Re: [PATCH] iomap: Fix the write_count in iomap_add_to_ioend().

[Christoph Hellwig]

On Sat, Aug 22, 2020 at 07:53:58AM +1000, Dave Chinner wrote:
> but iomap only allows BIO_MAX_PAGES when creating the bio. And:
> 
> #define BIO_MAX_PAGES 256
> 
> So even on a 64k page machine, we should not be building a bio with
> more than 16MB of data in it. So how are we getting 4GB of data into
> it?

BIO_MAX_PAGES is the number of bio_vecs in the bio, it has no
direct implication on the size, as each entry can fit up to UINT_MAX
bytes.