VFS_MOUNT(9)

💖 VFS_MOUNT — bestie, we're mounting a file system 💖

okay so this is VFS_MOUNT(9) from the Kernel Developer's Manual — yes, the section 9 one, the kernel-nerd one, not the lil baby section 1 ones. this is the macro that gets your file system into the namespace. iconic behavior honestly. 🦋

✨ SYNOPSIS ✨

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

int
VFS_MOUNT(struct mount *mp);

🌸 DESCRIPTION 🌸

The VFS_MOUNT() macro mounts a file system into the system's namespace, or updates the attributes of an already mounted file system. two jobs, one macro, main character energy fr fr. 👑

The arguments it expects are:

• mp — Structure representing the file system.

So the way this works is: VFS_MOUNT() gets called both to mount brand new file systems and to change the attributes of an existing one. same macro, different vibe depending on one lil flag. 🎀

if the MNT_UPDATE flag is set in mp->mnt_flag, then the file system should update its internal state from the value of mp->mnt_flag. yes, it reads itself. no, that's not a typo, that's just how it is. 💅

That MNT_UPDATE path is lowkey multipurpose — it can be used, for instance, to convert a read-only file system to read-write. it's also what mountd(8) uses to update the NFS export information for the file system. so like, glow-ups for file systems. ✨

And if the MNT_UPDATE flag is not specified? then congrats, this is a newly mounted file system, fresh out the box 🎁. The file system code should allocate and initialize any private data needed to represent the file system — and it can use the mp->mnt_data field to store this information. put ur stuff there bestie, that's literally what it's for. 🫶

👀 SEE ALSO 👀

• VFS(9)
• vnode(9)

💜 AUTHORS 💜

This manual page was written by Doug Rabson. king behavior, we stan. 🫡

and that's the whole page, no cap — written by Doug Rabson, living in the Debian edition of the manual, dated May 23, 2009. go mount something cute bestie, ily, mwah 💖✨🎀