From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oa1-f47.google.com (mail-oa1-f47.google.com [209.85.160.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EC8232F2730 for ; Thu, 3 Jul 2025 18:50:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751568645; cv=none; b=iCNsISa8dRhXj83/V90/GswsXj40LZ7vJttStEjgNHYD3joq77sDh3Py1P2JRLNyGjqEGO2h8lrX71+hM2t/fTTdqIzw2E0d5Gn6K9FD6xXVe8unFX8liWnr8B5zyM22beentkn5oNbfwonnPJWjcaL2YmbUDCNBgm5ujfQxvuc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751568645; c=relaxed/simple; bh=gsIhmfFsaL+5EF4z3f0VUnIpcZS1jFVcEdA2B4rIq38=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=cOuH7qb0jGdi+0nakU0bUss/0M1a/4oTHU/L17yS9DZmAzyNNoHPNoTzVrVEgKRf4d3BoXjfQYaKBNSTLHWZXL6lcXULIWTAkDvtAopMFeKwJYZ8dGJyflW6z/W5m2dclrhZWAinKISl+q8WSfr1ig52RcvHBT8Va1KsEhZzyJw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=Groves.net; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=ca4Ogmvn; arc=none smtp.client-ip=209.85.160.47 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=Groves.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ca4Ogmvn" Received: by mail-oa1-f47.google.com with SMTP id 586e51a60fabf-2e9071e3706so195597fac.0 for ; Thu, 03 Jul 2025 11:50:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1751568643; x=1752173443; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:from:to:cc:subject:date :message-id:reply-to; bh=37keBjnXcy0vWAMphYKQfFgDhN7R9v7a8FhgLd8vRyw=; b=ca4OgmvnYmgzGvvUiSMglE7rQiobI9FWRZoMvckwHFtWUCCJOTh7DbIVlDS9Miv3XF nrnCNtjSSKfnFBlJaQeVDnRIdSkPGYecOpA3hP6xyExpW2qouqf3zhJ0l5roCw3UhGLC H8OJ30OeZnzWH2+9ohKZoD5+2qNECzKFnOWYgAjSCb07ePV/vYcbC85LHQvXvRzWYbIZ XSvVlGDkE2WV7x8s7DI6lqiTm61oEqFC4SlYw6k+R0VeZRlx9+ZQtJDdIwbDwlb+dthe bvXum1/YDGyosBvMBVN8pPQ9O9MQgcRiYvp22JLNiUuj/iRgoVslVbYbfhut8LikzhSH HJrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751568643; x=1752173443; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:sender:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=37keBjnXcy0vWAMphYKQfFgDhN7R9v7a8FhgLd8vRyw=; b=EX3nuAXIZM7aDlK8hlzG5rEIjdNUC+hCEoDzncdptXvGzkWetcsvrplzrZRk7lmKh9 dUN/cZJ73KEUQqkdiGTEWqZzhyKDOqcT/FAt9crZc0X+0hjFPaPDi6tIz/qhlskLmnIj tP2xXVqQmaTMnGuCfhsih4ND5dqvYduZezvKg2W1t2aNYc9BBaylzl0gCthjde96uHYU OQP1yMtirOZ56S3eqvJYfIVs+nA1A0GVt/bScHDTTRY2SEGMnSUutv94F6YLh+8MYu3z xo8yCo+hTNSuaW8yrmKCu3xjDiGp6laVguaNcKgHLtHoXjCZ5NkArIxMX0/TCPGXKEaR Tv7g== X-Forwarded-Encrypted: i=1; AJvYcCVDNp0c4RwN8fSB6D/tguxK8E12UwkxCbO6dzOP937Oj9KgAIu8MuGatVnneTdNmfARS0cQ2mY=@lists.linux.dev X-Gm-Message-State: AOJu0Yx9rnrOKDMyYHtylR9Ga/ExUa23xn9BprsdXQaS2e5zCx2wbig5 m7B9WaC6Y+QGtmHA/oukXvhcswYibRuh/h8BWs8h9vzsbErFldT8Qxz7 X-Gm-Gg: ASbGncs/qAd7ok0lvP+pxzecuzHNJ1Bd+rUQyUyee+qXwE4CXBsZsZj0OTPwJ1fhnWL A+vgcjP9rTZs6pG9XSFeUN9YzEnJeIqFFwxYkj/aLv+JAMw86tigP3P41U49VhNM04d/6WGItV6 m3OWEBAFEjZyNu9SW0pdFafAq9AmcFEWYzZvN9sSqq9a5IU9n+YPHBS52KnicmWBsAaT1UJ5zFU Sq3j5Mj213uVHAh3JauBOBArwdorInXmMzF22VNkHb89uWPMawqwpWpU7dV7rh1U2ET8D9tHnoh mh55WHOc73I8NQ42FPlK2+H21slfd/z9MB+FQLowZ/4CQtrndFyvm955AiBh7S9r5ky21hEQvZz zXyY0PddE3s/ErUDGNMaIxuf0 X-Google-Smtp-Source: AGHT+IGGO26vNj25TCeR8caAFdVMd/7bQ1PotJARXetJW6yAE8gTTCz/lmho2fjx9+U6Hq3mnqrM6w== X-Received: by 2002:a05:6871:8416:b0:2f7:64ff:aae2 with SMTP id 586e51a60fabf-2f764ffaf42mr2834618fac.36.1751568642961; Thu, 03 Jul 2025 11:50:42 -0700 (PDT) Received: from localhost.localdomain ([2603:8080:1500:3d89:cd4:2776:8c4a:3597]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-73c9f90d1ccsm68195a34.44.2025.07.03.11.50.41 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 03 Jul 2025 11:50:42 -0700 (PDT) Sender: John Groves From: John Groves X-Google-Original-From: John Groves To: John Groves , Dan Williams , Miklos Szeredi , Bernd