548 lines
17 KiB
C
548 lines
17 KiB
C
/*
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* kernfs.h - pseudo filesystem decoupled from vfs locking
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*
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* This file is released under the GPLv2.
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*/
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#ifndef __LINUX_KERNFS_H
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#define __LINUX_KERNFS_H
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/idr.h>
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#include <linux/lockdep.h>
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#include <linux/rbtree.h>
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#include <linux/atomic.h>
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#include <linux/wait.h>
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struct file;
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struct dentry;
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struct iattr;
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struct seq_file;
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struct vm_area_struct;
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struct super_block;
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struct file_system_type;
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struct kernfs_open_node;
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struct kernfs_iattrs;
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enum kernfs_node_type {
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KERNFS_DIR = 0x0001,
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KERNFS_FILE = 0x0002,
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KERNFS_LINK = 0x0004,
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};
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#define KERNFS_TYPE_MASK 0x000f
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#define KERNFS_FLAG_MASK ~KERNFS_TYPE_MASK
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enum kernfs_node_flag {
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KERNFS_ACTIVATED = 0x0010,
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KERNFS_NS = 0x0020,
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KERNFS_HAS_SEQ_SHOW = 0x0040,
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KERNFS_HAS_MMAP = 0x0080,
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KERNFS_LOCKDEP = 0x0100,
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KERNFS_SUICIDAL = 0x0400,
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KERNFS_SUICIDED = 0x0800,
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KERNFS_EMPTY_DIR = 0x1000,
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KERNFS_HAS_RELEASE = 0x2000,
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};
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/* @flags for kernfs_create_root() */
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enum kernfs_root_flag {
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/*
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* kernfs_nodes are created in the deactivated state and invisible.
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* They require explicit kernfs_activate() to become visible. This
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* can be used to make related nodes become visible atomically
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* after all nodes are created successfully.
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*/
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KERNFS_ROOT_CREATE_DEACTIVATED = 0x0001,
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/*
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* For regular flies, if the opener has CAP_DAC_OVERRIDE, open(2)
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* succeeds regardless of the RW permissions. sysfs had an extra
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* layer of enforcement where open(2) fails with -EACCES regardless
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* of CAP_DAC_OVERRIDE if the permission doesn't have the
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* respective read or write access at all (none of S_IRUGO or
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* S_IWUGO) or the respective operation isn't implemented. The
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* following flag enables that behavior.
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*/
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KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK = 0x0002,
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/*
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* The filesystem supports exportfs operation, so userspace can use
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* fhandle to access nodes of the fs.
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*/
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KERNFS_ROOT_SUPPORT_EXPORTOP = 0x0004,
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};
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/* type-specific structures for kernfs_node union members */
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struct kernfs_elem_dir {
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unsigned long subdirs;
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/* children rbtree starts here and goes through kn->rb */
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struct rb_root children;
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/*
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* The kernfs hierarchy this directory belongs to. This fits
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* better directly in kernfs_node but is here to save space.
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*/
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struct kernfs_root *root;
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};
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struct kernfs_elem_symlink {
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struct kernfs_node *target_kn;
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};
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struct kernfs_elem_attr {
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const struct kernfs_ops *ops;
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struct kernfs_open_node *open;
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loff_t size;
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struct kernfs_node *notify_next; /* for kernfs_notify() */
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};
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/* represent a kernfs node */
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union kernfs_node_id {
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struct {
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/*
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* blktrace will export this struct as a simplified 'struct
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* fid' (which is a big data struction), so userspace can use
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* it to find kernfs node. The layout must match the first two
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* fields of 'struct fid' exactly.
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*/
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u32 ino;
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u32 generation;
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};
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u64 id;
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};
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/*
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* kernfs_node - the building block of kernfs hierarchy. Each and every
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* kernfs node is represented by single kernfs_node. Most fields are
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* private to kernfs and shouldn't be accessed directly by kernfs users.
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*
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* As long as s_count reference is held, the kernfs_node itself is
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* accessible. Dereferencing elem or any other outer entity requires
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* active reference.
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*/
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struct kernfs_node {
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atomic_t count;
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atomic_t active;
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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/*
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* Use kernfs_get_parent() and kernfs_name/path() instead of
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* accessing the following two fields directly. If the node is
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* never moved to a different parent, it is safe to access the
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* parent directly.
