Re: mkfs.xfs option for RAID

[Steve Lord <lord@xxxxxxx>]

> Andi,
> 
> Andi Kleen wrote:
> > 
> > Are you sure it works for MD automatically too? When I'm reading the code
> > correctly only LVM_BLK_MAJOR is checked for.
> 
>       No, I'm not sure.  It's worked for me correctly in the past, but I've
> not updated from CVS lately.  Russell?
> 


There is mkfs code in there for querying MD devices:

        /* MD volume */
        if (sb.st_rdev >> 8 == MD_MAJOR) {
                int fd;

                /* Open device */
                fd = open (dfile, O_RDONLY);
                if (fd == -1)
                        return;

                /* Is this thing on... */
                if (ioctl (fd, GET_ARRAY_INFO, &md)) {
                        fprintf (stderr, "Error getting array info from %s\n",
                                 dfile);
                        usage();
                }

                /* Check state */
                if (md.state) {
                        fprintf (stderr, "MD array %s not in clean state\n",
                                 dfile);
                        usage();
                }

                /* Deduct a disk from stripe width on RAID4/5 */
                if (md.level == 4 || md.level == 5)
                        md.nr_disks--;

                /* Update sizes */
                *sunit = md.chunk_size >> 9;
                *swidth = *sunit * md.nr_disks;

                return;
        }

Steve