Re: [PATCH] writeback: Account the number of pages written back

[Andrew Morton]

On Wed, 28 Jun 2023 19:55:48 +0100 "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> wrote:

> nr_to_write is a count of pages, so we need to decrease it by the number
> of pages in the folio we just wrote, not by 1.  Most callers specify
> either LONG_MAX or 1, so are unaffected, but writeback_sb_inodes()
> might end up writing 512x as many pages as it asked for.

512 is a big number,  Should we backport this?

> Fixes: 793917d997df ("mm/readahead: Add large folio readahead")

I'm not seeing how a readahead change messed up writeback accounting?