1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * fs/kernfs/kernfs-internal.h - kernfs internal header file 4 * 5 * Copyright (c) 2001-3 Patrick Mochel 6 * Copyright (c) 2007 SUSE Linux Products GmbH 7 * Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de> 8 */ 9 10 #ifndef __KERNFS_INTERNAL_H 11 #define __KERNFS_INTERNAL_H 12 13 #include <linux/lockdep.h> 14 #include <linux/fs.h> 15 #include <linux/mutex.h> 16 #include <linux/rwsem.h> 17 #include <linux/xattr.h> 18 19 #include <linux/kernfs.h> 20 #include <linux/fs_context.h> 21 22 extern rwlock_t kernfs_rename_lock; 23 24 struct kernfs_iattrs { 25 kuid_t ia_uid; 26 kgid_t ia_gid; 27 struct timespec64 ia_atime; 28 struct timespec64 ia_mtime; 29 struct timespec64 ia_ctime; 30 31 struct simple_xattrs xattrs; 32 atomic_t nr_user_xattrs; 33 atomic_t user_xattr_size; 34 }; 35 36 struct kernfs_root { 37 /* published fields */ 38 struct kernfs_node *kn; 39 unsigned int flags; /* KERNFS_ROOT_* flags */ 40 41 /* private fields, do not use outside kernfs proper */ 42 struct idr ino_idr; 43 u32 last_id_lowbits; 44 u32 id_highbits; 45 struct kernfs_syscall_ops *syscall_ops; 46 47 /* list of kernfs_super_info of this root, protected by kernfs_rwsem */ 48 struct list_head supers; 49 50 wait_queue_head_t deactivate_waitq; 51 struct rw_semaphore kernfs_rwsem; 52 struct rw_semaphore kernfs_iattr_rwsem; 53 struct rw_semaphore kernfs_supers_rwsem; 54 55 struct rcu_head rcu; 56 }; 57 58 /* +1 to avoid triggering overflow warning when negating it */ 59 #define KN_DEACTIVATED_BIAS (INT_MIN + 1) 60 61 /* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */ 62 63 /** 64 * kernfs_root - find out the kernfs_root a kernfs_node belongs to 65 * @kn: kernfs_node of interest 66 * 67 * Return: the kernfs_root @kn belongs to. 68 */ 69 static inline struct kernfs_root *kernfs_root(const struct kernfs_node *kn) 70 { 71 const struct kernfs_node *knp; 72 /* if parent exists, it's always a dir; otherwise, @sd is a dir */ 73 guard(rcu)(); 74 knp = rcu_dereference(kn->__parent); 75 if (knp) 76 kn = knp; 77 return kn->dir.root; 78 } 79 80 /* 81 * mount.c 82 */ 83 struct kernfs_super_info { 84 struct super_block *sb; 85 86 /* 87 * The root associated with this super_block. Each super_block is 88 * identified by the root and ns it's associated with. 89 */ 90 struct kernfs_root *root; 91 92 /* 93 * Each sb is associated with one namespace tag, currently the 94 * network namespace of the task which mounted this kernfs 95 * instance. If multiple tags become necessary, make the following 96 * an array and compare kernfs_node tag against every entry. 97 */ 98 const void *ns; 99 100 /* anchored at kernfs_root->supers, protected by kernfs_rwsem */ 101 struct list_head node; 102 }; 103 #define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info)) 104 105 static inline bool kernfs_root_is_locked(const struct kernfs_node *kn) 106 { 107 return lockdep_is_held(&kernfs_root(kn)->kernfs_rwsem); 108 } 109 110 static inline const char *kernfs_rcu_name(const struct kernfs_node *kn) 111 { 112 return rcu_dereference_check(kn->name, kernfs_root_is_locked(kn)); 113 } 114 115 static inline struct kernfs_node *kernfs_parent(const struct kernfs_node *kn) 116 { 117 /* 118 * The kernfs_node::__parent remains valid within a RCU section. The kn 119 * can be reparented (and renamed) which changes the entry. This can be 120 * avoided by locking kernfs_root::kernfs_rwsem or kernfs_rename_lock. 121 * Both locks can be used to obtain a reference on __parent. Once the 122 * reference count reaches 0 then the node is about to be freed 123 * and can not be renamed (or become a different parent) anymore. 124 */ 125 return rcu_dereference_check(kn->__parent, 126 kernfs_root_is_locked(kn) || 127 lockdep_is_held(&kernfs_rename_lock) || 128 !atomic_read(&kn->count)); 129 } 130 131 static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry) 132 { 133 if (d_really_is_negative(dentry)) 134 return NULL; 135 return d_inode(dentry)->i_private; 136 } 137 138 static inline void kernfs_set_rev(struct kernfs_node *parent, 139 struct dentry *dentry) 140 { 141 dentry->d_time = parent->dir.rev; 142 } 143 144 static inline void kernfs_inc_rev(struct kernfs_node *parent) 145 { 146 parent->dir.rev++; 147 } 148 149 static inline bool kernfs_dir_changed(struct kernfs_node *parent, 150 struct dentry *dentry) 151 { 152 if (parent->dir.rev != dentry->d_time) 153 return true; 154 return false; 155 } 156 157 extern const struct super_operations kernfs_sops; 158 extern struct kmem_cache *kernfs_node_cache, *kernfs_iattrs_cache; 159 160 /* 161 * inode.c 162 */ 163 extern const struct xattr_handler * const kernfs_xattr_handlers[]; 164 void kernfs_evict_inode(struct inode *inode); 165 int kernfs_iop_permission(struct mnt_idmap *idmap, 166 struct inode *inode, int mask); 167 int kernfs_iop_setattr(struct mnt_idmap *idmap, struct dentry *dentry, 168 struct iattr *iattr); 169 int kernfs_iop_getattr(struct mnt_idmap *idmap, 170 const struct path *path, struct kstat *stat, 171 u32 request_mask, unsigned int query_flags); 172 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size); 173 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr); 174 175 /* 176 * dir.c 177 */ 178 extern const struct dentry_operations kernfs_dops; 179 extern const struct file_operations kernfs_dir_fops; 180 extern const struct inode_operations kernfs_dir_iops; 181 182 struct kernfs_node *kernfs_get_active(struct kernfs_node *kn); 183 void kernfs_put_active(struct kernfs_node *kn); 184 int kernfs_add_one(struct kernfs_node *kn); 185 struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, 186 const char *name, umode_t mode, 187 kuid_t uid, kgid_t gid, 188 unsigned flags); 189 190 /* 191 * file.c 192 */ 193 extern const struct file_operations kernfs_file_fops; 194 195 bool kernfs_should_drain_open_files(struct kernfs_node *kn); 196 void kernfs_drain_open_files(struct kernfs_node *kn); 197 198 /* 199 * symlink.c 200 */ 201 extern const struct inode_operations kernfs_symlink_iops; 202 203 /* 204 * kernfs locks 205 */ 206 extern struct kernfs_global_locks *kernfs_locks; 207 #endif /* __KERNFS_INTERNAL_H */ 208