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Message-ID: <Ylz63bzfrTwcKKDK@li-bb2b2a4c-3307-11b2-a85c-8fa5c3a69313.ibm.com> Date: Mon, 18 Apr 2022 11:15:01 +0530 From: Ojaswin Mujoo <ojaswin@...ux.ibm.com> To: Eryu Guan <guaneryu@...il.com> Cc: fstests@...r.kernel.org, linux-ext4@...r.kernel.org, riteshh@...ux.ibm.com Subject: Re: [PATCH v2 2/2] ext4: Test to ensure resize with sparse_super2 is handled correctly On Sun, Apr 10, 2022 at 06:36:14PM +0800, Eryu Guan wrote: > On Tue, Feb 22, 2022 at 11:20:53PM +0530, Ojaswin Mujoo wrote: > > Kernel currently doesn't support resize of EXT4 mounted > > with sparse_super2 option enabled. Earlier, it used to leave the resize > > incomplete and the fs would be left in an inconsistent state, however commit > > b1489186cc83[1] fixed this to avoid the fs corruption by clearly returning > > -EOPNOTSUPP. > > > > Test to ensure that kernel handles resizing with sparse_super2 correctly. Run > > resize for multiple iterations because this sometimes leads to kernel crash due > > to fs corruption, which we want to detect. > > > > Related commit in mainline: > > > > [1] commit b1489186cc8391e0c1e342f9fbc3eedf6b944c61 > > > > ext4: add check to prevent attempting to resize an fs with sparse_super2 > > > > Signed-off-by: Ojaswin Mujoo <ojaswin@...ux.ibm.com> > > --- > > > > I would like to add a few comments on the approach followed in this > > test: > > > > 1. So although we check the return codes of the resize operation for > > proper logging, the test is only considered to be passed if fsck > > passes after the resize. This is because resizing a patched kernel > > always keeps the fs consistent whereas resizing on unpatched kernel > > always corrupts the fs. > > > > 2. I've noticed that running mkfs + resize multiple times on unpatched > > kernel sometimes results in KASAN reporting use-after-free. Hence, if > > we detect the kernel is unpatched (doesn't return EOPNOTSUPP on > > resize) we continue iterating to capture this. In this case, we don't > > run fsck in each iteration but run it only after all iterations are > > complete because _check_scratch_fs exits the test if it fails. > > > > 3. In case we detect patched kernel, we stop iterating, and run fsck to > > confirm success > > > > tests/ext4/056 | 108 +++++++++++++++++++++++++++++++++++++++++++++ > > tests/ext4/056.out | 2 + > > 2 files changed, 110 insertions(+) > > create mode 100755 tests/ext4/056 > > create mode 100644 tests/ext4/056.out > > > > diff --git a/tests/ext4/056 b/tests/ext4/056 > > new file mode 100755 > > index 00000000..0f275dea > > --- /dev/null > > +++ b/tests/ext4/056 > > @@ -0,0 +1,108 @@ > > +#! /bin/bash > > +# SPDX-License-Identifier: GPL-2.0 > > +# Copyright (c) 2022 IBM. All Rights Reserved. > > +# > > +# We don't currently support resize of EXT4 filesystems mounted > > +# with sparse_super2 option enabled. Earlier, kernel used to leave the resize > > +# incomplete and the fs would be left into an incomplete state, however commit > > +# b1489186cc83[1] fixed this to avoid the fs corruption by clearly returning > > +# -ENOTSUPP. > > +# > > +# This test ensures that kernel handles resizing with sparse_super2 correctly > > +# > > +# Related commit in mainline: > > +# > > +# [1] commit b1489186cc8391e0c1e342f9fbc3eedf6b944c61 > > +# ext4: add check to prevent attempting to resize an fs with sparse_super2 > > +# > > + > > +. ./common/preamble > > +_begin_fstest auto ioctl resize quick > > + > > +# real QA test starts here > > + > > +INITIAL_FS_SIZE=1G > > +RESIZED_FS_SIZE=$((2*1024*1024*1024)) # 2G > > +ONLINE_RESIZE_BLOCK_LIMIT=$((256*1024*1024)) > > + > > +STOP_ITER=255 # Arbitrary return code > > + > > +_supported_fs ext4 > > +_require_scratch_size $(($RESIZED_FS_SIZE/1024)) > > +_require_test_program "ext4_resize" > > + > > +log() > > +{ > > + echo "$seq: $*" >> $seqres.full 2>&1 > > +} > > + > > +do_resize() > > +{ > > + _mkfs_dev -E resize=$ONLINE_RESIZE_BLOCK_LIMIT -O sparse_super2 \ > > + $SCRATCH_DEV $INITIAL_FS_SIZE >> $seqres.full 2>&1 \ > > + || _fail "$MKFS_PROG failed. Exiting" > > + > > + _scratch_mount || _fail "Failed to mount scratch partition. Exiting" > > + > > + local BS=$(_get_block_size $SCRATCH_MNT) > > + local REQUIRED_BLOCKS=$(($RESIZED_FS_SIZE/$BS)) > > + > > + local RESIZE_RET > > + local EOPNOTSUPP=95 > > + > > + log "Resizing FS" > > + $here/src/ext4_resize $SCRATCH_MNT $REQUIRED_BLOCKS >> $seqres.full 2>&1 > > + RESIZE_RET=$? > > + > > + # Test appears to be successful. Stop iterating and confirm if FS is > > + # consistent. > > + if [ $RESIZE_RET = $EOPNOTSUPP ] > > + then > > + log "Resize operation not supported with sparse_super2" > > + log "Threw expected error $RESIZE_RET (EOPNOTSUPP)" > > + return $STOP_ITER > > + fi > > + > > + # Test appears to be unsuccessful. Most probably, the fs is corrupt, > > + # iterate a few more times to further stress test this. > > + log "Something is wrong. Output of resize = $RESIZE_RET. \ > > + Expected $EOPNOTSUPP (EOPNOTSUPP)" > > + > > + # unmount after ioctl sometimes fails with "device busy" so add a small > > + # delay > > + sleep 0.2 > > + _scratch_unmount >> $seqres.full 2>&1 \ > > + || _fail "$UMOUNT_PROG failed. Exiting" > > +} > > + > > +run_test() > > +{ > > + local FSCK_RET > > + local ITERS=8 > > + local RET=0 > > + > > + for i in $(seq 1 $ITERS) > > + do > > + log "----------- Iteration: $i ------------" > > + do_resize > > + RET=$? > > + > > + [ "$RET" = "$STOP_ITER" ] && break > > + done > > + > > + log "-------- Iterations Complete ---------" > > + log "Checking if FS is in consistent state" > > + _check_scratch_fs > > _check_scratch_fs will exit the test on failure and print error message, > which will break the golden image, so there's no need to check fsck ret. > > > + FSCK_RET=$? > > + > > + [ "$FSCK_RET" -ne "0" ] && \ > > + echo "fs corrupt. Check $seqres.full for more details" > > + > > + return $FSCK_RET > > So I removed above hunk on commit. > > Thanks for the test! And my apology to the HUGE delay on review.. No worries Eryu, thanks a lot for the review :) Regards, Ojaswin > > Thanks, > Eryu > > > +} > > + > > +echo "Silence is golden" > > +run_test > > +status=$? > > + > > +exit > > diff --git a/tests/ext4/056.out b/tests/ext4/056.out > > new file mode 100644 > > index 00000000..6142fcd2 > > --- /dev/null > > +++ b/tests/ext4/056.out > > @@ -0,0 +1,2 @@ > > +QA output created by 056 > > +Silence is golden > > -- > > 2.27.0
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