On Jun. 15, 2010, 14:19 -0400, Trond Myklebust <trond.myklebust@xxxxxxxxxx> wrote:
> On Tue, 2010-06-15 at 13:52 -0400, Fred Isaman wrote:
>> On Tue, Jun 15, 2010 at 1:33 PM, Trond Myklebust
>> <trond.myklebust@xxxxxxxxxx> wrote:
>>> On Tue, 2010-06-15 at 13:32 -0400, Fred Isaman wrote:
>>>> On Tue, Jun 15, 2010 at 1:06 PM, Benny Halevy <bhalevy@xxxxxxxxxxx> wrote:
>>>>> On Jun. 14, 2010, 21:46 -0400, Fred Isaman <iisaman@xxxxxxxxxx> wrote:
>>>>>> This prepares for the next patch.
>>>>>>
>>>>>> NOTE this doesn't really fix any current race, since
>>>>>> layout going to NULL is OK. But layout changing from NULL to nonNULL
>>>>>> is a real race that is not fixed
>>>>>>
>>>>>> Signed-off-by: Fred Isaman <iisaman@xxxxxxxxxx>
>>>>>> ---
>>>>>> fs/nfs/nfs4state.c | 5 +++--
>>>>>> fs/nfs/pnfs.c | 11 +++++++++++
>>>>>> include/linux/nfs4_pnfs.h | 2 ++
>>>>>> 3 files changed, 16 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
>>>>>> index d5144bd..8a7a64c 100644
>>>>>> --- a/fs/nfs/nfs4state.c
>>>>>> +++ b/fs/nfs/nfs4state.c
>>>>>> @@ -594,11 +594,12 @@ static void __nfs4_close(struct path *path, struct nfs4_state *state,
>>>>>> } else {
>>>>>> #ifdef CONFIG_NFS_V4_1
>>>>>> struct nfs_inode *nfsi = NFS_I(state->inode);
>>>>>> + int roc = nfs4_roc_iomode(nfsi);
>>>>>>
>>>>>> - if (has_layout(nfsi) && nfsi->layout.roc_iomode) {
>>>>>> + if (roc) {
>>>>>> struct nfs4_pnfs_layout_segment range;
>>>>>>
>>>>>> - range.iomode = nfsi->layout.roc_iomode;
>>>>>> + range.iomode = roc;
>>>>>> range.offset = 0;
>>>>>> range.length = NFS4_MAX_UINT64;
>>>>>> pnfs_return_layout(state->inode, &range, NULL,
>>>>>> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
>>>>>> index 6def09c..bd11ec7 100644
>>>>>> --- a/fs/nfs/pnfs.c
>>>>>> +++ b/fs/nfs/pnfs.c
>>>>>> @@ -321,6 +321,17 @@ pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
>>>>>> #define BUG_ON_UNLOCKED_LO(lo) do {} while (0)
>>>>>> #endif /* CONFIG_SMP */
>>>>>>
>>>>>> +int nfs4_roc_iomode(struct nfs_inode *nfsi)
>>>>>> +{
>>>>>> + int rv = 0;
>>>>>> +
>>>>>> + spin_lock(&pnfs_spinlock);
>>>>>
>>>>> Why take the global lock rather than nfsi->lo_lock?
>>>>>
>>>>> Benny
>>>>
>>>> You are right. That would be a copy-paste error.
>>>
>>> What's an nfsi->lo_lock, and why do we need one?
>>>
>>> Trond
>>>
>>>
>>
>> It protects nfsi->layout and its contents.
>>
>> Fred
>
> Yes, but why do we need an extra spinlock? We already have
> inode->i_lock. Why can't you just reuse that?
>
I agree. We can and should reuse i_lock.
Benny
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