jbd2_journal_lock_updates(9)

📦 version 7.3.1, in nixpkgs unstable

💅 jbd2_journal_lock_updates — like, the transaction barrier era

okay so this is a page from the Kernel API Manual bestie, and it's about one little function that is genuinely SO important, no cap. also it's void, so it doesn't even return anything, it just does things. main character energy fr.

Let me put the function signature right here so you can see her in all her glory:

void jbd2_journal_lock_updates (journal_t *journal);

✨ NAME ✨

jbd2_journal_lock_updates — establish a transaction barrier. that's it, that's the whole vibe. a barrier. a literal "nobody moves until I say so" moment. 🛑

🦋 SYNOPSIS 🦋

void jbd2_journal_lock_updates (journal_t *journal);

🎀 ARGUMENTS 🎀

  • journal — the journal you wanna establish that barrier on. that's the whole parameter. she's the star of the show 💖

🌸 DESCRIPTION 🌸

okay so here's what she does, and it's kind of iconic actually:

she locks out any further updates from being started, and then she blocks until all existing updates have completed. like she's the bouncer at the club and she's not letting anybody new in until everyone already inside has left. 🫶

she returns only once the journal is in a quiescent state with no updates running. quiescent. quiet. calm. no updates running. periodt.

⚠️ important caveat bestie, don't skip this one: the journal lock should not be held on entry. like, do NOT walk in already holding the lock. that's not the move. 🙈

👑 SEE ALSO 👑

the kernel file this lives in is ./fs/jbd2/transaction.c, and here's her whole friend group, all listed exactly like this:

🌸✨ and that's the whole page, bestie! this one came out of ./fs/jbd2 and she's dated October 2026 — so like, future girlie energy. slay. 💜🎀✨

📦 where this page comes from