diff options
Diffstat (limited to '')
| -rw-r--r-- | fs/kernfs/dir.c | 1835 |
1 files changed, 1835 insertions, 0 deletions
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c new file mode 100644 index 000000000..44842e6cf --- /dev/null +++ b/fs/kernfs/dir.c @@ -0,0 +1,1835 @@ +// 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" + +static DEFINE_SPINLOCK(kernfs_rename_lock); /* kn->parent and ->name */ +/* + * Don't use rename_lock to piggy back on pr_cont_buf. We don't want to + * call pr_cont() while holding rename_lock. Because sometimes pr_cont() + * will perform wakeups when releasing console_sem. Holding rename_lock + * will introduce deadlock if the scheduler reads the kernfs_name in the + * wakeup path. + */ +static DEFINE_SPINLOCK(kernfs_pr_cont_lock); +static char kernfs_pr_cont_buf[PATH_MAX]; /* protected by pr_cont_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) +{ + return atomic_read(&kn->active) >= 0; +} + +static bool kernfs_active(struct kernfs_node *kn) +{ + lockdep_assert_held(&kernfs_root(kn)->kernfs_rwsem); + return __kernfs_active(kn); +} + +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_pr_cont_lock, flags); + + kernfs_name(kn, kernfs_pr_cont_buf, sizeof(kernfs_pr_cont_buf)); + pr_cont("%s", kernfs_pr_cont_buf); + + spin_unlock_irqrestore(&kernfs_pr_cont_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_pr_cont_lock, flags); + + sz = kernfs_path_from_node(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_pr_cont_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: + * kernfs_rwsem held exclusive + * + * 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++; + kernfs_inc_rev(kn->parent); + + 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: + * kernfs_rwsem held exclusive + */ +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--; + kernfs_inc_rev(kn->parent); + + 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_root(kn)->kernfs_rwsem) + __acquires(&kernfs_root(kn)->kernfs_rwsem) +{ + struct kernfs_root *root = kernfs_root(kn); + + lockdep_assert_held_write(&root->kernfs_rwsem); + WARN_ON_ONCE(kernfs_active(kn)); + + /* + * Skip draining if already fully drained. This avoids draining and its + * lockdep annotations for nodes which have never been activated + * allowing embedding kernfs_remove() in create error paths without + * worrying about draining. + */ + if (atomic_read(&kn->active) == KN_DEACTIVATED_BIAS && + !kernfs_should_drain_open_files(kn)) + return; + + up_write(&root->kernfs_rwsem); + + 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, _RET_IP_); + } + + if (kernfs_should_drain_open_files(kn)) + kernfs_drain_open_files(kn); + + down_write(&root->kernfs_rwsem); +} + +/** + * 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); + +/** + * 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: + spin_lock(&kernfs_idr_lock); + idr_remove(&root->ino_idr, (u32)kernfs_ino(kn)); + spin_unlock(&kernfs_idr_lock); + 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; + } + + /* + * We should fail if @kn has never been activated and guarantee success + * if the caller knows that @kn is active. Both can be achieved by + * __kernfs_active() which tests @kn->active without kernfs_rwsem. + */ + if (unlikely(!__kernfs_active(kn) || !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_root *root = kernfs_root(parent); + struct kernfs_iattrs *ps_iattr; + bool has_ns; + int ret; + + down_write(&root->kernfs_rwsem); + + 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_REMOVING | KERNFS_EMPTY_DIR)) + 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; + } + + up_write(&root->kernfs_rwsem); + + /* + * 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: + up_write(&root->kernfs_rwsem); + 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_root(parent)->kernfs_rwsem); + + 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_read(&kernfs_root(parent)->kernfs_rwsem); + + spin_lock_irq(&kernfs_pr_cont_lock); + + len = strlcpy(kernfs_pr_cont_buf, path, sizeof(kernfs_pr_cont_buf)); + + if (len >= sizeof(kernfs_pr_cont_buf)) { + spin_unlock_irq(&kernfs_pr_cont_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_pr_cont_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; + struct