| /* |
| * fs/kernfs/dir.c - kernfs directory implementation |
| * |
| * Copyright (c) 2001-3 Patrick Mochel |
| * Copyright (c) 2007 SUSE Linux Products GmbH |
| * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org> |
| * |
| * This file is released under the GPLv2. |
| */ |
| |
| #include <linux/sched.h> |
| #include <linux/fs.h> |
| #include <linux/namei.h> |
| #include <linux/idr.h> |
| #include <linux/slab.h> |
| #include <linux/security.h> |
| #include <linux/hash.h> |
| |
| #include "kernfs-internal.h" |
| |
| DEFINE_MUTEX(kernfs_mutex); |
| |
| #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) |
| |
| static bool kernfs_lockdep(struct kernfs_node *kn) |
| { |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| return kn->flags & KERNFS_LOCKDEP; |
| #else |
| return false; |
| #endif |
| } |
| |
| /** |
| * kernfs_name_hash |
| * @name: Null terminated string to hash |
| * @ns: Namespace tag to hash |
| * |
| * Returns 31 bit hash of ns + name (so it fits in an off_t ) |
| */ |
| static unsigned int kernfs_name_hash(const char *name, const void *ns) |
| { |
| unsigned long hash = init_name_hash(); |
| unsigned int len = strlen(name); |
| while (len--) |
| hash = partial_name_hash(*name++, hash); |
| hash = (end_name_hash(hash) ^ hash_ptr((void *)ns, 31)); |
| hash &= 0x7fffffffU; |
| /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ |
| if (hash < 1) |
| hash += 2; |
| if (hash >= INT_MAX) |
| hash = INT_MAX - 1; |
| return hash; |
| } |
| |
| static int kernfs_name_compare(unsigned int hash, const char *name, |
| const void *ns, const struct kernfs_node *kn) |
| { |
| if (hash != kn->hash) |
| return hash - kn->hash; |
| if (ns != kn->ns) |
| return ns - kn->ns; |
| return strcmp(name, kn->name); |
| } |
| |
| static int kernfs_sd_compare(const struct kernfs_node *left, |
| const struct kernfs_node *right) |
| { |
| return kernfs_name_compare(left->hash, left->name, left->ns, right); |
| } |
| |
| /** |
| * kernfs_link_sibling - link kernfs_node into sibling rbtree |
| * @kn: kernfs_node of interest |
| * |
| * Link @kn into its sibling rbtree which starts from |
| * @kn->parent->dir.children. |
| * |
| * Locking: |
| * mutex_lock(kernfs_mutex) |
| * |
| * RETURNS: |
| * 0 on susccess -EEXIST on failure. |
| */ |
| static int kernfs_link_sibling(struct kernfs_node *kn) |
| { |
| struct rb_node **node = &kn->parent->dir.children.rb_node; |
| struct rb_node *parent = NULL; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| kn->parent->dir.subdirs++; |
| |
| while (*node) { |
| struct kernfs_node *pos; |
| int result; |
| |
| pos = rb_to_kn(*node); |
| parent = *node; |
| result = kernfs_sd_compare(kn, pos); |
| if (result < 0) |
| node = &pos->rb.rb_left; |
| else if (result > 0) |
| node = &pos->rb.rb_right; |
| else |
| return -EEXIST; |
| } |
| /* add new node and rebalance the tree */ |
| rb_link_node(&kn->rb, parent, node); |
| rb_insert_color(&kn->rb, &kn->parent->dir.children); |
| return 0; |
| } |
| |
| /** |
| * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree |
| * @kn: kernfs_node of interest |
| * |
| * Unlink @kn from its sibling rbtree which starts from |
| * kn->parent->dir.children. |
| * |
| * Locking: |
| * mutex_lock(kernfs_mutex) |
| */ |
| static bool kernfs_unlink_sibling(struct kernfs_node *kn) |
| { |
| if (RB_EMPTY_NODE(&kn->rb)) |
| return false; |
| |
| if (kernfs_type(kn) == KERNFS_DIR) |
| kn->parent->dir.subdirs--; |
| |
| rb_erase(&kn->rb, &kn->parent->dir.children); |
| RB_CLEAR_NODE(&kn->rb); |
| return true; |
| } |
| |
| /** |
| * kernfs_get_active - get an active reference to kernfs_node |
| * @kn: kernfs_node to get an active reference to |
| * |
| * Get an active reference of @kn. This function is noop if @kn |
| * is NULL. |
| * |
| * RETURNS: |
| * Pointer to @kn on success, NULL on failure. |
| */ |
| struct kernfs_node *kernfs_get_active(struct kernfs_node *kn) |
| { |
| if (unlikely(!kn)) |
| return NULL; |
| |
| if (kernfs_lockdep(kn)) |
| rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); |
| |
| /* |
| * Try to obtain an active ref. If @kn is deactivated, we block |
| * till either it's reactivated or killed. |
| */ |
| do { |
| if (atomic_inc_unless_negative(&kn->active)) |
| return kn; |
| |
| wait_event(kernfs_root(kn)->deactivate_waitq, |
| atomic_read(&kn->active) >= 0 || |
| RB_EMPTY_NODE(&kn->rb)); |
| } while (!RB_EMPTY_NODE(&kn->rb)); |
| |
| if (kernfs_lockdep(kn)) |
| rwsem_release(&kn->dep_map, 1, _RET_IP_); |
