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

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

[Arthur Marsh]

 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 

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

amarsh04@victoria:~$ mount|grep vic/dev/sdb6 on /vict type vfat
(rw,relatime,uid=65534,gid=65534,fmask=0000,dmask=0000,allow_utime=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro)

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

Arthur. 


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

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

[Shuah Khan]

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

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

[Arthur Marsh]

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

# CONFIG_KUNIT is not set

I am re-running the git-bisect without the " - - fs/fat" qualifier but it will take a few days.

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

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

[Shuah Khan]

On 9/10/21 12:33 PM, Arthur Marsh wrote:
>> Can you send your config and dmesg? This will help determine if
>> KUNIT is enabled - it shouldn't be.
> 
> # CONFIG_KUNIT is not set
> 
> I am re-running the git-bisect without the " - - fs/fat" qualifier but it will take a few days.
> 

Can you run a quick test reverting the following one
at a time to isolate:

b0d4adaf3b3c4402d9c3b6186e02aa1e4f7985cd (this is the other one in
you bisect log)

c815f04ba94940fbc303a6ea9669e7da87f8e77d (This is the KUnit patch)
(This one shouldn't be in play without CONFIG_KUNIT)

thanks,
-- Shuah

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

[Brendan Higgins]

+David Gow - just FYI since you are the only KUnit person who touched
VFAT. PTAL at other emails in thread too, please.

On Fri, Sep 10, 2021 at 4:57 AM Arthur Marsh
<arthur.marsh@internode.on.net> 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
>
> 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
> git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftestgit
> bisect bad c815f04ba94940fbc303a6ea9669e7da87f8e77d# first bad commit:
> [c815f04ba94940fbc303a6ea9669e7da87f8e77d] Merge tag
> 'linux-kselftest-kunit-5.15-rc1' of
> git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
>
> amarsh04@victoria:~$ mount|grep vic/dev/sdb6 on /vict type vfat
> (rw,relatime,uid=65534,gid=65534,fmask=0000,dmask=0000,allow_utime=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro)

I don't see how our patch could have caused this either. Nevertheless,
I CC'ed David who has worked on VFAT who may be able to provide more
info.

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

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

[Shuah Khan]

On 9/10/21 3:23 PM, Brendan Higgins wrote:
> +David Gow - just FYI since you are the only KUnit person who touched
> VFAT. PTAL at other emails in thread too, please.
> 

Agree. Arthur confirmed CONFIG_KUNIT isn't enabled.

I requested for a quick test with (repeating this for David's benefit)

reverting the following one
at a time to isolate:

b0d4adaf3b3c4402d9c3b6186e02aa1e4f7985cd (this is the other one in
you bisect log)

c815f04ba94940fbc303a6ea9669e7da87f8e77d (This is the KUnit patch)
(This one shouldn't be in play without CONFIG_KUNIT)

thanks,
-- Shuah

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

[David Gow]

On Fri, Sep 10, 2021 at 8:02 PM Arthur Marsh
<arthur.marsh@internode.on.net> 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
>

I can't reproduce this on my machine (which is openSUSE Tumbleweed
with their "vanilla" 5.14 kernel package on x86_64, mounting a FAT16
filesystem).

# mount /dev/sda1 /mnt/victoria
# mount | grep vic
/dev/sda1 on /mnt/victoria type vfat
(rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
# uname -a
Linux patpat 5.14.0-1-vanilla #1 SMP Mon Aug 30 07:01:36 UTC 2021
(dc06e24) x86_64 x86_64 x86_64 GNU/Linux

I can try it again on an older i386 machine, but I doubt that'd change
things: this doesn't smell architecture-specific to me.

This seems a lot more like it's something to do with /proc/mounts or
similar, rather than a FAT specific issue (and, unless something
really strange has happened with the CONFIG_FAT_DEFAULT_CODEPAGE
config option, which I doubt), this change shouldn't affect anything
at all when KUnit isn't enabled and used. I suspect it just shows up
in the bisect because it's basically the only change in fs/fat for a
while.

The bisect against the whole kernel tree seems likely to be of more use.

-- David