[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/fs/kernfs/dir.c b/src/kernel/linux/v4.14/fs/kernfs/dir.c
new file mode 100644
index 0000000..8697b75
--- /dev/null
+++ b/src/kernel/linux/v4.14/fs/kernfs/dir.c
@@ -0,0 +1,1677 @@
+/*
+ * fs/kernfs/dir.c - kernfs directory implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/idr.h>
+#include <linux/slab.h>
+#include <linux/security.h>
+#include <linux/hash.h>
+
+#include "kernfs-internal.h"
+
+DEFINE_MUTEX(kernfs_mutex);
+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);
+
+ 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);
+
+ if (buf)
+ 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)
+{
+ struct kernfs_root *root = kernfs_root(kn);
+ int v;
+
+ if (unlikely(!kn))
+ return;
+
+ if (kernfs_lockdep(kn))
+ rwsem_release(&kn->dep_map, 1, _RET_IP_);
+ v = atomic_dec_return(&kn->active);
+ if (likely(v != KN_DEACTIVATED_BIAS))
+ return;
+
+ wake_up_all(&root->deactivate_waitq);
+}
+
+/**
+ * kernfs_drain - drain kernfs_node
+ * @kn: kernfs_node to drain
+ *
+ * Drain existing usages 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, 1, _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;
+
+ /*
+ * kernfs_node is freed with ->count 0, kernfs_find_and_get_node_by_ino
+ * depends on this to filter reused stale node
+ */
+ 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) {
+ if (kn->iattr->ia_secdata)
+ security_release_secctx(kn->iattr->ia_secdata,
+ kn->iattr->ia_secdata_len);
+ simple_xattrs_free(&kn->iattr->xattrs);
+ }
+ kfree(kn->iattr);
+ spin_lock(&kernfs_idr_lock);
+ idr_remove(&root->ino_idr, kn->id.ino);
+ 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 &&
+ !d_really_is_negative(dentry))
+ return kernfs_dentry_node(dentry);
+ return NULL;
+}
+
+static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
+ const char *name, umode_t mode,
+ unsigned flags)
+{
+ struct kernfs_node *kn;
+ u32 gen;
+ 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_ino)
+ root->next_generation++;
+ gen = root->next_generation;
+ root->last_ino = ret;
+ spin_unlock(&kernfs_idr_lock);
+ idr_preload_end();
+ if (ret < 0)
+ goto err_out2;
+ kn->id.ino = ret;
+ kn->id.generation = gen;
+
+ /*
+ * set ino first. This RELEASE is paired with atomic_inc_not_zero in
+ * kernfs_find_and_get_node_by_ino
+ */
+ atomic_set_release(&kn->count, 1);
+ atomic_set(&kn->active, KN_DEACTIVATED_BIAS);
+ RB_CLEAR_NODE(&kn->rb);
+
+ kn->name = name;
+ kn->mode = mode;
+ kn->flags = flags;
+
+ return kn;
+
+ err_out2:
+ kmem_cache_free(kernfs_node_cache, kn);
+ err_out1:
+ kfree_const(name);
+ return NULL;
+}
+
+struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
+ const char *name, umode_t mode,
+ unsigned flags)
+{
+ struct kernfs_node *kn;
+
+ kn = __kernfs_new_node(kernfs_root(parent), name, mode, flags);
+ if (kn) {
+ kernfs_get(parent);
+ kn->parent = parent;
+ }
+ return kn;
+}
+
+/*
+ * kernfs_find_and_get_node_by_ino - get kernfs_node from inode number
+ * @root: the kernfs root
+ * @ino: inode number
+ *
+ * RETURNS:
+ * NULL on failure. Return a kernfs node with reference counter incremented
+ */
+struct kernfs_node *kernfs_find_and_get_node_by_ino(struct kernfs_root *root,
+ unsigned int ino)
+{
+ struct kernfs_node *kn;
+
+ rcu_read_lock();
+ kn = idr_find(&root->ino_idr, ino);
+ if (!kn)
+ goto out;
+
+ /*
+ * Since kernfs_node is freed in RCU, it's possible an old node for ino
+ * is freed, but reused before RCU grace period. But a freed node (see
+ * kernfs_put) or an incompletedly initialized node (see
+ * __kernfs_new_node) should have 'count' 0. We can use this fact to
+ * filter out such node.
+ */
+ if (!atomic_inc_not_zero(&kn->count)) {
+ kn = NULL;
+ goto out;
+ }
+
+ /*
+ * The node could be a new node or a reused node. If it's a new node,
+ * we are ok. If it's reused because of RCU (because of
+ * SLAB_TYPESAFE_BY_RCU), the __kernfs_new_node always sets its 'ino'
+ * before 'count'. So if 'count' is uptodate, 'ino' should be uptodate,
+ * hence we can use 'ino' to filter stale node.
+ */
+ if (kn->id.ino != ino)
+ goto out;
+ rcu_read_unlock();
+
+ return kn;
+out:
+ rcu_read_unlock();
+ kernfs_put(kn);
+ 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) {
+ struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
+ ktime_get_real_ts(&ps_iattrs->ia_ctime);
+ ps_iattrs->ia_mtime = ps_iattrs->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);
+ root->next_generation = 1;
+
+ kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
+ 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
+ * @priv: opaque data associated with the new directory
+ * @ns: optional namespace tag of the directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
+ const char *name, umode_t mode,
+ void *priv, const void *ns)
+{
+ struct kernfs_node *kn;
+ int rc;
+
+ /* allocate */
+ kn = kernfs_new_node(parent, name, mode | S_IFDIR, KERNFS_DIR);
+ if (!kn)
+ return ERR_PTR(-ENOMEM);
+
+ kn->dir.root = parent->dir.root;
+ kn->ns = ns;
+ kn->priv = priv;
+
+ /* link in */
+ rc = kernfs_add_one(kn);
+ 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, 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 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 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 || (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_ts(&ps_iattr->ia_iattr.ia_ctime);
+ ps_iattr->ia_iattr.ia_mtime =
+ ps_iattr->ia_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 s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct kernfs_node *kn)
+{
+ return (kn->mode >> 12) & 15;
+}
+
+static int kernfs_dir_fop_release(struct inode *inode, struct file *filp)
+{
+ kernfs_put(filp->private_data);
+ return 0;
+}
+
+static struct kernfs_node *kernfs_dir_pos(const void *ns,
+ struct kernfs_node *parent, loff_t hash, struct kernfs_node *pos)
+{
+ if (pos) {
+ int valid = 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 = pos->id.ino;
+
+ ctx->pos = pos->hash;
+ file->private_data = pos;
+ kernfs_get(pos);
+
+ mutex_unlock(&kernfs_mutex);
+ if (!dir_emit(ctx, name, len, ino, type))
+ return 0;
+ mutex_lock(&kernfs_mutex);
+ }
+ mutex_unlock(&kernfs_mutex);
+ file->private_data = NULL;
+ ctx->pos = INT_MAX;
+ return 0;
+}
+
+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,
+};