| return NULL; |
| } |
| |
| /** |
| * kernfs_put_active - put an active reference to kernfs_node |
| * @kn: kernfs_node to put an active reference to |
| * |
| * Put an active reference to @kn. This function is noop if @kn |
| * is NULL. |
| */ |
| void kernfs_put_active(struct kernfs_node *kn) |
| { |
| struct kernfs_root *root = kernfs_root(kn); |
| int v; |
| |
| if (unlikely(!kn)) |
| return; |
| |
| if (kernfs_lockdep(kn)) |
| rwsem_release(&kn->dep_map, 1, _RET_IP_); |
| v = atomic_dec_return(&kn->active); |
| if (likely(v != KN_DEACTIVATED_BIAS)) |
| return; |
| |
| wake_up_all(&root->deactivate_waitq); |
| } |
| |
| /** |
| * kernfs_drain - drain kernfs_node |
| * @kn: kernfs_node to drain |
| * |
| * Drain existing usages of @kn. Mutiple removers may invoke this function |
| * concurrently on @kn and all will return after draining is complete. |
| * Returns %true if drain is performed and kernfs_mutex was temporarily |
| * released. %false if @kn was already drained and no operation was |
| * necessary. |
| * |
| * The caller is responsible for ensuring @kn stays pinned while this |
| * function is in progress even if it gets removed by someone else. |
| */ |
| static bool kernfs_drain(struct kernfs_node *kn) |
| __releases(&kernfs_mutex) __acquires(&kernfs_mutex) |
| { |
| struct kernfs_root *root = kernfs_root(kn); |
| |
| lockdep_assert_held(&kernfs_mutex); |
| WARN_ON_ONCE(atomic_read(&kn->active) >= 0); |
| |
| /* |
| * We want to go through the active ref lockdep annotation at least |
| * once for all node removals, but the lockdep annotation can't be |
| * nested inside kernfs_mutex and deactivation can't make forward |
| * progress if we keep dropping the mutex. Use JUST_ACTIVATED to |
| * force the slow path once for each deactivation if lockdep is |
| * enabled. |
| */ |
| if ((!kernfs_lockdep(kn) || !(kn->flags & KERNFS_JUST_DEACTIVATED)) && |
| atomic_read(&kn->active) == KN_DEACTIVATED_BIAS) |
| return false; |
| |
| kn->flags &= ~KERNFS_JUST_DEACTIVATED; |
| mutex_unlock(&kernfs_mutex); |
| |
| if (kernfs_lockdep(kn)) { |
| rwsem_acquire(&kn->dep_map, 0, 0, _RET_IP_); |
| if (atomic_read(&kn->active) != KN_DEACTIVATED_BIAS) |
| lock_contended(&kn->dep_map, _RET_IP_); |
| } |
| |
| wait_event(root->deactivate_waitq, |
| atomic_read(&kn->active) == KN_DEACTIVATED_BIAS); |
| |
| if (kernfs_lockdep(kn)) { |
| lock_acquired(&kn->dep_map, _RET_IP_); |
| rwsem_release(&kn->dep_map, 1, _RET_IP_); |
| } |
| |
| mutex_lock(&kernfs_mutex); |
| return true; |
| } |
| |
| /** |
| * kernfs_get - get a reference count on a kernfs_node |
| * @kn: the target kernfs_node |
| */ |
| void kernfs_get(struct kernfs_node *kn) |
| { |
| if (kn) { |
| WARN_ON(!atomic_read(&kn->count)); |
| atomic_inc(&kn->count); |
| } |
| } |
| EXPORT_SYMBOL_GPL(kernfs_get); |
| |
| /** |
| * kernfs_put - put a reference count on a kernfs_node |
| * @kn: the target kernfs_node |
| * |
| * Put a reference count of @kn and destroy it if it reached zero. |
| */ |
| void kernfs_put(struct kernfs_node *kn) |
| { |
| struct kernfs_node *parent; |
| struct kernfs_root *root; |
| |
| if (!kn || !atomic_dec_and_test(&kn->count)) |
| return; |
| root = kernfs_root(kn); |
| repeat: |
| /* |
| * Moving/renaming is always done while holding reference. |
| * kn->parent won't change beneath us. |
| */ |
| parent = kn->parent; |
| |
| WARN_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS, |
| "kernfs_put: %s/%s: released with incorrect active_ref %d\n", |
| parent ? parent->name : "", kn->name, atomic_read(&kn->active)); |
| |
| if (kernfs_type(kn) == KERNFS_LINK) |
| kernfs_put(kn->symlink.target_kn); |
| if (!(kn->flags & KERNFS_STATIC_NAME)) |
| kfree(kn->name); |
| if (kn->iattr) { |
| if (kn->iattr->ia_secdata) |
| security_release_secctx(kn->iattr->ia_secdata, |
| kn->iattr->ia_secdata_len); |
| simple_xattrs_free(&kn->iattr->xattrs); |
| } |
| kfree(kn->iattr); |
| ida_simple_remove(&root->ino_ida, kn->ino); |
| kmem_cache_free(kernfs_node_cache, kn); |
| |
| kn = parent; |
| if (kn) { |
| if (atomic_dec_and_test(&kn->count)) |
| goto repeat; |
| } else { |
| /* just released the root kn, free @root too */ |
| ida_destroy(&root->ino_ida); |
| kfree(root); |
| } |
| } |
| EXPORT_SYMBOL_GPL(kernfs_put); |
| |
| static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) |
| { |
| struct kernfs_node *kn; |
| |
| if (flags & LOOKUP_RCU) |
| return -ECHILD; |
| |
| /* Always perform fresh lookup for negatives */ |
