| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * 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> |
| */ |
| |
| #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); |
| static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ |
| static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by rename_lock */ |
| static DEFINE_SPINLOCK(kernfs_idr_lock); /* root->ino_idr */ |
| |
| #define rb_to_kn(X) rb_entry((X), struct kernfs_node, rb) |
| |
| static bool kernfs_active(struct kernfs_node *kn) |
| { |
| lockdep_assert_held(&kernfs_mutex); |
| return atomic_read(&kn->active) >= 0; |
| } |
| |
| static bool kernfs_lockdep(struct kernfs_node *kn) |
| { |
| #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| return kn->flags & KERNFS_LOCKDEP; |
| #else |
| return false; |
| #endif |
| } |
| |
| static int kernfs_name_locked(struct kernfs_node *kn, char *buf, size_t buflen) |
| { |
| if (!kn) |
| return strlcpy(buf, "(null)", buflen); |
| |
| return strlcpy(buf, kn->parent ? kn->name : "/", buflen); |
| } |
| |
| /* kernfs_node_depth - compute depth from @from to @to */ |
| static size_t kernfs_depth(struct kernfs_node *from, struct kernfs_node *to) |
| { |
| size_t depth = 0; |
| |
| while (to->parent && to != from) { |
| depth++; |
| to = to->parent; |
| } |
| return depth; |
| } |
| |
| static struct kernfs_node *kernfs_common_ancestor(struct kernfs_node *a, |
| struct kernfs_node *b) |
| { |
| size_t da, db; |
| struct kernfs_root *ra = kernfs_root(a), *rb = kernfs_root(b); |
| |
| if (ra != rb) |
| return NULL; |
| |
| da = kernfs_depth(ra->kn, a); |
| db = kernfs_depth(rb->kn, b); |
| |
| while (da > db) { |
| a = a->parent; |
| da--; |
| } |
| while (db > da) { |
| b = b->parent; |
| db--; |
| } |
| |
| /* worst case b and a will be the same at root */ |
| while (b != a) { |
| b = b->parent; |
| a = a->parent; |
| } |
| |
| return a; |
| } |
| |
| /** |
| * kernfs_path_from_node_locked - find a pseudo-absolute path to @kn_to, |
| * where kn_from is treated as root of the path. |
| * @kn_from: kernfs node which should be treated as root for the path |
| * @kn_to: kernfs node to which path is needed |
| * @buf: buffer to copy the path into |
| * @buflen: size of @buf |
| * |
| * We need to handle couple of scenarios here: |
| * [1] when @kn_from is an ancestor of @kn_to at some level |
| * kn_from: /n1/n2/n3 |
| * kn_to: /n1/n2/n3/n4/n5 |
| * result: /n4/n5 |
| * |
| * [2] when @kn_from is on a different hierarchy and we need to find common |
| * ancestor between @kn_from and @kn_to. |
| * kn_from: /n1/n2/n3/n4 |
| * kn_to: /n1/n2/n5 |
| * result: /../../n5 |
| * OR |
| * kn_from: /n1/n2/n3/n4/n5 [depth=5] |
| * kn_to: /n1/n2/n3 [depth=3] |
| * result: /../.. |
| * |
| * [3] when @kn_to is NULL result will be "(null)" |
| * |
| * Returns the length of the full path. If the full length is equal to or |
| * greater than @buflen, @buf contains the truncated path with the trailing |
| * '\0'. On error, -errno is returned. |
| */ |
| static int kernfs_path_from_node_locked(struct kernfs_node *kn_to, |
| struct kernfs_node *kn_from, |
| char *buf, size_t buflen) |
| { |
| struct kernfs_node *kn, *common; |
| const char parent_str[] = "/.."; |
| size_t depth_from, depth_to, len = 0; |
| int i, j; |
| |
| if (!kn_to) |
| return strlcpy(buf, "(null)", buflen); |
| |
| if (!kn_from) |
| kn_from = kernfs_root(kn_to)->kn; |
| |
| if (kn_from == kn_to) |
| return strlcpy(buf, "/", buflen); |
| |
| if (!buf) |
| return -EINVAL; |
| |
| common = kernfs_common_ancestor(kn_from, kn_to); |
| if (WARN_ON(!common)) |
| return -EINVAL; |
| |
| depth_to = kernfs_depth(common, kn_to); |
| depth_from = kernfs_depth(common, kn_from); |
| |
| buf[0] = '\0'; |
| |
| for (i = 0; i < depth_from; i++) |
| len += strlcpy(buf + len, parent_str, |
| len < buflen ? buflen - len : 0); |
| |
| /* Calculate how many bytes we need for the rest */ |
