Solved r/w access to UFS from Linux

Machiaveli said:
The counter intuitiveness comes from the numerous GNU/Linux distributions having their own kernel configuration but once you know what the kernel supports (either via loadable modules or builded ones directly onto the kernel) things got clearer.
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What I don't understand is why they include a module in a kernel just to blacklist it later on. Why not simply leave that module out?
Then again, I find it hard sometimes to understand all these Linux innovations. You mentioned systemd already.
 
Um, if you are using a Debian or Ubuntu Linux box then you are out of luck with the stock kernel of having write support for UFS partitions, as they have write support disabled by default and the only way to get that would be to roll your own Linux kernel with that option re-enabled when you configure the (hundreds of) options for it. Despite this Stack Exchange answer being very old the state of affairs is still the same: Answer to "Mounting ufs partition with read/write permissions on ubuntu 10.04" - as when you try to include rw in a sudo mount -t ufs -o ufstype=ufs2,rw,user /dev/sdXX /media/somewhere you get this in your syslog:
Code: 
[19043.734096] ufs: ufs was compiled with read-only support, can't be mounted as read-write

I just found this out the hard way - I need to tweak an installer and I thought I could edit /boot/loader.conf in that on a working GNU/Linux ("Devuan 4") OS so as to reinstall on a borked FreeBSD OS.
 
I've used the Suse Tumbleweed,that has all the kernel parameters already well configured to enable the read and write feature for the UFS fs,as you can see :

# zcat /proc/config.gz|grep -i ufs

CONFIG_SCSI_UFSHCD=m
CONFIG_SCSI_UFS_BSG=y
CONFIG_SCSI_UFS_CRYPTO=y
# CONFIG_SCSI_UFS_FAULT_INJECTION is not set
CONFIG_SCSI_UFS_HWMON=y
CONFIG_SCSI_UFSHCD_PCI=m
# CONFIG_SCSI_UFS_DWC_TC_PCI is not set
CONFIG_SCSI_UFSHCD_PLATFORM=m
CONFIG_SCSI_UFS_CDNS_PLATFORM=m
CONFIG_UFS_FS=m
CONFIG_UFS_FS_WRITE=y
# CONFIG_UFS_DEBUG is not set

Despite this,when I mounted it,It stayed / staid in read only mode :

# mount -t ufs -o ufstype=ufs2,rw,user /dev/vdc2 /mnt/vdc2
 
Last edited:
cracauer@ said:
No, there is a compile time option for read/write access.
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You will damage your UFS partition (and lose data) with rw. I had lost some myself. That's why most distros don't build their kernels with it by default. Even the option's name and description advise against it:
UFS file system write support (DANGEROUS)
CONFIG_UFS_FS_WRITE:

Say Y here if you want to try writing to UFS partitions. This is experimental, so you should back up your UFS partitions beforehand.
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So the OP's question of accessing UFS from linux passed by? Not forgetting virtualisation techniques, anyway, now unwatching this if you're suggesting any self respecting geek only has one PC...
 
RypPn said:
So the OP's question of accessing UFS from linux passed by?
Click to expand...

I did this on openSUSE Tumbleweed and Leap GNOME LiveUSBs a month ago, but didn't try rw (not sure if it didn't work or if it was just more-convenient to keep ro from a copy/paste :p):

Code: 
mount -t ufs -o loop,ro,ufstype=ufs2 /dev/nvme0n1p2 /media/p2
 
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