X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=io_u.c;h=af2d05f360eaed2f4d6c169f6ee5eb5f62da18f8;hp=16c98b1f454869c43e4862b91c57b1278898de28;hb=de78976982fe7f57ccadd15a19dae167f0ce62ab;hpb=a66da7a2354aac16757c75a824ad7cbba678535c

diff --git a/io_u.c b/io_u.c
index 16c98b1f..af2d05f3 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1120,6 +1120,19 @@ static int check_get_verify(struct thread_data *td, struct io_u *io_u)
 	return 0;
 }
 
+/*
+ * Fill offset and start time into the buffer content, to prevent too
+ * easy compressible data for simple de-dupe attempts.
+ */
+static void small_content_scramble(struct io_u *io_u)
+{
+	void *end;
+
+	*((unsigned long long *) io_u->xfer_buf) = io_u->offset;
+	end = io_u->xfer_buf + io_u->xfer_buflen - sizeof(io_u->start_time);
+	memcpy(end, &io_u->start_time, sizeof(io_u->start_time));
+}
+
 /*
  * Return an io_u to be processed. Gets a buflen and offset, sets direction,
  * etc. The returned io_u is fully ready to be prepped and submitted.
@@ -1128,6 +1141,7 @@ struct io_u *get_io_u(struct thread_data *td)
 {
 	struct fio_file *f;
 	struct io_u *io_u;
+	int do_scramble = 0;
 
 	io_u = __get_io_u(td);
 	if (!io_u) {
@@ -1173,6 +1187,8 @@ struct io_u *get_io_u(struct thread_data *td)
 			populate_verify_io_u(td, io_u);
 		else if (td->o.refill_buffers && io_u->ddir == DDIR_WRITE)
 			io_u_fill_buffer(td, io_u, io_u->xfer_buflen);
+		else if (io_u->ddir == DDIR_WRITE)
+			do_scramble = 1;
 		else if (io_u->ddir == DDIR_READ) {
 			/*
 			 * Reset the buf_filled parameters so next time if the
@@ -1193,6 +1209,8 @@ out:
 	if (!td_io_prep(td, io_u)) {
 		if (!td->o.disable_slat)
 			fio_gettime(&io_u->start_time, NULL);
+		if (do_scramble)
+			small_content_scramble(io_u);
 		return io_u;
 	}
 err_put:
@@ -1450,7 +1468,7 @@ void io_u_fill_buffer(struct thread_data *td, struct io_u *io_u,
 	io_u->buf_filled_len = 0;
 
 	if (!td->o.zero_buffers)
-		fill_random_buf(io_u->buf, max_bs);
+		fill_random_buf(&td->buf_state, io_u->buf, max_bs);
 	else
 		memset(io_u->buf, 0, max_bs);
 }