[0/2] readahead: Reintroduce fix for improper RA window sizing

Message

Jan Kara Dec. 4, 2024, 6:10 p.m. UTC

Hello,

this small patch series reintroduces a fix of readahead window confusion (and
thus read throughput reduction) when page_cache_ra_order() ends up failing due
to folios already present in the page cache. After thinking about this for
a while I have ended up with a dumb fix that just rechecks if we have something
to read before calling do_page_cache_ra(). This fixes the problem reported in
[1]. I still think it doesn't make much sense to update readahead window size
in read_pages() so patch 1 removes that but the real fix in patch 2 does not
depend on it.

Patches are based on top of my revert that's in MM tree as of today but I
expect it lands in Linus' tree very soon.

								Honza

[1] https://lore.kernel.org/all/[e-mail]