| if (!dentry->d_inode) |
| goto out_bad_unlocked; |
| |
| kn = dentry->d_fsdata; |
| mutex_lock(&kernfs_mutex); |
| |
| /* Force fresh lookup if removed */ |
| if (kn->parent && RB_EMPTY_NODE(&kn->rb)) |
| goto out_bad; |
| |
| /* The kernfs node has been moved? */ |
| if (dentry->d_parent->d_fsdata != kn->parent) |
| goto out_bad; |
| |
| /* The kernfs node has been renamed */ |
| if (strcmp(dentry->d_name.name, kn->name) != 0) |
| goto out_bad; |
| |
| /* The kernfs node has been moved to a different namespace */ |
| if (kn->parent && kernfs_ns_enabled(kn->parent) && |
| kernfs_info(dentry->d_sb)->ns != kn->ns) |
| goto out_bad; |
| |
| mutex_unlock(&kernfs_mutex); |
| out_valid: |
| return 1; |
| out_bad: |
| mutex_unlock(&kernfs_mutex); |
| out_bad_unlocked: |
| /* |
| * @dentry doesn't match the underlying kernfs node, drop the |
| * dentry and force lookup. If we have submounts we must allow the |
| * vfs caches to lie about the state of the filesystem to prevent |
| * leaks and other nasty things, so use check_submounts_and_drop() |
| * instead of d_drop(). |
| */ |
| if (check_submounts_and_drop(dentry) != 0) |
| goto out_valid; |
| |
| return 0; |
| } |
| |
| static void kernfs_dop_release(struct dentry *dentry) |
| { |
| kernfs_put(dentry->d_fsdata); |
| } |
| |
| const struct dentry_operations kernfs_dops = { |
| .d_revalidate = kernfs_dop_revalidate, |
| .d_release = kernfs_dop_release, |
| }; |
| |
| struct kernfs_node *kernfs_new_node(struct kernfs_root *root, const char *name, |
| umode_t mode, unsigned flags) |
| { |
| char *dup_name = NULL; |
| struct kernfs_node *kn; |
| int ret; |
| |
| if (!(flags & KERNFS_STATIC_NAME)) { |
| name = dup_name = kstrdup(name, GFP_KERNEL); |
| if (!name) |
| return NULL; |
| } |
| |
| kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL); |
| if (!kn) |
| goto err_out1; |
| |
| ret = ida_simple_get(&root->ino_ida, 1, 0, GFP_KERNEL); |
| if (ret < 0) |
| goto err_out2; |
| kn->ino = ret; |
| |
| atomic_set(&kn->count, 1); |
| atomic_set(&kn->active, KN_DEACTIVATED_BIAS); |
| kn->deact_depth = 1; |
| RB_CLEAR_NODE(&kn->rb); |
| |
| kn->name = name; |
| kn->mode = mode; |
| kn->flags = flags; |
| |
| return kn; |
| |
| err_out2: |
| kmem_cache_free(kernfs_node_cache, kn); |
| err_out1: |
| kfree(dup_name); |
| return NULL; |
| } |
| |
| /** |
| * kernfs_add_one - add kernfs_node to parent without warning |
| * @kn: kernfs_node to be added |
| * @parent: the parent kernfs_node to add @kn to |
| * |
| * Get @parent and set @kn->parent to it and increment nlink of the |
| * parent inode if @kn is a directory and link into the children list |
| * of the parent. |
| * |
| * RETURNS: |
| * 0 on success, -EEXIST if entry with the given name already |
| * exists. |
| */ |
| int kernfs_add_one(struct kernfs_node *kn, struct kernfs_node *parent) |
| { |
| struct kernfs_iattrs *ps_iattr; |
| bool has_ns; |
| int ret; |
| |
| if (!kernfs_get_active(parent)) |
| return -ENOENT; |
| |
| mutex_lock(&kernfs_mutex); |
| |
| ret = -EINVAL; |
| has_ns = kernfs_ns_enabled(parent); |
| if (WARN(has_ns != (bool)kn->ns, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", |
| has_ns ? "required" : "invalid", parent->name, kn->name)) |
| goto out_unlock; |
| |
| if (kernfs_type(parent) != KERNFS_DIR) |
| goto out_unlock; |
| |
| kn->hash = kernfs_name_hash(kn->name, kn->ns); |
| kn->parent = parent; |
| kernfs_get(parent); |
| |
| ret = kernfs_link_sibling(kn); |
| if (ret) |
| goto out_unlock; |
| |
| /* Update timestamps on the parent */ |
| ps_iattr = parent->iattr; |
| if (ps_iattr) { |
| struct iattr *ps_iattrs = &ps_iattr->ia_iattr; |
| ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME; |
| } |
| |
| /* Mark the entry added into directory tree */ |
| atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); |
| kn->deact_depth--; |
| ret = 0; |
| out_unlock: |
| mutex_unlock(&kernfs_mutex); |
| kernfs_put_active(parent); |
| return ret; |
| } |
| |
| /** |
| * kernfs_find_ns - find kernfs_node with the given name |
| * @parent: kernfs_node to search under |
| * @name: name to look for |
| * @ns: the namespace tag to use |
| * |
| * Look for kernfs_node with name @name under @parent. Returns pointer to |
| * the found kernfs_node on success, %NULL on failure. |
| */ |
| static struct kernfs_node *kernfs_find_ns(struct kernfs_node *parent, |
| const unsigned char *name, |
| const void *ns) |
| { |
| struct rb_node *node = parent->dir.children.rb_node; |
