VFS_GETNEWFSID(9)

💖 VFS_GETNEWFSID(9) 💖

ok bestie so this is a page from the Kernel Developer's Manual (section 9, kernel land, we're in the deep end and it's giving main character energy 🫶) and it's all about one lil function that hands out file system IDs like they're friendship bracelets.

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✨ NAME ✨

vfs_getnewfsid — allocate a new file system identifier 🎀

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🌸 SYNOPSIS 🌸

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

void
vfs_getnewfsid(struct mount *mp);

like yes it takes one (1) pointer and returns nothing, humble of it honestly 💅

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🦋 DESCRIPTION 🦋

okay so vfs_getnewfsid() allocates a brand new file system identifier for the mount point you give it. no cap, that's the whole job.

File systems typically call vfs_getnewfsid() in their mount routine so they can snag a unique ID within the system — and that ID can later be used to uniquely identify the file system through calls like vfs_getvfs(9). it's giving "get your own name tag at the party so people know who you are" 🎀

the actual fsid is made up of two 32 bit integers, and they live in the statfs structure of mp. breaking it down:

• the first integer is unique in the set of mounted file systems ✨
• the second holds the file system type 💫

and here's the struct, verbatim, no edits bestie:

typedef struct fsid {
        int32_t val[2];
} fsid_t;

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🧚 PSEUDOCODE 🧚

here's how it looks inside a mount routine, so you can clock the vibe:

xxx_mount(struct mount *mp, char *path, caddr_t data,
        struct nameidata *ndp, struct thread *td)
{
        ...
        vfs_getnewfsid(mp);
        ...
}

like, you literally just call it in the middle of everything else and it does its thing. obsessed. 🌈

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👑 SEE ALSO 👑

• vfs_getvfs(9) — the bestie that looks up the fsid later 💜

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💜 AUTHORS 💜

This manual page was written by Chad David <davidc@acns.ab.ca>.

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fr fr that's the whole page. it's short, it's sweet, it ate and left no crumbs 💅

kay bye ily, this page came from Debian and it's dated November 21, 2001 — yeah it's a vintage icon, we stan a classic 🎀✨💖