On Sun, Nov 01, 2020 at 12:52:17PM +0100, Christoph Hellwig wrote: > On Sun, Nov 01, 2020 at 11:04:06AM +0000, Matthew Wilcox wrote: > > > I'll stop for now. > > > > http://git.infradead.org/users/willy/pagecache.git/shortlog/refs/heads/next > > > > is what i currently have. Haven't pulled in everything from you; certainly not renaming generic_file_buffered_read to filemap_read(), which is awesome. > > i'm about 500 seconds into an xfstests run. > > A bunch of comments from a very quick look: > > mm/filemap: Rename generic_file_buffered_read subfunctions > > - the commit log still mentions the old names Hm? I have this: mm/filemap: Rename generic_file_buffered_read subfunctions The recent split of generic_file_buffered_read() created some very long function names which are hard to distinguish from each other. Rename as follows: generic_file_buffered_read_readpage -> filemap_read_page generic_file_buffered_read_pagenotuptodate -> filemap_update_page generic_file_buffered_read_no_cached_page -> filemap_create_page generic_file_buffered_read_get_pages -> filemap_get_pages > mm/filemap: Change calling convention for buffered read functions > > - please also drop the mapping argument to the various functions while > you're at it Not sure I see the point to it. Sure, they _can_ retrieve it with iocb->ki_filp->f_mapping, but usually we like to pass the mapping argument to functions which do something with the mapping. > mm/filemap: Reduce indentation in gfbr_read_page > > - still mentionds the old function name Fixed. > mm/filemap: Support readpage splitting a page > > - nitpick, I find this a little hard to read: > > + } else if (!trylock_page(page)) { > + put_and_wait_on_page_locked(page, TASK_KILLABLE); > + return NULL; > } > > and would write this a little more coarse as: > > } else { > if (!trylock_page(page)) { > put_and_wait_on_page_locked(page, TASK_KILLABLE); > return NULL; > } > } No strong feeling here. I'll change it. > Also I think the messy list of uptodate checks could now be simplified > down to: > > if (!PageUptodate(page)) { > if (inode->i_blkbits <= PAGE_SHIFT && I've been wondering about this test's usefulness in the presence of THP. Do we want to make it 'if (inode->i_blkbits < (thp_order(page) + PAGE_SHIFT)'? It doesn't make sense to leave it as it is because then a 1kB and 4kB blocksize filesystem will behave differently. > mapping->a_ops->is_partially_uptodate && > !iov_iter_is_pipe(iter)) { > if (!page->mapping) > goto truncated; > if (mapping->a_ops->is_partially_uptodate(page, > pos & (thp_size(page) - 1), count)) > goto uptodate; > } Now that you've rearranged it like this, it's obvious that the truncated check is in the wrong place. We don't want to call filemap_read_page() if the page has been truncated either. > return filemap_read_page(iocb, mapping, page); > } > > mm/filemap: Convert filemap_read_page to return an errno: > > - using a goto label for the put_page + return error case like in my > patch would be cleaner I think A later patch hoists the put_page to the caller, so I think you'll like where it ends up. > mm/filemap: Restructure filemap_get_pages > > - I have to say I still like my little helper here for > the two mapping_get_read_thps calls plus page_cache_sync_readahead I'll take a look at that. Looking at all this again, I think I want to pull the IOCB checks out of filemap_read_page() and just pass a struct file to it. It'll make it more clear that NOIO, NOWAIT and WAITQ can't get to calling ->readpage. I'll send another rev tomorrow.
