On Sun, Apr 14, 2024 at 01:50:16PM -0700, Luis Chamberlain wrote: > On Wed, Apr 10, 2024 at 05:05:20AM +0100, Matthew Wilcox wrote: > > Have you tried just using the buffer_head code? I think you heard bad > > advice at last LSFMM. Since then I've landed a bunch of patches which > > remove PAGE_SIZE assumptions throughout the buffer_head code, and while > > I haven't tried it, it might work. And it might be easier to make work > > than adding more BH hacks to the iomap code. > > I have considered it but the issue is that *may work* isn't good enough and > without a test plan for buffer-heads on a real filesystem this may never > suffice. Addressing a buffere-head iomap compat for the block device cache > is less error prone here for now. Is it really your position that testing the code I already wrote is harder than writing and testing some entirely new code? Surely the tests are the same for both. Besides, we aren't talking about a filesystem on top of the bdev here. We're talking about accessing the bdev's page cache directly.