From patchwork Fri Dec 13 14:36:08 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Brian Foster X-Patchwork-Id: 13907262 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 04C031E2009 for ; Fri, 13 Dec 2024 14:34:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734100473; cv=none; b=OJyrfwVfS4+wR4IFm9JiUOo4iT7cl3gK6k8bAOiHTdw4IfdFgB1XvohCSeWgGRQKLTLjyrUUalRJr2Uj/9D79q3vWfKXmpIzSSzpHMzh6LsMR1kLrGy2PASJ59TH8FA0m0L4C8KULEE5mTwv4prJ6x+/B7iAdC9qVae1TNwkrJ0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734100473; c=relaxed/simple; bh=OKAIQS7yoj53v6aPmr/2QbPOoplwTQWSySIf6C79NBs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=BiTsFMfqhKWn0nOiyCxcQQ5y2fAypSYZCxiU6iWwepiwCAQMkP4ye08ifJBTdnH76XHdQtSMIcOqSvC9lz3/6VQpWBwYuQhPbHSAkMB21kaB9iYWDK255KiOQYPLMCWufbw/RqsKHzvic1bKyHS6KuS6Xpqg7LyXMrjXXUZgZh0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ObCIjUaB; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ObCIjUaB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734100471; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pofMAyHFR1hGi6iQD9ByZ17lIz/vNbdpdYcS8TQbk7Q=; b=ObCIjUaB7eoHoZ7Szu08iqtHfDcggO8xA/Bg/EXYvwE2p9WlIGOQLTq4WK2E6niS8eGDii Kl/EJoHItDubNFWaV30q++G/w7zybQh3BJtBIP+HSa5JHEWQscvPxL76cEjPYipCBH7ip9 prDx1D4UVVeVacbjYZTx6uuB51HsfLE= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-21-nsQQE1qkM8u7SQBDncD88Q-1; Fri, 13 Dec 2024 09:34:27 -0500 X-MC-Unique: nsQQE1qkM8u7SQBDncD88Q-1 X-Mimecast-MFC-AGG-ID: nsQQE1qkM8u7SQBDncD88Q Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E21651955F09; Fri, 13 Dec 2024 14:34:26 +0000 (UTC) Received: from bfoster.redhat.com (unknown [10.22.90.12]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 48485195605A; Fri, 13 Dec 2024 14:34:26 +0000 (UTC) From: Brian Foster To: linux-fsdevel@vger.kernel.org Cc: linux-xfs@vger.kernel.org Subject: [PATCH 4/6] iomap: advance the iter directly on buffered writes Date: Fri, 13 Dec 2024 09:36:08 -0500 Message-ID: <20241213143610.1002526-5-bfoster@redhat.com> In-Reply-To: <20241213143610.1002526-1-bfoster@redhat.com> References: <20241213143610.1002526-1-bfoster@redhat.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Modify the buffered write path to advance the iter directly. Replace the local pos and length calculations with direct advances and loop based on iter state instead. Also remove the -EAGAIN return hack as it is no longer necessary now that separate return channels exist for processing progress and error returns. For example, the existing write handler must return either a count of bytes written or error if the write is interrupted, but presumably wants to return -EAGAIN directly in order to break the higher level iomap_iter() loop. Since the current iteration may have made some progress, it unwinds the iter on the way out to return the error while ensuring that portion of the write can be retried. If -EAGAIN occurs at any point beyond the first iteration, iomap_file_buffered_write() will then observe progress based on iter->pos to return a short write. With incremental advances on the iomap_iter, iomap_write_iter() can simply return the error. iomap_iter() completes whatever progress was made based on iomap_iter position and still breaks out of the iter loop based on the error code in iter.processed. The end result of the write is similar in terms of being a short write if progress was made or error return otherwise. Signed-off-by: Brian Foster --- fs/iomap/buffered-io.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 955f19e27e47..3ece0bee803d 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -909,8 +909,6 @@ static bool iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len, static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) { - loff_t length = iomap_length(iter); - loff_t pos = iter->pos; ssize_t total_written = 0; long status = 0; struct address_space *mapping = iter->inode->i_mapping; @@ -924,6 +922,8 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) size_t bytes; /* Bytes to write to folio */ size_t copied; /* Bytes copied from user */ size_t written; /* Bytes have been written */ + loff_t pos = iter->pos; + loff_t length = iomap_length(iter); bytes = iov_iter_count(i); retry: @@ -1006,17 +1006,12 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) goto retry; } } else { - pos += written; total_written += written; - length -= written; + iomap_iter_advance(iter, written); } - } while (iov_iter_count(i) && length); + } while (iov_iter_count(i) && iomap_length(iter)); - if (status == -EAGAIN) { - iov_iter_revert(i, total_written); - return -EAGAIN; - } - return total_written ? total_written : status; + return total_written ? 0 : status; } ssize_t