NFS: fix subtle change in COMMIT behavior

Recent work in the pgio layer made it possible for there to be more than one
request per page. This caused a subtle change in commit behavior, because
write.c:nfs_commit_unstable_pages compares the number of *pages* waiting for
writeback against the number of requests on a commit list to choose when to
send a COMMIT in a non-blocking flush.

This is probably hard to hit in normal operation - you have to be using
rsize/wsize < PAGE_SIZE, or pnfs with lots of boundaries that are not page
aligned to have a noticeable change in behavior.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index c72d1ad..6d627b9 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -163,7 +163,7 @@
 	 */
 	__be32			cookieverf[2];
 
-	unsigned long		npages;
+	unsigned long		nrequests;
 	struct nfs_mds_commit_info commit_info;
 
 	/* Open contexts for shared mmap writes */
@@ -520,7 +520,7 @@
 static inline int
 nfs_have_writebacks(struct inode *inode)
 {
-	return NFS_I(inode)->npages != 0;
+	return NFS_I(inode)->nrequests != 0;
 }
 
 /*