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Matthew Wilcox (Oracle) <willy@infradead.org> says: There are four benefits to this patchset. First, it removes an indirect function call from the completion path. Instead of setting bio->bi_end_io to end_bio_bh_io_sync() which then calls bh->b_end_io(), we set bio->bi_end_io to the appropriate completion handler, replacing two indirect function calls with one. Second, there is a slight security advantage to this. It is one fewer function pointer in the middle of a writable data structure that can be corrupted. Third, it shrinks struct buffer_head from 104 bytes to 96 bytes, allowing for appropriximately 7% reduction in the amount of memory used by buffer_heads (or, alternatively, allows 7% more buffer_heads to be cached in the same amount of memory). Fourth, it removes some atomic operations as the buffer refcount is no longer incremented before calling the end_io handler. I've run ext4 through its paces, and everything seems OK. I've only compiled ocfs2/gfs2/nilfs/md-bitmap. Hopefully the maintainers can give this series a try. I'm sending the entire series to linux-fsdevel and cc'ing the fs-specific mailing lists for the fs-specific patches. * patches from https://patch.msgid.link/20260528173150.1093780-1-willy@infradead.org: (34 commits) buffer: Remove end_buffer_write_sync() buffer: Change calling convention for end_buffer_read_sync() buffer: Remove b_end_io buffer: Remove submit_bh() md-bitmap: Convert read_file_page and write_file_page to bh_submit() nilfs2: Convert nilfs_mdt_submit_block to bh_submit() nilfs2: Convert nilfs_gccache_submit_read_data to bh_submit() nilfs2: Convert nilfs_btnode_submit_block to bh_submit() buffer: Remove mark_buffer_async_write() gfs2: Convert gfs2_aspace_write_folio to bh_submit() gfs2: Remove use of b_end_io in gfs2_meta_read_endio() gfs2: Convert gfs2_dir_readahead to bh_submit() gfs2: Convert gfs2_metapath_ra to bh_submit() ocfs2: Convert ocfs2_write_super_or_backup to bh_submit() ocfs2: Convert ocfs2_read_blocks to bh_submit() ocfs2: Convert ocfs2_read_block to bh_submit() ocfs2: Convert ocfs2_write_block to bh_submit() jbd2: Convert jbd2_write_superblock() to bh_submit() jbd2: Convert journal commit to bh_submit() ext4: Convert ext4_commit_super() to bh_submit() ... Link: https://patch.msgid.link/20260528173150.1093780-1-willy@infradead.org Signed-off-by: Christian Brauner <brauner@kernel.org>
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros * AI Coding Assistant - LLMs and AI-powered development tools For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst AI Coding Assistant ------------------- CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and follow the AI coding assistants documentation before contributing to the Linux kernel: * Documentation/process/coding-assistants.rst This documentation contains essential requirements about licensing, attribution, and the Developer Certificate of Origin that all AI tools must comply with. Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst