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Subject: Re: After KUnit update for Linux 5.15-rc1 - unable to share VFAT
 filesystem via samba
To:     Arthur Marsh <arthur.marsh@internode.on.net>
Cc:     linux-kernel@vger.kernel.org, brendanhiggins@google.com,
        linux-kselftest@vger.kernel.org,
        Shuah Khan <skhan@linuxfoundation.org>
References: <6A72EAE4-A0F7-4CD2-89BB-36A8F4A7D321@internode.on.net>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <f1d84102-6edf-271f-52f9-0d4bbc85c0c7@linuxfoundation.org>
Date:   Fri, 10 Sep 2021 11:43:28 -0600
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Hi Arthur,

On 9/10/21 5:57 AM, Arthur Marsh wrote:
> 
>   Hi, I have been sharing an old VFAT formatted hard disk on one pc to
> another using Samba and sometime after kernel 5.14.0 it stopped working (apparently no longer being shared as the mount.smbfs command
> on the client failed with error -13 yet mount.smbfs still worked for
> ext3 filesytems shared from the same machine which had the VFAT
> filesystem).
>   The only error I saw on the machine with the VFAT formatted hard disk
> was the output of the mount command had truncated the name of the
> mount to only include the first 4 characters of the base name of the
> mount point.
>   e.g. when VFAT filesystem was mounted on /mnt/victoria, the output of
> the mount command showed the filesytem mounted on /mnt/vict
> 

This could be path name related to the second bad commit in your bisect.

> The kernel build used was i386 with gcc 11.2.0-4 using
> 
> make - j2 menuconfig bindeb-pkg
> 
> .config available on request.
> 

Can you send your config and dmesg? This will help determine if
KUNIT is enabled - it shouldn't be.

>   The git-bisect was:
> victoria:/usr/src/linux# git bisect loggit bisect start '--' 'fs/fat'#
> good: [7d2a07b769330c34b4deabeed939325c77a7ec2f] Linux 5.14git bisect
> good 7d2a07b769330c34b4deabeed939325c77a7ec2f# bad:
> [a3fa7a101dcff93791d1b1bdb3affcad1410c8c1] Merge branches 'akpm' and
> 'akpm-hotfixes' (patches from Andrew)git bisect bad
> a3fa7a101dcff93791d1b1bdb3affcad1410c8c1# good:
> [edb0872f44ec9976ea6d052cb4b93cd2d23ac2ba] block: move the bdi from
> the request_queue to the gendiskgit bisect good
> edb0872f44ec9976ea6d052cb4b93cd2d23ac2ba# good:
> [b0d4adaf3b3c4402d9c3b6186e02aa1e4f7985cd] fat: Add KUnit tests for
> checksums and timestampsgit bisect good


> b0d4adaf3b3c4402d9c3b6186e02aa1e4f7985cd# bad:

This one is a KUnit patch
Subject: [PATCH] fat: Add KUnit tests for checksums and timestamps


> [c815f04ba94940fbc303a6ea9669e7da87f8e77d] Merge tag
> 'linux-kselftest-kunit-5.15-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftestgit
> bisect bad c815f04ba94940fbc303a6ea9669e7da87f8e77d# first bad commit:
> [c815f04ba94940fbc303a6ea9669e7da87f8e77d] Merge tag

Subject: [PATCH] d_path: make 'prepend()' fill up the buffer exactly on
  overflow

> 'linux-kselftest-kunit-5.15-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
>
thanks,
-- Shuah