| for (i = depth_to - 1; i >= 0; i--) { |
| for (kn = kn_to, j = 0; j < i; j++) |
| kn = kn->parent; |
| len += strlcpy(buf + len, "/", |
| len < buflen ? buflen - len : 0); |
| len += strlcpy(buf + len, kn->name, |
| len < buflen ? buflen - len : 0); |
| } |
| |
| return len; |
| } |
| |
| /** |
| * kernfs_name - obtain the name of a given node |
| * @kn: kernfs_node of interest |
| * @buf: buffer to copy @kn's name into |
| * @buflen: size of @buf |
| * |
| * Copies the name of @kn into @buf of @buflen bytes. The behavior is |
| * similar to strlcpy(). It returns the length of @kn's name and if @buf |
| * isn't long enough, it's filled upto @buflen-1 and nul terminated. |
| * |
| * Fills buffer with "(null)" if @kn is NULL. |
| * |
| * This function can be called from any context. |
| */ |
| int kernfs_name(struct kernfs_node *kn, char *buf, size_t buflen) |
| { |
| unsigned long flags; |
| int ret; |
| |
| spin_lock_irqsave(&kernfs_rename_lock, flags); |
| ret = kernfs_name_locked(kn, buf, buflen); |
| spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
| return ret; |
| } |
| |
| /** |
| * kernfs_path_from_node - build path of node @to relative to @from. |
| * @from: parent kernfs_node relative to which we need to build the path |
| * @to: kernfs_node of interest |
| * @buf: buffer to copy @to's path into |
| * @buflen: size of @buf |
| * |
| * Builds @to's path relative to @from in @buf. @from and @to must |
| * be on the same kernfs-root. If @from is not parent of @to, then a relative |
| * path (which includes '..'s) as needed to reach from @from to @to is |
| * returned. |
| * |
| * Returns the length of the full path. If the full length is equal to or |
| * greater than @buflen, @buf contains the truncated path with the trailing |
| * '\0'. On error, -errno is returned. |
| */ |
| int kernfs_path_from_node(struct kernfs_node *to, struct kernfs_node *from, |
| char *buf, size_t buflen) |
| { |
| unsigned long flags; |
| int ret; |
| |
| spin_lock_irqsave(&kernfs_rename_lock, flags); |
| ret = kernfs_path_from_node_locked(to, from, buf, buflen); |
| spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(kernfs_path_from_node); |
| |
| /** |
| * pr_cont_kernfs_name - pr_cont name of a kernfs_node |
| * @kn: kernfs_node of interest |
| * |
| * This function can be called from any context. |
| */ |
| void pr_cont_kernfs_name(struct kernfs_node *kn) |
| { |
| unsigned long flags; |
| |
| spin_lock_irqsave(&kernfs_rename_lock, flags); |
| |
| kernfs_name_locked(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); |
| pr_cont("%s", kernfs_pr_cont_buf); |
| |
| spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
| } |
| |
| /** |
| * pr_cont_kernfs_path - pr_cont path of a kernfs_node |
| * @kn: kernfs_node of interest |
| * |
| * This function can be called from any context. |
| */ |
| void pr_cont_kernfs_path(struct kernfs_node *kn) |
| { |
| unsigned long flags; |
| int sz; |
| |
| spin_lock_irqsave(&kernfs_rename_lock, flags); |
| |
| sz = kernfs_path_from_node_locked(kn, NULL, kernfs_pr_cont_buf, |
| sizeof(kernfs_pr_cont_buf)); |
| if (sz < 0) { |
| pr_cont("(error)"); |
| goto out; |
| } |
| |
| if (sz >= sizeof(kernfs_pr_cont_buf)) { |
| pr_cont("(name too long)"); |
| goto out; |
| } |
| |
| pr_cont("%s", kernfs_pr_cont_buf); |
| |
| out: |
| spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
| } |
| |
| /** |
| * kernfs_get_parent - determine the parent node and pin it |
| * @kn: kernfs_node of interest |
| * |
| * Determines @kn's parent, pins and returns it. This function can be |
| * called from any context. |
| */ |
| struct kernfs_node *kernfs_get_parent(struct kernfs_node *kn) |
| { |
| struct kernfs_node *parent; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&kernfs_rename_lock, flags); |
| parent = kn->parent; |
| kernfs_get(parent); |
