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|
// SPDX-License-Identifier: GPL-2.0-only
/*
* event_inode.c - part of tracefs, a pseudo file system for activating tracing
*
* Copyright (C) 2020-23 VMware Inc, author: Steven Rostedt <rostedt@goodmis.org>
* Copyright (C) 2020-23 VMware Inc, author: Ajay Kaher <akaher@vmware.com>
* Copyright (C) 2023 Google, author: Steven Rostedt <rostedt@goodmis.org>
*
* eventfs is used to dynamically create inodes and dentries based on the
* meta data provided by the tracing system.
*
* eventfs stores the meta-data of files/dirs and holds off on creating
* inodes/dentries of the files. When accessed, the eventfs will create the
* inodes/dentries in a just-in-time (JIT) manner. The eventfs will clean up
* and delete the inodes/dentries when they are no longer referenced.
*/
#include <linux/fsnotify.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/tracefs.h>
#include <linux/kref.h>
#include <linux/delay.h>
#include "internal.h"
static DEFINE_MUTEX(eventfs_mutex);
DEFINE_STATIC_SRCU(eventfs_srcu);
static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
static int dcache_dir_open_wrapper(struct inode *inode, struct file *file);
static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx);
static int eventfs_release(struct inode *inode, struct file *file);
static const struct inode_operations eventfs_root_dir_inode_operations = {
.lookup = eventfs_root_lookup,
};
static const struct file_operations eventfs_file_operations = {
.open = dcache_dir_open_wrapper,
.read = generic_read_dir,
.iterate_shared = dcache_readdir_wrapper,
.llseek = generic_file_llseek,
.release = eventfs_release,
};
/**
* create_file - create a file in the tracefs filesystem
* @name: the name of the file to create.
* @mode: the permission that the file should have.
* @parent: parent dentry for this file.
* @data: something that the caller will want to get to later on.
* @fop: struct file_operations that should be used for this file.
*
* This function creates a dentry that represents a file in the eventsfs_inode
* directory. The inode.i_private pointer will point to @data in the open()
* call.
*/
static struct dentry *create_file(const char *name, umode_t mode,
struct dentry *parent, void *data,
const struct file_operations *fop)
{
struct tracefs_inode *ti;
struct dentry *dentry;
struct inode *inode;
if (!(mode & S_IFMT))
mode |= S_IFREG;
if (WARN_ON_ONCE(!S_ISREG(mode)))
return NULL;
WARN_ON_ONCE(!parent);
dentry = eventfs_start_creating(name, parent);
if (IS_ERR(dentry))
return dentry;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return eventfs_failed_creating(dentry);
inode->i_mode = mode;
inode->i_fop = fop;
inode->i_private = data;
ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE;
d_instantiate(dentry, inode);
fsnotify_create(dentry->d_parent->d_inode, dentry);
return eventfs_end_creating(dentry);
};
/**
* create_dir - create a dir in the tracefs filesystem
* @name: the name of the file to create.
* @parent: parent dentry for this file.
*
* This function will create a dentry for a directory represented by
* a eventfs_inode.
*/
static struct dentry *create_dir(const char *name, struct dentry *parent)
{
struct tracefs_inode *ti;
struct dentry *dentry;
struct inode *inode;
dentry = eventfs_start_creating(name, parent);
if (IS_ERR(dentry))
return dentry;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
return eventfs_failed_creating(dentry);
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
inode->i_op = &eventfs_root_dir_inode_operations;
inode->i_fop = &eventfs_file_operations;
ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE;
inc_nlink(inode);
d_instantiate(dentry, inode);
inc_nlink(dentry->d_parent->d_inode);
fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
return eventfs_end_creating(dentry);
}
static void free_ei(struct eventfs_inode *ei)
{
kfree_const(ei->name);
kfree(ei->d_children);
kfree(ei);
}
/**
* eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode
* @ti: the tracefs_inode of the dentry
* @dentry: dentry which has the reference to remove.
*
* Remove the association between a dentry from an eventfs_inode.
