After KUnit update for Linux 5.15-rc1 - unable to share VFAT filesystem via samba

From: Arthur Marsh
Date: Fri Sep 10 2021 - 08:02:36 EST

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
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

The kernel build used was i386 with gcc 11.2.0-4 using

make - j2 menuconfig bindeb-pkg

.config available on request.

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:
[c815f04ba94940fbc303a6ea9669e7da87f8e77d] Merge tag
'linux-kselftest-kunit-5.15-rc1' of
bisect bad c815f04ba94940fbc303a6ea9669e7da87f8e77d# first bad commit:
[c815f04ba94940fbc303a6ea9669e7da87f8e77d] Merge tag
'linux-kselftest-kunit-5.15-rc1' of

amarsh04@victoria:~$ mount|grep vic/dev/sdb6 on /vict type vfat

Happy to run any further tests but kernel builds are slow on this machine (Pentium Dl.


Sent from my Android device with K-9 Mail. Please excuse my brevity.