VFS_VGET(9)

💖 NAME 💖

okay so bestie, this is VFS_VGET(9) — a page from the Kernel Developer's Manual — and it’s literally about converting an inode number to a vnode. ✨ That’s the whole assignment. No cap. 🫶

🌸 SYNOPSIS 🌸

bestie, here’s the spell you need to cast at the top of your file:

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

int
VFS_VGET(struct mount *mp, ino_t ino, int flags, struct vnode **vpp);

That function signature is the main character, periodt. 👑

🦋 DESCRIPTION 🦋

VFS_VGET() literally looks up or creates a vnode from a (mount, inode#) tuple. It’s giving “matchmaker for filesystem objects” energy. 💅

Its arguments are:

• mp — the mount point. like, the mount point. that’s it. 🎀
• ino — the inode representing the file. this is a unique number assigned by the file system when vnodes are first created. unique number moment, iykyk. ✨
• flags — additional locking flags to pass through to vget(9). pass them through, bestie, don’t gatekeep. 🔥
• vpp — return parameter for the vnode. this is where the vnode comes back out. 🫶

This is an optional file system entry-point for file systems mainly intended for NFS server use, but many file systems use it internally in VOP_LOOKUP(9) and similar. so it’s lowkey everywhere. 😭

If the file system does not support this call, then it should return EOPNOTSUPP. that’s the polite “not supported, bestie” signal. 🚫

Please see ffs_vget() in sys/ufs/ffs/ffs_vfsops.c for the canonical example. like, the blueprint. the reference fit. the one to study. 📚✨

🌈 SEE ALSO 🌈

• VFS(9)
• vget(9)
• vnode(9)

💜 AUTHORS 💜

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

mwah 💋 — huge shoutout to Debian (the source/version from the footer) and January 7, 2005 (the date), folded into this cute sign-off, bestie. 🎀🦋