nilfs_cpfile_get_cpinfo(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nilfs_cpfile_get_cpinfo(9) — or, how to peek at checkpoints, bestie

okay so this is a Kernel API Manual page for nilfs_cpfile_get_cpinfo, which lives in the kernel. yes, that kernel. we're in the big leagues now 🫶

✨ NAME ✨

nilfs_cpfile_get_cpinfo — literally just "get information on checkpoints" 💖 that's the whole vibe. she retrieves checkpoint deets, no cap.

🌸 SYNOPSIS 🌸

ssize_t nilfs_cpfile_get_cpinfo (struct inode *cpfile , __u64 *cnop ,
int mode , void *buf , unsigned int cisz , size_t nci );

look at her. six args. main character energy fr fr 👑

🎀 ARGUMENTS 🎀

  • cpfile — the checkpoint file inode 💅 like, the actual checkpoint file, as an inode. that's your source of truth.
  • cnop — the place where you pass in a starting checkpoint number, and the same spot receives a checkpoint number so you can keep searching 🔁 it's giving input-and-output, she does both.
  • mode — the mode of checkpoints that the caller wants to retrieve 🦋 you're being picky on purpose, and that's iconic.
  • buf — the buffer where the checkpoints' information gets stored 🎁
  • cisz — byte size of one checkpoint info item in the array 📏 yes, in the array. sizes matter.
  • nci — number of checkpoint info items to retrieve 🔢 how many you want, bestie.

🌈 DESCRIPTION 🌈

so nilfs_cpfile_get_cpinfo searches for checkpoints that are in the mode state, starting from the checkpoint number stored in cnop, and then it stores information about the checkpoints it found into buf ✨

the buffer pointed to by buf must be large enough to store information for nci checkpoints. like, non-negotiable. do the math before you call her 🙈

and if at least one checkpoint information is successfully retrieved, cnop gets updated so it points to the checkpoint number to continue searching 🔁 so you can loop her and keep going. obsessed.

⭐ RETURN ⭐

on success you get the count of checkpoint info items stored in the output buffer 🎉 otherwise you get one of these negative error codes, and honestly, mood:

  • -EINVAL — Invalid checkpoint mode. 🚫
  • -ENOMEM — Insufficient memory available. 😭
  • -EIO — I/O error (including metadata corruption). 💀 (yes, including metadata corruption. be scared.)
  • -ENOENT — Invalid checkpoint number specified. 👻

🦋 SEE ALSO 🦋

Kernel file ./fs/nilfs2/cpfile.c — and the whole friend group:

okay that's the whole page, go be a kernel dev about it 🧚💜 this one's from ./fs/nilfs2, dated October 2026 — so like, future iconic. periodt. 💅✨

📦 where this page comes from