VGET(9)

💜 VGET(9) — the Kernel Developer's Manual page you didn't know you needed

okay so bestie, real talk: this is vget from section 9 (that's the kernel-functions section, iykyk). It's short, it's sweet, and it's genuinely important if you're doing vnode shit. Let's get into it. 🦋

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✨ NAME ✨

vget — get a vnode from the free list. that's it. that's the whole vibe. 🎀

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🌸 SYNOPSIS 🌸

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

int
vget(struct vnode *vp, int lockflag, struct thread *td);

literally just include those two headers and you're off to the races, bestie. 🫶

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💅 DESCRIPTION 💅

So the actual main character move here: get a vnode from the free list and increment its reference count. That's the whole job. Two-for-one. Ate. 🔥

Here's what the arguments are giving:

• vp — the vnode you're pulling off the free list. this is the one, bestie.
• lockflag — if this is non-zero, the vnode will also be locked. not zero = locked. that's the rule. 🔒

Now the lore 💀 — when vnodes aren't in use, they get parked on a free list. The important detail: those vnodes still reference valid files, but they may be reused to refer to a new file at any time. so like... they're valid but also not yours yet. respect the ambiguity. 🙈

And usually these free-list vnodes are also chilling in caches around the system — the name cache being the classic example.

So here's the scenario: you've got a vnode that's on the free list, and you want to use it again. Like — say the vnode turned up in the name cache because of a call to VOP_LOOKUP(9). In that case the new user (that's you 💖) must call vget() to increment the reference count and remove it from the free list. Non-negotiable. Do it. periodt. 👑

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🦋 SEE ALSO 🦋

• vnode(9)
• vput(9)
• vref(9)
• vrele(9)

the whole vnode friend group, honestly. go read them. 🧚

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🌈 AUTHORS 🌈

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

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💖 cute little sign-off: this page ships from Debian, dated July 24, 1996, and it lives at VGET(9) in the Kernel Developer's Manual. yes, 1996. vintage. slay. 🎀✨