*/
void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry)
{
struct tracefs_inode *ti_parent;
struct eventfs_inode *ei_child, *tmp;
struct eventfs_inode *ei;
int i;
/* The top level events directory may be freed by this */
if (unlikely(ti->flags & TRACEFS_EVENT_TOP_INODE)) {
LIST_HEAD(ef_del_list);
mutex_lock(&eventfs_mutex);
ei = ti->private;
/* Record all the top level files */
list_for_each_entry_srcu(ei_child, &ei->children, list,
lockdep_is_held(&eventfs_mutex)) {
list_add_tail(&ei_child->del_list, &ef_del_list);
}
/* Nothing should access this, but just in case! */
ti->private = NULL;
mutex_unlock(&eventfs_mutex);
/* Now safely free the top level files and their children */
list_for_each_entry_safe(ei_child, tmp, &ef_del_list, del_list) {
list_del(&ei_child->del_list);
eventfs_remove_dir(ei_child);
}
free_ei(ei);
return;
}
mutex_lock(&eventfs_mutex);
ti_parent = get_tracefs(dentry->d_parent->d_inode);
if (!ti_parent || !(ti_parent->flags & TRACEFS_EVENT_INODE))
goto out;
ei = dentry->d_fsdata;
if (!ei)
goto out;
/*
* If ei was freed, then the LSB bit is set for d_fsdata.
* But this should not happen, as it should still have a
* ref count that prevents it. Warn in case it does.
*/
if (WARN_ON_ONCE((unsigned long)ei & 1))
goto out;
/* This could belong to one of the files of the ei */
if (ei->dentry != dentry) {
for (i = 0; i < ei->nr_entries; i++) {
if (ei->d_children[i] == dentry)
break;
}
if (WARN_ON_ONCE(i == ei->nr_entries))
goto out;
ei->d_children[i] = NULL;
} else {
ei->dentry = NULL;
}
dentry->d_fsdata = NULL;
out:
mutex_unlock(&eventfs_mutex);
}
/**
* create_file_dentry - create a dentry for a file of an eventfs_inode
* @ei: the eventfs_inode that the file will be created under
* @e_dentry: a pointer to the d_children[] of the @ei
* @parent: The parent dentry of the created file.
* @name: The name of the file to create
* @mode: The mode of the file.
* @data: The data to use to set the inode of the file with on open()
* @fops: The fops of the file to be created.
* @lookup: If called by the lookup routine, in which case, dput() the created dentry.
*
* Create a dentry for a file of an eventfs_inode @ei and place it into the
* address located at @e_dentry. If the @e_dentry already has a dentry, then
* just do a dget() on it and return. Otherwise create the dentry and attach it.
*/
static struct dentry *
create_file_dentry(struct eventfs_inode *ei, struct dentry **e_dentry,
struct dentry *parent, const char *name, umode_t mode, void *data,
const struct file_operations *fops, bool lookup)
{
struct dentry *dentry;
bool invalidate = false;
mutex_lock(&eventfs_mutex);
/* If the e_dentry already has a dentry, use it */
if (*e_dentry) {
/* lookup does not need to up the ref count */
if (!lookup)
dget(*e_dentry);
mutex_unlock(&eventfs_mutex);
return *e_dentry;
}
mutex_unlock(&eventfs_mutex);
/* The lookup already has the parent->d_inode locked */
if (!lookup)
inode_lock(parent->d_inode);
dentry = create_file(name, mode, parent, data, fops);
if (!lookup)
inode_unlock(parent->d_inode);
mutex_lock(&eventfs_mutex);
if (IS_ERR_OR_NULL(dentry)) {
/*
* When the mutex was released, something else could have
* created the dentry for this e_dentry. In which case
* use that one.
*
* Note, with the mutex held, the e_dentry cannot have content
* and the ei->is_freed be true at the same time.
*/
dentry = *e_dentry;
if (WARN_ON_ONCE(dentry && ei->is_freed))
dentry = NULL;
/* The lookup does not need to up the dentry refcount */
if (dentry && !lookup)
dget(dentry);
mutex_unlock(&eventfs_mutex);
return dentry;
}
if (!*e_dentry && !ei->is_freed) {
*e_dentry = dentry;
dentry->d_fsdata = ei;
} else {
/*
* Should never happen unless we get here due to being freed.
* Otherwise it means two dentries exist with the same name.
