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ad9e767657
Originally it was thought it would be useful to split up the kmods by functionality. This would allow external consumers to only load what was needed. However, in practice we've never had a case where this functionality would be needed, and conversely managing multiple kmods can be awkward. Therefore, this change merges all but the spl.ko kmod in to a single zfs.ko kmod. Reviewed-by: Tony Hutter <hutter2@llnl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Closes #13274
39 lines
1.6 KiB
Markdown
39 lines
1.6 KiB
Markdown
# ZSTD-On-ZFS Library Manual
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## Introduction
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This subtree contains the ZSTD library used in ZFS. It is heavily cut-down by
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dropping any unneeded files, and combined into a single file, but otherwise is
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intentionally unmodified. Please do not alter the file containing the zstd
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library, besides upgrading to a newer ZSTD release.
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Tree structure:
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* `zfs_zstd.c` are the actual `zfs` kernel module hooks.
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* `lib/` contains the unmodified version of the `Zstandard` library
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* `zstd-in.c` is our template file for generating the single-file library
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* `include/`: This directory contains supplemental includes for platform
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compatibility, which are not expected to be used by ZFS elsewhere in the
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future. Thus we keep them private to ZSTD.
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## Updating ZSTD
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To update ZSTD the following steps need to be taken:
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1. Grab the latest release of [ZSTD](https://github.com/facebook/zstd/releases).
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2. Copy the files output by the following script to `module/zstd/lib/`:
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`grep include [path to zstd]/contrib/single_file_libs/zstd-in.c | awk '{ print $2 }'`
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3. Remove debug.c, threading.c, and zstdmt_compress.c.
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4. Update Makefiles with resulting file lists.
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5. Follow symbol renaming notes in `include/zstd_compat_wrapper.h`
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## Altering ZSTD and breaking changes
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If ZSTD made changes that break compatibility or you need to make breaking
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changes to the way we handle ZSTD, it is required to maintain backwards
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compatibility.
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We already save the ZSTD version number within the block header to be used
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to add future compatibility checks and/or fixes. However, currently it is
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not actually used in such a way.
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