| spin_unlock_irqrestore(&kernfs_rename_lock, flags); |
| |
| return parent; |
| } |
| |
| /** |
| * 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(ns); |
| unsigned int len = strlen(name); |
| while (len--) |
| hash = partial_name_hash(*name++, hash); |
| hash = end_name_hash(hash); |
| hash &= 0x7fffffffU; |
| /* Reserve hash numbers 0, 1 and INT_MAX for magic directory entries */ |
| if (hash < 2) |
| 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 -1; |
| if (hash > kn->hash) |
| return 1; |
| if (ns < kn->ns) |
| return -1; |
| if (ns > kn->ns) |
| return 1; |
| 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; |
| |
| 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); |
| |
| /* successfully added, account subdir number */ |
| if (kernfs_type(kn) == KERNFS_DIR) |
| kn->parent->dir.subdirs++; |
| |
| return 0; |
| } |
| |
| /** |
| * kernfs_unlink_sibling - unlink kernfs_node from sibling rbtree |
| * @kn: kernfs_node of interest |
| * |
| * Try to unlink @kn from its sibling rbtree which starts from |
| * kn->parent->dir.children. Returns %true if @kn was actually |
| * removed, %false if @kn wasn't on the rbtree. |
| * |
| * 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 (!atomic_inc_unless_negative(&kn->active)) |
| return NULL; |
| |
| if (kernfs_lockdep(kn)) |
| rwsem_acquire_read(&kn->dep_map, 0, 1, _RET_IP_); |
| return kn; |
| } |
| |
| /** |
| * 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) |
| { |
| int v; |
| |
| if (unlikely(!kn)) |
| return; |
| |
| if (kernfs_lockdep(kn)) |
| rwsem_release(&kn->dep_map, _RET_IP_); |
| v = atomic_dec_return(&kn->active); |
| if (likely(v != KN_DEACTIVATED_BIAS)) |
| return; |
| |
| wake_up_all(&kernfs_root(kn)->deactivate_waitq); |
| } |
| |
| /** |
| * kernfs_drain - drain kernfs_node |
| * @kn: kernfs_node to drain |
| * |
| * Drain existing usages and nuke all existing mmaps of @kn. Mutiple |
| * removers may invoke this function concurrently on @kn and all will |
| * return after draining is complete. |
| */ |
| static void 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(kernfs_active(kn)); |
| |
| 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_); |
| } |
| |
| /* but everyone should wait for draining */ |
| 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, _RET_IP_); |
| } |
| |
| kernfs_drain_open_files(kn); |
| |
| mutex_lock(&kernfs_mutex); |
| } |
| |
| /** |
| * 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); |
| |
| kfree_const(kn->name); |
| |
| if (kn->iattr) { |
| simple_xattrs_free(&kn->iattr->xattrs); |
| kmem_cache_free(kernfs_iattrs_cache, kn->iattr); |
| } |
| spin_lock(&kernfs_idr_lock); |
| idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
| spin_unlock(&kernfs_idr_lock); |
| 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 */ |
| idr_destroy(&root->ino_idr); |
| 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 (d_really_is_negative(dentry)) |
| goto out_bad_unlocked; |
| |
| kn = kernfs_dentry_node(dentry); |
| mutex_lock(&kernfs_mutex); |
| |
| /* The kernfs node has been deactivated */ |
| if (!kernfs_active(kn)) |
| goto out_bad; |
| |
| /* The kernfs node has been moved? */ |
| if (kernfs_dentry_node(dentry->d_parent) != 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); |
| return 1; |
| out_bad: |
| mutex_unlock(&kernfs_mutex); |
| out_bad_unlocked: |
| return 0; |
| } |
| |
| const struct dentry_operations kernfs_dops = { |
| .d_revalidate = kernfs_dop_revalidate, |
| }; |
| |
| /** |
| * kernfs_node_from_dentry - determine kernfs_node associated with a dentry |
| * @dentry: the dentry in question |
| * |
| * Return the kernfs_node associated with @dentry. If @dentry is not a |
| * kernfs one, %NULL is returned. |
| * |
| * While the returned kernfs_node will stay accessible as long as @dentry |
| * is accessible, the returned node can be in any state and the caller is |
