[PATCHv3 1/4] generic/468: Add another falloc test entry

[Ritesh Harjani <ritesh.list@gmail.com>]

From: Ritesh Harjani <riteshh@linux.ibm.com>

Add another falloc test entry which could hit a kernel bug
with ext4 fast_commit feature w/o below kernel commit [1].

<log>
[  410.888496][ T2743] BUG: KASAN: use-after-free in ext4_mb_mark_bb+0x26a/0x6c0
[  410.890432][ T2743] Read of size 8 at addr ffff888171886000 by task mount/2743

This happens when falloc -k size is huge which spans across more than
1 flex block group in ext4. This causes a bug in fast_commit replay
code which is fixed by kernel commit at [1].

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git/commit/?h=dev&id=bfdc502a4a4c058bf4cbb1df0c297761d528f54d

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
---
 tests/generic/468     | 8 ++++++++
 tests/generic/468.out | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/tests/generic/468 b/tests/generic/468
index 95752d3b..5e73cff9 100755
--- a/tests/generic/468
+++ b/tests/generic/468
@@ -34,6 +34,13 @@ _scratch_mkfs >/dev/null 2>&1
 _require_metadata_journaling $SCRATCH_DEV
 _scratch_mount
 
+# blocksize and fact are used in the last case of the fsync/fdatasync test.
+# This is mainly trying to test recovery operation in case where the data
+# blocks written, exceeds the default flex group size (32768*4096*16) in ext4.
+blocks=32768
+blocksize=4096
+fact=18
+
 testfile=$SCRATCH_MNT/testfile
 
 # check inode metadata after shutdown
@@ -85,6 +92,7 @@ for i in fsync fdatasync; do
 	test_falloc $i "-k " 1024
 	test_falloc $i "-k " 4096
 	test_falloc $i "-k " 104857600
+	test_falloc $i "-k " $(($blocks*$blocksize*$fact))
 done
 
 status=0
diff --git a/tests/generic/468.out b/tests/generic/468.out
index b3a28d5e..a09cedb8 100644
--- a/tests/generic/468.out
+++ b/tests/generic/468.out
@@ -5,9 +5,11 @@ QA output created by 468
 ==== falloc -k 1024 test with fsync ====
 ==== falloc -k 4096 test with fsync ====
 ==== falloc -k 104857600 test with fsync ====
+==== falloc -k 2415919104 test with fsync ====
 ==== falloc 1024 test with fdatasync ====
 ==== falloc 4096 test with fdatasync ====
 ==== falloc 104857600 test with fdatasync ====
 ==== falloc -k 1024 test with fdatasync ====
 ==== falloc -k 4096 test with fdatasync ====
 ==== falloc -k 104857600 test with fdatasync ====
+==== falloc -k 2415919104 test with fdatasync ====
-- 
2.31.1