Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 931 insertions, 0 deletions

diff --git a/fs/autofs/root.c b/fs/autofs/root.c
new file mode 100644
index 000000000..b36439f45
--- /dev/null
+++ b/fs/autofs/root.c
@@ -0,0 +1,931 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ * Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
+ * Copyright 2001-2006 Ian Kent <raven@themaw.net>
+ */
+
+#include <linux/capability.h>
+#include <linux/compat.h>
+#include <linux/string.h>
+
+#include "autofs_i.h"
+
+static int autofs_dir_permission(struct mnt_idmap *, struct inode *, int);
+static int autofs_dir_symlink(struct mnt_idmap *, struct inode *,
+			      struct dentry *, const char *);
+static int autofs_dir_unlink(struct inode *, struct dentry *);
+static int autofs_dir_rmdir(struct inode *, struct dentry *);
+static struct dentry *autofs_dir_mkdir(struct mnt_idmap *, struct inode *,
+				       struct dentry *, umode_t);
+static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
+#ifdef CONFIG_COMPAT
+static long autofs_root_compat_ioctl(struct file *,
+				     unsigned int, unsigned long);
+#endif
+static int autofs_dir_open(struct inode *inode, struct file *file);
+static struct dentry *autofs_lookup(struct inode *,
+				    struct dentry *, unsigned int);
+static struct vfsmount *autofs_d_automount(struct path *);
+static int autofs_d_manage(const struct path *, bool);
+static void autofs_dentry_release(struct dentry *);
+
+const struct file_operations autofs_root_operations = {
+	.open		= dcache_dir_open,
+	.release	= dcache_dir_close,
+	.read		= generic_read_dir,
+	.iterate_shared	= dcache_readdir,
+	.llseek		= dcache_dir_lseek,
+	.unlocked_ioctl	= autofs_root_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= autofs_root_compat_ioctl,
+#endif
+};
+
+const struct file_operations autofs_dir_operations = {
+	.open		= autofs_dir_open,
+	.release	= dcache_dir_close,
+	.read		= generic_read_dir,
+	.iterate_shared	= dcache_readdir,
+	.llseek		= dcache_dir_lseek,
+};
+
+const struct inode_operations autofs_dir_inode_operations = {
+	.lookup		= autofs_lookup,
+	.permission	= autofs_dir_permission,
+	.unlink		= autofs_dir_unlink,
+	.symlink	= autofs_dir_symlink,
+	.mkdir		= autofs_dir_mkdir,
+	.rmdir		= autofs_dir_rmdir,
+};
+
+const struct dentry_operations autofs_dentry_operations = {
+	.d_automount	= autofs_d_automount,
+	.d_manage	= autofs_d_manage,
+	.d_release	= autofs_dentry_release,
+};
+
+static void autofs_del_active(struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct autofs_info *ino;
+
+	ino = autofs_dentry_ino(dentry);
+	spin_lock(&sbi->lookup_lock);
+	list_del_init(&ino->active);
+	spin_unlock(&sbi->lookup_lock);
+}
+
+static int autofs_dir_open(struct inode *inode, struct file *file)
+{
+	struct dentry *dentry = file->f_path.dentry;
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+
+	pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
+
+	if (autofs_oz_mode(sbi))
+		goto out;
+
+	/*
+	 * An empty directory in an autofs file system is always a
+	 * mount point. The daemon must have failed to mount this
+	 * during lookup so it doesn't exist. This can happen, for
+	 * example, if user space returns an incorrect status for a
+	 * mount request. Otherwise we're doing a readdir on the
+	 * autofs file system so just let the libfs routines handle
+	 * it.
