On 2/17/25 22:58, Matthew Wilcox wrote:
On Tue, Feb 04, 2025 at 03:12:05PM -0800, Luis Chamberlain wrote:
@@ -182,7 +182,7 @@ static struct bio *do_mpage_readpage(struct mpage_readpage_args *args)
goto confused;
block_in_file = folio_pos(folio) >> blkbits;
- last_block = block_in_file + args->nr_pages * blocks_per_page;
+ last_block = block_in_file + args->nr_pages * blocks_per_folio;
In mpage_readahead(), we set args->nr_pages to the nunber of pages (not
folios) being requested. In mpage_read_folio() we currently set it to
1. So this is going to read too far ahead for readahead if using large
folios.
I think we need to make nr_pages continue to mean nr_pages. Or we pass
in nr_bytes or nr_blocks.
I had been pondering this, too, while developing the patch.
The idea I had here was to change counting by pages over to counting by
folios, as then the logic is essentially unchanged.
Not a big fan of 'nr_pages', as then the question really is how much
data we should read at the end of the day. So I'd rather go with
'nr_blocks' to avoid any confusion.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
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