Re: [PATCH] NFS: Fix a commit bug

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On Jun 7, 2012, at 11:05 AM, Chuck Lever wrote:

> This does not appear to fix the problem I'm seeing.
> 
> With this patch applied, the client is silly renaming the file, deleting it, then writing it again and failing with NFS4ERR_STALE.

What command(s) are you running?

-dros

> 
> I had to apply the change by hand, so I could have missed something.  I'll go back and check.
> 
> On Jun 6, 2012, at 9:59 AM, Adamson, Dros wrote:
> 
>> ACK - This fixes the problem I was seeing!
>> 
>> For the list, we were seeing duplicate writes sent to unstable servers even though the COMMIT succeeds (with matching verf):
>> 
>> - mount a server that returns writes with committed = UNSTABLE4
>> - run "dd if=/dev/zero of=/mnt/foo bs=1024 count=10240"
>> - umount
>> - in wireshark, you'll see the COMMIT succeed, but after a short pause there will be a flurry of FILE_SYNC4 writes that are duplicates (same ranges, data) of the writes associated with the COMMIT.
>> 
>> -dros
>> 
>> On Jun 5, 2012, at 6:43 PM, Trond Myklebust wrote:
>> 
>>> The new commit code fails to copy the verifier into the wb_verf field
>>> of _all_ the nfs_page structures; it only copies it into the first entry.
>>> The consequence is that most requests end up failing to match in
>>> nfs_commit_release.
>>> 
>>> Fix is to copy the verifier into the req->wb_verf field in
>>> nfs_write_completion.
>>> 
>>> Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
>>> Cc: Fred Isaman <iisaman@xxxxxxxxxx>
>>> ---
>>> fs/nfs/direct.c         |    4 ++--
>>> fs/nfs/write.c          |    7 ++++---
>>> include/linux/nfs_xdr.h |    2 ++
>>> 3 files changed, 8 insertions(+), 5 deletions(-)
>>> 
>>> diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
>>> index 23d170b..b5385a7 100644
>>> --- a/fs/nfs/direct.c
>>> +++ b/fs/nfs/direct.c
>>> @@ -710,12 +710,12 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
>>> 			if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
>>> 				bit = NFS_IOHDR_NEED_RESCHED;
>>> 			else if (dreq->flags == 0) {
>>> -				memcpy(&dreq->verf, &req->wb_verf,
>>> +				memcpy(&dreq->verf, hdr->verf,
>>> 				       sizeof(dreq->verf));
>>> 				bit = NFS_IOHDR_NEED_COMMIT;
>>> 				dreq->flags = NFS_ODIRECT_DO_COMMIT;
>>> 			} else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
>>> -				if (memcmp(&dreq->verf, &req->wb_verf, sizeof(dreq->verf))) {
>>> +				if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
>>> 					dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
>>> 					bit = NFS_IOHDR_NEED_RESCHED;
>>> 				} else
>>> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
>>> index e6fe3d6..4d6861c 100644
>>> --- a/fs/nfs/write.c
>>> +++ b/fs/nfs/write.c
>>> @@ -80,6 +80,7 @@ struct nfs_write_header *nfs_writehdr_alloc(void)
>>> 		INIT_LIST_HEAD(&hdr->rpc_list);
>>> 		spin_lock_init(&hdr->lock);
>>> 		atomic_set(&hdr->refcnt, 0);
>>> +		hdr->verf = &p->verf;
>>> 	}
>>> 	return p;
>>> }
>>> @@ -619,6 +620,7 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
>>> 			goto next;
>>> 		}
>>> 		if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
>>> +			memcpy(&req->wb_verf, hdr->verf, sizeof(req->wb_verf));
>>> 			nfs_mark_request_commit(req, hdr->lseg, &cinfo);
>>> 			goto next;
>>> 		}
>>> @@ -1255,15 +1257,14 @@ static void nfs_writeback_release_common(void *calldata)
>>> 	struct nfs_write_data	*data = calldata;
>>> 	struct nfs_pgio_header *hdr = data->header;
>>> 	int status = data->task.tk_status;
>>> -	struct nfs_page *req = hdr->req;
>>> 
>>> 	if ((status >= 0) && nfs_write_need_commit(data)) {
>>> 		spin_lock(&hdr->lock);
>>> 		if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags))
>>> 			; /* Do nothing */
>>> 		else if (!test_and_set_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags))
>>> -			memcpy(&req->wb_verf, &data->verf, sizeof(req->wb_verf));
>>> -		else if (memcmp(&req->wb_verf, &data->verf, sizeof(req->wb_verf)))
>>> +			memcpy(hdr->verf, &data->verf, sizeof(*hdr->verf));
>>> +		else if (memcmp(hdr->verf, &data->verf, sizeof(*hdr->verf)))
>>> 			set_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags);
>>> 		spin_unlock(&hdr->lock);
>>> 	}
>>> diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
>>> index 7519bae..8aadd90 100644
>>> --- a/include/linux/nfs_xdr.h
>>> +++ b/include/linux/nfs_xdr.h
>>> @@ -1237,6 +1237,7 @@ struct nfs_pgio_header {
>>> 	struct list_head	rpc_list;
>>> 	atomic_t		refcnt;
>>> 	struct nfs_page		*req;
>>> +	struct nfs_writeverf	*verf;
>>> 	struct pnfs_layout_segment *lseg;
>>> 	loff_t			io_start;
>>> 	const struct rpc_call_ops *mds_ops;
>>> @@ -1274,6 +1275,7 @@ struct nfs_write_data {
>>> struct nfs_write_header {
>>> 	struct nfs_pgio_header	header;
>>> 	struct nfs_write_data	rpc_data;
>>> +	struct nfs_writeverf	verf;
>>> };
>>> 
>>> struct nfs_mds_commit_info {
>>> -- 
>>> 1.7.10.2
>>> 
>> 
> 
> ---
> Chuck Lever
> chuck [dot] lever [at] oracle [dot] com
> 
> 
> 
> 

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