splice: update mtime and atime on files

Splice should update the modification and access times on regular
files just like read and write. Not updating mtime will confuse
backup tools, etc...

This patch only adds the time updates for regular files.  For pipes
and other special files that splice touches the need for updating the
times is less clear.  Let's discuss and fix that separately.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

fs/splice.c

@@ -502,8 +502,10 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
 		len = left;
 
 	ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
-	if (ret > 0)
+	if (ret > 0) {
 		*ppos += ret;
+		file_accessed(in);
+	}
 
 	return ret;
 }
@@ -963,8 +965,10 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 		mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
 		ret = file_remove_suid(out);
-		if (!ret)
+		if (!ret) {
+			file_update_time(out);
 			ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file);
+		}
 		mutex_unlock(&inode->i_mutex);
 	} while (ret > 0);
 	splice_from_pipe_end(pipe, &sd);