*/
WARN_ON_ONCE(!ei->is_freed);
invalidate = true;
}
mutex_unlock(&eventfs_mutex);
if (invalidate)
d_invalidate(dentry);
if (lookup || invalidate)
dput(dentry);
return invalidate ? NULL : dentry;
}
/**
* eventfs_post_create_dir - post create dir routine
* @ei: eventfs_inode of recently created dir
*
* Map the meta-data of files within an eventfs dir to their parent dentry
*/
static void eventfs_post_create_dir(struct eventfs_inode *ei)
{
struct eventfs_inode *ei_child;
struct tracefs_inode *ti;
/* srcu lock already held */
/* fill parent-child relation */
list_for_each_entry_srcu(ei_child, &ei->children, list,
srcu_read_lock_held(&eventfs_srcu)) {
ei_child->d_parent = ei->dentry;
}
ti = get_tracefs(ei->dentry->d_inode);
ti->private = ei;
}
/**
* create_dir_dentry - Create a directory dentry for the eventfs_inode
* @ei: The eventfs_inode to create the directory for
* @parent: The dentry of the parent of this directory
* @lookup: True if this is called by the lookup code
*
* This creates and attaches a directory dentry to the eventfs_inode @ei.
*/
static struct dentry *
create_dir_dentry(struct eventfs_inode *ei, struct dentry *parent, bool lookup)
{
bool invalidate = false;
struct dentry *dentry = NULL;
mutex_lock(&eventfs_mutex);
if (ei->dentry) {
/* If the dentry already has a dentry, use it */
dentry = ei->dentry;
/* lookup does not need to up the ref count */
if (!lookup)
dget(dentry);
mutex_unlock(&eventfs_mutex);
return dentry;
}
mutex_unlock(&eventfs_mutex);
/* The lookup already has the parent->d_inode locked */
if (!lookup)
inode_lock(parent->d_inode);
dentry = create_dir(ei->name, parent);
if (!lookup)
inode_unlock(parent->d_inode);
mutex_lock(&eventfs_mutex);
if (IS_ERR_OR_NULL(dentry) && !ei->is_freed) {
/*
* When the mutex was released, something else could have
* created the dentry for this e_dentry. In which case
* use that one.
*
* Note, with the mutex held, the e_dentry cannot have content
* and the ei->is_freed be true at the same time.
*/
dentry = ei->dentry;
if (dentry && !lookup)
dget(dentry);
mutex_unlock(&eventfs_mutex);
return dentry;
}
if (!ei->dentry && !ei->is_freed) {
ei->dentry = dentry;
eventfs_post_create_dir(ei);
dentry->d_fsdata = ei;
} else {
/*
* Should never happen unless we get here due to being freed.
* Otherwise it means two dentries exist with the same name.
*/
WARN_ON_ONCE(!ei->is_freed);
invalidate = true;
}
mutex_unlock(&eventfs_mutex);
if (invalidate)
d_invalidate(dentry);
if (lookup || invalidate)
dput(dentry);
return invalidate ? NULL : dentry;
}
/**
* eventfs_root_lookup - lookup routine to create file/dir
* @dir: in which a lookup is being done
* @dentry: file/dir dentry
* @flags: Just passed to simple_lookup()
*
* Used to create dynamic file/dir with-in @dir, search with-in @ei
* list, if @dentry found go ahead and create the file/dir
*/
static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags)
{
const struct file_operations *fops;
const struct eventfs_entry *entry;
struct eventfs_inode *ei_child;
struct tracefs_inode *ti;
struct eventfs_inode *ei;
struct dentry *ei_dentry = NULL;
struct dentry *ret = NULL;
const char *name = dentry->d_name.name;
bool created = false;
umode_t mode;
void *data;
int idx;
int i;
int r;
ti = get_tracefs(dir);
if (!(ti->flags & TRACEFS_EVENT_INODE))
return NULL;
/* Grab srcu to prevent the ei from going away */
idx = srcu_read_lock(&eventfs_srcu);
/*
* Grab the eventfs_mutex to consistent value from ti->private.
