Re: [PATCH] NFS: Fix a commit bug

["Adamson, Dros" <Weston.Adamson@netapp.com>]

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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@netapp.com>
> Cc: Fred Isaman <iisaman@netapp.com>
> ---
> 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
> 


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