From patchwork Thu Dec 21 09:54:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 13501544 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (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 B6B3B4CB36; Thu, 21 Dec 2023 09:54:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com 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="QQFlcgzY" Received: by mail-wm1-f51.google.com with SMTP id 5b1f17b1804b1-40d3c4bfe45so5998125e9.1; Thu, 21 Dec 2023 01:54:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703152456; x=1703757256; darn=vger.kernel.org; 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=q2ZdmV6mFZSXgUlUGvSfZl6UXJ+WcSkP8ofHyoJDlUo=; b=QQFlcgzYNeRmf807AeTAPoZH7Z6DaZhIskLkbnC9dVQ8PdX8YFBOAB08R61e3txr8y 8NOwkXCpZbzDHrkbOIeZ5KqBC2v/1OREW2hwbOlgt0WaiT/ukI4qKBDfmDpPba5TOvjP iIPMgGVl/tksWW1sfV+7iWDVpQQtnNlPXie503R1e6cpsJgKU1E5rN5XF61VTKX346nl QDFmPZ3ekYtoza8eKC4vBvy3qkSSKaM48SsLVvatGIxXTdZTJLxg2CmgsrHF3tH/rGq+ HCKJf7NB6MfIo13xqdrtOBTAdIHNb749nXC5uufKwBNc/O+Oe8F4u7zYAQIvqUuGMgi4 gzsA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703152456; x=1703757256; 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=q2ZdmV6mFZSXgUlUGvSfZl6UXJ+WcSkP8ofHyoJDlUo=; b=RmobWePbsm8wQVQhPv3zFIC1peYkdPuyKqS8izsEEarSD6yAshM2gxZ+TYD7HgbvKP kEvRgJ+FeLjjdfVYI297ASz1t5XfqfU+JyvITw6u1MoTU6Ryo9cWwCVkzMb7SIfwP4yV pYT+xFKnbHBHwk3MuT9hQOhOXmDTDYxX99foCzhpQpF1LWXvNzBiiPXof7aRFAMuVUgO lWe5/ideXb8xRwVtnnUwYrwzO7Hi7RyV4SpJGc8Fy/G3Ocdt+KAdZawVJ3Ds0UfTY7dx GW/jO7nVkcB/x36x1I5UsMtJzVWqfHtLk6S0xCbSX/Jdhr47jgS+QI8mfOgtNW3UjKXj xNRQ== X-Gm-Message-State: AOJu0Yz+M0ym72rIvmalMiC2HH4olNghUoDML/Ah2p9j0LMwqQ20aLRm UYGHFQMxma3pEyFaRx/lQn0= X-Google-Smtp-Source: AGHT+IFLmD2Ht8k20JOg16jZtHulpwgQ5lurg6Fuxg5jhT9zRPAFnoz5TmHlKEhFPi2R56vqyqnjGA== X-Received: by 2002:a05:600c:46c6:b0:40d:3758:3251 with SMTP id q6-20020a05600c46c600b0040d37583251mr288655wmo.262.1703152455603; Thu, 21 Dec 2023 01:54:15 -0800 (PST) Received: from amir-ThinkPad-T480.lan ([5.29.249.86]) by smtp.gmail.com with ESMTPSA id f5-20020adff8c5000000b003367dad4a58sm1628082wrq.70.2023.12.21.01.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Dec 2023 01:54:14 -0800 (PST) From: Amir Goldstein To: Christian Brauner , Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org Subject: [RFC][PATCH 1/4] fs: prepare for stackable filesystems backing file helpers Date: Thu, 21 Dec 2023 11:54:07 +0200 Message-Id: <20231221095410.801061-2-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231221095410.801061-1-amir73il@gmail.com> References: <20231221095410.801061-1-amir73il@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In preparation for factoring out some backing file io helpers from overlayfs, move backing_file_open() into a new file fs/backing-file.c and header. Add a MAINTAINERS entry for stackable filesystems and add a Kconfig FS_STACK which stackable filesystems need to select. For now, the backing_file struct, the backing_file alloc/free functions and the backing_file_real_path() accessor remain internal to file_table.c. We may change that in the future. Signed-off-by: Amir Goldstein --- MAINTAINERS | 9 +++++++ fs/Kconfig | 4 +++ fs/Makefile | 1 + fs/backing-file.c | 48 ++++++++++++++++++++++++++++++++++++ fs/open.c | 38 ---------------------------- fs/overlayfs/Kconfig | 1 + fs/overlayfs/file.c | 1 + include/linux/backing-file.h | 17 +++++++++++++ include/linux/fs.h | 3 --- 9 files changed, 81 insertions(+), 41 deletions(-) create mode 100644 fs/backing-file.c create mode 100644 include/linux/backing-file.h diff --git a/MAINTAINERS b/MAINTAINERS index 788be9ab5b73..9115a4f0dec7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8186,6 +8186,15 @@ S: Supported F: fs/iomap/ F: include/linux/iomap.h +FILESYSTEMS [STACKABLE] +M: Miklos Szeredi +M: Amir Goldstein +L: linux-fsdevel@vger.kernel.org +L: linux-unionfs@vger.kernel.org +S: Maintained +F: fs/backing-file.c +F: include/linux/backing-file.h + FINTEK F75375S HARDWARE MONITOR AND FAN CONTROLLER DRIVER M: Riku Voipio L: linux-hwmon@vger.kernel.org diff --git a/fs/Kconfig b/fs/Kconfig index fd1f655b4f1f..c47fa4eb9282 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -18,6 +18,10 @@ config VALIDATE_FS_PARSER config FS_IOMAP bool +# Stackable filesystems +config FS_STACK + bool + config BUFFER_HEAD bool diff --git a/fs/Makefile b/fs/Makefile index 75522f88e763..a6962c588962 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -39,6 +39,7 @@ obj-$(CONFIG_COMPAT_BINFMT_ELF) += compat_binfmt_elf.o obj-$(CONFIG_BINFMT_ELF_FDPIC) += binfmt_elf_fdpic.o obj-$(CONFIG_BINFMT_FLAT) += binfmt_flat.o +obj-$(CONFIG_FS_STACK) += backing-file.o obj-$(CONFIG_FS_MBCACHE) += mbcache.o obj-$(CONFIG_FS_POSIX_ACL) += posix_acl.o obj-$(CONFIG_NFS_COMMON) += nfs_common/ diff --git a/fs/backing-file.c b/fs/backing-file.c new file mode 100644 index 000000000000..04b33036f709 --- /dev/null +++ b/fs/backing-file.