First try to implement ashift property.

[BjoKaSH]

Hello Alex,

As pushed forward by Daniel on the mailing list, implements "zpool create -o ashift=xxx ...". I have tested it on Snow Leopard (using my makefile-build system) and it seems to work.

This commit should work as "fast-forward" on your master.

-- Björn

This commit tries to implement the ashift pool property as used
in ZFSonLinux and the ZEVO beta releases. It is based on the
ZFSonLinux implementation, and follows this comment:
openzfs/zfs#195 (comment)
and the resulting final patch for ZFSonLinux found here:
openzfs/zfs@df30f56
The original inventors are

• Darik Horn [email protected]
• Richard Laager [email protected]
• Christian Kohlschütter [email protected]

Due to the large distance between macZFS and ZFSonLinux
(pool version 8 vs. 28) it was necessary to redo and adapt their
approach instead of just copying the changes.

Note that this solution is technical not fully correct:
(a) it introduces a pool property that should not exist in pool
version 8
(b) it introduces a new property type, PROP_ONTIME that should not
exist in pool version 8
(c) the ashift value is really a property of individual top-level
vdevs, and not a pool-wide value. A pool can (and should under
certain conditions) have top-level vdevs of different block size.

However, using a pool-wide property is what other implementations do,
so we do the same for the sake of compatibility.

[BjoKaSH]

If have ported this changes over to your untested, to be found here:
BjoKaSH@70dff54

The diff untested_ashift to untested is smaller then the diff maczfs_74+ashift to maczfs_74, because maczfs_78 already has all the infrastructure for pool properties that was still missing from maczfs_74.

However, this commit kernel panics. But as the bare untest kernel panics in the same situation, I am quite sure the panic is unrelated to my ashift implementation.

[BjoKaSH]

I moved the ashift stuff for untested form the untested branch itself into a feature branch untested_ashift. That required rewriting history and dropping my two commits from untesting, both commits ore now part of untested_ashift (unmodified, i.e same IDs as before). Sorry for the confusion

Different topic:
I added the missing input sanitization in the untested_ashift branch, but not yet in the ashift12 branch of maczfs_74. Reason is, that the maczfs_74 revision misses all the needed infrastructure to easily do the input checking. Will think about how I can add something.

[BjoKaSH]

Hi Alex,
the last commit tries to add input sanitization. Unfortunately maczfs_74 misses most of the needed infrastructure, so I had to work around the limitations. Especially, I needed a way to know if the property is set at creation time or any other time (which is forbidden). In lack of the needed flags in_74, I instead test the zhp in zfs_validate_props for being NULL. I think it should be zero at creation time and only at creation time. Please review especially that last commit. All the rest should be fine.
-- Björn

[BjoKaSH]

Obsoleted by new request #4

Closed by BjoKaSH