>> Cc: stable@vger.kernel.org # 2.6.33+
>>> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
>>> ---
>>>  fs/nfs/nfs4proc.c | 19 +++++++++++++------
>>>  1 file changed, 13 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>>> index 75ae8d22f067..7d67d5b332d4 100644
>>> --- a/fs/nfs/nfs4proc.c
>>> +++ b/fs/nfs/nfs4proc.c
>>> @@ -2601,6 +2601,7 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
>>>       struct nfs4_closedata *calldata = data;
>>>       struct nfs4_state *state = calldata->state;
>>>       struct inode *inode = calldata->inode;
>>> +     bool is_rdonly, is_wronly, is_rdwr;
>>>       int call_close = 0;
>>>
>>>       dprintk("%s: begin!\n", __func__);
>>> @@ -2608,24 +2609,30 @@ static void nfs4_close_prepare(struct rpc_task *task, void *data)
>>>               goto out_wait;
>>>
>>>       task->tk_msg.rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_OPEN_DOWNGRADE];
>>> -     calldata->arg.fmode = FMODE_READ|FMODE_WRITE;
>>>       spin_lock(&state->owner->so_lock);
>>> +     is_rdwr = test_bit(NFS_O_RDWR_STATE, &state->flags);
>>> +     is_rdonly = test_bit(NFS_O_RDONLY_STATE, &state->flags);
>>> +     is_wronly = test_bit(NFS_O_WRONLY_STATE, &state->flags);
>>> +     spin_unlock(&state->owner->so_lock);
>>> +     /* Calculate the current open share mode */
>>> +     calldata->arg.fmode = 0;
>>> +     if (is_rdonly || is_rdwr)
>>> +             calldata->arg.fmode |= FMODE_READ;
>>> +     if (is_wronly || is_rdwr)
>>> +             calldata->arg.fmode |= FMODE_WRITE;
>>>       /* Calculate the change in open mode */
>>>       if (state->n_rdwr == 0) {
>> Do we need the owner lock for reading state->n_rdwr, n_rdonly, and n_wronly?
> 
> Duh, yes, you're right. I'll revert that part of the change.

I could be wrong!  I checked for other uses, and nfs4proc.c:can_open_cached() reads these values without a lock.

Anna

> 
>> Anna
>>>               if (state->n_rdonly == 0) {
>>> -                     call_close |= test_bit(NFS_O_RDONLY_STATE, &state->flags);
>>> -                     call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
>>> +                     call_close |= is_rdonly || is_rdwr;
>>>                       calldata->arg.fmode &= ~FMODE_READ;
>>>               }
>>>               if (state->n_wronly == 0) {
>>> -                     call_close |= test_bit(NFS_O_WRONLY_STATE, &state->flags);
>>> -                     call_close |= test_bit(NFS_O_RDWR_STATE, &state->flags);
>>> +                     call_close |= is_wronly || is_rdwr;
>>>                       calldata->arg.fmode &= ~FMODE_WRITE;
>>>               }
>>>       }
>>>       if (!nfs4_valid_open_stateid(state))
>>>               call_close = 0;
>>> -     spin_unlock(&state->owner->so_lock);
>>>
>>>       if (!call_close) {
>>>               /* Note: exit _without_ calling nfs4_close_done */
>>
> 
> 
>