Re: [PATCH] mm/filemap: Implement fast short reads

[Linus Torvalds <torvalds@linux-foundation.org>]

On Fri, 17 Oct 2025 at 04:15, Kiryl Shutsemau <kirill@shutemov.name> wrote:
>
> To address this issue, introduce i_pages_delete_seqcnt, which increments
> each time a folio is deleted from the page cache and implement a modified
> page cache lookup protocol for short reads:

So this patch looks good to me, but to avoid the stack size warnings,
let's just make FAST_READ_BUF_SIZE be 768 bytes or something like
that, not the full 1k.

It really shouldn't make much of a difference, and we do have that
stack size limit check for a reason.

And obviously

> --- a/fs/inode.c
> +++ b/fs/inode.c
> +       seqcount_spinlock_init(&mapping->i_pages_delete_seqcnt,
> +                              &mapping->i_pages->xa_lock);

will need to use '&mapping->i_pages.xa_lock', since mapping->i_pages
is the embedded xarray, not a pointer to it.

But I do think the patch looks quite good.

               Linus