| bool has_ns = kernfs_ns_enabled(parent); |
| unsigned int hash; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| if (has_ns != (bool)ns) { |
| WARN(1, KERN_WARNING "kernfs: ns %s in '%s' for '%s'\n", |
| has_ns ? "required" : "invalid", parent->name, name); |
| return NULL; |
| } |
| |
| hash = kernfs_name_hash(name, ns); |
| while (node) { |
| struct kernfs_node *kn; |
| int result; |
| |
| kn = rb_to_kn(node); |
| result = kernfs_name_compare(hash, name, ns, kn); |
| if (result < 0) |
| node = node->rb_left; |
| else if (result > 0) |
| node = node->rb_right; |
| else |
| return kn; |
| } |
| return NULL; |
| } |
| |
| /** |
| * kernfs_find_and_get_ns - find and get kernfs_node with the given name |
| * @parent: kernfs_node to search under |
| * @name: name to look for |
| * @ns: the namespace tag to use |
| * |
| * Look for kernfs_node with name @name under @parent and get a reference |
| * if found. This function may sleep and returns pointer to the found |
| * kernfs_node on success, %NULL on failure. |
| */ |
| struct kernfs_node *kernfs_find_and_get_ns(struct kernfs_node *parent, |
| const char *name, const void *ns) |
| { |
| struct kernfs_node *kn; |
| |
| mutex_lock(&kernfs_mutex); |
| kn = kernfs_find_ns(parent, name, ns); |
| kernfs_get(kn); |
| mutex_unlock(&kernfs_mutex); |
| |
| return kn; |
| } |
| EXPORT_SYMBOL_GPL(kernfs_find_and_get_ns); |
| |
| /** |
| * kernfs_create_root - create a new kernfs hierarchy |
| * @kdops: optional directory syscall operations for the hierarchy |
| * @priv: opaque data associated with the new directory |
| * |
| * Returns the root of the new hierarchy on success, ERR_PTR() value on |
| * failure. |
| */ |
| struct kernfs_root *kernfs_create_root(struct kernfs_dir_ops *kdops, void *priv) |
| { |
| struct kernfs_root *root; |
| struct kernfs_node *kn; |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) |
| return ERR_PTR(-ENOMEM); |
| |
| ida_init(&root->ino_ida); |
| |
| kn = kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO, KERNFS_DIR); |
| if (!kn) { |
| ida_destroy(&root->ino_ida); |
| kfree(root); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); |
| kn->deact_depth--; |
| kn->priv = priv; |
| kn->dir.root = root; |
| |
| root->dir_ops = kdops; |
| root->kn = kn; |
| init_waitqueue_head(&root->deactivate_waitq); |
| |
| return root; |
| } |
| |
| /** |
| * kernfs_destroy_root - destroy a kernfs hierarchy |
| * @root: root of the hierarchy to destroy |
| * |
| * Destroy the hierarchy anchored at @root by removing all existing |
| * directories and destroying @root. |
| */ |
| void kernfs_destroy_root(struct kernfs_root *root) |
| { |
| kernfs_remove(root->kn); /* will also free @root */ |
| } |
| |
| /** |
| * kernfs_create_dir_ns - create a directory |
| * @parent: parent in which to create a new directory |
| * @name: name of the new directory |
| * @mode: mode of the new directory |
| * @priv: opaque data associated with the new directory |
| * @ns: optional namespace tag of the directory |
| * |
| * Returns the created node on success, ERR_PTR() value on failure. |
| */ |
| struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent, |
| const char *name, umode_t mode, |
| void *priv, const void *ns) |
| { |
| struct kernfs_node *kn; |
| int rc; |
| |
| /* allocate */ |
| kn = kernfs_new_node(kernfs_root(parent), name, mode | S_IFDIR, |
| KERNFS_DIR); |
| if (!kn) |
| return ERR_PTR(-ENOMEM); |
| |
| kn->dir.root = parent->dir.root; |
| kn->ns = ns; |
| kn->priv = priv; |
| |
| /* link in */ |
| rc = kernfs_add_one(kn, parent); |
| if (!rc) |
| return kn; |
| |
| kernfs_put(kn); |
| return ERR_PTR(rc); |
| } |
| |
| static struct dentry *kernfs_iop_lookup(struct inode *dir, |
| struct dentry *dentry, |
| unsigned int flags) |
| { |
| struct dentry *ret; |
| struct kernfs_node *parent = dentry->d_parent->d_fsdata; |
| struct kernfs_node *kn; |
| struct inode *inode; |
| const void *ns = NULL; |
| |
| mutex_lock(&kernfs_mutex); |
| |
| if (kernfs_ns_enabled(parent)) |
| ns = kernfs_info(dir->i_sb)->ns; |
| |
| kn = kernfs_find_ns(parent, dentry->d_name.name, ns); |
| |
| /* no such entry */ |
| if (!kn) { |
| ret = NULL; |
| goto out_unlock; |
| } |
| kernfs_get(kn); |
| dentry->d_fsdata = kn; |
| |
| /* attach dentry and inode */ |
| inode = kernfs_get_inode(dir->i_sb, kn); |
| if (!inode) { |
| ret = ERR_PTR(-ENOMEM); |
| goto out_unlock; |
| } |
| |
| /* instantiate and hash dentry */ |
| ret = d_materialise_unique(dentry, inode); |