| * fully responsible for determining what's accessible. |
| */ |
| struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry) |
| { |
| if (dentry->d_sb->s_op == &kernfs_sops) |
| return kernfs_dentry_node(dentry); |
| return NULL; |
| } |
| |
| static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root, |
| struct kernfs_node *parent, |
| const char *name, umode_t mode, |
| kuid_t uid, kgid_t gid, |
| unsigned flags) |
| { |
| struct kernfs_node *kn; |
| u32 id_highbits; |
| int ret; |
| |
| name = kstrdup_const(name, GFP_KERNEL); |
| if (!name) |
| return NULL; |
| |
| kn = kmem_cache_zalloc(kernfs_node_cache, GFP_KERNEL); |
| if (!kn) |
| goto err_out1; |
| |
| idr_preload(GFP_KERNEL); |
| spin_lock(&kernfs_idr_lock); |
| ret = idr_alloc_cyclic(&root->ino_idr, kn, 1, 0, GFP_ATOMIC); |
| if (ret >= 0 && ret < root->last_id_lowbits) |
| root->id_highbits++; |
| id_highbits = root->id_highbits; |
| root->last_id_lowbits = ret; |
| spin_unlock(&kernfs_idr_lock); |
| idr_preload_end(); |
| if (ret < 0) |
| goto err_out2; |
| |
| kn->id = (u64)id_highbits << 32 | ret; |
| |
| atomic_set(&kn->count, 1); |
| atomic_set(&kn->active, KN_DEACTIVATED_BIAS); |
| RB_CLEAR_NODE(&kn->rb); |
| |
| kn->name = name; |
| kn->mode = mode; |
| kn->flags = flags; |
| |
| if (!uid_eq(uid, GLOBAL_ROOT_UID) || !gid_eq(gid, GLOBAL_ROOT_GID)) { |
| struct iattr iattr = { |
| .ia_valid = ATTR_UID | ATTR_GID, |
| .ia_uid = uid, |
| .ia_gid = gid, |
| }; |
| |
| ret = __kernfs_setattr(kn, &iattr); |
| if (ret < 0) |
| goto err_out3; |
| } |
| |
| if (parent) { |
| ret = security_kernfs_init_security(parent, kn); |
| if (ret) |
| goto err_out3; |
| } |
| |
| return kn; |
| |
| err_out3: |
| idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); |
| err_out2: |
| kmem_cache_free(kernfs_node_cache, kn); |
| err_out1: |
| kfree_const(name); |
| return NULL; |
| } |
| |
| struct kernfs_node *kernfs_new_node(struct kernfs_node *parent, |
| const char *name, umode_t mode, |
| kuid_t uid, kgid_t gid, |
| unsigned flags) |
| { |
| struct kernfs_node *kn; |
| |
| kn = __kernfs_new_node(kernfs_root(parent), parent, |
| name, mode, uid, gid, flags); |
| if (kn) { |
| kernfs_get(parent); |
| kn->parent = parent; |
| } |
| return kn; |
| } |
| |
| /* |
| * kernfs_find_and_get_node_by_id - get kernfs_node from node id |
| * @root: the kernfs root |
| * @id: the target node id |
| * |
| * @id's lower 32bits encode ino and upper gen. If the gen portion is |
| * zero, all generations are matched. |
| * |
| * RETURNS: |
| * NULL on failure. Return a kernfs node with reference counter incremented |
| */ |
| struct kernfs_node *kernfs_find_and_get_node_by_id(struct kernfs_root *root, |
| u64 id) |
| { |
| struct kernfs_node *kn; |
| ino_t ino = kernfs_id_ino(id); |
| u32 gen = kernfs_id_gen(id); |
| |
| spin_lock(&kernfs_idr_lock); |
| |
| kn = idr_find(&root->ino_idr, (u32)ino); |
| if (!kn) |
| goto err_unlock; |
| |
| if (sizeof(ino_t) >= sizeof(u64)) { |
| /* we looked up with the low 32bits, compare the whole */ |
| if (kernfs_ino(kn) != ino) |
| goto err_unlock; |
| } else { |
| /* 0 matches all generations */ |
| if (unlikely(gen && kernfs_gen(kn) != gen)) |
| goto err_unlock; |
| } |
| |
| /* |
| * ACTIVATED is protected with kernfs_mutex but it was clear when |
| * @kn was added to idr and we just wanna see it set. No need to |
| * grab kernfs_mutex. |
| */ |
| if (unlikely(!(kn->flags & KERNFS_ACTIVATED) || |
| !atomic_inc_not_zero(&kn->count))) |
| goto err_unlock; |
| |
| spin_unlock(&kernfs_idr_lock); |
| return kn; |
| err_unlock: |
| spin_unlock(&kernfs_idr_lock); |
| return NULL; |
| } |
| |
| /** |
| * kernfs_add_one - add kernfs_node to parent without warning |
| * @kn: kernfs_node to be added |
| * |
| * The caller must already have initialized @kn->parent. This |