+	 */
+	spin_lock(&sbi->lookup_lock);
+	if (!path_is_mountpoint(&file->f_path) && autofs_empty(ino)) {
+		spin_unlock(&sbi->lookup_lock);
+		return -ENOENT;
+	}
+	spin_unlock(&sbi->lookup_lock);
+
+out:
+	return dcache_dir_open(inode, file);
+}
+
+static void autofs_dentry_release(struct dentry *de)
+{
+	struct autofs_info *ino = autofs_dentry_ino(de);
+	struct autofs_sb_info *sbi = autofs_sbi(de->d_sb);
+
+	pr_debug("releasing %p\n", de);
+
+	if (!ino)
+		return;
+
+	if (sbi) {
+		spin_lock(&sbi->lookup_lock);
+		if (!list_empty(&ino->active))
+			list_del(&ino->active);
+		if (!list_empty(&ino->expiring))
+			list_del(&ino->expiring);
+		spin_unlock(&sbi->lookup_lock);
+	}
+
+	autofs_free_ino(ino);
+}
+
+static struct dentry *autofs_lookup_active(struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct dentry *parent = dentry->d_parent;
+	const struct qstr *name = &dentry->d_name;
+	unsigned int len = name->len;
+	unsigned int hash = name->hash;
+	const unsigned char *str = name->name;
+	struct list_head *p, *head;
+
+	head = &sbi->active_list;
+	if (list_empty(head))
+		return NULL;
+	spin_lock(&sbi->lookup_lock);
+	list_for_each(p, head) {
+		struct autofs_info *ino;
+		struct dentry *active;
+		const struct qstr *qstr;
+
+		ino = list_entry(p, struct autofs_info, active);
+		active = ino->dentry;
+
+		spin_lock(&active->d_lock);
+
+		/* Already gone? */
+		if ((int) d_count(active) <= 0)
+			goto next;
+
+		qstr = &active->d_name;
+
+		if (active->d_name.hash != hash)
+			goto next;
+		if (active->d_parent != parent)
+			goto next;
+
+		if (qstr->len != len)
+			goto next;
+		if (memcmp(qstr->name, str, len))
+			goto next;
+
+		if (d_unhashed(active)) {
+			dget_dlock(active);
+			spin_unlock(&active->d_lock);
+			spin_unlock(&sbi->lookup_lock);
+			return active;
+		}
+next:
+		spin_unlock(&active->d_lock);
+	}
+	spin_unlock(&sbi->lookup_lock);
+
+	return NULL;
+}
+
+static struct dentry *autofs_lookup_expiring(struct dentry *dentry,
+					     bool rcu_walk)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct dentry *parent = dentry->d_parent;
+	const struct qstr *name = &dentry->d_name;
+	unsigned int len = name->len;
+	unsigned int hash = name->hash;
+	const unsigned char *str = name->name;
+	struct list_head *p, *head;
+
+	head = &sbi->expiring_list;
+	if (list_empty(head))
+		return NULL;
+	spin_lock(&sbi->lookup_lock);
+	list_for_each(p, head) {
+		struct autofs_info *ino;
+		struct dentry *expiring;
+		const struct qstr *qstr;
+
+		if (rcu_walk) {
+			spin_unlock(&sbi->lookup_lock);
+			return ERR_PTR(-ECHILD);
+		}
+
+		ino = list_entry(p, struct autofs_info, expiring);
+		expiring = ino->dentry;
+
+		spin_lock(&expiring->d_lock);
+
+		/* We've already been dentry_iput or unlinked */
+		if (d_really_is_negative(expiring))
+			goto next;
+
+		qstr = &expiring->d_name;
+
+		if (expiring->d_name.hash != hash)
+			goto next;
+		if (expiring->d_parent != parent)
+			goto next;
+
+		if (qstr->len != len)
+			goto next;
+		if (memcmp(qstr->name, str, len))
+			goto next;
+
+		if (d_unhashed(expiring)) {
+			dget_dlock(expiring);
+			spin_unlock(&expiring->d_lock);
+			spin_unlock(&sbi->lookup_lock);
+			return expiring;
+		}
+next:
+		spin_unlock(&expiring->d_lock);
+	}
+	spin_unlock(&sbi->lookup_lock);
+
+	return NULL;
+}
+
+static int autofs_mount_wait(const struct path *path, bool rcu_walk)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
+	struct autofs_info *ino = autofs_dentry_ino(path->dentry);
+	int status = 0;
+
+	if (ino->flags & AUTOFS_INF_PENDING) {
+		if (rcu_walk)
+			return -ECHILD;
+		pr_debug("waiting for mount name=%pd\n", path->dentry);
+		status = autofs_wait(sbi, path, NFY_MOUNT);
+		pr_debug("mount wait done status=%d\n", status);
+		ino->last_used = jiffies;
+		return status;
+	}
+	if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
+		ino->last_used = jiffies;
+	return status;
+}
+
+static int do_expire_wait(const struct path *path, bool rcu_walk)
+{
+	struct dentry *dentry = path->dentry;
+	struct dentry *expiring;
+
+	expiring = autofs_lookup_expiring(dentry, rcu_walk);
+	if (IS_ERR(expiring))
+		return PTR_ERR(expiring);
+	if (!expiring)
+		return autofs_expire_wait(path, rcu_walk);
+	else {
+		const struct path this = { .mnt = path->mnt, .dentry = expiring };
+		/*
+		 * If we are racing with expire the request might not
+		 * be quite complete, but the directory has been removed
+		 * so it must have been successful, just wait for it.
