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Joanne Koong <joannelkoong@gmail.com> says: iomap: convert to in-iter iomap_next() model This series implements a suggestion by Christoph for finishing the conversion of iomap to an iterator model. This revives Matthew's previous RFC [1], which had the same intention. Every iomap operation currently drives its iteration through a struct iomap_ops, which contains two callbacks, ->iomap_begin() and ->iomap_end(). iomap_iter() only ever sees these as pointers, so every step of every iteration is an indirect call, including on the hottest paths. This series replaces the begin/end pair with a single ->iomap_next() callback that finishes the previous mapping (if any) and produces the next one. Collapsing to one callback lets a performance-critical caller inline its iteration loop and pass its ->iomap_next() function as a compile-time constant, where the compiler can devirtualize the callback into a direct and inlineable call rather than an indirect one. It also allows future callers more flexibility in expressing custom logic in the IO path for driving the iteration forward. This series has no functional changes intended. The patches are broken down as follows: 1) Patch 1: Brian's fix for folio batch release on iomap callback failures. The bug was reported by Sashiko and is an unlikely/second order error scenario [2] that doesn't need backporting to stable. 2) Patch 2: refactors existing iomap_iter() logic into an iomap_iter_next() function. Sets up DEFINE_IOMAP_ITER_NEXT/DEFINE_IOMAP_ITER_NEXT_END macro. 3) Patch 3 and 4: Christoph's patches for decoupling simple direct i/o reads from iomap_dio_rw and improvement for using GFP_NOWAIT for non-blocking iocbs [3] 4) Patch 5: Adds ->iomap_next() callback as an iomap op 5) Patches 6 to 19: converts each filesystem to ->iomap_next() model [1] https://lore.kernel.org/linux-fsdevel/20200728173216.7184-1-willy@infradead.org/T/#u [2] https://lore.kernel.org/linux-fsdevel/amjztG-DisHYbV9W@bfoster/ [3] https://lore.kernel.org/linux-fsdevel/20260723050201.3381045-1-hch@lst.de/ * patches from https://patch.msgid.link/20260729192737.3190206-1-joannelkoong@gmail.com: exfat: convert iomap ops to ->iomap_next() fuse: convert iomap ops to ->iomap_next() hpfs: convert iomap ops to ->iomap_next() gfs2: convert iomap ops to ->iomap_next() f2fs: convert iomap ops to ->iomap_next() block: convert iomap ops to ->iomap_next() ext2: convert iomap ops to ->iomap_next() zonefs: convert iomap ops to ->iomap_next() erofs: convert iomap ops to ->iomap_next() ext4: convert iomap ops to ->iomap_next() ntfs: convert iomap ops to ->iomap_next() ntfs3: convert iomap ops to ->iomap_next() btrfs: convert iomap ops to ->iomap_next() xfs: convert iomap ops to ->iomap_next() iomap: add ->iomap_next() iomap: use GFP_NOWAIT when application for iomap_dio_simple allocations iomap: decouple simple direct I/O reads from iomap_dio_rw iomap: split iomap_iter() logic into iomap_iter_next() iomap: release the folio batch on iomap callback failures Link: https://patch.msgid.link/20260729192737.3190206-1-joannelkoong@gmail.com Signed-off-by: Christian Brauner (Amutable) <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. 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