.TH LLAPI_CHANGELOG_DEREGISTER 3 2026-09-12 "Lustre User API" "Lustre Library Functions"
.SH NAME
llapi_changelog_deregister \- Deregister changelog user on specific MDT device
.SH SYNOPSIS
.nf
.B #include <lustre/lustreapi.h>
.PP
.BI "int llapi_changelog_deregister(const char *" mdtname ", const char *" regname );
.fi
.SH DESCRIPTION
The function
.B llapi_changelog_deregister()
deregisters changelog
.I regname
on specific MDT device
.I mdtname
(e.g.
.BR lustrefs-MDT0000 ).
It must be run on the MDS node where the MDT is currently mounted.
.PP
The
.I regname
argument preferably uses the
.I username
specified during
.IR llapi_changelog_register (3)
(e.g.
.RB ' audit ')
as this allows an application to deregister its changelog user by the preferred
name regardless of which changelog user number was assigned, but it can also be
the changelog user number (e.g.
.RB ' cl4 "' or '" 4 '),
or both (e.g.
.RB ' cl4-audit ').
.SH RETURN VALUES
Return 0 on success or a negative errno value on failure.
.SH ERRORS
.TP 15
.SM -EINVAL
MDT device is invalid or not found.
.TP
.SM -ENOENT
Username is not found.
.SH EXAMPLE
To deregister a previously-registered changelog user:
.EX
#include <lustre/lustreapi.h>

int main(int argc, char *argv[])
{
	char *mdtname = argv[1]; /* e.g. "testfs-MDT0000" */
	char *username = argv[2]; /* e.g. "cl4-audit" */
	int rc;

	rc = llapi_changelog_deregister(mdtname, username);
}
.EE
.SH AVAILABILITY
.B llapi_changelog_deregister()
is part of the
.BR lustre (7)
user application interface library since release 2.18.0
.\" Added in commit 2.17.5x
.SH SEE ALSO
.BR llapi_changelog_register (3),
.BR lustreapi (7),
.BR lctl-changelog_deregister (8)