VOP_LOCK(9)

✨ VOP_LOCK — it's giving "one at a time, bestie" ✨

okay so welcome to VOP_LOCK(9), a page from the Kernel Developer's Manual 💅 and honestly? this one is so important it's not even funny.

🌸 NAME 🌸

VOP_LOCK, VOP_UNLOCK, VOP_ISLOCKED, vn_lock — the way to serialize access to a vnode 🫶

🎀 SYNOPSIS 🎀

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/vnode.h>

int
VOP_LOCK(struct vnode *vp, int flags);

int
VOP_UNLOCK(struct vnode *vp, int flags);

int
VOP_ISLOCKED(struct vnode *vp);

int
vn_lock(struct vnode *vp, int flags);

💖 DESCRIPTION 💖

These calls are literally the bouncers of the filesystem — they serialize access to the file system, so like, two writes to the same file don't happen at the same time and cause chaos 😭 no cap.

The arguments are, bestie:

• vp — the vnode getting locked or unlocked. the main character of this whole situation 👑
• flags — one of the lock request types:
  • LK_SHARED — shared lock. we're all just vibing here 🌈
  • LK_EXCLUSIVE — exclusive lock. my vnode, my rules 💅
  • LK_UPGRADE — shared-to-exclusive upgrade. glow-up arc ✨
  • LK_DOWNGRADE — exclusive-to-shared downgrade. humble era 🙈
  • LK_RELEASE — release any type of lock. bye bestie 🦋
  • LK_DRAIN — wait for all lock activity to end. we're not leaving until everyone's gone, periodt 💀

The lock type may be or'ed with these lock flags:

• LK_NOWAIT — do not sleep to wait for lock. no napping on the job 😴🚫
• LK_SLEEPFAIL — sleep, then return failure. wake up and choose violence 💀
• LK_CANRECURSE — allow recursive exclusive lock. it's giving inception 🌀
• LK_NOWITNESS — instruct witness(4) to ignore this instance. not me telling witness to look away 🙈

The lock type may be or'ed with these control flags:

• LK_INTERLOCK — specify when the caller already has a simple lock (VOP_LOCK() will unlock the simple lock after getting the lock). 🧚
• LK_RETRY — retry until locked. we try again and again until it works, obsessed fr fr 🔥

🚨 real talk, kernel devs: kernel code should use vn_lock() to lock a vnode rather than calling VOP_LOCK() directly. and btw vn_lock() also does not want a thread specified as argument, but it assumes curthread to be used. iykyk 💜

⭐ RETURN VALUES ⭐

Zero is returned on success, otherwise an error is returned. that's it, that's the tea 🍓

🌈 SEE ALSO 🌈

• vnode(9)

💜 AUTHORS 💜

This manual page was written by Doug Rabson. iconic behavior, honestly 👑

Debian · February 25, 2008 — yeah she's been slaying since '08, and this is your girl signing off, mwah 💋 🫶✨