Re: [PATCH 5/9] libxlog: import the kernel's log recovery, log items and AIL

[Christoph Hellwig <hch@infradead.org>]

On Wed, Aug 26, 2026 at 10:09:03PM -0700, Chris Wedgwood wrote:
> xfs_repair cannot replay a dirty log.  The code that can is in the
> kernel, and xfsprogs already carries kernel code rather than
> reimplementing it, so import it.
> 
> libxfs/ mirrors the kernel's fs/xfs/libxfs/ and these files are not from
> there; they are from the top level of fs/xfs.  They go in libxlog/,
> which is where this tree keeps log code, so that each directory has one
> kernel counterpart and tools/libxfs-diff can check both.
> 
> The files are copied from Linux v7.1 and are byte-identical to their
> kernel counterparts apart from their #include lists, which is the
> adaptation libxfs has always used.  v7.1 is the kernel this tree's
> libxfs/ is currently in sync with: comparing xfsprogs libxfs/ against
> v7.1 reports no difference in any of 102 files, while against v7.2 it

As in changes except for the include file mess ignored by libxfs-diff?
Because otherwise we should have a lot more..

> reports 33.  Importing from a newer kernel than libxfs/ is synced to
> would mix two kernel versions in one tree.

We're about to merge the 7.2 merge.  Either way we'll need to coordinate
them.

> diff --git a/include/kernel_compat.h b/include/kernel_compat.h
> new file mode 100644
> index 00000000..0dbb2800
> --- /dev/null
> +++ b/include/kernel_compat.h
> @@ -0,0 +1,231 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Kernel infrastructure that xfs kernel sources refer to but which has no
> + * userspace equivalent.
> + *
> + * libxfs adapts kernel sources by rewriting their include list and nothing
> + * else, so the annotations, types and helpers those sources use have to be
> + * supplied from outside them.  Concurrency primitives collapse to no-ops
> + * because libxfs is single-threaded with respect to the log, and the
> + * deferred-work and I/O types only ever appear as struct members that
> + * userspace never schedules or submits.
> + *
> + * This header is included both by libxfs internals (via xfs_platform.h) and
> + * by the tools (via libxfs.h), because struct xlog embeds several of these
> + * types and the tools inspect struct xlog directly.

Please split this out into a separate patch, and make sure all the
other kernel compat bits are consistent with this.

Also usually kernel files need some amount of changes