Schubert Cc: John Groves , Jonathan Corbet , Vishal Verma , Dave Jiang , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , "Darrick J . Wong" , Randy Dunlap , Jeff Layton , Kent Overstreet , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev, linux-cxl@vger.kernel.org, linux-fsdevel@vger.kernel.org, Amir Goldstein , Jonathan Cameron , Stefan Hajnoczi , Joanne Koong , Josef Bacik , Aravind Ramesh , Ajay Joshi , John Groves Subject: [RFC V2 02/18] dev_dax_iomap: Add fs_dax_get() func to prepare dax for fs-dax usage Date: Thu, 3 Jul 2025 13:50:16 -0500 Message-Id: <20250703185032.46568-3-john@groves.net> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250703185032.46568-1-john@groves.net> References: <20250703185032.46568-1-john@groves.net> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This function should be called by fs-dax file systems after opening the devdax device. This adds holder_operations, which effects exclusivity between callers of fs_dax_get(). This function serves the same role as fs_dax_get_by_bdev(), which dax file systems call after opening the pmem block device. This also adds the CONFIG_DEV_DAX_IOMAP Kconfig parameter Signed-off-by: John Groves --- drivers/dax/Kconfig | 6 ++++++ drivers/dax/super.c | 30 ++++++++++++++++++++++++++++++ include/linux/dax.h | 5 +++++ 3 files changed, 41 insertions(+) diff --git a/drivers/dax/Kconfig b/drivers/dax/Kconfig index d656e4c0eb84..ad19fa966b8b 100644 --- a/drivers/dax/Kconfig +++ b/drivers/dax/Kconfig @@ -78,4 +78,10 @@ config DEV_DAX_KMEM Say N if unsure. +config DEV_DAX_IOMAP + depends on DEV_DAX && DAX + def_bool y + help + Support iomap mapping of devdax devices (for FS-DAX file + systems that reside on character /dev/dax devices) endif diff --git a/drivers/dax/super.c b/drivers/dax/super.c index e16d1d40d773..48bab9b5f341 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -122,6 +122,36 @@ void fs_put_dax(struct dax_device *dax_dev, void *holder) EXPORT_SYMBOL_GPL(fs_put_dax); #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */ +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) +/** + * fs_dax_get() + * + * fs-dax file systems call this function to prepare to use a devdax device for + * fsdax. This is like fs_dax_get_by_bdev(), but the caller already has struct + * dev_dax (and there * is no bdev). The holder makes this exclusive. + * + * @dax_dev: dev to be prepared for fs-dax usage + * @holder: filesystem or mapped device inside the dax_device + * @hops: operations for the inner holder + * + * Returns: 0 on success, <0 on failure + */ +int fs_dax_get(struct dax_device *dax_dev, void *holder, + const struct dax_holder_operations *hops) +{ + if (!dax_dev || !dax_alive(dax_dev) || !igrab(&dax_dev->inode)) + return -ENODEV; + + if (cmpxchg(&dax_dev->holder_data, NULL, holder)) + return -EBUSY; + + dax_dev->holder_ops = hops; + + return 0; +} +EXPORT_SYMBOL_GPL(fs_dax_get); +#endif /* DEV_DAX_IOMAP */ + enum dax_device_flags { /* !alive + rcu grace period == no new operations / mappings */ DAXDEV_ALIVE, diff --git a/include/linux/dax.h b/include/linux/dax.h index df41a0017b31..86bf5922f1b0 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -51,6 +51,11 @@ struct dax_holder_operations { #if IS_ENABLED(CONFIG_DAX) struct dax_device *alloc_dax(void *private, const struct dax_operations *ops); + +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) +int fs_dax_get(struct dax_device *dax_dev, void *holder, const struct dax_holder_operations *hops); +struct dax_device *inode_dax(struct inode *inode); +#endif void *dax_holder(struct dax_device *dax_dev); void put_dax(struct dax_device *dax_dev); void kill_dax(struct dax_device *dax_dev); -- 2.49.0