Re: [PATCHv3 00/11] dm-zoned: metadata version 2

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On 4/11/20 2:30 PM, Bob Liu wrote:
On 4/9/20 2:45 PM, Hannes Reinecke wrote:
Hi all,

this patchset adds a new metadata version 2, which brings the following
improvements:
- UUIDs and labels: Adding three more fields to the metadata containing
   the dm-zoned device UUID and label, and the device UUID. This allows
   for an unique identification of the devices, so that several dm-zoned
   sets can coexist and have a persistent identification.
- Extend random zones by an additional regular disk device: A regular
   block device can be added together with the zoned block device, providing
   additional (emulated) random write zones. With this it's possible to
   handle sequential zones only devices; also there will be a speed-up if
   the regular block device resides on a fast medium. The regular block device
   is placed logically in front of the zoned block device, so that metadata
   and mapping tables reside on the regular block device, not the zoned device.
- Tertiary superblock support: In addition to the two existing sets of metadata
   another, tertiary, superblock is written to the first block of the zoned
   block device. This superblock is for identification only; the generation
   number is set to '0' and the block itself it never updated. The additional
   metadate like bitmap tables etc are not copied.

To handle this, some changes to the original handling are introduced:
- Zones are now equidistant. Originally, runt zones were ignored, and
   not counted when sizing the mapping tables. With the dual device setup
   runt zones might occur at the end of the regular block device, making
   direct translation between zone number and sector/block number complex.
   For metadata version 2 all zones are considered to be of the same size,
   and runt zones are simply marked as 'offline' to have them ignored when
   allocating a new zone.
- The block number in the superblock is now the global number, and refers to
   the location of the superblock relative to the resulting device-mapper
   device. Which means that the tertiary superblock contains absolute block
   addresses, which needs to be translated to the relative device addresses
   to find the referenced block.

There is an accompanying patchset for dm-zoned-tools for writing and checking
this new metadata.

As usual, comments and reviews are welcome.

Changes to v2:
- Kill dmz_id()
- Include reviews from Damien
- Sanitize uuid handling as suggested by John Dorminy


This series looks good to me, feel free to add my
Reviewed-by: Bob Liu <bob.liu@xxxxxxxxxx>

By the way, have you completed the patches for regular device support?
I was considering rebase my previous patches to this series but not sure is it still necessary.

I have combined both patchsets, this one now also included regular device support. So no need to resend from your side.

Cheers,

Hannes
--
Dr. Hannes Reinecke            Teamlead Storage & Networking
hare@xxxxxxx                               +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer


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