| * function increments nlink of the parent's 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 = kn->parent; |
| struct kernfs_iattrs *ps_iattr; |
| bool has_ns; |
| int ret; |
| |
| 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; |
| |
| ret = -ENOENT; |
| if (parent->flags & KERNFS_EMPTY_DIR) |
| goto out_unlock; |
| |
| if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent)) |
| goto out_unlock; |
| |
| kn->hash = kernfs_name_hash(kn->name, kn->ns); |
| |
| ret = kernfs_link_sibling(kn); |
| if (ret) |
| goto out_unlock; |
| |
| /* Update timestamps on the parent */ |
| ps_iattr = parent->iattr; |
| if (ps_iattr) { |
| ktime_get_real_ts64(&ps_iattr->ia_ctime); |
| ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
| } |
| |
| mutex_unlock(&kernfs_mutex); |
| |
| /* |
| * Activate the new node unless CREATE_DEACTIVATED is requested. |
| * If not activated here, the kernfs user is responsible for |
| * activating the node with kernfs_activate(). A node which hasn't |
| * been activated is not visible to userland and its removal won't |
| * trigger deactivation. |
| */ |
| if (!(kernfs_root(kn)->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
| kernfs_activate(kn); |
| return 0; |
| |
| out_unlock: |
| mutex_unlock(&kernfs_mutex); |
| 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; |
| } |
| |
| static struct kernfs_node *kernfs_walk_ns(struct kernfs_node *parent, |
| const unsigned char *path, |
| const void *ns) |
| { |
| size_t len; |
| char *p, *name; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| /* grab kernfs_rename_lock to piggy back on kernfs_pr_cont_buf */ |
| spin_lock_irq(&kernfs_rename_lock); |
| |
| len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); |
| |
| if (len >= sizeof(kernfs_pr_cont_buf)) { |
| spin_unlock_irq(&kernfs_rename_lock); |
| return NULL; |
| } |
| |
| p = kernfs_pr_cont_buf; |
| |
| while ((name = strsep(&p, "/")) && parent) { |
| if (*name == '\0') |
| continue; |
| parent = kernfs_find_ns(parent, name, ns); |
| } |
| |
| spin_unlock_irq(&kernfs_rename_lock); |
| |
| return parent; |
| } |
| |
| /** |
| * 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_walk_and_get_ns - find and get kernfs_node with the given path |
| * @parent: kernfs_node to search under |
| * @path: path to look for |
| * @ns: the namespace tag to use |
| * |
| * Look for kernfs_node with path @path 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_walk_and_get_ns(struct kernfs_node *parent, |
| const char *path, const void *ns) |
| { |
| struct kernfs_node *kn; |
| |
| mutex_lock(&kernfs_mutex); |
| kn = kernfs_walk_ns(parent, path, ns); |
| kernfs_get(kn); |
| mutex_unlock(&kernfs_mutex); |
| |
| return kn; |
| } |
| |
| /** |
| * kernfs_create_root - create a new kernfs hierarchy |
| * @scops: optional syscall operations for the hierarchy |
| * @flags: KERNFS_ROOT_* flags |
| * @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_syscall_ops *scops, |
| unsigned int flags, void *priv) |
| { |
| struct kernfs_root *root; |
| struct kernfs_node *kn; |
| |
| root = kzalloc(sizeof(*root), GFP_KERNEL); |
| if (!root) |
| return ERR_PTR(-ENOMEM); |
| |
| idr_init(&root->ino_idr); |
| INIT_LIST_HEAD(&root->supers); |
| |
| /* |
| * On 64bit ino setups, id is ino. On 32bit, low 32bits are ino. |
| * High bits generation. The starting value for both ino and |
| * genenration is 1. Initialize upper 32bit allocation |
| * accordingly. |
| */ |
| if (sizeof(ino_t) >= sizeof(u64)) |
| root->id_highbits = 0; |
| else |
| root->id_highbits = 1; |
| |
| kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO, |
| GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
| KERNFS_DIR); |
| if (!kn) { |
| idr_destroy(&root->ino_idr); |
| kfree(root); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| kn->priv = priv; |
| kn->dir.root = root; |
| |
| root->syscall_ops = scops; |
| root->flags = flags; |
| root->kn = kn; |