* This s
*/
mutex_lock(&eventfs_mutex);
ei = READ_ONCE(ti->private);
if (ei)
ei_dentry = READ_ONCE(ei->dentry);
mutex_unlock(&eventfs_mutex);
if (!ei || !ei_dentry)
goto out;
data = ei->data;
list_for_each_entry_srcu(ei_child, &ei->children, list,
srcu_read_lock_held(&eventfs_srcu)) {
if (strcmp(ei_child->name, name) != 0)
continue;
ret = simple_lookup(dir, dentry, flags);
create_dir_dentry(ei_child, ei_dentry, true);
created = true;
break;
}
if (created)
goto out;
for (i = 0; i < ei->nr_entries; i++) {
entry = &ei->entries[i];
if (strcmp(name, entry->name) == 0) {
void *cdata = data;
r = entry->callback(name, &mode, &cdata, &fops);
if (r <= 0)
continue;
ret = simple_lookup(dir, dentry, flags);
create_file_dentry(ei, &ei->d_children[i],
ei_dentry, name, mode, cdata,
fops, true);
break;
}
}
out:
srcu_read_unlock(&eventfs_srcu, idx);
return ret;
}
struct dentry_list {
void *cursor;
struct dentry **dentries;
};
/**
* eventfs_release - called to release eventfs file/dir
* @inode: inode to be released
* @file: file to be released (not used)
*/
static int eventfs_release(struct inode *inode, struct file *file)
{
struct tracefs_inode *ti;
struct dentry_list *dlist = file->private_data;
void *cursor;
int i;
ti = get_tracefs(inode);
if (!(ti->flags & TRACEFS_EVENT_INODE))
return -EINVAL;
if (WARN_ON_ONCE(!dlist))
return -EINVAL;
for (i = 0; dlist->dentries && dlist->dentries[i]; i++) {
dput(dlist->dentries[i]);
}
cursor = dlist->cursor;
kfree(dlist->dentries);
kfree(dlist);
file->private_data = cursor;
return dcache_dir_close(inode, file);
}
static int add_dentries(struct dentry ***dentries, struct dentry *d, int cnt)
{
struct dentry **tmp;
tmp = krealloc(*dentries, sizeof(d) * (cnt + 2), GFP_KERNEL);
if (!tmp)
return -1;
tmp[cnt] = d;
tmp[cnt + 1] = NULL;
*dentries = tmp;
return 0;
}
/**
* dcache_dir_open_wrapper - eventfs open wrapper
* @inode: not used
* @file: dir to be opened (to create it's children)
*
* Used to dynamic create file/dir with-in @file, all the
* file/dir will be created. If already created then references
* will be increased
*/
static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
{
const struct file_operations *fops;
const struct eventfs_entry *entry;
struct eventfs_inode *ei_child;
struct tracefs_inode *ti;
struct eventfs_inode *ei;
struct dentry_list *dlist;
struct dentry **dentries = NULL;
struct dentry *parent = file_dentry(file);
struct dentry *d;
struct inode *f_inode = file_inode(file);
const char *name = parent->d_name.name;
umode_t mode;
void *data;
int cnt = 0;
int idx;
int ret;
int i;
int r;
ti = get_tracefs(f_inode);
if (!(ti->flags & TRACEFS_EVENT_INODE))
return -EINVAL;
if (WARN_ON_ONCE(file->private_data))
return -EINVAL;
idx = srcu_read_lock(&eventfs_srcu);
mutex_lock(&eventfs_mutex);
ei = READ_ONCE(ti->private);
mutex_unlock(&eventfs_mutex);
if (!ei) {
srcu_read_unlock(&eventfs_srcu, idx);
return -EINVAL;
}
data = ei->data;
dlist = kmalloc(sizeof(*dlist), GFP_KERNEL);
if (!dlist) {
srcu_read_unlock(&eventfs_srcu, idx);
return -ENOMEM;
}
list_for_each_entry_srcu(ei_child, &ei->children, list,
srcu_read_lock_held(&eventfs_srcu)) {
d = create_dir_dentry(ei_child, parent, false);
if (d) {
ret = add_dentries(&dentries, d, cnt);
if (ret < 0)
break;
cnt++;
}
}
for (i = 0; i < ei->nr_entries; i++) {
void *cdata = data;
entry = &ei->entries[i];
name = entry->name;
r = entry->callback(name, &mode, &cdata, &fops);
if (r <= 0)
continue;
d = create_file_dentry(ei, &ei->d_children[i],
parent, name, mode, cdata, fops, false);
if (d) {
ret = add_dentries(&dentries, d, cnt);
if (ret < 0)
break;
cnt++;
}
}
srcu_read_unlock(&eventfs_srcu, idx);
ret = dcache_dir_open(inode, file);
/*
* dcache_dir_open() sets file->private_data to a dentry cursor.
