From: Amir Goldstein <amir73il@gmail.com> mainline inclusion from mainline-v6.8-rc1 commit f91a704f7161c2cf0fcd41fa9fbec4355b813fff category: feature bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBHLU4 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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 <amir73il@gmail.com> Signed-off-by: Yifan Qiao <qiaoyifan4@huawei.com> --- include/linux/backing-file.h | 17 +++++++++++++ include/linux/fs.h | 3 --- fs/backing-file.c | 48 ++++++++++++++++++++++++++++++++++++ fs/open.c | 38 ---------------------------- fs/overlayfs/file.c | 1 + MAINTAINERS | 9 +++++++ fs/Kconfig | 4 +++ fs/Makefile | 1 + fs/overlayfs/Kconfig | 1 + 9 files changed, 81 insertions(+), 41 deletions(-) create mode 100644 include/linux/backing-file.h create mode 100644 fs/backing-file.c 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 <linux/file.h> + +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 e6e5d30bb424..dbed3b704e4f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2654,9 +2654,6 @@ 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); /* 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 <linux/fs.h> +#include <linux/backing-file.h> + +#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 ec0e471ef5cc..4679db501d43 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1177,44 +1177,6 @@ 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/file.c b/fs/overlayfs/file.c index 0d0ba0240fa5..9c4272d10e99 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -13,6 +13,7 @@ #include <linux/security.h> #include <linux/mm.h> #include <linux/fs.h> +#include <linux/backing-file.h> #include "overlayfs.h" #include "../internal.h" /* for sb_init_dio_done_wq */ diff --git a/MAINTAINERS b/MAINTAINERS index 6ddb6b82eef5..987227695971 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8064,6 +8064,15 @@ F: include/linux/fs_types.h F: include/uapi/linux/fs.h F: include/uapi/linux/openat2.h +FILESYSTEMS [STACKABLE] +M: Miklos Szeredi <miklos@szeredi.hu> +M: Amir Goldstein <amir73il@gmail.com> +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 <riku.voipio@iki.fi> L: linux-hwmon@vger.kernel.org diff --git a/fs/Kconfig b/fs/Kconfig index 9765213bf01d..3d1185e3e6a8 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 45e54c34c309..81428bad22f0 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -40,6 +40,7 @@ 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/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 -- 2.39.2