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*/
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struct kernfs_node *parent;
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const char *name;
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struct rb_node rb;
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const void *ns; /* namespace tag */
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unsigned int hash; /* ns + name hash */
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union {
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struct kernfs_elem_dir dir;
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struct kernfs_elem_symlink symlink;
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struct kernfs_elem_attr attr;
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};
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void *priv;
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union kernfs_node_id id;
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unsigned short flags;
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umode_t mode;
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struct kernfs_iattrs *iattr;
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};
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/*
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* kernfs_syscall_ops may be specified on kernfs_create_root() to support
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* syscalls. These optional callbacks are invoked on the matching syscalls
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* and can perform any kernfs operations which don't necessarily have to be
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* the exact operation requested. An active reference is held for each
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* kernfs_node parameter.
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*/
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struct kernfs_syscall_ops {
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int (*remount_fs)(struct kernfs_root *root, int *flags, char *data);
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int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
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int (*mkdir)(struct kernfs_node *parent, const char *name,
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umode_t mode);
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int (*rmdir)(struct kernfs_node *kn);
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int (*rename)(struct kernfs_node *kn, struct kernfs_node *new_parent,
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const char *new_name);
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int (*show_path)(struct seq_file *sf, struct kernfs_node *kn,
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struct kernfs_root *root);
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};
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struct kernfs_root {
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/* published fields */
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struct kernfs_node *kn;
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unsigned int flags; /* KERNFS_ROOT_* flags */
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/* private fields, do not use outside kernfs proper */
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struct idr ino_idr;
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u32 next_generation;
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struct kernfs_syscall_ops *syscall_ops;
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/* list of kernfs_super_info of this root, protected by kernfs_mutex */
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struct list_head supers;
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wait_queue_head_t deactivate_waitq;
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};
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struct kernfs_open_file {
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/* published fields */
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struct kernfs_node *kn;
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struct file *file;
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struct seq_file *seq_file;
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void *priv;
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/* private fields, do not use outside kernfs proper */
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struct mutex mutex;
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struct mutex prealloc_mutex;
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int event;
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struct list_head list;
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char *prealloc_buf;
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size_t atomic_write_len;
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bool mmapped:1;
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bool released:1;
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const struct vm_operations_struct *vm_ops;
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};
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struct kernfs_ops {
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/*
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* Optional open/release methods. Both are called with
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* @of->seq_file populated.
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*/
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int (*open)(struct kernfs_open_file *of);
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void (*release)(struct kernfs_open_file *of);
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/*
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* Read is handled by either seq_file or raw_read().
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*
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* If seq_show() is present, seq_file path is active. Other seq
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* operations are optional and if not implemented, the behavior is
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* equivalent to single_open(). @sf->private points to the
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* associated kernfs_open_file.
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*
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* read() is bounced through kernel buffer and a read larger than
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* PAGE_SIZE results in partial operation of PAGE_SIZE.
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*/
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int (*seq_show)(struct seq_file *sf, void *v);
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void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
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void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
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void (*seq_stop)(struct seq_file *sf, void *v);
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ssize_t (*read)(struct kernfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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/*
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* write() is bounced through kernel buffer. If atomic_write_len
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* is not set, a write larger than PAGE_SIZE results in partial
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* operations of PAGE_SIZE chunks. If atomic_write_len is set,
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* writes upto the specified size are executed atomically but
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* larger ones are rejected with -E2BIG.
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*/
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size_t atomic_write_len;
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/*
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* "prealloc" causes a buffer to be allocated at open for
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* all read/write requests. As ->seq_show uses seq_read()
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* which does its own allocation, it is incompatible with
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* ->prealloc. Provide ->read and ->write with ->prealloc.
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*/
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bool prealloc;
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ssize_t (*write)(struct kernfs_open_file *of, char *buf, size_t bytes,
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loff_t off);
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int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lock_class_key lockdep_key;
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#endif
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};
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#ifdef CONFIG_KERNFS
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static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
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{
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return kn->flags & KERNFS_TYPE_MASK;
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}
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/**
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* kernfs_enable_ns - enable namespace under a directory
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* @kn: directory of interest, should be empty
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*
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* This is to be called right after @kn is created to enable namespace
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* under it. All children of @kn must have non-NULL namespace tags and
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* only the ones which match the super_block's tag will be visible.
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*/
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static inline void kernfs_enable_ns(struct kernfs_node *kn)
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{
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WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
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WARN_ON_ONCE(!RB_EMPTY_ROOT(&kn->dir.children));
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kn->flags |= KERNFS_NS;
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}
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/**
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* kernfs_ns_enabled - test whether namespace is enabled
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* @kn: the node to test
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*
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* Test whether namespace filtering is enabled for the children of @ns.
