On Fri, Jun 12, 2026 at 02:54:47PM +0800, Gao Xiang wrote: > hmm, currently erofs could return block-sized iomap (if the chunk > size is 4k) even it can be merged with the following chunks. > > Previously it was fairly good since consecutive chunks will be > added to the current bio if possible, but after this patch, > there will be a lot of 4k bios. > > But if iomap goes into this way, I could make iomap_begin maps > more chunks in one shot, but that needs more changes in erofs, > it's fine anyway. > > ... I was thinking the following diff (space-damaged):
That should work too for your case. But we definitively have various cases where merging over iomaps is a bad idea. You'll also end up with other efficiency gains by merging consecutive entries, especially for direct I/O and when using large folios.
