Re: [PATCH] btrfs: Replace kmap() with kmap_local_page() in zstd.c

[David Sterba]

On Thu, Jul 14, 2022 at 08:25:20AM +0800, Wang Yugui wrote:
> Hi,
> 
> Compiler warning:
> 
> fs/btrfs/zstd.c:478:55: warning: passing argument 1 of ‘__kunmap_local’ discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
>   478 |                         kunmap_local(workspace->in_buf.src);
> ./include/linux/highmem-internal.h:284:24: note: in definition of macro ‘kunmap_local’
>   284 |         __kunmap_local(__addr);                                 \
>       |                        ^~~~~~
> ./include/linux/highmem-internal.h:200:41: note: expected ‘void *’ but argument is of type ‘const void *’
>   200 | static inline void __kunmap_local(void *addr)
>       |                                   ~~~~~~^~~~

This requires patch
https://lore.kernel.org/all/20220706111520.12858-2-fmdefrancesco@xxxxxxxxx/
that adds const to kmap/kunmap API.