pnfs: fix filelayout_retry_commit when idx > 0

filelayout_retry_commit was recently split out from alloc_ds_commits,
but was done in such a way that the bucket pointer always starts at
index 0 no matter what the @idx argument is set to.

The intention of the @idx argument is to retry commits starting at
bucket @idx. This is called when alloc_ds_commits fails for a bucket.
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/filelayout/filelayout.c

@@ -1269,11 +1269,12 @@ filelayout_search_commit_reqs(struct nfs_commit_info *cinfo, struct page *page)
 static void filelayout_retry_commit(struct nfs_commit_info *cinfo, int idx)
 {
 	struct pnfs_ds_commit_info *fl_cinfo = cinfo->ds;
-	struct pnfs_commit_bucket *bucket = fl_cinfo->buckets;
+	struct pnfs_commit_bucket *bucket;
 	struct pnfs_layout_segment *freeme;
 	int i;
 
-	for (i = idx; i < fl_cinfo->nbuckets; i++, bucket++) {
+	for (i = idx; i < fl_cinfo->nbuckets; i++) {
+		bucket = &fl_cinfo->buckets[i];
 		if (list_empty(&bucket->committing))
 			continue;
 		nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);