* Need to save that but also save all the dentries that were
* opened by this function.
*/
dlist->cursor = file->private_data;
dlist->dentries = dentries;
file->private_data = dlist;
return ret;
}
/*
* This just sets the file->private_data back to the cursor and back.
*/
static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx)
{
struct dentry_list *dlist = file->private_data;
int ret;
file->private_data = dlist->cursor;
ret = dcache_readdir(file, ctx);
dlist->cursor = file->private_data;
file->private_data = dlist;
return ret;
}
/**
* eventfs_create_dir - Create the eventfs_inode for this directory
* @name: The name of the directory to create.
* @parent: The eventfs_inode of the parent directory.
* @entries: A list of entries that represent the files under this directory
* @size: The number of @entries
* @data: The default data to pass to the files (an entry may override it).
*
* This function creates the descriptor to represent a directory in the
* eventfs. This descriptor is an eventfs_inode, and it is returned to be
* used to create other children underneath.
*
* The @entries is an array of eventfs_entry structures which has:
* const char *name
* eventfs_callback callback;
*
* The name is the name of the file, and the callback is a pointer to a function
* that will be called when the file is reference (either by lookup or by
* reading a directory). The callback is of the prototype:
*
* int callback(const char *name, umode_t *mode, void **data,
* const struct file_operations **fops);
*
* When a file needs to be created, this callback will be called with
* name = the name of the file being created (so that the same callback
* may be used for multiple files).
* mode = a place to set the file's mode
* data = A pointer to @data, and the callback may replace it, which will
* cause the file created to pass the new data to the open() call.
* fops = the fops to use for the created file.
*/
struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent,
const struct eventfs_entry *entries,
int size, void *data)
{
struct eventfs_inode *ei;
if (!parent)
return ERR_PTR(-EINVAL);
ei = kzalloc(sizeof(*ei), GFP_KERNEL);
if (!ei)
return ERR_PTR(-ENOMEM);
ei->name = kstrdup_const(name, GFP_KERNEL);
if (!ei->name) {
kfree(ei);
return ERR_PTR(-ENOMEM);
}
if (size) {
ei->d_children = kzalloc(sizeof(*ei->d_children) * size, GFP_KERNEL);
if (!ei->d_children) {
kfree_const(ei->name);
kfree(ei);
return ERR_PTR(-ENOMEM);
}
}
ei->entries = entries;
ei->nr_entries = size;
ei->data = data;
INIT_LIST_HEAD(&ei->children);
mutex_lock(&eventfs_mutex);
list_add_tail(&ei->list, &parent->children);
ei->d_parent = parent->dentry;
mutex_unlock(&eventfs_mutex);
return ei;
}
/**
* eventfs_create_events_dir - create the top level events directory
* @name: The name of the top level directory to create.
* @parent: Parent dentry for this file in the tracefs directory.
* @entries: A list of entries that represent the files under this directory
* @size: The number of @entries
* @data: The default data to pass to the files (an entry may override it).
*
* This function creates the top of the trace event directory.
*/
struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent,
const struct eventfs_entry *entries,
int size, void *data)
{
struct dentry *dentry = tracefs_start_creating(name, parent);
struct eventfs_inode *ei;
struct tracefs_inode *ti;
struct inode *inode;
if (security_locked_down(LOCKDOWN_TRACEFS))
return NULL;
if (IS_ERR(dentry))
return ERR_CAST(dentry);
ei = kzalloc(sizeof(*ei), GFP_KERNEL);
if (!ei)
goto fail_ei;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
goto fail;
if (size) {
ei->d_children = kzalloc(sizeof(*ei->d_children) * size, GFP_KERNEL);
if (!ei->d_children)
goto fail;
}
ei->dentry = dentry;
ei->entries = entries;
ei->nr_entries = size;
ei->data = data;
ei->name = kstrdup_const(name, GFP_KERNEL);
if (!ei->name)
goto fail;
INIT_LIST_HEAD(&ei->children);
INIT_LIST_HEAD(&ei->list);
ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE | TRACEFS_EVENT_TOP_INODE;
ti->private = ei;
inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
inode->i_op = &eventfs_root_dir_inode_operations;
inode->i_fop = &eventfs_file_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
d_instantiate(dentry, inode);
inc_nlink(dentry->d_parent->d_inode);
fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
tracefs_end_creating(dentry);
return ei;
fail:
kfree(ei->d_children);
kfree(ei);
fail_ei:
tracefs_failed_creating(dentry);
return ERR_PTR(-ENOMEM);
}
static void free_rcu_ei(struct rcu_head *head)
{
struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu);
free_ei(ei);
}
/**
* eventfs_remove_rec - remove eventfs dir or file from list
* @ei: eventfs_inode to be removed.
