Align struct file_operations with upstream v6.14 #311
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lkmpg.tex
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| @@ -908,46 +908,52 @@ \subsection{The file\_operations Structure} | |||
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| For example, every character driver needs to define a function that reads from the device. | |||
| The \cpp|file_operations| structure holds the address of the module's function that performs that operation. | |||
| Here is what the definition looks like for kernel 5.4: | |||
| Here is what the definition looks like for kernel 6.14: | |||
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Don't do that. Linux v5.4 is a long-term support kernel. LKMPG maintains compatibility with LTS kernels, which means all content should be compatible with Linux v5.4 and newer versions, rather than focusing exclusively on recent Linux releases. Instead of modifying the struct definitions, please document any changes to member fields in the descriptions.
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Thanks for your clarification! That make sense.
I just want to confirm that my understanding aligns with your intent:
I’ll revert the struct file_operations example to the original Linux 5.4 definition (undoing my earlier changes) so it stays compatible with all LTS kernels.
To cover newer kernels without breaking the build, I’ll add a short note right after the code that lists the fields added, removed, or modified since 5.4.
As of Linux kernel 6.12, several member fields have been added or removed, or had their prototypes changed:
- Added:
fop_flags,splice_eof,uring_cmd,uring_cmd_iopoll,mmap_capabilities- Removed:
iterate,sendpage,mmap_supported_flags(!CONFIG_MMU)- Modified:
iopollnow takesstruct io_comp_batch *andunsigned int flagssetleasenow usesstruct file_lease **andintinstead oflong
Let me know if this approach fits the documentation style you prefer, or if you'd suggest any adjustments.
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Go ahead on top of Linux v5.4 codebase.
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Any progress? |
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Thanks for the ping and sorry for the long delay. I've just pushed the updated version with the revised commit message as we discussed. The main text now remains on the v5.4 baseline, and a footnote has been added to summarize the API changes in modern kernels. |
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lkmpg.tex
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| \begin{itemize} | ||
| \item Added: \texttt{fop\_flags}, \texttt{splice\_eof}, \texttt{uring\_cmd}, \texttt{uring\_cmd\_iopoll}, \texttt{mmap\_capabilities} | ||
| \item Removed: \texttt{iterate}, \texttt{sendpage}, \texttt{mmap\_supported\_flags} (!CONFIG\_MMU) | ||
| \item Modified: | ||
| \begin{itemize} | ||
| \item \texttt{iopoll} now takes \texttt{struct io\_comp\_batch *} and \texttt{unsigned int flag} | ||
| \item \texttt{setlease} now uses \texttt{struct file\_lease **} and \texttt{int} instead of \texttt{long} | ||
| \end{itemize} | ||
| \end{itemize} |
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Keep footnotes lean still informative. Don't place items here. Instead, plaintext with notation works.
The main text's 'struct file_operations' example is intentionally kept at the v5.4 LTS version to ensure compatibility with the guide's code. To bridge the gap with modern kernels, a new footnote is introduced. It summarizes the evolution of the struct up to Linux v6.12, documenting key additions, removals, and modifications to its members. This provides crucial context for readers working with newer kernel versions. Co-authored-by: EricccTaiwan <yphbchou0911@gmail.com>
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Thank @Jordymalone for contributing! |
Chapter 6, "Character Device Drivers", section 6.1 still showed the v5.4 layout of 'struct file_operations'. Replace it with the version shipped in upstream Linux v6.14, keeping the example buildable and the API in step with modern kernels.
Upstream reference: https://elixir.bootlin.com/linux/v6.14/source/include/linux/fs.h#L2131
Summary by Bito
This pull request updates the documentation for 'struct file_operations' to align with changes in Linux kernel version 6.14, enhancing clarity for developers by detailing modifications to member fields and ensuring accuracy with modern kernel APIs.