On Mon, Apr 03, 2023 at 03:22:17PM +0200, Pankaj Raghav wrote:
> zram_bvec_read() is called with the bio set to NULL only in
> writeback_store() function. When a writeback is triggered,
> zram_bvec_read() is called only if ZRAM_WB flag is not set. That will
> result only calling zram_read_from_zspool() in __zram_bvec_read().
>
> rw_page callback used to call read_from_bdev_async with a NULL parent
> bio but that has been removed since commit 3222d8c2a7f8
> ("block: remove ->rw_page").
>
> We can now safely always call bio_chain() as read_from_bdev_async() will
> be called with a parent bio set. A WARN_ON_ONCE is added if this function
> is called with parent set to NULL.
I'm pretty sure this is wrong. I've now sent a series to untangle
and fix up the zram I/O path, which should address the underlying
issue here.
It will obviously conflict with this patch, so maybe the best thing is
to get the other page_endio removals into their respective maintainer
trees, and then just do the final removal of the unused function after
-rc1.
