bud_wbuf_callback(9)

📦 version 7.3.1, in nixpkgs unstable

💅 bud_wbuf_callback(9) — like, the UBIFS kernel API manual, bestie 🌸

okay so this is a page from the Kernel API Manual and it's all about bud_wbuf_callback, which — no cap — is the bud LEB write-buffer synchronization call-back. yes that's a mouthful, we'll get through it together 🫶

✨ NAME ✨

bud_wbuf_callback — the bud LEB write-buffer synchronization call-back. that's the whole vibe. 💫

🦋 SYNOPSIS 🦋

int bud_wbuf_callback (struct ubifs_info *c , int lnum , int free , int
pad );

literally just that one function, she's got four args and she's iconic for it 👑

🎀 ARGUMENTS 🎀

  • c — the UBIFS file-system description object. your main character struct 💖
  • lnum — the LEB the write-buffer was synchronized to. yes, that LEB 🍓
  • free — how many free bytes are left in this LEB. budget check, bestie 💸
  • pad — how many bytes were padded. the padding receipt 🧾

🔥 DESCRIPTION 🔥

so this is a callback function, right? and the way that the I/O unit just calls it when the write-buffer is synchronized? yeah. that's the whole thing. we need this to correctly maintain space accounting in bud logical eraseblocks — like, the math has to math, and this function is how we make sure it does 🧮✨

it returns zero in case of success and a negative error code in case of failure. zero = slay, negative = something went sideways 😭

and here's the little lore drop: this function actually belongs to the journal, but we keep it here because we want to keep it static. it's living in the wrong neighborhood on purpose, and honestly? valid 💅

🌈 SEE ALSO 🌈

Kernel file ./fs/ubifs/super.c, and honestly the whole friend group:

go read them, they're all in ./fs/ubifs and they ate 🔥👑

anyway that's the page!! it's from ./fs/ubifs, dated October 2026, and it's bud_wbuf_callback(9) forever and always. mwah, bye bestie 🎀💜🦋

📦 where this page comes from