DTRACE_VFS(4)

💖 DTRACE_VFS(4) — dtrace_vfs, the VFS DTrace provider, bestie ✨

🌸 NAME 🌸

dtrace_vfs — a DTrace provider for Virtual File System. Yes bestie, that's the whole vibe: tracing VFS stuff with DTrace. 💅

✨ SYNOPSIS ✨

vfs:fplookup:function:name
vfs:namecache:function:name
vfs:namei:function:name
vfs:vop:function:name

💅 DESCRIPTION 💅

The DTrace vfs provider lets you trace events in the VFS(9) layer — that's the kernel interface for file systems on FreeBSD. 🦋

Run dtrace -l -P vfs to list all vfs probes. Add -v to generate program stability reports, which contain information about the number of probe arguments and their types. Very demure, very useful. ✨

• fplookup — this module defines a single probe, vfs:fplookup:lookup:done(struct nameidata *ndp, int line, bool status_code), that instruments the fast path lookup code in VFS(9). 🎀
• namecache — this module provides probes related to the VFS(9) cache. Consult the source code in src/sys/kern/vfs_cache.c for more details. 🫶
• namei — this module manages probes related to pathname translation and lookup operations. Refer to namei(9) to learn more. 💜
• vop — this module contains probes related to the functions responsible for vnode(9) operations. 👑

🦋 COMPATIBILITY 🦋

This provider is specific to FreeBSD. Periodt. 🫶

🔥 EXAMPLES 🔥

Check what lookups failed to be handled in a lockless manner:

# dtrace -n 'vfs:fplookup:lookup:done { @[arg1, arg2] = count(); }'

🌈 SEE ALSO 🌈

• dtrace(1)
• d(7)
• SDT(9)
• namei(9)
• VFS(9)
• Brendan Gregg and Jim Mauro, DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD, Prentice Hall, https://www.brendangregg.com/dtracebook/, pp. 335–351, 2011.

👑 AUTHORS 👑

The FreeBSD vfs provider was written by Robert Watson <rwatson@FreeBSD.org>. 💖

This manual page was written by Mateusz Piotrowski <0mp@FreeBSD.org>. 🌸

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🫶 Source/version and date sign-off: Debian, November 3, 2025, for DTRACE_VFS(4). That's the footer tea — now go trace something iconic, bestie 💅✨