Re: f2fs bug: Unable to mount big volumes in kernel 4.5

[Matthias Prager <linux@matthiasprager.de>]

Am 22.03.2016 um 21:36 schrieb Jaegeuk Kim:
> Hi,
> 
> On Mon, Mar 21, 2016 at 11:56:02PM +0100, Matthias Prager wrote:
>> Hello everyone,
>>
>> if there really is a suboptimal/faulty alignment being done by
>> f2fs-tools <=1.6.0 (and I haven't done the math, so I'm just assuming),
>> wouldn't it be prudent to include a modified kernel patch, which allows
>> for mounting of older filesystems, but puts out a warning in dmesg which
>> advises the user to run fsck.f2fs some time in the future?
> 
> So, could you check the patch that I replied or the same patch that I attached
> here?
> That should dynamically fix this issue when mounting f2fs.
I will do so tomorrow and report back.

> 
> Thanks,
> 
>>
>> ---
>> Matthias
>>
>> Am 21.03.2016 um 21:58 schrieb David Gnedt:
>>> Hello,
>>>
>>>> Following commit in dev branch of f2fs-tools has fixed this issue, could you
>>> test this
>>>> patch firstly?
>>>> ("mkfs.f2fs: set segment_count in super block correctly")
>>>
>>> Sorry, I cannot recreate the volume on the 8TB Seagate drive right now, but I
>>> did a test with a loopback device of equal size.
>>>
>>> Should I be worried about the changes in mkfs.f2fs since 1.6.0? Would it be
>>> suggested to recreate the filesystem? Or is it maybe possible to manually fix it?
>>> If it is really only the alignment, I think it shouldn't matter for SMR drives,
>>> as they are not using constant size zones anyway, so misalignment cannot be
>>> avoided with f2fs.
>>>
>>>>> Could you test the attached patch?
>>>
>>> I did a roundup test of all kernel/f2fs-tools version I thought that make sense.
>>> I hope the patch will be included in upcoming mainline kernels.
>>>
>>> Short summary:
>>> --------------
>>> Filesystems created with a recent dev version of f2fs-tools work without any
>>> problems and don't need the f2fs kernel patch.
>>> Filesystems created with older f2fs-tools need the f2fs kernel patch to mount
>>> correctly.
>>> I guess that is exactly what everyone expected to be the outcome.
>>>
>>> Full details:
>>> -------------
>>> f2fs-tools D:  release 1.6.0 (Seagate SMR drive)
>>> f2fs-tools L1: release 1.6.0 (Loopback)
>>> f2fs-tools L2: 2016-01-08 mkfs.f2fs: introduce zone align for main area (Loopback)
>>> f2fs-tools L3: 2016-03-16 mkfs.f2fs: set segment_count in super block correctly
>>> (Loopback)
>>>
>>> Test procedure:
>>> $ truncate -s 8001559724032 f2fs-tools-1.6.0.img
>>> $ losetup -f f2fs-tools-1.6.0.img
>>> $ mkfs.f2fs -s64 -t0 -a0 /dev/loop0
>>> $ mount -t f2fs -onoinline_data,noatime,flush_merge,no_heap,ro /dev/loop0 /mnt
>>> $ umount /mnt
>>>
>>> Kernel: Linux 4.4.6 x86_64
>>> f2fs-tools D:  Works
>>> f2fs-tools L1: Works
>>> f2fs-tools L2: Works
>>> f2fs-tools L3: Works
>>>
>>> Kernel: Linux 4.5.0 x86_64
>>> f2fs-tools D:  Failed -> Same errors as before
>>> f2fs-tools L1: Failed -> Same errors as before
>>> f2fs-tools L2: Failed -> Same errors as before
>>> f2fs-tools L3: Works
>>>
>>> Kernel: Linux 4.5.0+patch x86_64
>>> f2fs-tools D:  Works
>>> f2fs-tools L1: Works
>>> f2fs-tools L2: Works
>>> f2fs-tools L3: Works
>>>
>>> Best regards,
>>> David Gnedt
>>>


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