Re: [PATCH] erofs-utils: tests: add a splice() test for inode_share mode

Hi Xusheng,

On Fri, Aug 21, 2026 at 09:57:22AM +0800, Zhan Xusheng wrote:
> From: Zhan Xusheng <[email protected]>
> 
> From: Zhan Xusheng <[email protected]>
> 
> splice() and sendfile() went through filemap_splice_read() on the user
> file, so they populated the per-inode page cache instead of the shared one
> that read() and mmap() use.  The content was correct either way, which is
> why nothing caught it: only which mapping the pages land in changes.
> 
> Observe that instead.  cachestat() works on the file's own mapping, while
> fincore's mmap()+mincore() fallback goes through erofs_ishare_mmap(), which

Actually we shouldn't rely on the fact that cachestat() works on the
file's own mapping since it's another misfeature, similar to:

https://lore.kernel.org/linux-unionfs/[email protected]/

we should find another way to replace the cachestat() usage here.

Thanks,
Gao Xiang