From patchwork Mon Jul 24 22:55:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 13325423 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 2CD85C04A6A for ; Mon, 24 Jul 2023 22:55:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230141AbjGXWzU (ORCPT ); Mon, 24 Jul 2023 18:55:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229496AbjGXWzU (ORCPT ); Mon, 24 Jul 2023 18:55:20 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34DC0E5A for ; Mon, 24 Jul 2023 15:55:19 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id d9443c01a7336-1bbadf9ed37so1478725ad.0 for ; Mon, 24 Jul 2023 15:55:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1690239318; x=1690844118; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Wx3gDejnv+MYuO8cUn67Qw106/rsCHumB4kwemSJRZY=; b=bm+YKX6D1BwkR4vrs42vdWoeqGRLlquEzDtbB0b00LKREL0LWQEHHMtZV+Lve3k79k nJlObut1EZppwPrHtzilkZnngV2wP5bNloU+coVqsuEOL/nmSD5mM5mVyfZeCs0KdGrc eUjDg+Mswj6k7ivu7z7L/9wxEMuwiEJoztbGAfmnGDVcsfkIIXcDMR+CB0aT5Fb3WpO0 qaS049XZo1myuKfEwG+guOIHssrbJ1NhrfOxOG3Kyrt8JeE64/L+kHziZl6wDN70GdmX P92zM73IY4gVZwhJJBo4VQCBKTWrSEt9KqfghLeUxNDlFBApp8YNLhVNxJA/StUHYMAp px6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690239318; x=1690844118; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Wx3gDejnv+MYuO8cUn67Qw106/rsCHumB4kwemSJRZY=; b=T4+sPsiG84QqypDQ23YN7SA05tDW/TDa7ao5O7YBFlxnPrFoHvQCAgXI2SvgzFDZa7 LEqX0nLIrQZezspVrn3ONSwRHf3ATyngMQ0n1DlAFx5hMECyarXFREzZ3rHWlC3SDzZA j6RL6lA7XKPz/bZW/lTyYnf5N9nxkC7oQshpC54uAUJlpG9ZOTEZ7oUASolmL0fD6gio X5Ipqewq+zKUpWjgbO5/bzECWCB2aJHzDCVDCkps3agYXXMxJpFgDwO3FnTMMn10IN3b ssooM2ETtDKkrcEuiAUkjeI4WJs2edwgIbzT2kAJVfo6uLw/dKeOSJwT1FbvpYYtqMJc Pxfw== X-Gm-Message-State: ABy/qLbfmukuXp6vFUjQToyO6lGN+cFGLnVWRKlFlISbVeQVDqXknxfe 1XXsi3dHtdgHoS/oCDIquMwQSw== X-Google-Smtp-Source: APBJJlHvNGqZ/QpFqqw+CFa53OAtegzHdOldV4x76K1a9aUXPkJY8NVWbAeVvyGXes1jwAY4Frt8tw== X-Received: by 2002:a17:902:e74d:b0:1bb:ac37:384b with SMTP id p13-20020a170902e74d00b001bbac37384bmr3491050plf.6.1690239318701; Mon, 24 Jul 2023 15:55:18 -0700 (PDT) Received: from localhost.localdomain ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id p7-20020a1709026b8700b001acae9734c0sm9424733plk.266.2023.07.24.15.55.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 15:55:18 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org, linux-xfs@vger.kernel.org Cc: hch@lst.de, andres@anarazel.de, david@fromorbit.com, djwong@kernel.org, Jens Axboe Subject: [PATCH 3/8] iomap: treat a write through cache the same as FUA Date: Mon, 24 Jul 2023 16:55:06 -0600 Message-Id: <20230724225511.599870-4-axboe@kernel.dk> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230724225511.599870-1-axboe@kernel.dk> References: <20230724225511.599870-1-axboe@kernel.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Whether we have a write back cache and are using FUA or don't have a write back cache at all is the same situation. Treat them the same. This makes the IOMAP_DIO_WRITE_FUA name a bit misleading, as we have two cases that provide stable writes: 1) Volatile write cache with FUA writes 2) Normal write without a volatile write cache Rename that flag to IOMAP_DIO_STABLE_WRITE to make that clearer, and update some of the FUA comments as well. Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- fs/iomap/direct-io.c | 34 ++++++++++++++++++++-------------- 1 file changed, 20 insertions(+), 14 deletions(-) diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index 7d627d43d10b..6b690fc22365 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -20,7 +20,7 @@ * Private flags for iomap_dio, must not overlap with the public ones in * iomap.h: */ -#define IOMAP_DIO_WRITE_FUA (1U << 28) +#define IOMAP_DIO_WRITE_THROUGH (1U << 28) #define IOMAP_DIO_NEED_SYNC (1U << 29) #define IOMAP_DIO_WRITE (1U << 30) #define IOMAP_DIO_DIRTY (1U << 31) @@ -219,7 +219,7 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio, /* * Figure out the bio's operation flags from the dio request, the * mapping, and whether or not we want FUA. Note that we can end up - * clearing the WRITE_FUA flag in the dio request. + * clearing the WRITE_THROUGH flag in the dio request. */ static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio, const struct iomap *iomap, bool use_fua) @@ -233,7 +233,7 @@ static inline blk_opf_t iomap_dio_bio_opflags(struct iomap_dio *dio, if (use_fua) opflags |= REQ_FUA; else - dio->flags &= ~IOMAP_DIO_WRITE_FUA; + dio->flags &= ~IOMAP_DIO_WRITE_THROUGH; return opflags; } @@ -273,11 +273,13 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter, * Use a FUA write if we need datasync semantics, this is a pure * data IO that doesn't require any metadata updates (including * after IO completion such as unwritten extent conversion) and - * the underlying device supports FUA. This allows us to avoid - * cache flushes on IO completion. + * the underlying device either supports FUA or doesn't have + * a volatile write cache. This allows us to avoid cache flushes + * on IO completion. */ if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) && - (dio->flags & IOMAP_DIO_WRITE_FUA) && bdev_fua(iomap->bdev)) + (dio->flags & IOMAP_DIO_WRITE_THROUGH) && + (bdev_fua(iomap->bdev) || !bdev_write_cache(iomap->bdev))) use_fua = true; } @@ -553,13 +555,16 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, dio->flags |= IOMAP_DIO_NEED_SYNC; /* - * For datasync only writes, we optimistically try - * using FUA for this IO. Any non-FUA write that - * occurs will clear this flag, hence we know before - * completion whether a cache flush is necessary. + * For datasync only writes, we optimistically try using + * WRITE_THROUGH for this IO. This flag requires either + * FUA writes through the device's write cache, or a + * normal write to a device without a volatile write + * cache. For the former, Any non-FUA write that occurs + * will clear this flag, hence we know before completion + * whether a cache flush is necessary. */ if (!(iocb->ki_flags & IOCB_SYNC)) - dio->flags |= IOMAP_DIO_WRITE_FUA; + dio->flags |= IOMAP_DIO_WRITE_THROUGH; } /* @@ -621,10 +626,11 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, iomap_dio_set_error(dio, ret); /* - * If all the writes we issued were FUA, we don't need to flush the - * cache on IO completion. Clear the sync flag for this case. + * If all the writes we issued were already written through to the + * media, we don't need to flush the cache on IO completion. Clear the + * sync flag for this case. */ - if (dio->flags & IOMAP_DIO_WRITE_FUA) + if (dio->flags & IOMAP_DIO_WRITE_THROUGH) dio->flags &= ~IOMAP_DIO_NEED_SYNC; WRITE_ONCE(iocb->private, dio->submit.poll_bio);