Mount (2.8a from redhat 5.2)
always reports lineno 0 for errors in an fstab:

To reproduce:

Damage the /etc/fstab for e.g. /mnt/floppy by adding an
aditional nonsense field before the options, the try to
mount:

prompt> mount /mnt/floppy
[mntent]: line 0 in /etc/fstab is bad
mount: can't find /mnt/floppy in /etc/mtab or /etc/fstab
prompt>

After applying this one line patch the correct lineno is
reported:

prompt> mount /mnt/floppy
[mntent]: line 7 in /etc/fstab is bad
mount: can't find /mnt/floppy in /etc/mtab or /etc/fstab
prompt>

====patch follows:===========
*** mntent.c.old        Sat May 29 12:51:22 1999
--- mntent.c    Sat May 29 12:51:14 1999
***************
*** 148,157 ****
--- 148,158 ----

        /* read the next non-blank non-comment line */
        do {
                if (fgets (buf, sizeof(buf), mfp->mntent_fp)
== NULL)
                        return NULL;
+               mfp->mntent_lineno++;

                s = index (buf, '\n');
                if (s == NULL) {
                        /* extremely long line - assume file
was corrupted */
                        mfp->mntent_errs = 1;