[LU-14616] ra_cur_pages broken readahead

Duplicate — Tue, 27 Jul 2021 21:56:11 +0000

@ra_cur_pages could be broken in few cases:

1 )in ll_ra_count_get() @ret might be negative, in that case, we should

add @pages_min, rather than @pages_min - @ret.

2) use atomic_add(pages_min - ret) could be racy, as @ra_cur_pages might have changed, we need atomic_cmpxchg() helper to do this job.

3) with Readahead disabled, @vpg_defer_uptodate should not be set as we don't reserve credits for such read. In vvp_page_completion_read() we will call ll_ra_count_put(), so this will make @ra_cur_pages negative.

Whamcloud Community JIRA

[LU-14616] ra_cur_pages broken readahead