kernfs_root *root = kernfs_root(parent); + + down_read(&root->kernfs_rwsem); + kn = kernfs_find_ns(parent, name, ns); + kernfs_get(kn); + up_read(&root->kernfs_rwsem); + + 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; + struct kernfs_root *root = kernfs_root(parent); + + down_read(&root->kernfs_rwsem); + kn = kernfs_walk_ns(parent, path, ns); + kernfs_get(kn); + up_read(&root->kernfs_rwsem); + + 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_rwsem(&root->kernfs_rwsem); + 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 holds kernfs_rwsem from the root so the root + * shouldn't be freed during the operation. + */ + kernfs_get(root->kn); + kernfs_remove(root->kn); + kernfs_put(root->kn); /* will also free @root */ +} + +/** + * kernfs_root_to_node - return the kernfs_node associated with a kernfs_root + * @root: root to use to lookup + */ +struct kernfs_node *kernfs_root_to_node(struct kernfs_root *root) +{ + return root->kn; +} + +/** + * 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 int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct kernfs_node *kn; + struct kernfs_root *root; + + if (flags & LOOKUP_RCU) + return -ECHILD; + + /* Negative hashed dentry? */ + if (d_really_is_negative(dentry)) { + struct kernfs_node *parent; + + /* If the kernfs parent node has changed discard and + * proceed to ->lookup. + */ + spin_lock(&dentry->d_lock); + parent = kernfs_dentry_node(dentry->d_parent); + if (parent) { + spin_unlock(&dentry->d_lock); + root = kernfs_root(parent); + down_read(&root->kernfs_rwsem); + if (kernfs_dir_changed(parent, dentry)) { + up_read(&root->kernfs_rwsem); + return 0; + } + up_read(&root->kernfs_rwsem); + } else + spin_unlock(&dentry->d_lock); + + /* The kernfs parent node hasn't changed, leave the + * dentry negative and return success. + */ + return 1; + } + + kn = kernfs_dentry_node(dentry); + root = kernfs_root(kn); + down_read(&root->kernfs_rwsem); + + /* 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; + + up_read(&root->kernfs_rwsem); + return 1; +out_bad: + up_read(&root->kernfs_rwsem); + return 0; +} + +const struct dentry_operations kernfs_dops = { + .d_revalidate = kernfs_dop_revalidate, +}; + +static struct dentry *kernfs_iop_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + struct kernfs_node *parent = dir->i_private; + struct kernfs_node *kn; + struct kernfs_root *root; + struct inode *inode = NULL; + const void *ns = NULL; + + root = kernfs_root(parent); + down_read(&root->kernfs_rwsem); + if (kernfs_ns_enabled(parent)) + ns = kernfs_info(dir->i_sb)->ns; + + kn = kernfs_find_ns(parent, dentry->d_name.name, ns); + /* attach dentry and inode */ + if (kn) { + /* Inactive nodes are invisible to the VFS so don't + * create a negative. + */ + if (!kernfs_active(kn)) { + up_read(&root->kernfs_rwsem); + return NULL; + } + inode = kernfs_get_inode(dir->i_sb, kn); + if (!inode) + inode = ERR_PTR(-ENOMEM); + } + /* + * Needed for negative dentry validation. + * The negative dentry can be created in kernfs_iop_lookup() + * or transforms from positive dentry in dentry_unlink_inode() + * called from vfs_rmdir(). + */ + if (!IS_ERR(inode)) + kernfs_set_rev(parent, dentry); + up_read(&root->kernfs_rwsem); + + /* instantiate and hash (possibly negative) dentry */ + return d_splice_alias(inode, dentry); +} + +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_write(&kernfs_root(root)->kernfs_rwsem); + + /* 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_activate_one(struct kernfs_node *kn) +{ + lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); + + kn->flags |= KERNFS_ACTIVATED; + + if (kernfs_active(kn) || (kn->flags & (KERNFS_HIDDEN | KERNFS_REMOVING))) + return; + + WARN_ON_ONCE(kn->parent && RB_EMPTY_NODE(&kn->rb)); + WARN_ON_ONCE(atomic_read(&kn->active) != KN_DEACTIVATED_BIAS); + + atomic_sub(KN_DEACTIVATED_BIAS, &kn->active); +} + +/** + * 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; + struct kernfs_root *root = kernfs_root(kn); + + down_write(&root->kernfs_rwsem); + + pos = NULL; + while ((pos = kernfs_next_descendant_post(pos, kn))) + kernfs_activate_one(pos); + + up_write(&root->kernfs_rwsem); +} + +/** + * kernfs_show - show or hide a node + * @kn: kernfs_node to show or hide + * @show: whether to show or hide + * + * If @show is %false, @kn is marked hidden and deactivated. A hidden node is + * ignored in future activaitons. If %true, the mark is removed and activation + * state is restored. This function won't implicitly activate a new node in a + * %KERNFS_ROOT_CREATE_DEACTIVATED root which hasn't been activated yet. + * + * To avoid recursion complexities, directories aren't supported for now. + */ +void kernfs_show(struct kernfs_node *kn, bool show) +{ + struct kernfs_root *root = kernfs_root(kn); + + if (WARN_ON_ONCE(kernfs_type(kn) == KERNFS_DIR)) + return; + + down_write(&root->kernfs_rwsem); + + if (show) { + kn->flags &= ~KERNFS_HIDDEN; + if (kn->flags & KERNFS_ACTIVATED) + kernfs_activate_one(kn); + } else { + kn->flags |= KERNFS_HIDDEN; + if (kernfs_active(kn)) + atomic_add(KN_DEACTIVATED_BIAS, &kn->active); + kernfs_drain(kn); + } + + up_write(&root->kernfs_rwsem); +} + +static void __kernfs_remove(struct kernfs_node *kn) +{ + struct kernfs_node *pos; + + /* Short-circuit if non-root @kn has already finished removal. */ + if (!kn) + return; + + lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); + + /* + * This is for kernfs_remove_self() which plays with active ref + * after removal. + */ + if (kn->parent && RB_EMPTY_NODE(&kn->rb)) + return; + + pr_debug("kernfs %s: removing\n", kn->name); + + /* prevent new usage by marking all nodes removing and deactivating */ + pos = NULL; + while ((pos = kernfs_next_descendant_post(pos, kn))) { + pos->flags |= KERNFS_REMOVING; + 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() may drop kernfs_rwsem 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); + + kernfs_drain(pos); + + /* + * 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) +{ + struct kernfs_root *root; + + if (!kn) + return; + + root = kernfs_root(kn); + + down_write(&root->kernfs_rwsem); + __kernfs_remove(kn); + up_write(&root->kernfs_rwsem); +} + +/** + * 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; + struct kernfs_root *root = kernfs_root(kn); + + down_write(&root->kernfs_rwsem); + 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 kernfs_rwsem for held exclusive. The ones which lost + * arbitration waits for SUICIDED && 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; + + up_write(&root->kernfs_rwsem); + schedule(); + down_write(&root->kernfs_rwsem); + } + finish_wait(waitq, &wait); + WARN_ON_ONCE(!RB_EMPTY_NODE(&kn->rb)); + ret = false; + } + + /* + * This must be done while kernfs_rwsem held exclusive; otherwise, + * waiting for SUICIDED && deactivated could finish prematurely. + */ + kernfs_unbreak_active_protection(kn); + + up_write(&root->kernfs_rwsem); + 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; + struct kernfs_root *root; + + if (!parent) { + WARN(1, KERN_WARNING "kernfs: can not remove '%s', no directory\n", + name); + return -ENOENT; + } + + root = kernfs_root(parent); + down_write(&root->kernfs_rwsem); + + kn = kernfs_find_ns(parent, name, ns); + if (kn) { + kernfs_get(kn); + __kernfs_remove(kn); + kernfs_put(kn); + } + + up_write(&root->kernfs_rwsem); + + 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; + struct kernfs_root *root; + const char *old_name = NULL; + int error; + + /* can't move or rename root */ + if (!kn->parent) + return -EINVAL; + + root = kernfs_root(kn); + down_write(&root->kernfs_rwsem); + + 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: + up_write(&root->kernfs_rwsem); + 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; + struct kernfs_root *root; + const void *ns = NULL; + + if (!dir_emit_dots(file, ctx)) + return 0; + + root = kernfs_root(parent); + down_read(&root->kernfs_rwsem); + + 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); + + up_read(&root->kernfs_rwsem); + if (!dir_emit(ctx, name, len, ino, type)) + return 0; + down_read(&root->kernfs_rwsem); + } + up_read(&root->kernfs_rwsem); + 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, +}; |