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Common helpers for stackable filesystems and backing files. + * + * Copyright (C) 2023 CTERA Networks. + */ + +#include +#include + +#include "internal.h" + +/** + * backing_file_open - open a backing file for kernel internal use + * @user_path: path that the user reuqested to open + * @flags: open flags + * @real_path: path of the backing file + * @cred: credentials for open + * + * Open a backing file for a stackable filesystem (e.g., overlayfs). + * @user_path may be on the stackable filesystem and @real_path on the + * underlying filesystem. In this case, we want to be able to return the + * @user_path of the stackable filesystem. This is done by embedding the + * returned file into a container structure that also stores the stacked + * file's path, which can be retrieved using backing_file_user_path(). + */ +struct file *backing_file_open(const struct path *user_path, int flags, + const struct path *real_path, + const struct cred *cred) +{ + struct file *f; + int error; + + f = alloc_empty_backing_file(flags, cred); + if (IS_ERR(f)) + return f; + + path_get(user_path); + *backing_file_user_path(f) = *user_path; + error = vfs_open(real_path, f); + if (error) { + fput(f); + f = ERR_PTR(error); + } + + return f; +} +EXPORT_SYMBOL_GPL(backing_file_open); diff --git a/fs/open.c b/fs/open.c index d877228d5939..a75054237437 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1184,44 +1184,6 @@ struct file *kernel_file_open(const struct path *path, int flags, } EXPORT_SYMBOL_GPL(kernel_file_open); -/** - * backing_file_open - open a backing file for kernel internal use - * @user_path: path that the user reuqested to open - * @flags: open flags - * @real_path: path of the backing file - * @cred: credentials for open - * - * Open a backing file for a stackable filesystem (e.g., overlayfs). - * @user_path may be on the stackable filesystem and @real_path on the - * underlying filesystem. In this case, we want to be able to return the - * @user_path of the stackable filesystem. This is done by embedding the - * returned file into a container structure that also stores the stacked - * file's path, which can be retrieved using backing_file_user_path(). - */ -struct file *backing_file_open(const struct path *user_path, int flags, - const struct path *real_path, - const struct cred *cred) -{ - struct file *f; - int error; - - f = alloc_empty_backing_file(flags, cred); - if (IS_ERR(f)) - return f; - - path_get(user_path); - *backing_file_user_path(f) = *user_path; - f->f_path = *real_path; - error = do_dentry_open(f, d_inode(real_path->dentry), NULL); - if (error) { - fput(f); - f = ERR_PTR(error); - } - - return f; -} -EXPORT_SYMBOL_GPL(backing_file_open); - #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) #define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig index fec5020c3495..2ac67e04a6fb 100644 --- a/fs/overlayfs/Kconfig +++ b/fs/overlayfs/Kconfig @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only config OVERLAY_FS tristate "Overlay filesystem support" + select FS_STACK select EXPORTFS help An overlay filesystem combines two filesystems - an 'upper' filesystem diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 4e46420c8fdd..a6da3eaf6d4f 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "overlayfs.h" #include "../internal.h" /* for sb_init_dio_done_wq */ diff --git a/include/linux/backing-file.h b/include/linux/backing-file.h new file mode 100644 index 000000000000..55c9e804f780 --- /dev/null +++ b/include/linux/backing-file.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Common helpers for stackable filesystems and backing files. + * + * Copyright (C) 2023 CTERA Networks. + */ + +#ifndef _LINUX_BACKING_FILE_H +#define _LINUX_BACKING_FILE_H + +#include + +struct file *backing_file_open(const struct path *user_path, int flags, + const struct path *real_path, + const struct cred *cred); + +#endif /* _LINUX_BACKING_FILE_H */ diff --git a/include/linux/fs.h b/include/linux/fs.h index 900d0cd55b50..db5d07e6e02e 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2575,9 +2575,6 @@ struct file *dentry_open(const struct path *path, int flags, const struct cred *creds); struct file *dentry_create(const struct path *path, int flags, umode_t mode, const struct cred *cred); -struct file *backing_file_open(const struct path *user_path, int flags, - const struct path *real_path, - const struct cred *cred); struct path *backing_file_user_path(struct file *f); /*