NFS: Make stat() return updated mtimes after a write()

The SuS states that a call to write() will cause mtime to be updated on
 the file. In order to satisfy that requirement, we need to flush out
 any cached writes in nfs_getattr().
 Speed things up slightly by not committing the writes.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/inode.c

@@ -952,6 +952,8 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 	int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME;
 	int err;
 
+	/* Flush out writes to the server in order to update c/mtime */
+	nfs_sync_inode(inode, 0, 0, FLUSH_WAIT|FLUSH_NOCOMMIT);
 	if (__IS_FLG(inode, MS_NOATIME))
 		need_atime = 0;
 	else if (__IS_FLG(inode, MS_NODIRATIME) && S_ISDIR(inode->i_mode))

fs/nfs/write.c

@@ -1377,22 +1377,23 @@ int nfs_commit_inode(struct inode *inode, int how)
 int nfs_sync_inode(struct inode *inode, unsigned long idx_start,
 		  unsigned int npages, int how)
 {
-	int	error,
-		wait;
+	int nocommit = how & FLUSH_NOCOMMIT;
+	int wait = how & FLUSH_WAIT;
+	int error;
 
-	wait = how & FLUSH_WAIT;
-	how &= ~FLUSH_WAIT;
+	how &= ~(FLUSH_WAIT|FLUSH_NOCOMMIT);
 
 	do {
-		error = 0;
-		if (wait)
+		if (wait) {
 			error = nfs_wait_on_requests(inode, idx_start, npages);
-		if (error == 0)
-			error = nfs_flush_inode(inode, idx_start, npages, how);
-#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
-		if (error == 0)
+			if (error != 0)
+				continue;
+		}
+		error = nfs_flush_inode(inode, idx_start, npages, how);
+		if (error != 0)
+			continue;
+		if (!nocommit)
 			error = nfs_commit_inode(inode, how);
-#endif
 	} while (error > 0);
 	return error;
 }

include/linux/nfs_fs.h

@@ -62,6 +62,7 @@
 #define FLUSH_STABLE		4	/* commit to stable storage */
 #define FLUSH_LOWPRI		8	/* low priority background flush */
 #define FLUSH_HIGHPRI		16	/* high priority memory reclaim flush */
+#define FLUSH_NOCOMMIT		32	/* Don't send the NFSv3/v4 COMMIT */
 
 #ifdef __KERNEL__