* @head: the list head to place the deleted @ei and children
* @level: prevent recursion from going more than 3 levels deep.
*
* This function recursively removes eventfs_inodes which
* contains info of files and/or directories.
*/
static void eventfs_remove_rec(struct eventfs_inode *ei, struct list_head *head, int level)
{
struct eventfs_inode *ei_child;
if (!ei)
return;
/*
* Check recursion depth. It should never be greater than 3:
* 0 - events/
* 1 - events/group/
* 2 - events/group/event/
* 3 - events/group/event/file
*/
if (WARN_ON_ONCE(level > 3))
return;
/* search for nested folders or files */
list_for_each_entry_srcu(ei_child, &ei->children, list,
lockdep_is_held(&eventfs_mutex)) {
eventfs_remove_rec(ei_child, head, level + 1);
}
ei->is_freed = 1;
list_del_rcu(&ei->list);
list_add_tail(&ei->del_list, head);
}
static void unhook_dentry(struct dentry **dentry, struct dentry **list)
{
if (*dentry) {
unsigned long ptr = (unsigned long)*list;
/* Keep the dentry from being freed yet */
dget(*dentry);
/*
* Paranoid: The dget() above should prevent the dentry
* from being freed and calling eventfs_set_ei_status_free().
* But just in case, set the link list LSB pointer to 1
* and have eventfs_set_ei_status_free() check that to
* make sure that if it does happen, it will not think
* the d_fsdata is an eventfs_inode.
*
* For this to work, no eventfs_inode should be allocated
* on a odd space, as the ef should always be allocated
* to be at least word aligned. Check for that too.
*/
WARN_ON_ONCE(ptr & 1);
(*dentry)->d_fsdata = (void *)(ptr | 1);
*list = *dentry;
*dentry = NULL;
}
}
/**
* eventfs_remove_dir - remove eventfs dir or file from list
* @ei: eventfs_inode to be removed.
*
* This function acquire the eventfs_mutex lock and call eventfs_remove_rec()
*/
void eventfs_remove_dir(struct eventfs_inode *ei)
{
struct eventfs_inode *tmp;
LIST_HEAD(ei_del_list);
struct dentry *dentry_list = NULL;
struct dentry *dentry;
int i;
if (!ei)
return;
mutex_lock(&eventfs_mutex);
eventfs_remove_rec(ei, &ei_del_list, 0);
list_for_each_entry_safe(ei, tmp, &ei_del_list, del_list) {
for (i = 0; i < ei->nr_entries; i++)
unhook_dentry(&ei->d_children[i], &dentry_list);
unhook_dentry(&ei->dentry, &dentry_list);
call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
}
mutex_unlock(&eventfs_mutex);
while (dentry_list) {
unsigned long ptr;
dentry = dentry_list;
ptr = (unsigned long)dentry->d_fsdata & ~1UL;
dentry_list = (struct dentry *)ptr;
dentry->d_fsdata = NULL;
d_invalidate(dentry);
mutex_lock(&eventfs_mutex);
/* dentry should now have at least a single reference */
WARN_ONCE((int)d_count(dentry) < 1,
"dentry %px (%s) less than one reference (%d) after invalidate\n",
dentry, dentry->d_name.name, d_count(dentry));
mutex_unlock(&eventfs_mutex);
dput(dentry);
}
}
/**
* eventfs_remove_events_dir - remove the top level eventfs directory
* @ei: the event_inode returned by eventfs_create_events_dir().
*
* This function removes the events main directory
*/
void eventfs_remove_events_dir(struct eventfs_inode *ei)
{
struct dentry *dentry = ei->dentry;
eventfs_remove_dir(ei);
/* Matches the dget() from eventfs_create_events_dir() */
dput(dentry);
}
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