From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 17 Apr 2018 23:48:43 +0000 (-0600)
Subject: init: ensure that read/write use the same random seed for verify
X-Git-Tag: fio-3.7~28
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=a2e313142546aa5cb95ba7cb3708b7e06f58518c

init: ensure that read/write use the same random seed for verify

If we are verifying, then reads need to use the same blockrange
random trim as writes. Otherwise doing a deferred verify of
a write job may not yield the same block size ranges, causing
verify to fail.

Example of failed job:

$ cat job.fio
[global]
ioengine=sync
verify=md5
bsrange=1k-16k
rw=randwrite
randseed=50
size=10m
filename=foo

[write]
rw=randwrite
do_verify=0
write_iolog=wlog

[read]
rw=randread
do_verify=1
verify_fatal=1
verify_dump=1
write_iolog=rlog

$ fio --section=write job.fio
$ fio --section=read job.fio

Fixes: https://github.com/axboe/fio/issues/582
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/init.c b/init.c
index f5ff73d0..07d1cdd3 100644
--- a/init.c
+++ b/init.c
@@ -997,23 +997,26 @@ void td_fill_verify_state_seed(struct thread_data *td)
 
 static void td_fill_rand_seeds_internal(struct thread_data *td, bool use64)
 {
+	unsigned int read_seed = td->rand_seeds[FIO_RAND_BS_OFF];
+	unsigned int write_seed = td->rand_seeds[FIO_RAND_BS1_OFF];
+	unsigned int trim_seed = td->rand_seeds[FIO_RAND_BS2_OFF];
 	int i;
 
 	/*
 	 * trimwrite is special in that we need to generate the same
 	 * offsets to get the "write after trim" effect. If we are
 	 * using bssplit to set buffer length distributions, ensure that
-	 * we seed the trim and write generators identically.
+	 * we seed the trim and write generators identically. Ditto for
+	 * verify, read and writes must have the same seed, if we are doing
+	 * read verify.
 	 */
-	if (td_trimwrite(td)) {
-		init_rand_seed(&td->bsrange_state[DDIR_READ], td->rand_seeds[FIO_RAND_BS_OFF], use64);
-		init_rand_seed(&td->bsrange_state[DDIR_WRITE], td->rand_seeds[FIO_RAND_BS1_OFF], use64);
-		init_rand_seed(&td->bsrange_state[DDIR_TRIM], td->rand_seeds[FIO_RAND_BS1_OFF], use64);
-	} else {
-		init_rand_seed(&td->bsrange_state[DDIR_READ], td->rand_seeds[FIO_RAND_BS_OFF], use64);
-		init_rand_seed(&td->bsrange_state[DDIR_WRITE], td->rand_seeds[FIO_RAND_BS1_OFF], use64);
-		init_rand_seed(&td->bsrange_state[DDIR_TRIM], td->rand_seeds[FIO_RAND_BS2_OFF], use64);
-	}
+	if (td->o.verify != VERIFY_NONE)
+		write_seed = read_seed;
+	if (td_trimwrite(td))
+		trim_seed = write_seed;
+	init_rand_seed(&td->bsrange_state[DDIR_READ], read_seed, use64);
+	init_rand_seed(&td->bsrange_state[DDIR_WRITE], write_seed, use64);
+	init_rand_seed(&td->bsrange_state[DDIR_TRIM], trim_seed, use64);
 
 	td_fill_verify_state_seed(td);
 	init_rand_seed(&td->rwmix_state, td->rand_seeds[FIO_RAND_MIX_OFF], false);