| out_unlock: |
| mutex_unlock(&kernfs_mutex); |
| return ret; |
| } |
| |
| static int kernfs_iop_mkdir(struct inode *dir, struct dentry *dentry, |
| umode_t mode) |
| { |
| struct kernfs_node *parent = dir->i_private; |
| struct kernfs_dir_ops *kdops = kernfs_root(parent)->dir_ops; |
| |
| if (!kdops || !kdops->mkdir) |
| return -EPERM; |
| |
| return kdops->mkdir(parent, dentry->d_name.name, mode); |
| } |
| |
| static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| struct kernfs_node *kn = dentry->d_fsdata; |
| struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; |
| |
| if (!kdops || !kdops->rmdir) |
| return -EPERM; |
| |
| return kdops->rmdir(kn); |
| } |
| |
| static int kernfs_iop_rename(struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry) |
| { |
| struct kernfs_node *kn = old_dentry->d_fsdata; |
| struct kernfs_node *new_parent = new_dir->i_private; |
| struct kernfs_dir_ops *kdops = kernfs_root(kn)->dir_ops; |
| |
| if (!kdops || !kdops->rename) |
| return -EPERM; |
| |
| return kdops->rename(kn, new_parent, new_dentry->d_name.name); |
| } |
| |
| const struct inode_operations kernfs_dir_iops = { |
| .lookup = kernfs_iop_lookup, |
| .permission = kernfs_iop_permission, |
| .setattr = kernfs_iop_setattr, |
| .getattr = kernfs_iop_getattr, |
| .setxattr = kernfs_iop_setxattr, |
| .removexattr = kernfs_iop_removexattr, |
| .getxattr = kernfs_iop_getxattr, |
| .listxattr = kernfs_iop_listxattr, |
| |
| .mkdir = kernfs_iop_mkdir, |
| .rmdir = kernfs_iop_rmdir, |
| .rename = kernfs_iop_rename, |
| }; |
| |
| static struct kernfs_node *kernfs_leftmost_descendant(struct kernfs_node *pos) |
| { |
| struct kernfs_node *last; |
| |
| while (true) { |
| struct rb_node *rbn; |
| |
| last = pos; |
| |
| if (kernfs_type(pos) != KERNFS_DIR) |
| break; |
| |
| rbn = rb_first(&pos->dir.children); |
| if (!rbn) |
| break; |
| |
| pos = rb_to_kn(rbn); |
| } |
| |
| return last; |
| } |
| |
| /** |
| * kernfs_next_descendant_post - find the next descendant for post-order walk |
| * @pos: the current position (%NULL to initiate traversal) |
| * @root: kernfs_node whose descendants to walk |
| * |
| * Find the next descendant to visit for post-order traversal of @root's |
| * descendants. @root is included in the iteration and the last node to be |
| * visited. |
| */ |
| static struct kernfs_node *kernfs_next_descendant_post(struct kernfs_node *pos, |
| struct kernfs_node *root) |
| { |
| struct rb_node *rbn; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| /* if first iteration, visit leftmost descendant which may be root */ |
| if (!pos) |
| return kernfs_leftmost_descendant(root); |
| |
| /* if we visited @root, we're done */ |
| if (pos == root) |
| return NULL; |
| |
| /* if there's an unvisited sibling, visit its leftmost descendant */ |
| rbn = rb_next(&pos->rb); |
| if (rbn) |
| return kernfs_leftmost_descendant(rb_to_kn(rbn)); |
| |
| /* no sibling left, visit parent */ |
| return pos->parent; |
| } |
| |
| static void __kernfs_deactivate(struct kernfs_node *kn) |
| { |
| struct kernfs_node *pos; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| /* prevent any new usage under @kn by deactivating all nodes */ |
| pos = NULL; |
| while ((pos = kernfs_next_descendant_post(pos, kn))) { |
| if (!pos->deact_depth++) { |
| WARN_ON_ONCE(atomic_read(&pos->active) < 0); |
| atomic_add(KN_DEACTIVATED_BIAS, &pos->active); |
| pos->flags |= KERNFS_JUST_DEACTIVATED; |
| } |
| } |
| |
| /* |
| * Drain the subtree. If kernfs_drain() blocked to drain, which is |
| * indicated by %true return, it temporarily released kernfs_mutex |
| * and the rbtree might have been modified inbetween breaking our |
| * future walk. Restart the walk after each %true return. |
| */ |
| pos = NULL; |
| while ((pos = kernfs_next_descendant_post(pos, kn))) { |
| bool drained; |
| |
| kernfs_get(pos); |
| drained = kernfs_drain(pos); |
| kernfs_put(pos); |
| if (drained) |
| pos = NULL; |
| } |
| } |
| |
| static void __kernfs_reactivate(struct kernfs_node *kn) |
| { |
| struct kernfs_node *pos; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| pos = NULL; |
| while ((pos = kernfs_next_descendant_post(pos, kn))) { |
| if (!--pos->deact_depth) { |
| WARN_ON_ONCE(atomic_read(&pos->active) >= 0); |
| atomic_sub(KN_DEACTIVATED_BIAS, &pos->active); |
| } |
| WARN_ON_ONCE(pos->deact_depth < 0); |
| } |
| |
| /* some nodes reactivated, kick get_active waiters */ |
| wake_up_all(&kernfs_root(kn)->deactivate_waitq); |