| init_waitqueue_head(&root->deactivate_waitq); |
| |
| if (!(root->flags & KERNFS_ROOT_CREATE_DEACTIVATED)) |
| kernfs_activate(kn); |
| |
| 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 |
| * @uid: uid of the new directory |
| * @gid: gid 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, |
| kuid_t uid, kgid_t gid, |
| void *priv, const void *ns) |
| { |
| struct kernfs_node *kn; |
| int rc; |
| |
| /* allocate */ |
| kn = kernfs_new_node(parent, name, mode | S_IFDIR, |
| uid, gid, 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); |
| if (!rc) |
| return kn; |
| |
| kernfs_put(kn); |
| return ERR_PTR(rc); |
| } |
| |
| /** |
| * kernfs_create_empty_dir - create an always empty directory |
| * @parent: parent in which to create a new directory |
| * @name: name of the new directory |
| * |
| * Returns the created node on success, ERR_PTR() value on failure. |
| */ |
| struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent, |
| const char *name) |
| { |
| struct kernfs_node *kn; |
| int rc; |
| |
| /* allocate */ |
| kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, |
| GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, KERNFS_DIR); |
| if (!kn) |
| return ERR_PTR(-ENOMEM); |
| |
| kn->flags |= KERNFS_EMPTY_DIR; |
| kn->dir.root = parent->dir.root; |
| kn->ns = NULL; |
| kn->priv = NULL; |
| |
| /* link in */ |
| rc = kernfs_add_one(kn); |
| 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 = dir->i_private; |
| 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 || !kernfs_active(kn)) { |
| ret = NULL; |
| goto out_unlock; |
| } |
| |
| /* 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_splice_alias(inode, dentry); |
| out_unlock: |
| mutex_unlock(&kernfs_mutex); |
| return ret; |
| } |
| |
| static int kernfs_iop_mkdir(struct user_namespace *mnt_userns, |
| struct inode *dir, struct dentry *dentry, |
| umode_t mode) |
| { |
| struct kernfs_node *parent = dir->i_private; |
| struct kernfs_syscall_ops *scops = kernfs_root(parent)->syscall_ops; |
| int ret; |
| |
| if (!scops || !scops->mkdir) |
| return -EPERM; |
| |
| if (!kernfs_get_active(parent)) |
| return -ENODEV; |
| |
| ret = scops->mkdir(parent, dentry->d_name.name, mode); |
| |
| kernfs_put_active(parent); |
| return ret; |
| } |
| |
| static int kernfs_iop_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| struct kernfs_node *kn = kernfs_dentry_node(dentry); |
| struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
| int ret; |
| |
| if (!scops || !scops->rmdir) |
| return -EPERM; |
| |
| if (!kernfs_get_active(kn)) |
| return -ENODEV; |
| |
| ret = scops->rmdir(kn); |
| |
| kernfs_put_active(kn); |
| return ret; |
| } |
| |
| static int kernfs_iop_rename(struct user_namespace *mnt_userns, |
| struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry, |
| unsigned int flags) |
| { |
| struct kernfs_node *kn = kernfs_dentry_node(old_dentry); |
| struct kernfs_node *new_parent = new_dir->i_private; |
| struct kernfs_syscall_ops *scops = kernfs_root(kn)->syscall_ops; |
| int ret; |
| |
| if (flags) |
| return -EINVAL; |
| |
| if (!scops || !scops->rename) |
| return -EPERM; |
| |
| if (!kernfs_get_active(kn)) |
| return -ENODEV; |
| |
| if (!kernfs_get_active(new_parent)) { |
| kernfs_put_active(kn); |
| return -ENODEV; |
| } |
| |
| ret = scops->rename(kn, new_parent, new_dentry->d_name.name); |
| |
| kernfs_put_active(new_parent); |
| kernfs_put_active(kn); |
| return ret; |
| } |
| |
| const struct inode_operations kernfs_dir_iops = { |
| .lookup = kernfs_iop_lookup, |
| .permission = kernfs_iop_permission, |
| .setattr = kernfs_iop_setattr, |
| .getattr = kernfs_iop_getattr, |
| .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; |
| } |
| |
| /** |
| * kernfs_activate - activate a node which started deactivated |
| * @kn: kernfs_node whose subtree is to be activated |
| * |