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*/
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static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
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{
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return kn->flags & KERNFS_NS;
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}
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int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen);
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int kernfs_path_from_node(struct kernfs_node *root_kn, struct kernfs_node *kn,
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char *buf, size_t buflen);
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void pr_cont_kernfs_name(struct kernfs_node *kn);
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void pr_cont_kernfs_path(struct kernfs_node *kn);
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struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn);
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struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent,
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const char *name, const void *ns);
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struct kernfs_node *kernfs_walk_and_get_ns(struct kernfs_node *parent,
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const char *path, const void *ns);
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void kernfs_get(struct kernfs_node *kn);
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void kernfs_put(struct kernfs_node *kn);
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struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry);
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struct kernfs_root *kernfs_root_from_sb(struct super_block *sb);
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struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
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struct dentry *kernfs_node_dentry(struct kernfs_node *kn,
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struct super_block *sb);
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struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
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unsigned int flags, void *priv);
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void kernfs_destroy_root(struct kernfs_root *root);
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struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
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const char *name, umode_t mode,
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void *priv, const void *ns);
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struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
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const char *name);
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struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
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const char *name,
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umode_t mode, loff_t size,
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const struct kernfs_ops *ops,
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void *priv, const void *ns,
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struct lock_class_key *key);
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struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
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const char *name,
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struct kernfs_node *target);
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void kernfs_activate(struct kernfs_node *kn);
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void kernfs_remove(struct kernfs_node *kn);
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void kernfs_break_active_protection(struct kernfs_node *kn);
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void kernfs_unbreak_active_protection(struct kernfs_node *kn);
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bool kernfs_remove_self(struct kernfs_node *kn);
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int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name,
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const void *ns);
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int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
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const char *new_name, const void *new_ns);
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int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr);
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void kernfs_notify(struct kernfs_node *kn);
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const void *kernfs_super_ns(struct super_block *sb);
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struct dentry *kernfs_mount_ns(struct file_system_type *fs_type, int flags,
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struct kernfs_root *root, unsigned long magic,
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bool *new_sb_created, const void *ns);
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void kernfs_kill_sb(struct super_block *sb);
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struct super_block *kernfs_pin_sb(struct kernfs_root *root, const void *ns);
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void kernfs_init(void);
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struct kernfs_node *kernfs_get_node_by_id(struct kernfs_root *root,
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const union kernfs_node_id *id);
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#else /* CONFIG_KERNFS */
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static inline enum kernfs_node_type kernfs_type(struct kernfs_node *kn)
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{ return 0; } /* whatever */
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static inline void kernfs_enable_ns(struct kernfs_node *kn) { }
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static inline bool kernfs_ns_enabled(struct kernfs_node *kn)
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{ return false; }
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static inline int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen)
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{ return -ENOSYS; }
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static inline int kernfs_path_from_node(struct kernfs_node *root_kn,
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struct kernfs_node *kn,
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char *buf, size_t buflen)
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{ return -ENOSYS; }
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static inline void pr_cont_kernfs_name(struct kernfs_node *kn) { }
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static inline void pr_cont_kernfs_path(struct kernfs_node *kn) { }
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static inline struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn)
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{ return NULL; }
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static inline struct kernfs_node *
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kernfs_find_and_get_ns(struct kernfs_node *parent, const char *name,
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const void *ns)
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{ return NULL; }
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static inline struct kernfs_node *
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kernfs_walk_and_get_ns(struct kernfs_node *parent, const char *path,
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const void *ns)
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{ return NULL; }
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static inline void kernfs_get(struct kernfs_node *kn) { }