| } |
| |
| static void __kernfs_deactivate_self(struct kernfs_node *kn) |
| { |
| /* |
| * Take out ourself out of the active ref dependency chain and |
| * deactivate. If we're called without an active ref, lockdep will |
| * complain. |
| */ |
| kernfs_put_active(kn); |
| __kernfs_deactivate(kn); |
| } |
| |
| static void __kernfs_reactivate_self(struct kernfs_node *kn) |
| { |
| __kernfs_reactivate(kn); |
| /* |
| * Restore active ref dropped by deactivate_self() so that it's |
| * balanced on return. put_active() will soon be called on @kn, so |
| * this can't break anything regardless of @kn's state. |
| */ |
| atomic_inc(&kn->active); |
| if (kernfs_lockdep(kn)) |
| rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); |
| } |
| |
| /** |
| * kernfs_deactivate - deactivate subtree of a node |
| * @kn: kernfs_node to deactivate subtree of |
| * |
| * Deactivate the subtree of @kn. On return, there's no active operation |
| * going on under @kn and creation or renaming of a node under @kn is |
| * blocked until @kn is reactivated or removed. This function can be |
| * called multiple times and nests properly. Each invocation should be |
| * paired with kernfs_reactivate(). |
| * |
| * For a kernfs user which uses simple locking, the subsystem lock would |
| * nest inside active reference. This becomes problematic if the user |
| * tries to remove nodes while holding the subystem lock as it would create |
| * a reverse locking dependency from the subsystem lock to active ref. |
| * This function can be used to break such reverse dependency. The user |
| * can call this function outside the subsystem lock and then proceed to |
| * invoke kernfs_remove() while holding the subsystem lock without |
| * introducing such reverse dependency. |
| */ |
| void kernfs_deactivate(struct kernfs_node *kn) |
| { |
| mutex_lock(&kernfs_mutex); |
| __kernfs_deactivate(kn); |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| /** |
| * kernfs_reactivate - reactivate subtree of a node |
| * @kn: kernfs_node to reactivate subtree of |
| * |
| * Undo kernfs_deactivate(). |
| */ |
| void kernfs_reactivate(struct kernfs_node *kn) |
| { |
| mutex_lock(&kernfs_mutex); |
| __kernfs_reactivate(kn); |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| /** |
| * kernfs_deactivate_self - deactivate subtree of a node from its own method |
| * @kn: the self kernfs_node to deactivate subtree of |
| * |
| * The caller must be running off of a kernfs operation which is invoked |
| * with an active reference - e.g. one of kernfs_ops. Once this function |
| * is called, @kn may be removed by someone else while the enclosing method |
| * is in progress. Other than that, this function is equivalent to |
| * kernfs_deactivate() and should be paired with kernfs_reactivate_self(). |
| */ |
| void kernfs_deactivate_self(struct kernfs_node *kn) |
| { |
| mutex_lock(&kernfs_mutex); |
| __kernfs_deactivate_self(kn); |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| /** |
| * kernfs_reactivate_self - reactivate subtree of a node from its own method |
| * @kn: the self kernfs_node to reactivate subtree of |
| * |
| * Undo kernfs_deactivate_self(). |
| */ |
| void kernfs_reactivate_self(struct kernfs_node *kn) |
| { |
| mutex_lock(&kernfs_mutex); |
| __kernfs_reactivate_self(kn); |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| static void __kernfs_remove(struct kernfs_node *kn) |
| { |
| struct kernfs_root *root = kernfs_root(kn); |
| struct kernfs_node *pos; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| pr_debug("kernfs %s: removing\n", kn->name); |
| |
| __kernfs_deactivate(kn); |
| |
| /* unlink the subtree node-by-node */ |
| do { |
| pos = kernfs_leftmost_descendant(kn); |
| |
| /* |
| * We're gonna release kernfs_mutex to unmap bin files, |
| * Make sure @pos doesn't go away inbetween. |
| */ |
| kernfs_get(pos); |
| |
| /* |
| * This must be come before unlinking; otherwise, when |
| * there are multiple removers, some may finish before |
| * unmapping is complete. |
| */ |
| if (pos->flags & KERNFS_HAS_MMAP) { |
| mutex_unlock(&kernfs_mutex); |
| kernfs_unmap_file(pos); |
| mutex_lock(&kernfs_mutex); |
| } |
| |
| /* |
| * kernfs_unlink_sibling() succeeds once per node. Use it |
| * to decide who's responsible for cleanups. |
| */ |
| if (!pos->parent || kernfs_unlink_sibling(pos)) { |
| struct kernfs_iattrs *ps_iattr = |
| pos->parent ? pos->parent->iattr : NULL; |
| |
| /* update timestamps on the parent */ |
