From: Christoph Hellwig <hch@lst.de>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>,
Andrew Morton <akpm@linux-foundation.org>,
Kent Overstreet <kent.overstreet@gmail.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 04/13] mm: handle readahead in generic_file_buffered_read_pagenotuptodate
Date: Sun, 1 Nov 2020 11:31:44 +0100 [thread overview]
Message-ID: <20201101103144.GC26447@lst.de> (raw)
In-Reply-To: <20201031170646.GT27442@casper.infradead.org>
On Sat, Oct 31, 2020 at 05:06:46PM +0000, Matthew Wilcox wrote:
> > +static int filemap_make_page_uptodate(struct kiocb *iocb, struct iov_iter *iter,
> > + struct page *page, pgoff_t pg_index, bool first)
>
> I prefer "filemap_update_page".
That has the advantage of being shorter, while I find it less descriptive.
I can updated it and add a comment explaining what it does, as that is
probably warranted anyway.
> I don't understand why you pass in pg_index instead of using page->index.
> We dereferenced the page pointer already to check PageReadahead(), so
> there's no performance issue here.
Yes, we should do that.
> Also, if filemap_find_get_pages() stops on the first !Uptodate or
> Readahead page, as I had it in my patchset, then we don't need the loop
> at all -- filemap_read_pages() looks like:
>
> nr_pages = filemap_find_get_pages(iocb, iter, pages, nr);
> if (!nr_pages) {
> pages[0] = filemap_create_page(iocb, iter);
> if (!IS_ERR_OR_NULL(pages[0]))
> return 1;
> if (!pages[0])
> goto retry;
> return PTR_ERR(pages[0]);
> }
>
> page = pages[nr_pages - 1];
> if (PageUptodate(page) && !PageReadahead(page))
> return nr_pages;
> err = filemap_update_page(iocb, iter, page);
> if (!err)
> return nr_pages;
> nr_pages -= 1;
> if (nr_pages)
> return nr_pages;
> return err;
This looks sensible, but goes beyond the simple refactoring I had
intended. Let me take a more detailed look at your series (I had just
updated my existing series to to the latest linux-next) and see how
it can nicely fit in.
next prev parent reply other threads:[~2020-11-01 10:31 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-31 8:59 clean up the generic pagecache read helpers Christoph Hellwig
2020-10-31 8:59 ` [PATCH 01/13] mm: simplify generic_file_buffered_read_readpage Christoph Hellwig
2020-10-31 8:59 ` [PATCH 02/13] mm: simplify generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31 8:59 ` [PATCH 03/13] mm: lift the nowait checks into generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31 8:59 ` [PATCH 04/13] mm: handle readahead in generic_file_buffered_read_pagenotuptodate Christoph Hellwig
2020-10-31 17:06 ` Matthew Wilcox
2020-11-01 10:31 ` Christoph Hellwig [this message]
2020-11-01 10:49 ` Matthew Wilcox
2020-11-01 10:51 ` Christoph Hellwig
2020-11-01 10:51 ` Christoph Hellwig
2020-11-01 11:04 ` Matthew Wilcox
2020-11-01 11:52 ` Christoph Hellwig
2020-11-01 14:55 ` Matthew Wilcox
2020-11-02 8:18 ` Christoph Hellwig
2020-10-31 8:59 ` [PATCH 05/13] mm: simplify generic_file_buffered_read_no_cached_page Christoph Hellwig
2020-10-31 16:20 ` Matthew Wilcox
2020-10-31 16:28 ` Matthew Wilcox
2020-11-01 10:29 ` Christoph Hellwig
2020-10-31 8:59 ` [PATCH 06/13] mm: factor out a filemap_find_get_pages helper Christoph Hellwig
2020-10-31 8:59 ` [PATCH 07/13] mm: refactor generic_file_buffered_read_get_pages Christoph Hellwig
2020-11-01 11:18 ` Matthew Wilcox
2020-10-31 8:59 ` [PATCH 08/13] mm: move putting the page on error out of filemap_readpage Christoph Hellwig
2020-10-31 9:00 ` [PATCH 09/13] mm: move putting the page on error out of filemap_make_page_uptodate Christoph Hellwig
2020-10-31 9:00 ` [PATCH 10/13] mm: open code readahead in filemap_new_page Christoph Hellwig
2020-11-01 11:20 ` Matthew Wilcox
2020-10-31 9:00 ` [PATCH 11/13] mm: streamline the partially uptodate checks in filemap_make_page_uptodate Christoph Hellwig
2020-11-01 11:23 ` Matthew Wilcox
2020-10-31 9:00 ` [PATCH 12/13] mm: rename generic_file_buffered_read to filemap_read Christoph Hellwig
2020-10-31 9:00 ` [PATCH 13/13] mm: simplify generic_file_read_iter Christoph Hellwig
2020-10-31 15:42 ` clean up the generic pagecache read helpers Matthew Wilcox
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