[LU-15916] stock pages for debug buffer use are never filled

• Type: Bug
• Resolution: Unresolved
• Priority: Major
• Affects Version/s: Lustre 2.16.0, Lustre 2.12.9
• Severity: 3
• Assignee: WC Triage
• Reporter: Oleg Drokin

Description

Looks like all the logic around tcd_cur_stock_pages in a tcd structure is dead.

The number is never increased since the function that did it - cfs_trace_refill_stock() was removed in commit 9dfbed6fa33dfcd69afa3383f20c3973215e8000 (https://review.whamcloud.com/38913) because it was never called anyway.

As such the TCD_STOCK_PAGES define is dead and this bit in cfs_trace_get_tage_try() as well:

if (tcd->tcd_cur_stock_pages > 0) {
                        tage = cfs_tage_from_list(tcd->tcd_stock_pages.prev);
                        --tcd->tcd_cur_stock_pages;
                        list_del_init(&tage->linkage); 

It's kinda strange we actually never populate this list from the "freed" pages and instead always free them to allocate anew as we need them.