1.\" 2.\" Copyright (c) 2025 Mateusz Piotrowski <0mp@FreeBSD.org> 3.\" 4.\" SPDX-License-Identifier: BSD-2-Clause 5.\" 6.Dd November 3, 2025 7.Dt DTRACE_VFS 4 8.Os 9.Sh NAME 10.Nm dtrace_vfs 11.Nd a DTrace provider for Virtual File System 12.Sh SYNOPSIS 13.Sm off 14.Nm vfs Cm : fplookup : Ar function Cm : Ar name 15.Nm vfs Cm : namecache : Ar function Cm : Ar name 16.Nm vfs Cm : namei : Ar function Cm : Ar name 17.Nm vfs Cm : vop : Ar function Cm : Ar name 18.Sm on 19.Sh DESCRIPTION 20The DTrace 21.Nm vfs 22provider allows users to trace events in the 23.Xr VFS 9 24layer, the kernel interface for file systems on 25.Fx . 26.Pp 27Run 28.Ql dtrace -l -P vfs 29to list all 30.Nm vfs 31probes. 32Add 33.Fl v 34to generate program stability reports, 35which contain information about the number of probe arguments and their types. 36.Pp 37The 38.Cm fplookup 39module defines a single probe, 40.Fn vfs:fplookup:lookup:done "struct nameidata *ndp" "int line" "bool status_code" , 41that instruments the fast path lookup code in 42.Xr VFS 9 . 43.Pp 44The 45.Cm namecache 46module provides probes related to the 47.Xr VFS 9 48cache. 49Consult the source code in 50.Pa src/sys/kern/vfs_cache.c 51for more details. 52.Pp 53The 54.Cm namei 55module manages probes related to pathname translation and lookup operations. 56Refer to 57.Xr namei 9 58to learn more. 59.Pp 60The 61.Cm vop 62module contains probes related to the functions responsible for 63.Xr vnode 9 64operations. 65.Sh COMPATIBILITY 66This provider is specific to 67.Fx . 68.Sh EXAMPLES 69Check what lookups failed to be handled in a lockless manner: 70.Bd -literal -offset 2n 71# dtrace -n 'vfs:fplookup:lookup:done { @[arg1, arg2] = count(); }' 72.Ed 73.Sh SEE ALSO 74.Xr dtrace 1 , 75.Xr d 7 , 76.Xr SDT 9 , 77.Xr namei 9 , 78.Xr VFS 9 79.Rs 80.%A Brendan Gregg 81.%A Jim Mauro 82.%B DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD 83.%I Prentice Hall 84.%P pp. 335\(en351 85.%D 2011 86.%U https://www.brendangregg.com/dtracebook/ 87.Re 88.Sh AUTHORS 89.An -nosplit 90The 91.Fx 92.Nm vfs 93provider was written by 94.An Robert Watson Aq Mt rwatson@FreeBSD.org . 95.Pp 96This manual page was written by 97.An Mateusz Piotrowski Aq Mt 0mp@FreeBSD.org . 98