On Tue 03-10-23 12:40:17, Jan Kara wrote: > On Thu 21-09-23 21:07:39, Matthew Wilcox (Oracle) wrote: > > Support in this function for large folios is limited to supporting > > filesystems with block size > PAGE_SIZE. This new functionality will only > > be supported on machines without HIGHMEM, so the problem of kmap_local > > only being able to map a single page in the folio can be ignored. > > We will not use large folios for ext2 directories on HIGHMEM machines. > > OK, but can we perhaps enforce this with some checks & error messages > instead of a silent failure? Like: > > #ifdef CONFIG_HIGHMEM > if (sb->s_blocksize > PAGE_SIZE) > bail with error > #endif > > somewhere in ext2_fill_super()? Or maybe force allocation of lowmem pages > when blocksize > PAGE_SIZE? > > > @@ -195,9 +195,9 @@ static void *ext2_get_page(struct inode *dir, unsigned long n, > > > > if (IS_ERR(folio)) > > return ERR_CAST(folio); > > - page_addr = kmap_local_folio(folio, n & (folio_nr_pages(folio) - 1)); > > + page_addr = kmap_local_folio(folio, 0); Oh, and I think this change breaks the code whenever we get back higher order folio because the page_addr we get back is not for the page index 'n'. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
