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Date:      Mon, 7 Jul 2014 21:39:15 -0700
From:      Kevin Oberman <rkoberman@gmail.com>
To:        Mathias Picker <Mathias.Picker@virtual-earth.de>
Cc:        questions@freebsd.org
Subject:   Re: Cannot create files on exfat card / 10-stable
Message-ID:  <CAN6yY1t-e=47HRcHVoxD7saDu0KZADf-pt-mU1CZKJ5x-td1vw@mail.gmail.com>
In-Reply-To: <1403792937.2308.16.camel@marcopolo.fritz.box>
References:  <CAN6yY1sHvy0BM2XuSRroSPPXjGV4nR1w60sOg==Sbic72Tw4pQ@mail.gmail.com> <1403792937.2308.16.camel@marcopolo.fritz.box>

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On Thu, Jun 26, 2014 at 7:28 AM, Mathias Picker <
Mathias.Picker@virtual-earth.de> wrote:

> Am Mittwoch, den 25.06.2014, 13:48 -0700 schrieb Kevin Oberman:
> > > Hi all,
> > >
> > > I just got my first exfat formatted sdxc card.
> > >
> > > If I mount it with (as root) mount.exfat /dev/da2s1 /mnt I can read the
> > > content, create *directories*, but *not files*???
> > >
> > >
> > >     root@marcopolo:/mnt # touch test1
> > >     touch: test1: Invalid argument
> > >     root@marcopolo:/mnt # mkdir test1
> > >     root@marcopolo:/mnt # touch test1/test
> > >     touch: test1/test: Invalid argument
> > >     root@marcopolo:/mnt # ll -d test1
> > >     drwxr-xr-x  1 root  wheel  131072 16 Feb 19:46 test1/
> > >     root@marcopolo:/mnt # ll test1
> > >     total 0
> > >
> > >
> > >
> > > Shouldn't this work?
> > >
> > > I rebuilt fusefs-lib and fusefs-exfat with gcc48, same result...
> > >
> > > This is on a recent stable:
> > > marcopolo% uname -a
> > > FreeBSD marcopolo 10.0-STABLE FreeBSD 10.0-STABLE #14 r261827: Thu Feb
> > > 13 13:13:01 CET 2014     mathiasp@marcopolo
> :/usr/obj/usr/src/sys/GENERIC
> > > amd64
> > >
> > > The card is a Sandisk Extreme MicroSDXC 64Gb. Works fine in my phone.
> > >
> > > Any tips, hints, experiences?
> > >
> > > Thanks, Mathias
> >
> > I have no answer as I found this message in the archive while
> > researching the root cause of the problem.
> >
>
> Thanks, first feedback, now I finally know it's not just me...
> >
> > Workaround: After writing to the device on FreeBSD, put the card into
> > a Windows system. (It will also be usable to write to the device.)
> > Open an explorer (not Internet Explorer) window
> > Right click on the ExFAT device
> > Select "Properties"
> > In the Properties window, select the "Tools" tab
> >
> > In the tools window click "Check now"
> >
> > In the disk check window click start
> >
> > No errors should be found, but the disk will now be writable on
> > Windows. Note that the directories you appeared to be creating on
> > FreeBSD will be gone.
> >
> > Eject the media and mount it on the FreeBSD system I t will be
> > writable until it is re-mounted.
>
> :) Interesting approach, I switched to FAT for now, works well enough
> for me...
> >
> >
> > I believe the problem is that unmounting the file system fails to mark
> > the fs as clean. You might notice that a message that the device was
> > not cleanly dismounted is printed to the console and messages when the
> > device is re-mounted on FreeBSD. There is no fsck for ExFAT, so I need
> > to use Windows to do the same job.
> >
> >
> > It looks like all that is needed is to clear the second bit of byte
> > 106 of the VBR (block 0). I will try this some day when I am feeling
> > brave.
> >
> >
> > I'd love to see this fixed
>
> Me too! But way over my head.
>
> Again, thanks for the feedback!
>
> Mathias
> >
>

I have learned a bit more by monitoring the dirty bit with dumpexfat (part
of sysutils/exfat-utils) The second bit of  Volume State is set for "dirty".

If the system is shutdown, the dirty bit is not cleared. If I manually
umount the filesystem, the bit is cleared and subsequent mount can be
written to. I also noted that, even after the dirty mount of the
filesystem, a manual unmount and mount restores the system to its normal
condition. It appears that the device is not being correctly unmounted at
shutdown.
n any case, it is pretty quick to restore normal operations should you need
to deal with and exfat filesystem.
-- 
R. Kevin Oberman, Network Engineer, Retired
E-mail: rkoberman@gmail.com



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