+		 */
+		autofs_expire_wait(&this, 0);
+		autofs_del_expiring(expiring);
+		dput(expiring);
+	}
+	return 0;
+}
+
+static struct dentry *autofs_mountpoint_changed(struct path *path)
+{
+	struct dentry *dentry = path->dentry;
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+
+	/* If this is an indirect mount the dentry could have gone away
+	 * and a new one created.
+	 *
+	 * This is unusual and I can't remember the case for which it
+	 * was originally added now. But an example of how this can
+	 * happen is an autofs indirect mount that has the "browse"
+	 * option set and also has the "symlink" option in the autofs
+	 * map entry. In this case the daemon will remove the browse
+	 * directory and create a symlink as the mount leaving the
+	 * struct path stale.
+	 *
+	 * Another not so obvious case is when a mount in an autofs
+	 * indirect mount that uses the "nobrowse" option is being
+	 * expired at the same time as a path walk. If the mount has
+	 * been umounted but the mount point directory seen before
+	 * becoming unhashed (during a lockless path walk) when a stat
+	 * family system call is made the mount won't be re-mounted as
+	 * it should. In this case the mount point that's been removed
+	 * (by the daemon) will be stale and the a new mount point
+	 * dentry created.
+	 */
+	if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
+		struct dentry *parent = dentry->d_parent;
+		struct autofs_info *ino;
+		struct dentry *new;
+
+		new = d_lookup(parent, &dentry->d_name);
+		if (!new)
+			return NULL;
+		ino = autofs_dentry_ino(new);
+		ino->last_used = jiffies;
+		dput(path->dentry);
+		path->dentry = new;
+	}
+	return path->dentry;
+}
+
+static struct vfsmount *autofs_d_automount(struct path *path)
+{
+	struct dentry *dentry = path->dentry;
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+	int status;
+
+	pr_debug("dentry=%p %pd\n", dentry, dentry);
+
+	/* The daemon never triggers a mount. */
+	if (autofs_oz_mode(sbi))
+		return NULL;
+
+	/* Refuse to trigger mount if current namespace is not the owner
+	 * and the mount is propagation private.
+	 */
+	if (sbi->mnt_ns_id != to_ns_common(current->nsproxy->mnt_ns)->ns_id) {
+		if (vfsmount_to_propagation_flags(path->mnt) & MS_PRIVATE)
+			return ERR_PTR(-EPERM);
+	}
+
+	/*
+	 * If an expire request is pending everyone must wait.
+	 * If the expire fails we're still mounted so continue
+	 * the follow and return. A return of -EAGAIN (which only
+	 * happens with indirect mounts) means the expire completed
+	 * and the directory was removed, so just go ahead and try
+	 * the mount.
+	 */
+	status = do_expire_wait(path, 0);
+	if (status && status != -EAGAIN)
+		return NULL;
+
+	/* Callback to the daemon to perform the mount or wait */
+	spin_lock(&sbi->fs_lock);
+	if (ino->flags & AUTOFS_INF_PENDING) {
+		spin_unlock(&sbi->fs_lock);
+		status = autofs_mount_wait(path, 0);
+		if (status)
+			return ERR_PTR(status);
+		goto done;
+	}
+
+	/*
+	 * If the dentry is a symlink it's equivalent to a directory
+	 * having path_is_mountpoint() true, so there's no need to call
+	 * back to the daemon.
