nilfs_ioctl_change_cpmode(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nilfs_ioctl_change_cpmode(9) — the Kernel API Manual, bestie edition 🎀

okay so this page lives in the Kernel API Manual and it's literally called nilfs_ioctl_change_cpmode(9) — say that five times fast, i dare you 😭 it's the glow-up button for checkpoints, fr fr.

✨ NAME ✨

nilfs_ioctl_change_cpmode — change checkpoint mode (checkpoint/snapshot) 🦋

the way this function just. flips a checkpoint between two whole identities?? main character energy honestly 👑

🌸 SYNOPSIS 🌸

int nilfs_ioctl_change_cpmode (struct inode *inode , struct file *filp ,
unsigned int cmd , void __user *argp );

copy it exactly like that, spacing and all, don't come for me 💅

💖 ARGUMENTS 💖

  • inode — inode object. the little guy in question 🫶
  • filp — file object. yep, the file one ✨
  • cmd — ioctl's request code. it's giving "which flavour of request are we doing" 🍓
  • argp — pointer on argument from userspace. that pointer comes straight from userspace, no cap 👀

🔥 DESCRIPTION 🔥

so nilfs_ioctl_change_cpmode changes the mode of a given checkpoint between checkpoint and snapshot state. that's it, that's the whole vibe — one checkpoint, two states, one function to shuffle between them 💫

and where do you actually meet this icon? this ioctl is used in the chcp and mkcp utilities. yup, those ones. iykyk 🧚

⭐ RETURN ⭐

0 on success 🎉 or one of these negative error codes if it's not slaying:

  • -EFAULT — Failure during checkpoint mode changing. 😭 something went sideways mid-change
  • -EPERM — Operation not permitted. 💀 you simply do not have the range for this one
ngl, negative error codes are the "read the room" of the kernel — check them, bestie, always 🌈

🌸 SEE ALSO 🌸

the whole friend group, in order, zero skips:

like, that's a whole entourage 💜

🎀 sign-off 🎀

this little beauty comes from ./fs/nilfs2 and it's dated October 2026 — screenshot it, bookmark it, obsess over it, and go flip some checkpoints, bestie 💖✨👑

📦 where this page comes from