readahead: allocate folios with mapping_min_order in readahead

page_cache_ra_unbounded() was allocating single pages (0 order folios)
if there was no folio found in an index. Allocate mapping_min_order folios
as we need to guarantee the minimum order if it is set.

page_cache_ra_order() tries to allocate folio to the page cache with a
higher order if the index aligns with that order. Modify it so that the
order does not go below the mapping_min_order requirement of the page
cache. This function will do the right thing even if the new_order passed
is less than the mapping_min_order.
When adding new folios to the page cache we must also ensure the index
used is aligned to the mapping_min_order as the page cache requires the
index to be aligned to the order of the folio.

readahead_expand() is called from readahead aops to extend the range of
the readahead so this function can assume ractl->_index to be aligned with
min_order.

Signed-off-by: Pankaj Raghav <[email protected]>
Co-developed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Hannes Reinecke <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Tested-by: David Howells <[email protected]>
Acked-by: Darrick J. Wong <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Reviewed-by: Daniel Gomez <[email protected]>
Reviewed-by: Dave Chinner <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>

0 files changed, 0 insertions, 0 deletions