+	 */
+	if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
+		spin_unlock(&sbi->fs_lock);
+		goto done;
+	}
+
+	if (!path_is_mountpoint(path)) {
+		/*
+		 * It's possible that user space hasn't removed directories
+		 * after umounting a rootless multi-mount, although it
+		 * should. For v5 path_has_submounts() is sufficient to
+		 * handle this because the leaves of the directory tree under
+		 * the mount never trigger mounts themselves (they have an
+		 * autofs trigger mount mounted on them). But v4 pseudo direct
+		 * mounts do need the leaves to trigger mounts. In this case
+		 * we have no choice but to use the autofs_empty() check and
+		 * require user space behave.
+		 */
+		if (sbi->version > 4) {
+			if (path_has_submounts(path)) {
+				spin_unlock(&sbi->fs_lock);
+				goto done;
+			}
+		} else {
+			if (!autofs_empty(ino)) {
+				spin_unlock(&sbi->fs_lock);
+				goto done;
+			}
+		}
+		ino->flags |= AUTOFS_INF_PENDING;
+		spin_unlock(&sbi->fs_lock);
+		status = autofs_mount_wait(path, 0);
+		spin_lock(&sbi->fs_lock);
+		ino->flags &= ~AUTOFS_INF_PENDING;
+		if (status) {
+			spin_unlock(&sbi->fs_lock);
+			return ERR_PTR(status);
+		}
+	}
+	spin_unlock(&sbi->fs_lock);
+done:
+	/* Mount succeeded, check if we ended up with a new dentry */
+	dentry = autofs_mountpoint_changed(path);
+	if (!dentry)
+		return ERR_PTR(-ENOENT);
+
+	return NULL;
+}
+
+static int autofs_d_manage(const struct path *path, bool rcu_walk)
+{
+	struct dentry *dentry = path->dentry;
+	struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+	int status;
+
+	pr_debug("dentry=%p %pd\n", dentry, dentry);
+
+	/* The daemon never waits. */
+	if (autofs_oz_mode(sbi)) {
+		if (!path_is_mountpoint(path))
+			return -EISDIR;
+		return 0;
+	}
+
+	/* Wait for pending expires */
+	if (do_expire_wait(path, rcu_walk) == -ECHILD)
+		return -ECHILD;
+
+	/*
+	 * This dentry may be under construction so wait on mount
+	 * completion.
+	 */
+	status = autofs_mount_wait(path, rcu_walk);
+	if (status)
+		return status;
+
+	if (rcu_walk) {
+		/* We don't need fs_lock in rcu_walk mode,
+		 * just testing 'AUTOFS_INF_WANT_EXPIRE' is enough.
+		 *
+		 * We only return -EISDIR when certain this isn't
+		 * a mount-trap.
+		 */
+		struct inode *inode;
+
+		if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
+			return 0;
+		if (path_is_mountpoint(path))
+			return 0;
+		inode = d_inode_rcu(dentry);
+		if (inode && S_ISLNK(inode->i_mode))
+			return -EISDIR;
+		if (!autofs_empty(ino))
+			return -EISDIR;
+		return 0;
+	}
+
+	spin_lock(&sbi->fs_lock);
+	/*
+	 * If the dentry has been selected for expire while we slept
+	 * on the lock then it might go away. We'll deal with that in
+	 * ->d_automount() and wait on a new mount if the expire
+	 * succeeds or return here if it doesn't (since there's no
+	 * mount to follow with a rootless multi-mount).
+	 */
+	if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
+		/*
+		 * Any needed mounting has been completed and the path
+		 * updated so check if this is a rootless multi-mount so
+		 * we can avoid needless calls ->d_automount() and avoid
+		 * an incorrect ELOOP error return.
