Re: [PATCH] mm: Convert pagecache_isize_extended to use a folio

[David Hildenbrand <david@redhat.com>]

On 05.04.24 20:00, Matthew Wilcox (Oracle) wrote:
> Remove four hidden calls to compound_head().  Also exit early if the
> filesystem block size is >= PAGE_SIZE instead of just equal to PAGE_SIZE.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
>   mm/truncate.c | 36 +++++++++++++++++-------------------
>   1 file changed, 17 insertions(+), 19 deletions(-)
> 
> diff --git a/mm/truncate.c b/mm/truncate.c
> index 725b150e47ac..e99085bf3d34 100644
> --- a/mm/truncate.c
> +++ b/mm/truncate.c
> @@ -764,15 +764,15 @@ EXPORT_SYMBOL(truncate_setsize);
>    * @from:	original inode size
>    * @to:		new inode size
>    *
> - * Handle extension of inode size either caused by extending truncate or by
> - * write starting after current i_size. We mark the page straddling current
> - * i_size RO so that page_mkwrite() is called on the nearest write access to
> - * the page.  This way filesystem can be sure that page_mkwrite() is called on
> - * the page before user writes to the page via mmap after the i_size has been
> - * changed.
> + * Handle extension of inode size either caused by extending truncate or
> + * by write starting after current i_size.  We mark the page straddling
> + * current i_size RO so that page_mkwrite() is called on the first
> + * write access to the page.  The filesystem will update its per-block
> + * information before user writes to the page via mmap after the i_size
> + * has been changed.

Did you intend not to s/page/folio/ ?

>    *
>    * The function must be called after i_size is updated so that page fault
> - * coming after we unlock the page will already see the new i_size.
> + * coming after we unlock the folio will already see the new i_size.
>    * The function must be called while we still hold i_rwsem - this not only
>    * makes sure i_size is stable but also that userspace cannot observe new
>    * i_size value before we are prepared to store mmap writes at new inode size.
> @@ -781,31 +781,29 @@ void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)


Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb