From nobody Wed Oct 8 02:04:16 2025 Received: from mail-ot1-f41.google.com (mail-ot1-f41.google.com [209.85.210.41]) (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 6A5B4291C11; Thu, 3 Jul 2025 18:50:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.41 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751568654; cv=none; b=aZTZhDLJEY4oRIHHnemNIIHuVWBuoJaAhQwkYksmkZla51onymLrYrjE16m2pU2a3X76VKiIohks3AtEIp1pFnJW+lE/Lq/YV0mYfAQOQmOg5pCB9VCVExTGWraaAafdiqAT8NYlKeF41s1EQY8H0itGTLpR2MQOLS9dd9v4m/g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751568654; c=relaxed/simple; bh=Pw428QKL7vU/Q+rAmnYuMV/vyS2i6xzQE57G20v2vFg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=H65Ia5k/Ds0mZq03qGQgA/J2MPSfWXgcGK/pLMJyKrpjoFTY9aGhcMCZc1HKhJ1V8wPrGk2X5x4j3n+H+qnFUPWMkNvHI7SdMhUTAkxwrVhkSOkcWJCQApOf/Xomx4E/q06KqjP+wuiJLt6YcatPH4SsssmqRqA0HAHeYMwHaF8= 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=cTrLyX/T; arc=none smtp.client-ip=209.85.210.41 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="cTrLyX/T" Received: by mail-ot1-f41.google.com with SMTP id 46e09a7af769-72c47631b4cso193852a34.1; Thu, 03 Jul 2025 11:50:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1751568651; x=1752173451; darn=vger.kernel.org; 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=wgKTg4/Nk6wm5J+WL43f3KfjMbT1HMf3Vkuk3EBDHmU=; b=cTrLyX/Tbs89Rpf3SvB/1q3aaP8L0eO+9h+B6fsgho2tUU7wWtEw5our7cO4lVp3xp nozG2ib6Hg2qDUk6+jGxYBJW7zWexzD9A5GN1B4eCfCGdgnEhsc/oOaX9KKvT/IFciDj eUPKxE1u4Nwt/fc+6W14YtOkoKDsoW5ZfdsbeNYLFzSaop6lgjm36mJBMgEDTE2aETG9 WjcBpn6gieiqSryLNYq6WSwYS08VSZERLv7QOy1ngLo67PyDI31GY1yHYOZJqdQQZfTQ 9NpxiQnuvirSdGrAknKf00lrF4Dk1Fnrv/28vmix4wd8yGme/TJ8+2GZMQWUuFTRInDn DPIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751568651; x=1752173451; 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=wgKTg4/Nk6wm5J+WL43f3KfjMbT1HMf3Vkuk3EBDHmU=; b=PM8Pmh8PSCAsMj27UhtOELTy+CSeVOD5pX3qVLLM7d+820hC8ySlGv4xKdSMQVRQ/m DQTmJCL6aBwhlrmGWxyDewrNeWncV2cA20a8R/M9Fb55QmtGxusFE80vflghURYS0BAf RdQIlCPSJ139MHqwb4isoQsEFXOPdllHjQz9mKLLnup1ZTU+6gohIZBVrrSdiXg2h8zI wW/W7uemEdz8j8NCOKdyAsXAYk5PMr7c6CFOnYLJYeyvRJVLXrdrCEJtabBt02MBUz+X A3Wx+HFe7OvojwZ9VHkeZI8/H8OuOhWA8OZgKmVxesXx0D18fe+3YsThKhCBtGr6BGrd PpfA== X-Forwarded-Encrypted: i=1; AJvYcCVkpy6IrkX6r9JgPAZDfZw50YbFJUb2ttNhs2omI4Slw8p9lc/O87wg3FousmF/5rldvNpOek0J55NjODpL@vger.kernel.org, AJvYcCX5ZUxCTLByS+sGtAD4mYzObaBdNg2IFJbqcjg3D31oo3YRMr15+jb7MLiH+5toJHEE/rcW1A6kcytpMCffXw==@vger.kernel.org, AJvYcCXJwIm2xjFkvy9JvAYjcsnjWKhKbrHDbI2ptmrD2B/R77BydUSpA+AeHDV6Q5ZQocMH5HLqXl5anCZ5@vger.kernel.org, AJvYcCXyOdcunEjBfZVAvZC7MgHFJ5SEYrNcgZdX+xKOyoMW6D8iGD+ssW4W0n1+1OTdVOiucWDBBLcl9As=@vger.kernel.org X-Gm-Message-State: AOJu0YziLrRIMaM8jOT7IZxF6BfoFHlzmlaTeqYBc/lrH/7F3dl4qti3 iXXOyfsUrdSOIcn/5qX7Bulz9sn9VMxWaulhlnEJFcWNJqhkx1LvNLrp X-Gm-Gg: ASbGncuAh/dEiaLqFSH/A0/8binC2q36lT4e0fOdqSiNhdlEEp+CIeIk42iEdA12G94 lWwrrmphTEtxKiVUavJSmWDKp0RkyCCBTF+NODNmjVOtjbPHESeNfadPADTOMbwk7Bi+l8eTVp3 6fZySz+3HwxCNPCkd2a75Mz+BjZTXRuJEn2lfrIO/m6KPhnCOuDiX5+hBV9u60oK9UUjosXRzs8 Y2PFXMiSbwRfGa00qRNh9Vb8bqjDI8+RxWegLolWj9nw0h8wWJXugQ2gq3JfN+OwRvNolWDUxZ9 i+JJk8dmETc8gqFsYRwXGsVPJlbYNaXAxO53kT+X5bkPtmw9Tm5El4IADP35sAH6zDCeBrworjj eJjRMwmz0pZ8WSqpiY4ukNMd7 X-Google-Smtp-Source: AGHT+IGNEYE8azkCu6i4tdt/Jh/JzWWu2d955CfMIRLR2kAADDQEL7D+pI5ll8ogxoQ3Xa3+A+d+Cg== X-Received: by 2002:a05:6830:3c8d:b0:739:fcb4:db17 with SMTP id 46e09a7af769-73b4cb2f25amr6347478a34.15.1751568650976; Thu, 03 Jul 2025 11:50:50 -0700 (PDT) Received: from localhost.localdomain ([2603:8080:1500:3d89:cd4:2776:8c4a:3597]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-73c9f90d1ccsm68195a34.44.2025.07.03.11.50.48 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 03 Jul 2025 11:50:49 -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 04/18] dev_dax_iomap: Add dax_operations for use by fs-dax on devdax Date: Thu, 3 Jul 2025 13:50:18 -0500 Message-Id: <20250703185032.46568-5-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: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Notes about this commit: * These methods are based on pmem_dax_ops from drivers/nvdimm/pmem.c * dev_dax_direct_access() is returns the hpa, pfn and kva. The kva was newly stored as dev_dax->virt_addr by dev_dax_probe(). * The hpa/pfn are used for mmap (dax_iomap_fault()), and the kva is used for read/write (dax_iomap_rw()) * dev_dax_recovery_write() and dev_dax_zero_page_range() have not been tested yet. I'm looking for suggestions as to how to test those. Signed-off-by: John Groves --- drivers/dax/bus.c | 120 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 115 insertions(+), 5 deletions(-) diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c index 9d9a4ae7bbc0..61a8d1b3c07a 100644 --- a/drivers/dax/bus.c +++ b/drivers/dax/bus.c @@ -7,6 +7,10 @@ #include #include #include +#include +#include +#include +#include #include "dax-private.h" #include "bus.h" =20 @@ -1441,6 +1445,105 @@ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax= *dev_dax, pgoff_t pgoff, } EXPORT_SYMBOL_GPL(dax_pgoff_to_phys); =20 +#if IS_ENABLED(CONFIG_DEV_DAX_IOMAP) + +static void write_dax(void *pmem_addr, struct page *page, + unsigned int off, unsigned int len) +{ + unsigned int chunk; + void *mem; + + while (len) { + mem =3D kmap_local_page(page); + chunk =3D min_t(unsigned int, len, PAGE_SIZE - off); + memcpy_flushcache(pmem_addr, mem + off, chunk); + kunmap_local(mem); + len -=3D chunk; + off =3D 0; + page++; + pmem_addr +=3D chunk; + } +} + +static long __dev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pg= off, + long nr_pages, enum dax_access_mode mode, void **kaddr, + pfn_t *pfn) +{ + struct dev_dax *dev_dax =3D dax_get_private(dax_dev); + size_t size =3D nr_pages << PAGE_SHIFT; + size_t offset =3D pgoff << PAGE_SHIFT; + void *virt_addr =3D dev_dax->virt_addr + offset; + u64 flags =3D PFN_DEV|PFN_MAP; + phys_addr_t phys; + pfn_t local_pfn; + size_t dax_size; + + WARN_ON(!dev_dax->virt_addr); + + if (down_read_interruptible(&dax_dev_rwsem)) + return 0; /* no valid data since we were killed */ + dax_size =3D dev_dax_size(dev_dax); + up_read(&dax_dev_rwsem); + + phys =3D dax_pgoff_to_phys(dev_dax, pgoff, nr_pages << PAGE_SHIFT); + + if (kaddr) + *kaddr =3D virt_addr; + + local_pfn =3D phys_to_pfn_t(phys, flags); /* are flags correct? */ + if (pfn) + *pfn =3D local_pfn; + + /* This the valid size at the specified address */ + return PHYS_PFN(min_t(size_t, size, dax_size - offset)); +} + +static int dev_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgo= ff, + size_t nr_pages) +{ + long resid =3D nr_pages << PAGE_SHIFT; + long offset =3D pgoff << PAGE_SHIFT; + + /* Break into one write per dax region */ + while (resid > 0) { + void *kaddr; + pgoff_t poff =3D offset >> PAGE_SHIFT; + long len =3D __dev_dax_direct_access(dax_dev, poff, + nr_pages, DAX_ACCESS, &kaddr, NULL); + len =3D min_t(long, len, PAGE_SIZE); + write_dax(kaddr, ZERO_PAGE(0), offset, len); + + offset +=3D len; + resid -=3D len; + } + return 0; +} + +static long dev_dax_direct_access(struct dax_device *dax_dev, + pgoff_t pgoff, long nr_pages, enum dax_access_mode mode, + void **kaddr, pfn_t *pfn) +{ + return __dev_dax_direct_access(dax_dev, pgoff, nr_pages, mode, kaddr, pfn= ); +} + +static size_t dev_dax_recovery_write(struct dax_device *dax_dev, pgoff_t p= goff, + void *addr, size_t bytes, struct iov_iter *i) +{ + size_t off; + + off =3D offset_in_page(addr); + + return _copy_from_iter_flushcache(addr, bytes, i); +} + +static const struct dax_operations dev_dax_ops =3D { + .direct_access =3D dev_dax_direct_access, + .zero_page_range =3D dev_dax_zero_page_range, + .recovery_write =3D dev_dax_recovery_write, +}; + +#endif /* IS_ENABLED(CONFIG_DEV_DAX_IOMAP) */ + static struct dev_dax *__devm_create_dev_dax(struct dev_dax_data *data) { struct dax_region *dax_region =3D data->dax_region; @@ -1496,11 +1599,18 @@ static struct dev_dax *__devm_create_dev_dax(struct= dev_dax_data *data) } } =20 - /* - * No dax_operations since there is no access to this device outside of - * mmap of the resulting character device. - */ - dax_dev =3D alloc_dax(dev_dax, NULL); + if (IS_ENABLED(CONFIG_DEV_DAX_IOMAP)) + /* holder_ops currently populated separately in a slightly + * hacky way + */ + dax_dev =3D alloc_dax(dev_dax, &dev_dax_ops); + else + /* + * No dax_operations since there is no access to this device + * outside of mmap of the resulting character device. + */ + dax_dev =3D alloc_dax(dev_dax, NULL); + if (IS_ERR(dax_dev)) { rc =3D PTR_ERR(dax_dev); goto err_alloc_dax; --=20 2.49.0