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static inline void kernfs_put(struct kernfs_node *kn) { }
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static inline struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
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{ return NULL; }
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static inline struct kernfs_root *kernfs_root_from_sb(struct super_block *sb)
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{ return NULL; }
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static inline struct inode *
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kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
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{ return NULL; }
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static inline struct kernfs_root *
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kernfs_create_root(struct kernfs_syscall_ops *scops, unsigned int flags,
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void *priv)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_destroy_root(struct kernfs_root *root) { }
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static inline struct kernfs_node *
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kernfs_create_dir_ns(struct kernfs_node *parent, const char *name,
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umode_t mode, void *priv, const void *ns)
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{ return ERR_PTR(-ENOSYS); }
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static inline struct kernfs_node *
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__kernfs_create_file(struct kernfs_node *parent, const char *name,
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umode_t mode, loff_t size, const struct kernfs_ops *ops,
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void *priv, const void *ns, struct lock_class_key *key)
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{ return ERR_PTR(-ENOSYS); }
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static inline struct kernfs_node *
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kernfs_create_link(struct kernfs_node *parent, const char *name,
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struct kernfs_node *target)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_activate(struct kernfs_node *kn) { }
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static inline void kernfs_remove(struct kernfs_node *kn) { }
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static inline bool kernfs_remove_self(struct kernfs_node *kn)
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{ return false; }
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static inline int kernfs_remove_by_name_ns(struct kernfs_node *kn,
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const char *name, const void *ns)
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{ return -ENOSYS; }
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static inline int kernfs_rename_ns(struct kernfs_node *kn,
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struct kernfs_node *new_parent,
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const char *new_name, const void *new_ns)
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{ return -ENOSYS; }
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static inline int kernfs_setattr(struct kernfs_node *kn,
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const struct iattr *iattr)
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{ return -ENOSYS; }
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static inline void kernfs_notify(struct kernfs_node *kn) { }
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static inline const void *kernfs_super_ns(struct super_block *sb)
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{ return NULL; }
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static inline struct dentry *
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kernfs_mount_ns(struct file_system_type *fs_type, int flags,
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struct kernfs_root *root, unsigned long magic,
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bool *new_sb_created, const void *ns)
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{ return ERR_PTR(-ENOSYS); }
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static inline void kernfs_kill_sb(struct super_block *sb) { }
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static inline void kernfs_init(void) { }
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#endif /* CONFIG_KERNFS */
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/**
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* kernfs_path - build full path of a given node
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* @kn: kernfs_node of interest
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* @buf: buffer to copy @kn's name into
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* @buflen: size of @buf
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*
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* Builds and returns the full path of @kn in @buf of @buflen bytes. The
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* path is built from the end of @buf so the returned pointer usually
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* doesn't match @buf. If @buf isn't long enough, @buf is nul terminated
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* and %NULL is returned.
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*/
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static inline int kernfs_path(struct kernfs_node *kn, char *buf, size_t buflen)
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{
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return kernfs_path_from_node(kn, NULL, buf, buflen);
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}
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static inline struct kernfs_node *
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kernfs_find_and_get(struct kernfs_node *kn, const char *name)
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{
|
|
return kernfs_find_and_get_ns(kn, name, NULL);
|
|
}
|
|
|
|
static inline struct kernfs_node *
|
|
kernfs_walk_and_get(struct kernfs_node *kn, const char *path)
|
|
{
|
|
return kernfs_walk_and_get_ns(kn, path, NULL);
|
|
}
|
|
|
|
static inline struct kernfs_node *
|
|
kernfs_create_dir(struct kernfs_node *parent, const char *name, umode_t mode,
|
|
void *priv)
|
|
{
|
|
return kernfs_create_dir_ns(parent, name, mode, priv, NULL);
|
|
}
|
|
|
|
static inline struct kernfs_node *
|
|
kernfs_create_file_ns(struct kernfs_node *parent, const char *name,
|
|
umode_t mode, loff_t size, const struct kernfs_ops *ops,
|
|
void *priv, const void *ns)
|
|
{
|
|
struct lock_class_key *key = NULL;
|
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
|
key = (struct lock_class_key *)&ops->lockdep_key;
|
|
#endif
|
|
return __kernfs_create_file(parent, name, mode, size, ops, priv, ns,
|
|
key);
|
|
}
|
|
|
|
static inline struct kernfs_node *
|
|
kernfs_create_file(struct kernfs_node *parent, const char *name, umode_t mode,
|
|
loff_t size, const struct kernfs_ops *ops, void *priv)
|
|
{
|
|
return kernfs_create_file_ns(parent, name, mode, size, ops, priv, NULL);
|
|
}
|
|
|
|
static inline int kernfs_remove_by_name(struct kernfs_node *parent,
|
|
const char *name)
|
|
{
|
|
return kernfs_remove_by_name_ns(parent, name, NULL);
|
|
}
|
|
|
|
static inline int kernfs_rename(struct kernfs_node *kn,
|
|
struct kernfs_node *new_parent,
|
|
const char *new_name)
|
|
{
|
|
return kernfs_rename_ns(kn, new_parent, new_name, NULL);
|
|
}
|
|
|
|
static inline struct dentry *
|
|
kernfs_mount(struct file_system_type *fs_type, int flags,
|
|
struct kernfs_root *root, unsigned long magic,
|
|
bool *new_sb_created)
|
|
{
|
|
return kernfs_mount_ns(fs_type, flags, root,
|
|
magic, new_sb_created, NULL);
|
|
}
|
|
|
|
#endif /* __LINUX_KERNFS_H */
|