In my continued effort to finish the integration of ZSTD into ZFS, here is my second weekly status report:
There is still a number of existing feedback items and known issues that need to be addressed. I am trying to work through those now. https://github.com/openzfs/zfs/commit/622b7e1e50ab667a6af1685245a2f5a8d5e9bff3 - Addressed an issue where the user could manually set the hidden compress_level property, causing incorrect operation. The property is not marked with the PROP_READONLY flag because it requires PROP_INHERIT - It has been pointed out again recently that setting the compress=zstd property on a dataset, but not actually writing any blocks, does not set the zstd feature flag to 'active'. If this pool is then exported, and imported using an older version of ZFS that does not know of zstd, it will trigger an ASSERT() when the value of the compression property enum is out-of-range. The plan is to fully activate the feature when the property is set, but the details of how (and where) to do still still need to be worked out. - I am still working on the issue of inheritance for both the compress and the hidden compress_level properties. If you create a child dataset with the compress property set to zstd-13, it works as expected. But if you `zfs inherit compress` on that dataset, the output of `zfs get compress,compress_level` changes from: zof/inherit/zstd-10/zstd-13 compression zstd-13 local zof/inherit/zstd-10/zstd-13 compress_level 13 local to: zof/inherit/zstd-10/zstd-13 compression zstd-13 inherited from zof/inherit/zstd-10 zof/inherit/zstd-10/zstd-13 compress_level 13 local This is due to the fact that both the parent, and the child, actually have compress=16 (zstd), and the zstd-10 or zstd-13 is determined by combining the hidden compress_level property. The expected behaviour in this case would be that the compression type (and therefore the compress_level) would get reset to the value from the parent. There is a related problem when the child's compression setting is set to lz4 (or any other type that doesn't use a level). This project was sponsored by the FreeBSD Foundation. -- Allan Jude
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