Re: [PATCH] erofs: support SEEK_HOLE/SEEK_DATA in inode_share mode

[Jingbo Xu]

On 8/20/26 11:10 AM, Zhan Xusheng wrote:
> On Tue, 18 Aug 2026 19:37:13 +0800, Jingbo Xu wrote:
>> - .llseek   = generic_file_llseek,
>> + .llseek   = erofs_file_llseek,
> 
> No objection to the change.  While in that table, .splice_read is the entry
> left that touches the page cache without going through ->private_data:
> 
>   .read_iter   kiocb_clone() onto private_data, then filemap_read()
>   .mmap        vma_set_file(vma, realfile)
>   .fadvise     vfs_fadvise(file->private_data, ...)
>   .splice_read filemap_splice_read
> 
> filemap_splice_read() does init_sync_kiocb(&iocb, in), and
> filemap_get_pages() then takes iocb->ki_filp->f_mapping (mm/filemap.c:2686),
> so it works on the user file's mapping, which after your patch is confirmed
> to be the real inode's.  erofs_fill_inode() sets that mapping's a_ops
> unconditionally, so the data splice() and sendfile() return is correct, but
> they populate the per-file page cache from disk rather than the shared one
> read() and mmap() use, caching the same content twice.

Right.  I think that would be another patch to fix that.

-- 
Thanks,
Jingbo