[PATCH v6 00/10] block atomic writes

[Matthew Wilcox]

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.