Scramble fix

[fio.git] / io_u.c

diff --git a/io_u.c b/io_u.c
index 5959bf7f0587345bc72e094f085634915bad4fa0..38efcc16382874d685c1e7b027abff3a640ed560 100644 (file)
--- a/io_u.c
+++ b/io_u.c
@@ -1129,6 +1129,7 @@ static int check_get_verify(struct thread_data *td, struct io_u *io_u)
 static void small_content_scramble(struct io_u *io_u)
 {
        unsigned int i, nr_blocks = io_u->buflen / 512;
+       unsigned long long boffset;
        unsigned int offset;
        void *p, *end;
 
@@ -1136,20 +1137,23 @@ static void small_content_scramble(struct io_u *io_u)
                return;
 
        p = io_u->xfer_buf;
+       boffset= io_u->offset;
+
        for (i = 0; i < nr_blocks; i++) {
                /*
                 * Fill the byte offset into a "random" start offset of
                 * the buffer, given by the product of the usec time
                 * and the actual offset.
                 */
-               offset = (io_u->start_time.tv_usec * io_u->offset) & 511;
+               offset = (io_u->start_time.tv_usec ^ boffset) & 511;
                if (offset >= 512 - sizeof(unsigned long long))
                        offset -= sizeof(unsigned long long);
-               *((unsigned long long *) p + offset) = io_u->offset;
+               *((unsigned long long *) p + offset) = boffset;
 
                end = p + 512 - sizeof(io_u->start_time);
                memcpy(end, &io_u->start_time, sizeof(io_u->start_time));
                p += 512;
+               boffset += 512;
        }
 }