+		 */
+		if ((!path_is_mountpoint(path) && !autofs_empty(ino)) ||
+		    (d_really_is_positive(dentry) && d_is_symlink(dentry)))
+			status = -EISDIR;
+	}
+	spin_unlock(&sbi->fs_lock);
+
+	return status;
+}
+
+/* Lookups in the root directory */
+static struct dentry *autofs_lookup(struct inode *dir,
+				    struct dentry *dentry, unsigned int flags)
+{
+	struct autofs_sb_info *sbi;
+	struct autofs_info *ino;
+	struct dentry *active;
+
+	pr_debug("name = %pd\n", dentry);
+
+	/* File name too long to exist */
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+
+	sbi = autofs_sbi(dir->i_sb);
+
+	pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
+		 current->pid, task_pgrp_nr(current),
+		 sbi->flags & AUTOFS_SBI_CATATONIC,
+		 autofs_oz_mode(sbi));
+
+	active = autofs_lookup_active(dentry);
+	if (active)
+		return active;
+	else {
+		/*
+		 * A dentry that is not within the root can never trigger a
+		 * mount operation, unless the directory already exists, so we
+		 * can return fail immediately.  The daemon however does need
+		 * to create directories within the file system.
+		 */
+		if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
+			return ERR_PTR(-ENOENT);
+
+		ino = autofs_new_ino(sbi);
+		if (!ino)
+			return ERR_PTR(-ENOMEM);
+
+		spin_lock(&sbi->lookup_lock);
+		spin_lock(&dentry->d_lock);
+		/* Mark entries in the root as mount triggers */
+		if (IS_ROOT(dentry->d_parent) &&
+		    autofs_type_indirect(sbi->type))
+			__managed_dentry_set_managed(dentry);
+		dentry->d_fsdata = ino;
+		ino->dentry = dentry;
+
+		list_add(&ino->active, &sbi->active_list);
+		spin_unlock(&sbi->lookup_lock);
+		spin_unlock(&dentry->d_lock);
+	}
+	return NULL;
+}
+
+static int autofs_dir_permission(struct mnt_idmap *idmap,
+				 struct inode *inode, int mask)
+{
+	if (mask & MAY_WRITE) {
+		struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
+
+		if (!autofs_oz_mode(sbi))
+			return -EACCES;
+
+		/* autofs_oz_mode() needs to allow path walks when the
+		 * autofs mount is catatonic but the state of an autofs
+		 * file system needs to be preserved over restarts.
+		 */
+		if (sbi->flags & AUTOFS_SBI_CATATONIC)
+			return -EACCES;
+	}
+
+	return generic_permission(idmap, inode, mask);
+}
+
+static int autofs_dir_symlink(struct mnt_idmap *idmap,
+			      struct inode *dir, struct dentry *dentry,
+			      const char *symname)
+{
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+	struct autofs_info *p_ino;
+	struct inode *inode;
+	char *cp;
+
+	pr_debug("%s <- %pd\n", symname, dentry);
+
+	BUG_ON(!ino);
+
+	autofs_clean_ino(ino);
+
+	autofs_del_active(dentry);
+
+	cp = kstrdup(symname, GFP_KERNEL);
+	if (!cp)
+		return -ENOMEM;
+
+	inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555);
+	if (!inode) {
+		kfree(cp);
+		return -ENOMEM;
+	}
+	inode->i_private = cp;
+	inode->i_size = strlen(cp);
+
+	d_make_persistent(dentry, inode);
+	p_ino = autofs_dentry_ino(dentry->d_parent);
+	p_ino->count++;
+
+	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+
+	return 0;
+}
+
+/*
+ * NOTE!
+ *
+ * Normal filesystems would do a "d_delete()" to tell the VFS dcache
+ * that the file no longer exists. However, doing that means that the
+ * VFS layer can turn the dentry into a negative dentry.  We don't want
+ * this, because the unlink is probably the result of an expire.
+ * We simply d_drop it and add it to a expiring list in the super block,
+ * which allows the dentry lookup to check for an incomplete expire.
+ *
+ * If a process is blocked on the dentry waiting for the expire to finish,
+ * it will invalidate the dentry and try to mount with a new one.
+ *
+ * Also see autofs_dir_rmdir()..