| if (ps_iattr) { |
| ps_iattr->ia_iattr.ia_ctime = CURRENT_TIME; |
| ps_iattr->ia_iattr.ia_mtime = CURRENT_TIME; |
| } |
| |
| kernfs_put(pos); |
| } |
| |
| kernfs_put(pos); |
| } while (pos != kn); |
| |
| /* some nodes killed, kick get_active waiters */ |
| wake_up_all(&root->deactivate_waitq); |
| } |
| |
| /** |
| * kernfs_remove - remove a kernfs_node recursively |
| * @kn: the kernfs_node to remove |
| * |
| * Remove @kn along with all its subdirectories and files. |
| */ |
| void kernfs_remove(struct kernfs_node *kn) |
| { |
| mutex_lock(&kernfs_mutex); |
| __kernfs_remove(kn); |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| /** |
| * kernfs_remove_self - remove a kernfs_node from its own method |
| * @kn: the self kernfs_node to remove |
| * |
| * The caller must be running off of a kernfs operation which is invoked |
| * with an active reference - e.g. one of kernfs_ops. This can be used to |
| * implement a file operation which deletes itself. |
| * |
| * For example, the "delete" file for a sysfs device directory can be |
| * implemented by invoking kernfs_remove_self() on the "delete" file |
| * itself. This function breaks the circular dependency of trying to |
| * deactivate self while holding an active ref itself. It isn't necessary |
| * to modify the usual removal path to use kernfs_remove_self(). The |
| * "delete" implementation can simply invoke kernfs_remove_self() on self |
| * before proceeding with the usual removal path. kernfs will ignore later |
| * kernfs_remove() on self. |
| * |
| * kernfs_remove_self() can be called multiple times concurrently on the |
| * same kernfs_node. Only the first one actually performs removal and |
| * returns %true. All others will wait until the kernfs operation which |
| * won self-removal finishes and return %false. Note that the losers wait |
| * for the completion of not only the winning kernfs_remove_self() but also |
| * the whole kernfs_ops which won the arbitration. This can be used to |
| * guarantee, for example, all concurrent writes to a "delete" file to |
| * finish only after the whole operation is complete. |
| */ |
| bool kernfs_remove_self(struct kernfs_node *kn) |
| { |
| bool ret; |
| |
| mutex_lock(&kernfs_mutex); |
| __kernfs_deactivate_self(kn); |
| |
| /* |
| * SUICIDAL is used to arbitrate among competing invocations. Only |
| * the first one will actually perform removal. When the removal |
| * is complete, SUICIDED is set and the active ref is restored |
| * while holding kernfs_mutex. The ones which lost arbitration |
| * waits for SUICDED && drained which can happen only after the |
| * enclosing kernfs operation which executed the winning instance |
| * of kernfs_remove_self() finished. |
| */ |
| if (!(kn->flags & KERNFS_SUICIDAL)) { |
| kn->flags |= KERNFS_SUICIDAL; |
| __kernfs_remove(kn); |
| kn->flags |= KERNFS_SUICIDED; |
| ret = true; |
| } else { |
| wait_queue_head_t *waitq = &kernfs_root(kn)->deactivate_waitq; |
| DEFINE_WAIT(wait); |
| |
| while (true) { |
| prepare_to_wait(waitq, &wait, TASK_UNINTERRUPTIBLE); |
| |
| if ((kn->flags & KERNFS_SUICIDED) && |
| atomic_read(&kn->active) == KN_DEACTIVATED_BIAS) |
| break; |
| |
| mutex_unlock(&kernfs_mutex); |
| schedule(); |
| mutex_lock(&kernfs_mutex); |
| } |
| finish_wait(waitq, &wait); |
| WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); |
| ret = false; |
| } |
| |
| __kernfs_reactivate_self(kn); |
| mutex_unlock(&kernfs_mutex); |
| return ret; |
| } |
| |
| /** |
| * kernfs_remove_by_name_ns - find a kernfs_node by name and remove it |
| * @parent: parent of the target |
| * @name: name of the kernfs_node to remove |
| * @ns: namespace tag of the kernfs_node to remove |
| * |
| * Look for the kernfs_node with @name and @ns under @parent and remove it. |
| * Returns 0 on success, -ENOENT if such entry doesn't exist. |
| */ |
| int kernfs_remove_by_name_ns(struct kernfs_node *parent, const char *name, |
| const void *ns) |
| { |
| struct kernfs_node *kn; |
| |
| if (!parent) { |
| WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n", |
| name); |
| return -ENOENT; |
| } |
| |
| mutex_lock(&kernfs_mutex); |
| |
| kn = kernfs_find_ns(parent, name, ns); |
| if (kn) |
| __kernfs_remove(kn); |
| |
| mutex_unlock(&kernfs_mutex); |
| |
| if (kn) |
| return 0; |
| else |
| return -ENOENT; |
| } |
| |
| /** |
| * kernfs_rename_ns - move and rename a kernfs_node |
| * @kn: target node |
| * @new_parent: new parent to put @sd under |
