From patchwork Wed Oct 4 16:53:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13409057 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B87AE7C4E3 for ; Wed, 4 Oct 2023 16:54:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243581AbjJDQyK (ORCPT ); Wed, 4 Oct 2023 12:54:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56716 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243522AbjJDQxe (ORCPT ); Wed, 4 Oct 2023 12:53:34 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1B470A7; Wed, 4 Oct 2023 09:53:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:In-Reply-To:References; bh=LwA3p5YQj5OgBPSUkutIowOVEGM0rG3Lj5ULCLty+YM=; b=JRt10tJuArdHNRRYBWcWAKTL3L 5qoqHs+L3muErMYTGOiagRQEu5W1rLCQDiFr3Iwo196Be3buwEBHUBuhyJ2lkzSo5boAHD6BpdQHv kqco3WhNwcfQdxHLgIKr6jj1hCDFmwbEOi7zalI+OyPKeGZXwcyxU39WAzL3812ODwKoz8UIhx/vv o61fvI+j3BZ7GT/v6+KeSDyP9XVgSoWDWfOCSoQLKWZ0jA4gDvO0Oce/vZbGPFASGWxPj7GtcqhGH SzFZ2r52dVlmq2d4eN2U6+hmOI9Y86s4spZlVWUiqtlfz7/s5/BMdU/trJw0lt93QR3U5OocxHR28 nsv+z4xA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qo57f-004SEr-45; Wed, 04 Oct 2023 16:53:19 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, torvalds@linux-foundation.org, npiggin@gmail.com Subject: [PATCH v2 00/17] Add folio_end_read Date: Wed, 4 Oct 2023 17:53:00 +0100 Message-Id: <20231004165317.1061855-1-willy@infradead.org> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The core of this patchset is the new folio_end_read() call which filesystems can use when finishing a page cache read instead of separate calls to mark the folio uptodate and unlock it. As an illustration of its use, I converted ext4, iomap & mpage; more can be converted. I think that's useful by itself, but the interesting optimisation is that we can implement that with a single XOR instruction that sets the uptodate bit, clears the lock bit, tests the waiter bit and provides a write memory barrier. That removes one memory barrier and one atomic instruction from each page read, which seems worth doing. That's in patch 15. The last two patches could be a separate series, but basically we can do the same thing with the writeback flag that we do with the unlock flag; clear it and test the waiters bit at the same time. v2: - Update to 6.6-rc4 - Simplify iomap's use of folio_end_read() as suggested by Linus - Fix weird Alpha assembly, as suggested by Linus - Implement xor_unlock_is_negative_byte for Coldfire - Add a likely() to folio_end_read() after studying the Coldfire assembly Matthew Wilcox (Oracle) (17): iomap: Hold state_lock over call to ifs_set_range_uptodate() iomap: Protect read_bytes_pending with the state_lock mm: Add folio_end_read() ext4: Use folio_end_read() buffer: Use folio_end_read() iomap: Use folio_end_read() bitops: Add xor_unlock_is_negative_byte() alpha: Implement xor_unlock_is_negative_byte m68k: Implement xor_unlock_is_negative_byte mips: Implement xor_unlock_is_negative_byte powerpc: Implement arch_xor_unlock_is_negative_byte on 32-bit riscv: Implement xor_unlock_is_negative_byte s390: Implement arch_xor_unlock_is_negative_byte mm: Delete checks for xor_unlock_is_negative_byte() mm: Add folio_xor_flags_has_waiters() mm: Make __end_folio_writeback() return void mm: Use folio_xor_flags_has_waiters() in folio_end_writeback() arch/alpha/include/asm/bitops.h | 20 +++++ arch/m68k/include/asm/bitops.h | 21 +++++ arch/mips/include/asm/bitops.h | 25 +++++- arch/mips/lib/bitops.c | 14 ++++ arch/powerpc/include/asm/bitops.h | 21 ++--- arch/riscv/include/asm/bitops.h | 12 +++ arch/s390/include/asm/bitops.h | 10 +++ arch/x86/include/asm/bitops.h | 11 ++- fs/buffer.c | 16 +--- fs/ext4/readpage.c | 14 +--- fs/iomap/buffered-io.c | 57 ++++++++------ .../asm-generic/bitops/instrumented-lock.h | 28 ++++--- include/asm-generic/bitops/lock.h | 20 +---- include/linux/page-flags.h | 19 +++++ include/linux/pagemap.h | 1 + kernel/kcsan/kcsan_test.c | 9 +-- kernel/kcsan/selftest.c | 9 +-- mm/filemap.c | 77 ++++++++++--------- mm/kasan/kasan_test.c | 8 +- mm/page-writeback.c | 35 ++++----- 20 files changed, 255 insertions(+), 172 deletions(-)