Re: [External] Re: [PATCH] mm: zswap: fix the lack of page lru flag in zswap_writeback_entry

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Tue, Jan 16, 2024 at 09:40:05PM +0800, Zhongkun He wrote:
> 2)  __read_swap_cache_async has six parameters, so there is no space to
> add a new one, add_to_lru_head.

That's easy enough.  Define a new set of flags, make one of them the
equivalent of skip_if_exists.  Something like:

typedef unsigned int __bitwise read_swap_t;

#define READ_SWAP_SKIP_EXISTING	((__force read_swap_t)0x00000001)
#define READ_SWAP_ADD_TAIL	((__force read_swap_t)0x00000002)

There's only six callers of __read_swap_cache_async() to convert, so not
really a big deal.