linux-ext4 - [PATCH 7/7] generic/774: turn off lfsr

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Message-ID: <176279909135.605950.17114455316765178991.stgit@frogsfrogsfrogs>
Date: Mon, 10 Nov 2025 10:27:51 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: djwong@...nel.org, zlang@...hat.com
Cc: fstests@...r.kernel.org, fstests@...r.kernel.org,
 linux-ext4@...r.kernel.org
Subject: [PATCH 7/7] generic/774: turn off lfsr

From: Darrick J. Wong <djwong@...nel.org>

This test fails mostly-predictably across my testing fleet with:

 --- /run/fstests/bin/tests/generic/774.out	2025-10-20 10:03:43.432910446 -0700
 +++ /var/tmp/fstests/generic/774.out.bad	2025-11-10 01:14:58.941775866 -0800
 @@ -1,2 +1,11 @@
 QA output created by 774
 +fio: failed initializing LFSR
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 0, length 33554432 (requested block: offset=0, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 33554432, length 33554432 (requested block: offset=33554432, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 67108864, length 33554432 (requested block: offset=67108864, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 100663296, length 33554432 (requested block: offset=100663296, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 134217728, length 33554432 (requested block: offset=134217728, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 167772160, length 33554432 (requested block: offset=167772160, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 201326592, length 33554432 (requested block: offset=201326592, length=33554432)
 +verify: bad magic header 0, wanted acca at file /opt/test-file offset 234881024, length 33554432 (requested block: offset=234881024, length=33554432)
 Silence is golden

I'm not sure why the linear feedback shift register algorithm is
specifically needed for this test.

Cc: <fstests@...r.kernel.org> # v2025.10.20
Fixes: 9117fb93b41c38 ("generic: Add atomic write test using fio verify on file mixed mappings")
Signed-off-by: "Darrick J. Wong" <djwong@...nel.org>
---
 tests/generic/774 |    4 ----
 1 file changed, 4 deletions(-)


diff --git a/tests/generic/774 b/tests/generic/774
index 28886ed5b09ff7..86ab01fbd35874 100755
--- a/tests/generic/774
+++ b/tests/generic/774
@@ -56,14 +56,12 @@ group_reporting=1
 ioengine=libaio
 rw=randwrite
 io_size=$((filesize/3))
-random_generator=lfsr
 
 # Create unwritten extents
 [prep_unwritten_blocks]
 ioengine=falloc
 rw=randwrite
 io_size=$((filesize/3))
-random_generator=lfsr
 EOF
 
 cat >$fio_aw_config <<EOF
@@ -73,7 +71,6 @@ ioengine=libaio
 rw=randwrite
 direct=1
 atomic=1
-random_generator=lfsr
 group_reporting=1
 
 filename=$testfile
@@ -93,7 +90,6 @@ cat >$fio_verify_config <<EOF
 [verify_job]
 ioengine=libaio
 rw=read
-random_generator=lfsr
 group_reporting=1
 
 filename=$testfile