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80b9bbefc3
Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
1.7 KiB
C
79 lines
1.7 KiB
C
/*
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* fs/sysfs/symlink.c - operations for initializing and mounting sysfs
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#define DEBUG
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#include <linux/fs.h>
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#include <linux/mount.h>
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#include <linux/init.h>
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#include <linux/user_namespace.h>
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#include "sysfs.h"
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static struct kernfs_root *sysfs_root;
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struct kernfs_node *sysfs_root_kn;
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static struct dentry *sysfs_mount(struct file_system_type *fs_type,
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int flags, const char *dev_name, void *data)
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{
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struct dentry *root;
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void *ns;
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if (!(flags & MS_KERNMOUNT)) {
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if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
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return ERR_PTR(-EPERM);
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if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
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return ERR_PTR(-EPERM);
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}
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ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
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root = kernfs_mount_ns(fs_type, flags, sysfs_root, ns);
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if (IS_ERR(root))
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kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
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return root;
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}
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static void sysfs_kill_sb(struct super_block *sb)
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{
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void *ns = (void *)kernfs_super_ns(sb);
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kernfs_kill_sb(sb);
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kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
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}
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static struct file_system_type sysfs_fs_type = {
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.name = "sysfs",
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.mount = sysfs_mount,
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.kill_sb = sysfs_kill_sb,
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.fs_flags = FS_USERNS_MOUNT,
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};
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int __init sysfs_init(void)
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{
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int err;
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sysfs_root = kernfs_create_root(NULL, NULL);
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if (IS_ERR(sysfs_root))
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return PTR_ERR(sysfs_root);
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sysfs_root_kn = sysfs_root->kn;
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err = register_filesystem(&sysfs_fs_type);
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if (err) {
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kernfs_destroy_root(sysfs_root);
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return err;
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}
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return 0;
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}
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