pnfs/flexfiles: count io stat in rpc_count_stats callback

If client ever restarts IO due to some errors, we'll endup
mis-counting IO stats if we do the counting in .rpc_done
callback. Move it to .rpc_count_stats callback that is only
called when releasing RPC.
Signed-off-by: Peng Tao <tao.peng@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -1516,11 +1516,6 @@ static void ff_layout_write_call_done(struct rpc_task *task, void *data)
 {
 	struct nfs_pgio_header *hdr = data;
 
-	nfs4_ff_layout_stat_io_end_write(task,
-			FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
-			hdr->args.count, hdr->res.count,
-			hdr->res.verf->committed);
-
 	if (test_bit(NFS_IOHDR_REDO, &hdr->flags) &&
 	    task->tk_status == 0) {
 		nfs4_sequence_done(task, &hdr->res.seq_res);
@@ -1535,6 +1530,11 @@ static void ff_layout_write_count_stats(struct rpc_task *task, void *data)
 {
 	struct nfs_pgio_header *hdr = data;
 
+	nfs4_ff_layout_stat_io_end_write(task,
+			FF_LAYOUT_COMP(hdr->lseg, hdr->pgio_mirror_idx),
+			hdr->args.count, hdr->res.count,
+			hdr->res.verf->committed);
+
 	rpc_count_iostats_metrics(task,
 	    &NFS_CLIENT(hdr->inode)->cl_metrics[NFSPROC4_CLNT_WRITE]);
 }
@@ -1566,6 +1566,11 @@ static void ff_layout_commit_prepare_v4(struct rpc_task *task, void *data)
 }
 
 static void ff_layout_commit_done(struct rpc_task *task, void *data)
+{
+	pnfs_generic_write_commit_done(task, data);
+}
+
+static void ff_layout_commit_count_stats(struct rpc_task *task, void *data)
 {
 	struct nfs_commit_data *cdata = data;
 	struct nfs_page *req;
@@ -1580,13 +1585,6 @@ static void ff_layout_commit_done(struct rpc_task *task, void *data)
 			FF_LAYOUT_COMP(cdata->lseg, cdata->ds_commit_index),
 			count, count, NFS_FILE_SYNC);
 
-	pnfs_generic_write_commit_done(task, data);
-}
-
-static void ff_layout_commit_count_stats(struct rpc_task *task, void *data)
-{
-	struct nfs_commit_data *cdata = data;
-
 	rpc_count_iostats_metrics(task,
 	    &NFS_CLIENT(cdata->inode)->cl_metrics[NFSPROC4_CLNT_COMMIT]);
 }