| * If the root has KERNFS_ROOT_CREATE_DEACTIVATED set, a newly created node |
| * needs to be explicitly activated. A node which hasn't been activated |
| * isn't visible to userland and deactivation is skipped during its |
| * removal. This is useful to construct atomic init sequences where |
| * creation of multiple nodes should either succeed or fail atomically. |
| * |
| * The caller is responsible for ensuring that this function is not called |
| * after kernfs_remove*() is invoked on @kn. |
| */ |
| void kernfs_activate(struct kernfs_node *kn) |
| { |
| struct kernfs_node *pos; |
| |
| mutex_lock(&kernfs_mutex); |
| |
| pos = NULL; |
| while ((pos = kernfs_next_descendant_post(pos, kn))) { |
| if (pos->flags & KERNFS_ACTIVATED) |
| continue; |
| |
| WARN_ON_ONCE(pos->parent && RB_EMPTY_NODE(&pos->rb)); |
| WARN_ON_ONCE(atomic_read(&pos->active) != KN_DEACTIVATED_BIAS); |
| |
| atomic_sub(KN_DEACTIVATED_BIAS, &pos->active); |
| pos->flags |= KERNFS_ACTIVATED; |
| } |
| |
| mutex_unlock(&kernfs_mutex); |
| } |
| |
| static void __kernfs_remove(struct kernfs_node *kn) |
| { |
| struct kernfs_node *pos; |
| |
| lockdep_assert_held(&kernfs_mutex); |
| |
| /* |
| * Short-circuit if non-root @kn has already finished removal. |
| * This is for kernfs_remove_self() which plays with active ref |
| * after removal. |
| */ |
| if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb))) |
| return; |
| |
| pr_debug("kernfs %s: removing\n", kn->name); |
| |
| /* prevent any new usage under @kn by deactivating all nodes */ |
| pos = NULL; |
| while ((pos = kernfs_next_descendant_post(pos, kn))) |
| if (kernfs_active(pos)) |
| atomic_add(KN_DEACTIVATED_BIAS, &pos->active); |
| |
| /* deactivate and unlink the subtree node-by-node */ |
| do { |
| pos = kernfs_leftmost_descendant(kn); |
| |
| /* |
| * kernfs_drain() drops kernfs_mutex temporarily and @pos's |
| * base ref could have been put by someone else by the time |
| * the function returns. Make sure it doesn't go away |
| * underneath us. |
| */ |
| kernfs_get(pos); |
| |
| /* |
| * Drain iff @kn was activated. This avoids draining and |
| * its lockdep annotations for nodes which have never been |
| * activated and allows embedding kernfs_remove() in create |
| * error paths without worrying about draining. |
| */ |
| if (kn->flags & KERNFS_ACTIVATED) |
| kernfs_drain(pos); |
| else |
| WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); |
| |
| /* |
| * 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) { |
| ktime_get_real_ts64(&ps_iattr->ia_ctime); |
| ps_iattr->ia_mtime = ps_iattr->ia_ctime; |
| } |
| |
| kernfs_put(pos); |
| } |
| |
| kernfs_put(pos); |
| } while (pos != kn); |
| } |
| |
| /** |
| * 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_break_active_protection - break out of active protection |
| * @kn: the self kernfs_node |
| * |
| * The caller must be running off of a kernfs operation which is invoked |
| * with an active reference - e.g. one of kernfs_ops. Each invocation of |
| * this function must also be matched with an invocation of |
| * kernfs_unbreak_active_protection(). |
| * |
| * This function releases the active reference of @kn the caller is |
| * holding. Once this function is called, @kn may be removed at any point |
| * and the caller is solely responsible for ensuring that the objects it |
| * dereferences are accessible. |
| */ |
| void kernfs_break_active_protection(struct kernfs_node *kn) |
| { |
| /* |
| * Take out ourself out of the active ref dependency chain. If |
| * we're called without an active ref, lockdep will complain. |
| */ |
| kernfs_put_active(kn); |
| } |
| |
| /** |
| * kernfs_unbreak_active_protection - undo kernfs_break_active_protection() |
| * @kn: the self kernfs_node |
| * |
| * If kernfs_break_active_protection() was called, this function must be |
| * invoked before finishing the kernfs operation. Note that while this |
