Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > I suspect you don't need to call find_get_pages_contig(). If you look > at __readahead_batch() in pagemap.h, it does basically what you want > (other than being wrapped up inside the readahead iterator). You require > the pages already be pinned in the xarray, so there's no need for the > page_cache_get_speculative() dance that find_get_pages_contig) does, > nor the check for xa_is_value(). I'll have a look at that. > My main concern with your patchset is that it introduces a new page flag Technically, the flag already exists - I'm just using it for something different than the old fscache code used it for. > to sleep on which basically means "I am writing this page to the fscache". > I don't understand why you need it; you've elevated the refcount on > the pages so they're not going to get reused for another purpose. > All it does (as far as I can tell) is make a task calling truncate() > wait for the page to finish being written to cache, which isn't actually > necessary. It's also used to prevent starting overlapping async DIO writes to the cache. See fscache_read_done(), where it's set to cover writing what we've just read from the server to the cache, and afs_write_back_from_locked_page(), where it's set to cover writing the data to be written back to the cache. David