+ */
+static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
+	struct autofs_info *p_ino;
+
+	p_ino = autofs_dentry_ino(dentry->d_parent);
+	p_ino->count--;
+	d_make_discardable(dentry);
+
+	d_inode(dentry)->i_size = 0;
+	clear_nlink(d_inode(dentry));
+
+	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+
+	spin_lock(&sbi->lookup_lock);
+	__autofs_add_expiring(dentry);
+	d_drop(dentry);
+	spin_unlock(&sbi->lookup_lock);
+
+	return 0;
+}
+
+/*
+ * Version 4 of autofs provides a pseudo direct mount implementation
+ * that relies on directories at the leaves of a directory tree under
+ * an indirect mount to trigger mounts. To allow for this we need to
+ * set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
+ * of the directory tree. There is no need to clear the automount flag
+ * following a mount or restore it after an expire because these mounts
+ * are always covered. However, it is necessary to ensure that these
+ * flags are clear on non-empty directories to avoid unnecessary calls
+ * during path walks.
+ */
+static void autofs_set_leaf_automount_flags(struct dentry *dentry)
+{
+	struct dentry *parent;
+
+	/* root and dentrys in the root are already handled */
+	if (IS_ROOT(dentry->d_parent))
+		return;
+
+	managed_dentry_set_managed(dentry);
+
+	parent = dentry->d_parent;
+	/* only consider parents below dentrys in the root */
+	if (IS_ROOT(parent->d_parent))
+		return;
+	managed_dentry_clear_managed(parent);
+}
+
+static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
+{
+	struct dentry *parent;
+
+	/* flags for dentrys in the root are handled elsewhere */
+	if (IS_ROOT(dentry->d_parent))
+		return;
+
+	managed_dentry_clear_managed(dentry);
+
+	parent = dentry->d_parent;
+	/* only consider parents below dentrys in the root */
+	if (IS_ROOT(parent->d_parent))
+		return;
+	if (autofs_dentry_ino(parent)->count == 2)
+		managed_dentry_set_managed(parent);
+}
+
+static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+	struct autofs_info *p_ino;
+
+	pr_debug("dentry %p, removing %pd\n", dentry, dentry);
+
+	if (ino->count != 1)
+		return -ENOTEMPTY;
+
+	spin_lock(&sbi->lookup_lock);
+	__autofs_add_expiring(dentry);
+	d_drop(dentry);
+	spin_unlock(&sbi->lookup_lock);
+
+	if (sbi->version < 5)
+		autofs_clear_leaf_automount_flags(dentry);
+
+	p_ino = autofs_dentry_ino(dentry->d_parent);
+	p_ino->count--;
+	d_make_discardable(dentry);
+	d_inode(dentry)->i_size = 0;
+	clear_nlink(d_inode(dentry));
+
+	if (dir->i_nlink)
+		drop_nlink(dir);
+
+	return 0;
+}
+
+static struct dentry *autofs_dir_mkdir(struct mnt_idmap *idmap,
+				       struct inode *dir, struct dentry *dentry,
+				       umode_t mode)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
+	struct autofs_info *ino = autofs_dentry_ino(dentry);
+	struct autofs_info *p_ino;
+	struct inode *inode;
+
+	pr_debug("dentry %p, creating %pd\n", dentry, dentry);
+
+	BUG_ON(!ino);
+
+	autofs_clean_ino(ino);
+
+	autofs_del_active(dentry);
+
+	inode = autofs_get_inode(dir->i_sb, mode);
+	if (!inode)
+		return ERR_PTR(-ENOMEM);
+
+	if (sbi->version < 5)
+		autofs_set_leaf_automount_flags(dentry);
+
+	d_make_persistent(dentry, inode);
+	p_ino = autofs_dentry_ino(dentry->d_parent);
+	p_ino->count++;
+	inc_nlink(dir);
+	inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
+
+	return NULL;
+}
+
+/* Get/set timeout ioctl() operation */
+#ifdef CONFIG_COMPAT
+static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
+						 compat_ulong_t __user *p)
+{
+	unsigned long ntimeout;
+	int rv;
+
+	rv = get_user(ntimeout, p);
+	if (rv)
+		goto error;
+
+	rv = put_user(sbi->exp_timeout/HZ, p);
+	if (rv)
+		goto error;
+
+	if (ntimeout > UINT_MAX/HZ)
+		sbi->exp_timeout = 0;
+	else
+		sbi->exp_timeout = ntimeout * HZ;
+
+	return 0;
+error:
+	return rv;
+}
+#endif
+
