Bug#661580: mkfs.xfs fails to detect correct sector size

[Goswin von Brederlow <goswin-v-b@xxxxxx>]

Eric Sandeen <sandeen@xxxxxxxxxxx> writes:

> On 2/28/12 3:11 AM, Christoph Hellwig wrote:
>> Carlos, didn't you plan to look into this issue?
>> 
>> Goswin, how do you determin that mkfs is still doing unaligned I/O
>> when forcing the large sevtor size?  Once we set the sector size XFS
>> can't do I/O smaller than it.
>
> I did think this was supposed to be working already:
>
>         get_topology(&xi, &ft);
>
>         if (ft.sectoralign) {
>                 /*
>                  * Older Linux software RAID versions want the sector size
>                  * to match the block size to avoid switching I/O sizes.
>                  * For the legacy libdisk case we thus set the sector size to
>                  * match the block size.  For systems using libblkid we assume
>                  * that the kernel is recent enough to not require this and
>                  * ft.sectoralign will never be set.
>                  */
>                 sectorsize = blocksize;
>         } else if (!ssflag) {
>                 /*
>                  * Unless specified manually on the command line use the
>                  * advertised sector size of the device.
>                  */
>                 sectorsize = ft.sectorsize ? ft.sectorsize : 
> XFS_MIN_SECTORSIZE;
>         }
>
> but it may depend on whether or not it is being built with libblkid support 
> or not...?
>
> I'll try to test it when I have some time, unless Carlos beats me to it.
>
> -Eric

I'm asuming libblkid is used, otherwise a sectorsize of 512 would make
no sense.

It might be that NBD advertises the geometry wrong, as in ft.sectorsize
isn't set correctly. That would make that part at least a kernel bug.

MfG
        Goswin