VFS_BUSY(9)

💅 VFS_BUSY(9) — the vfs_busy girlies' guide 💅

okay so this is a page from the Kernel Developer's Manual and it's about vfs_busy, bestie. it's short, it's iconic, it's giving "small but mighty." let's get into it ✨

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🌸 NAME 🌸

vfs_busy — marks a mount point as busy

🎀 SYNOPSIS 🎀

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

int
vfs_busy(struct mount *mp, int flags);

🦋 DESCRIPTION 🦋

so the vfs_busy() function marks a mount point as busy by incrementing the reference count of a mount point. that's the whole glow-up, no cap 💅

it also delays unmounting by sleeping on mp if the MNTK_UNMOUNT flag is set in mp->mnt_kern_flag and the MBF_NOWAIT flag is not set. like, it literally says "not right now, we're busy" and takes a little nap about it 😴

its arguments are:

• mp — the mount point to busy. this is the main character, the one getting marked.
• flags — flags controlling how vfs_busy() should act. the vibes controller, basically 🎛️
  • MBF_NOWAIT — do not sleep if MNTK_UNMOUNT is set. no naps allowed, periodt 🙅‍♀️
  • MBF_MNTLSTLOCK — drop the mountlist_mtx in the critical path. release the lock, it's not holding you back bestie 🔓

⭐ RETURN VALUES ⭐

A 0 value is returned on success. slay! 🎉

If the mount point is being unmounted and the MBF_NOWAIT flag is specified, ENOENT will be returned. not the win we wanted, but the win we deserved 😭

🔥 ERRORS 🔥

• [ENOENT] — the mount point is being unmounted (MNTK_UNMOUNT is set). it's literally on its way out, sorry babe 💀

🌈 SEE ALSO 🌈

• vfs_unbusy(9) — the counterpart, the "okay we're done here" energy. iykyk 🫶

👑 AUTHORS 👑

This manual page was written by Chad David <davidc@acns.ab.ca>. thank you Chad, you ate that fr fr 🍓

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ngl this one's short, but everything in it matters — don't skip the flags, don't skip the errors, that's the whole plot 🧚

and that's the tea 🎀 — much love from Debian, dated February 11, 2013. go busy a mount point responsibly, bestie 💖