From c60166f04283ffba7b88b45d824bbfb2bfccee24 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 21 Jul 2020 11:12:08 +0200 Subject: [PATCH] init: add an init_mount helper Like do_mount, but takes a kernel pointer for the destination path. Switch over the mounts in the init code and devtmpfs to it, which just happen to work due to the implicit set_fs(KERNEL_DS) during early init right now. Signed-off-by: Christoph Hellwig --- drivers/base/devtmpfs.c | 5 +++-- fs/Makefile | 2 +- fs/init.c | 25 +++++++++++++++++++++++++ fs/internal.h | 4 ++++ fs/namespace.c | 2 +- include/linux/init_syscalls.h | 4 ++++ init/do_mounts.c | 8 ++++---- init/do_mounts.h | 1 + init/do_mounts_initrd.c | 6 +++--- 9 files changed, 46 insertions(+), 11 deletions(-) create mode 100644 fs/init.c create mode 100644 include/linux/init_syscalls.h diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index d697634bc0d48..32af6cb987b42 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include "base.h" @@ -359,7 +360,7 @@ int __init devtmpfs_mount(void) if (!thread) return 0; - err = do_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL); + err = init_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL); if (err) printk(KERN_INFO "devtmpfs: error mounting %i\n", err); else @@ -408,7 +409,7 @@ static int __init devtmpfs_setup(void *p) err = ksys_unshare(CLONE_NEWNS); if (err) goto out; - err = do_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL); + err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL); if (err) goto out; ksys_chdir("/.."); /* will traverse into overmounted root */ diff --git a/fs/Makefile b/fs/Makefile index 2ce5112b02c86..1c7b0e3f6daa1 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -13,7 +13,7 @@ obj-y := open.o read_write.o file_table.o super.o \ seq_file.o xattr.o libfs.o fs-writeback.o \ pnode.o splice.o sync.o utimes.o d_path.o \ stack.o fs_struct.o statfs.o fs_pin.o nsfs.o \ - fs_types.o fs_context.o fs_parser.o fsopen.o + fs_types.o fs_context.o fs_parser.o fsopen.o init.o ifeq ($(CONFIG_BLOCK),y) obj-y += buffer.o block_dev.o direct-io.o mpage.o diff --git a/fs/init.c b/fs/init.c new file mode 100644 index 0000000000000..c6eb724e1c7b2 --- /dev/null +++ b/fs/init.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Routines that mimic syscalls, but don't use the user address space or file + * descriptors. Only for init/ and related early init code. + */ +#include +#include +#include +#include +#include +#include "internal.h" + +int __init init_mount(const char *dev_name, const char *dir_name, + const char *type_page, unsigned long flags, void *data_page) +{ + struct path path; + int ret; + + ret = kern_path(dir_name, LOOKUP_FOLLOW, &path); + if (ret) + return ret; + ret = path_mount(dev_name, &path, type_page, flags, data_page); + path_put(&path); + return ret; +} diff --git a/fs/internal.h b/fs/internal.h index e903d5aae139a..72ea0b6f7435a 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -89,6 +89,10 @@ extern int __mnt_want_write_file(struct file *); extern void __mnt_drop_write_file(struct file *); extern void dissolve_on_fput(struct vfsmount *); + +int path_mount(const char *dev_name, struct path *path, + const char *type_page, unsigned long flags, void *data_page); + /* * fs_struct.c */ diff --git a/fs/namespace.c b/fs/namespace.c index 43834b59eff6c..2c4d759209748 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3111,7 +3111,7 @@ char *copy_mount_string(const void __user *data) * Therefore, if this magic number is present, it carries no information * and must be discarded. */ -static int path_mount(const char *dev_name, struct path *path, +int path_mount(const char *dev_name, struct path *path, const char *type_page, unsigned long flags, void *data_page) { unsigned int mnt_flags = 0, sb_flags; diff --git a/include/linux/init_syscalls.h b/include/linux/init_syscalls.h new file mode 100644 index 0000000000000..af9ea88a60e0b --- /dev/null +++ b/include/linux/init_syscalls.h @@ -0,0 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +int __init init_mount(const char *dev_name, const char *dir_name, + const char *type_page, unsigned long flags, void *data_page); diff --git a/init/do_mounts.c b/init/do_mounts.c index a7f22cf58c7ef..83db87b6e5d1e 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -395,16 +395,16 @@ static int __init do_mount_root(const char *name, const char *fs, int ret; if (data) { - /* do_mount() requires a full page as fifth argument */ + /* init_mount() requires a full page as fifth argument */ p = alloc_page(GFP_KERNEL); if (!p) return -ENOMEM; data_page = page_address(p); - /* zero-pad. do_mount() will make sure it's terminated */ + /* zero-pad. init_mount() will make sure it's terminated */ strncpy(data_page, data, PAGE_SIZE); } - ret = do_mount(name, "/root", fs, flags, data_page); + ret = init_mount(name, "/root", fs, flags, data_page); if (ret) goto out; @@ -628,7 +628,7 @@ void __init prepare_namespace(void) mount_root(); out: devtmpfs_mount(); - do_mount(".", "/", NULL, MS_MOVE, NULL); + init_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); } diff --git a/init/do_mounts.h b/init/do_mounts.h index 021e2f60223e2..20e7fec8cb499 100644 --- a/init/do_mounts.h +++ b/init/do_mounts.h @@ -8,6 +8,7 @@ #include #include #include +#include void mount_block_root(char *name, int flags); void mount_root(void); diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index e08669187d63b..1f9336209ad9c 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -62,7 +62,7 @@ static int __init init_linuxrc(struct subprocess_info *info, struct cred *new) console_on_rootfs(); /* move initrd over / and chdir/chroot in initrd root */ ksys_chdir("/root"); - do_mount(".", "/", NULL, MS_MOVE, NULL); + init_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); ksys_setsid(); return 0; @@ -99,7 +99,7 @@ static void __init handle_initrd(void) current->flags &= ~PF_FREEZER_SKIP; /* move initrd to rootfs' /old */ - do_mount("..", ".", NULL, MS_MOVE, NULL); + init_mount("..", ".", NULL, MS_MOVE, NULL); /* switch root and cwd back to / of rootfs */ ksys_chroot(".."); @@ -113,7 +113,7 @@ static void __init handle_initrd(void) mount_root(); printk(KERN_NOTICE "Trying to move old root to /initrd ... "); - error = do_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL); + error = init_mount("/old", "/root/initrd", NULL, MS_MOVE, NULL); if (!error) printk("okay\n"); else { -- 2.39.2