| * function restores the active reference, it doesn't and can't actually |
| * restore the active protection - @kn may already or be in the process of |
| * being removed. Once kernfs_break_active_protection() is invoked, that |
| * protection is irreversibly gone for the kernfs operation instance. |
| * |
| * While this function may be called at any point after |
| * kernfs_break_active_protection() is invoked, its most useful location |
| * would be right before the enclosing kernfs operation returns. |
| */ |
| void kernfs_unbreak_active_protection(struct kernfs_node *kn) |
| { |
| /* |
| * @kn->active could be in any state; however, the increment we do |
| * here will be undone as soon as the enclosing kernfs operation |
| * finishes and this temporary bump can't break anything. If @kn |
| * is alive, nothing changes. If @kn is being deactivated, the |
| * soon-to-follow put will either finish deactivation or restore |
| * deactivated state. If @kn is already removed, the temporary |
| * bump is guaranteed to be gone before @kn is released. |
| */ |
| atomic_inc(&kn->active); |
| if (kernfs_lockdep(kn)) |
| rwsem_acquire(&kn->dep_map, 0, 1, _RET_IP_); |
| } |
| |
| /** |
| * 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_break_active_protection(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; |
| } |
| |
| /* |
| * This must be done while holding kernfs_mutex; otherwise, waiting |
| * for SUICIDED && deactivated could finish prematurely. |
| */ |
| kernfs_unbreak_active_protection(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) |
| { |
| struct kernfs_node *old_parent; |
| const char *old_name = NULL; |
| int error; |
| |
| /* can't move or rename root */ |
| if (!kn->parent) |
| return -EINVAL; |
| |
| mutex_lock(&kernfs_mutex); |
| |
| error = -ENOENT; |
| if (!kernfs_active(kn) || !kernfs_active(new_parent) || |
| (new_parent->flags & KERNFS_EMPTY_DIR)) |
| goto out; |
| |
| error = 0; |
| if ((kn->parent == new_parent) && (kn->ns == new_ns) && |
| (strcmp(kn->name, new_name) == 0)) |
| goto out; /* nothing to rename */ |
| |
| error = -EEXIST; |
| if (kernfs_find_ns(new_parent, new_name, new_ns)) |
| goto out; |
| |
| /* rename kernfs_node */ |
| if (strcmp(kn->name, new_name) != 0) { |
| error = -ENOMEM; |
| new_name = kstrdup_const(new_name, GFP_KERNEL); |
| if (!new_name) |
| goto out; |
| } else { |
| new_name = NULL; |
| } |
| |
| /* |
| * Move to the appropriate place in the appropriate directories rbtree. |
| */ |
| kernfs_unlink_sibling(kn); |
| kernfs_get(new_parent); |
| |
| /* rename_lock protects ->parent and ->name accessors */ |
| spin_lock_irq(&kernfs_rename_lock); |
| |
| old_parent = kn->parent; |
| kn->parent = new_parent; |
| |
| kn->ns = new_ns; |
| if (new_name) { |
| old_name = kn->name; |
| kn->name = new_name; |
| } |
| |
| spin_unlock_irq(&kernfs_rename_lock); |
| |
| kn->hash = kernfs_name_hash(kn->name, kn->ns); |
| kernfs_link_sibling(kn); |
| |
| kernfs_put(old_parent); |
| kfree_const(old_name); |
| |
| error = 0; |
| out: |
| mutex_unlock(&kernfs_mutex); |
| return error; |
| } |
| |
| /* Relationship between 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 = kernfs_active(pos) && |
| 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 which are dying/dead or in the wrong namespace */ |
| while (pos && (!kernfs_active(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 && (!kernfs_active(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 = kernfs_dentry_node(dentry); |
| 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 = kernfs_ino(pos); |
| |
| 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; |
| } |
| |
| const struct file_operations kernfs_dir_fops = { |
| .read = generic_read_dir, |
| .iterate_shared = kernfs_fop_readdir, |
| .release = kernfs_dir_fop_release, |
| .llseek = generic_file_llseek, |
| }; |