Am Donnerstag, 13. Dezember 2018, 23:00:00 CET schrieb Kirill A. Shutemov: > > Let's wait a few days to give Kirill a chance to review, then I'll apply the patch. > > I don't remmeber much context now... > > Could you remind me why ubifs doesn't take additional pin when sets > PG_private? Because it does not use set_page_private(), it just sets the flag for internal accounting purposes. >From UBIFS docs: * UBIFS uses 2 page flags: @PG_private and @PG_checked. @PG_private is set if * the page is dirty and is used for optimization purposes - dirty pages are * not budgeted so the flag shows that 'ubifs_write_end()' should not release * the budget for this page. The @PG_checked flag is set if full budgeting is * required for the page e.g., when it corresponds to a file hole or it is * beyond the file size. The budgeting is done in 'ubifs_write_begin()', because * it is OK to fail in this function, and the budget is released in * 'ubifs_write_end()'. So the @PG_private and @PG_checked flags carry * information about how the page was budgeted, to make it possible to release * the budget properly. > Migration is not the only place where the additional pin is implied. > See all users of page_has_private() helper. Notably reclaim path. Hmmm, I need to dig into that. I this is a problem then f2fs suffers from it too. At least from what I can tell from reading f2fs_migrate_page(). Thanks, //richard
