.TH LLAPI_IOCTL 3 2026-08-23 "Lustre User API" "Lustre Library Functions"
.SH NAME
llapi_ioctl \- call ioctl() with possible command remapping
.SH SYNOPSIS
.nf
.B #include <lustre/lustreapi.h>
.B #include <linux/lustre/lustre_ioctl.h>
.PP
.BI "int llapi_ioctl(int " fd ", unsigned int " cmd ", void *" buf ");"
.fi
.SH DESCRIPTION
.B llapi_ioctl()
calls the
.BR ioctl (2)
system call with the supplied arguments.  However, if the ioctl() fails and sets
errno to
.B ENOTTY
(no such ioctl) then if
.I cmd
has been remapped from an older ioctl command number the ioctl() call will
be retried with the old ioctl command number.
.SH RETURN VALUES
.B llapi_ioctl()
typically returns:
.TP
>=0
on success, the value returned by the
.BR ioctl (2).
.TP
\-EBADF
if
.I fd
is negative, without calling
.BR ioctl (2).
.B errno
is also set to
.BR EBADF .
.TP
\-1
on failure, with
.B errno
set by
.BR ioctl (2).
.BR
Note: If ioctl command is not supported, errno will be set to
ENOTTY.  For this specific case, llapi_ioctl() may retry calling ioctl
again and return its result.
.PP
Due to the variety of ioctl commands, it may return different values
and errno as appropriate for the
.IR fd ,
.I cmd
number, and argument
.I buf
passed.
.SH EXAMPLES
.nf
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <lustre/lustreapi.h>
#include <linux/lustre/lustre_ioctl.h>
\&
int main(int argc, char *argv[])
{
        char lov_name[MAX_OBD_NAME];
        int rc, fd;
\&
        if (argc != 2) {
                fprintf(stderr, "Usage: %s <filename>\\n", argv[0]);
                return 1;
        }
\&
        fd = open(argv[1], O_RDONLY);
        if (fd < 0) {
                fprintf(stderr, "error opening file '%s': %s\\n",
                        argv[1], strerror(errno));
                return 1;
        }
\&
        rc = llapi_ioctl(fd, OBD_IOC_GETDTNAME, lov_name);
        if (rc < 0) {
                fprintf(stderr, "%s: ioctl error: %s\\n",
                        argv[1], strerror(errno));
                return 1;
        }
\&
        printf("%s: LOV device name %s\\n", argv[1], lov_name);
        return 0;
}
.fi
.SH AVAILABILITY
.B llapi_ioctl()
is part of the
.BR lustre (7)
user application interface library since release 2.16.0
.\" Added in commit v2_15_55-173-g594b780062
.SH SEE ALSO
.BR ioctl (2),
.BR lustre (7),
.BR lustreapi (7)