+static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
+					  unsigned long __user *p)
+{
+	unsigned long ntimeout;
+	int rv;
+
+	rv = get_user(ntimeout, p);
+	if (rv)
+		goto error;
+
+	rv = put_user(sbi->exp_timeout/HZ, p);
+	if (rv)
+		goto error;
+
+	if (ntimeout > ULONG_MAX/HZ)
+		sbi->exp_timeout = 0;
+	else
+		sbi->exp_timeout = ntimeout * HZ;
+
+	return 0;
+error:
+	return rv;
+}
+
+/* Return protocol version */
+static inline int autofs_get_protover(struct autofs_sb_info *sbi,
+				       int __user *p)
+{
+	return put_user(sbi->version, p);
+}
+
+/* Return protocol sub version */
+static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
+					  int __user *p)
+{
+	return put_user(sbi->sub_version, p);
+}
+
+/*
+* Tells the daemon whether it can umount the autofs mount.
+*/
+static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
+{
+	int status = 0;
+
+	if (may_umount(mnt))
+		status = 1;
+
+	pr_debug("may umount %d\n", status);
+
+	status = put_user(status, p);
+
+	return status;
+}
+
+/* Identify autofs_dentries - this is so we can tell if there's
+ * an extra dentry refcount or not.  We only hold a refcount on the
+ * dentry if its non-negative (ie, d_inode != NULL)
+ */
+int is_autofs_dentry(struct dentry *dentry)
+{
+	return dentry && d_really_is_positive(dentry) &&
+		dentry->d_op == &autofs_dentry_operations &&
+		dentry->d_fsdata != NULL;
+}
+
+/*
+ * ioctl()'s on the root directory is the chief method for the daemon to
+ * generate kernel reactions
+ */
+static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
+				       unsigned int cmd, unsigned long arg)
+{
+	struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
+	void __user *p = (void __user *)arg;
+
+	pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
+		 cmd, arg, sbi, task_pgrp_nr(current));
+
+	if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
+	     _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
+		return -ENOTTY;
+
+	if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	switch (cmd) {
+	case AUTOFS_IOC_READY:	/* Wait queue: go ahead and retry */
+		return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
+	case AUTOFS_IOC_FAIL:	/* Wait queue: fail with ENOENT */
+		return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
+	case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
+		autofs_catatonic_mode(sbi);
+		return 0;
+	case AUTOFS_IOC_PROTOVER: /* Get protocol version */
+		return autofs_get_protover(sbi, p);
+	case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
+		return autofs_get_protosubver(sbi, p);
+	case AUTOFS_IOC_SETTIMEOUT:
+		return autofs_get_set_timeout(sbi, p);
+#ifdef CONFIG_COMPAT
+	case AUTOFS_IOC_SETTIMEOUT32:
+		return autofs_compat_get_set_timeout(sbi, p);
+#endif
+
+	case AUTOFS_IOC_ASKUMOUNT:
+		return autofs_ask_umount(filp->f_path.mnt, p);
+
+	/* return a single thing to expire */
+	case AUTOFS_IOC_EXPIRE:
+		return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
+	/* same as above, but can send multiple expires through pipe */
+	case AUTOFS_IOC_EXPIRE_MULTI:
+		return autofs_expire_multi(inode->i_sb,
+					   filp->f_path.mnt, sbi, p);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static long autofs_root_ioctl(struct file *filp,
+			       unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+
+	return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
+}
+
+#ifdef CONFIG_COMPAT
+static long autofs_root_compat_ioctl(struct file *filp,
+				      unsigned int cmd, unsigned long arg)
+{
+	struct inode *inode = file_inode(filp);
+	int ret;
+
+	if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
+		ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
+	else
+		ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
+					      (unsigned long) compat_ptr(arg));
+
+	return ret;
+}
+#endif