| * @new_name: new name |
| * @new_ns: new namespace tag |
| */ |
| int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent, |
| const char *new_name, const void *new_ns) |
| { |
| int error; |
| |
| error = -ENOENT; |
| if (!kernfs_get_active(new_parent)) |
| goto out; |
| if (!kernfs_get_active(kn)) |
| goto out_put_new_parent; |
| |
| mutex_lock(&kernfs_mutex); |
| |
| error = 0; |
| if ((kn->parent == new_parent) && (kn->ns == new_ns) && |
| (strcmp(kn->name, new_name) == 0)) |
| goto out_unlock; /* nothing to rename */ |
| |
| error = -EEXIST; |
| if (kernfs_find_ns(new_parent, new_name, new_ns)) |
| goto out_unlock; |
| |
| /* rename kernfs_node */ |
| if (strcmp(kn->name, new_name) != 0) { |
| error = -ENOMEM; |
| new_name = kstrdup(new_name, GFP_KERNEL); |
| if (!new_name) |
| goto out_unlock; |
| |
| if (kn->flags & KERNFS_STATIC_NAME) |
| kn->flags &= ~KERNFS_STATIC_NAME; |
| else |
| kfree(kn->name); |
| |
| kn->name = new_name; |
| } |
| |
| /* |
| * Move to the appropriate place in the appropriate directories rbtree. |
| */ |
| kernfs_unlink_sibling(kn); |
| kernfs_get(new_parent); |
| kernfs_put(kn->parent); |
| kn->ns = new_ns; |
| kn->hash = kernfs_name_hash(kn->name, kn->ns); |
| kn->parent = new_parent; |
| kernfs_link_sibling(kn); |
| |
| error = 0; |
| out_unlock: |
| mutex_unlock(&kernfs_mutex); |
| kernfs_put_active(kn); |
| out_put_new_parent: |
| kernfs_put_active(new_parent); |
| out: |
| return error; |
| } |
| |
| /* Relationship between s_mode and the DT_xxx types */ |
| static inline unsigned char dt_type(struct kernfs_node *kn) |
| { |
| return (kn->mode >> 12) & 15; |
| } |
| |
| static int kernfs_dir_fop_release(struct inode *inode, struct file *filp) |
| { |
| kernfs_put(filp->private_data); |
| return 0; |
| } |
| |
| static struct kernfs_node *kernfs_dir_pos(const void *ns, |
| struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos) |
| { |
| if (pos) { |
| int valid = pos->parent == parent && hash == pos->hash; |
| kernfs_put(pos); |
| if (!valid) |
| pos = NULL; |
| } |
| if (!pos && (hash > 1) && (hash < INT_MAX)) { |
| struct rb_node *node = parent->dir.children.rb_node; |
| while (node) { |
| pos = rb_to_kn(node); |
| |
| if (hash < pos->hash) |
| node = node->rb_left; |
| else if (hash > pos->hash) |
| node = node->rb_right; |
| else |
| break; |
| } |
| } |
| /* Skip over entries in the wrong namespace */ |
| while (pos && pos->ns != ns) { |
| struct rb_node *node = rb_next(&pos->rb); |
| if (!node) |
| pos = NULL; |
| else |
| pos = rb_to_kn(node); |
| } |
| return pos; |
| } |
| |
| static struct kernfs_node *kernfs_dir_next_pos(const void *ns, |
| struct kernfs_node *parent, ino_t ino, struct kernfs_node *pos) |
| { |
| pos = kernfs_dir_pos(ns, parent, ino, pos); |
| if (pos) |
| do { |
| struct rb_node *node = rb_next(&pos->rb); |
| if (!node) |
| pos = NULL; |
| else |
| pos = rb_to_kn(node); |
| } while (pos && pos->ns != ns); |
| return pos; |
| } |
| |
| static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx) |
| { |
| struct dentry *dentry = file->f_path.dentry; |
| struct kernfs_node *parent = dentry->d_fsdata; |
| struct kernfs_node *pos = file->private_data; |
| const void *ns = NULL; |
| |
| if (!dir_emit_dots(file, ctx)) |
| return 0; |
| mutex_lock(&kernfs_mutex); |
| |
| if (kernfs_ns_enabled(parent)) |
| ns = kernfs_info(dentry->d_sb)->ns; |
| |
| for (pos = kernfs_dir_pos(ns, parent, ctx->pos, pos); |
| pos; |
| pos = kernfs_dir_next_pos(ns, parent, ctx->pos, pos)) { |
| const char *name = pos->name; |
| unsigned int type = dt_type(pos); |
| int len = strlen(name); |
| ino_t ino = pos->ino; |
| |
| ctx->pos = pos->hash; |
| file->private_data = pos; |
| kernfs_get(pos); |
| |
| mutex_unlock(&kernfs_mutex); |
| if (!dir_emit(ctx, name, len, ino, type)) |
| return 0; |
| mutex_lock(&kernfs_mutex); |
| } |
| mutex_unlock(&kernfs_mutex); |
| file->private_data = NULL; |
| ctx->pos = INT_MAX; |
| return 0; |
| } |
| |
| static loff_t kernfs_dir_fop_llseek(struct file *file, loff_t offset, |
| int whence) |
| { |
| struct inode *inode = file_inode(file); |
| loff_t ret; |
| |
| mutex_lock(&inode->i_mutex); |
| ret = generic_file_llseek(file, offset, whence); |
| mutex_unlock(&inode->i_mutex); |
| |
| return ret; |
| } |
| |
| const struct file_operations kernfs_dir_fops = { |
| .read = generic_read_dir, |
| .iterate = kernfs_fop_readdir, |
| .release = kernfs_dir_fop_release, |
| .llseek = kernfs_dir_fop_llseek, |
| }; |