NILFS2 Full Space Bug Reproduction

We have prepared a scripts to reproduce a Full Space Bug in NILFS2. We have used Linux Kernel v6.9.2 and v6.9.4 in our experiments, however, we recommend using v6.9.4. A sample log, captured while this problem was triggered using our script on NILFS2 (mounted on a ramdisk with Linux v6.9.4), is available in this repository as example_output.sh.

Setting up the Environment

We need to install Linux Kernel v6.9.4 before using the replayer. We have provided a kernel config, .kernel-6.9.4-config, that corresponds to the kernel used by us during the above experiment. On a Linux machine, follow the below steps to setup a Kernel with v6.9.4.

(Note: Reminder to backup/snapshot your machine before installing a new Kernel.)

• First clone the respository using the following git command:

git clone https://github.com/sbu-fsl/nilfs2-full-space.git

This will clone the repo in a folder name nilfs2-full-space

• To compile the kernel, you will need to install some packages, for Debian/Ubuntu Linux (the distro used for our experiments) use the below commands for installation:

sudo apt-get update sudo apt-get install build-essential libncurses-dev bison flex libssl-dev libelf-dev make

• Then clone the Kernel source code, extract it, and then cd into the folder:

wget https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.9.4.tar.xz

tar -xf linux-6.9.4.tar.xz

cd linux-6.9.4

• Copy the provided kernel config to the Linux kernel source directory and name it .config (the command assumes that nilfs2-full-space has been cloned in the root folder):

cp ~/nilfs2-full-space/.kernel-6.9.4-config .config

• Use the configuration tool to ensure your .config file is correctly set up.

make oldconfig

• Compile the kernel

make -j$(nproc)

• Compile kernel modules

sudo make modules_install

• Install the compiled kernel

sudo make install

• After executing the above steps, reboot your machine

sudo reboot

• Then verify that you have successfully installed Linux Kernel v6.9.4

uname -mars

NILFS2 Settings

• To work with NILFS2, you need to install the NILFS tools

sudo apt-get install nilfs-tools

• Open the nano editor to modify the nilfs_cleanerd.conf file

sudo nano /etc/nilfs_cleanerd.conf

In the editor, change the value of the protection_period parameter to 10 (from the default 3600) to make the cleaner run more frequently

Save and exit the editor

Running the script

• Navigate to the directory where the script is located

cd ~/nilfs2-full-space/

• Make the script executable

chmod +x stuck_at_100.sh

• Run the script

sudo ./stuck_at_100.sh > ~/nilfs2-full-space/output.log 2>&1