Hi Zorro,
> > Regression test for:
> > a6b3bfe176e8 ext4: fix corruption during on-line resize
> >
> > Signed-off-by: Srivathsa Dara <srivathsa.d.dara@xxxxxxxxxx>
> > ---
> > tests/ext4/060 | 43 +++++++++++++++++++++++++++++++++++++++++++
> > tests/ext4/060.out | 2 ++
> > 2 files changed, 45 insertions(+)
> > create mode 100755 tests/ext4/060
> > create mode 100644 tests/ext4/060.out
> >
> > diff --git a/tests/ext4/060 b/tests/ext4/060 new file mode 100755
> > index 00000000..440748ea
> > --- /dev/null
> > +++ b/tests/ext4/060
> > @@ -0,0 +1,43 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2024 Oracle. All Rights Reserved.
> > +#
> > +# FS QA Test 060
> > +#
> > +# This test ensures that kernel avoids FS corruption while online #
> > +resizing an ext4 filesystem with disabled resize_inode feature.
> > +#
> > +# The commit a6b3bfe176e8 ("ext4: fix corruption during on-line
> > +resize") # stops the corruption.
> > +#
> > +
> > +. ./common/preamble
> > +_begin_fstest auto resize quick
> > +
> > +_supported_fs ext4
> > +_fixed_by_kernel_commit a6b3bfe176e8 \
> > + "ext4: fix corruption during on-line resize"
> > +
> > +_require_command "$RESIZE2FS_PROG" resize2fs _require_command
> > +"$E2FSCK_PROG" e2fsck _require_scratch_size_nocheck $((9* 1024 *
> > +1024))
> > +
> > +# Initialize an EXT4 filesystem with the resize_inode feature
> > +disabled, # and a size of 128MiB less than 8GiB, i.e., short of 1
> > +block group in # an 8GiB filesystem.
> > +
> > +dev_size=$((8* 1024 * 1024 * 1024 - 128 * 1024 * 1024))
> > +MKFS_OPTIONS="-O ^resize_inode $MKFS_OPTIONS" _scratch_mkfs_sized $dev_size \
> > + >>$seqres.full 2>&1
>
> Just for sure, is the 8G fs size a necessary requirement to reproduce the bug?
> Is it related with the block size (e.g. different blocksize need different fs size for testing)?
Yes, the issue was that, before the fix, while performing an online
resize of a filesystem with the resize_inode feature disabled, the
kernel would corrupt the first block of the last group in the 0th meta_bg.
If the block size is 1024, each meta_bg has 16 (1024/64) block groups.
The last blockgroup of the 0th meta_bg is 15, and the block that gets
corrupted is the 122,880th block, which is the first block of the 15th block group.
If the block size is 2048, each meta_bg has 32 (2048/64) block groups.
The last blockgroup of the 0th meta_bg is 31, and the block that gets
corrupted is the 507,904th block, which is the first block of the 31st block group.
If the block size is 4096, each meta_bg has 64 (4096/64) block groups.
The last blockgroup of the 0th meta_bg is 63, and the block that gets
corrupted is the 2,064,384th block, which is the first block of the 63rd block group.
The corruption occurred because, when updating backup group descriptors,
the kernel failed to check whether the group descriptor being updated belonged
to the meta_bg layout or not, leading to an incorrect block being updated.
Hence, the corruption.
To reproduce the issue, the initial filesystem's descriptor block must have
some available space, and the resize operation should increase the filesystem
size enough to cross the meta_bg boundary.
In this case, the initial filesystem size was chosen as 8GiB minus 128MiB,
so that its descriptor block has space to accommodate an additional block group.
The filesystem is then resized to 9GiB ( 8GiB is the meta_bg boundary).
>
> > +
> > +_scratch_mount
> > +
> > +# Perform online-resize
> > +$RESIZE2FS_PROG $SCRATCH_DEV 9G >> $seqres.full 2>&1
> > +
> > +$E2FSCK_PROG -fn $SCRATCH_DEV >> $seqres.full 2>&1 || _fail "Filesystem corrupted"
>
> Do you want to test online resize or online fsck or both? (Does ext4 support online fsck?)
I want to test only the online resize. No, EXT4 doesn't support online fsck.
However, e2fsck with the -fn option reports corruption even if the device
is mounted.
Thanks,
Srivathsa
>
> > +
> > +echo "Silence is golden"
> > +
> > +status=0
> > +exit
> > diff --git a/tests/ext4/060.out b/tests/ext4/060.out new file mode
> > 100644 index 00000000..8ffce4de
> > --- /dev/null
> > +++ b/tests/ext4/060.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 060
> > +Silence is golden
> > --
> > 2.39.3
> >
> >
