@@ -31,6 +31,8 @@ struct eventfs_inode {
* struct eventfs_file - hold the properties of the eventfs files and
* directories.
* @name: the name of the file or directory to create
+ * @d_parent: holds parent's dentry
+ * @dentry: once accessed holds dentry
* @list: file or directory to be added to parent directory
* @ei: list of files and directories within directory
* @fop: file_operations for file or directory
@@ -40,22 +42,328 @@ struct eventfs_inode {
*/
struct eventfs_file {
const char *name;
+ struct dentry *d_parent;
+ struct dentry *dentry;
struct list_head list;
struct eventfs_inode *ei;
const struct file_operations *fop;
const struct inode_operations *iop;
+ union {
+ struct list_head del_list; /* list of eventfs_file to delete */
+ struct rcu_head rcu; /* eventfs_file to delete */
+ unsigned long is_freed; /* Freed if one of the above is set */
+ };
void *data;
umode_t mode;
};
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 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,
+ .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 is the basic "create a file" function for tracefs. It allows for a
+ * wide range of flexibility in creating a file.
+ *
+ * This function will return a pointer to a dentry if it succeeds. This
+ * pointer must be passed to the tracefs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.) If an error occurs, %NULL will be returned.
+ *
+ * If tracefs is not enabled in the kernel, the value -%ENODEV will be
+ * returned.
+ */
+static struct dentry *create_file(const char *name, umode_t mode,
+ struct dentry *parent, void *data,
+ const struct file_operations *fop)
+{
+ return NULL;
};
+/**
+ * create_dir - create a dir in the tracefs filesystem
+ * @name: the name of the file to create.
+ * @parent: parent dentry for this file.
+ * @data: something that the caller will want to get to later on.
+ *
+ * This is the basic "create a dir" function for eventfs. It allows for a
+ * wide range of flexibility in creating a dir.
+ *
+ * This function will return a pointer to a dentry if it succeeds. This
+ * pointer must be passed to the tracefs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.) If an error occurs, %NULL will be returned.
+ *
+ * If tracefs is not enabled in the kernel, the value -%ENODEV will be
+ * returned.
+ */
+static struct dentry *create_dir(const char *name, struct dentry *parent, void *data)
+{
+ return NULL;
+}
+
+/**
+ * eventfs_set_ef_status_free - set the ef->status to free
+ * @dentry: dentry who's status to be freed
+ *
+ * eventfs_set_ef_status_free will be called if no more
+ * references remain
+ */
+void eventfs_set_ef_status_free(struct dentry *dentry)
+{
+ struct tracefs_inode *ti_parent;
+ struct eventfs_file *ef;
+
+ mutex_lock(&eventfs_mutex);
+ ti_parent = get_tracefs(dentry->d_parent->d_inode);
+ if (!ti_parent || !(ti_parent->flags & TRACEFS_EVENT_INODE))
+ goto out;
+
+ ef = dentry->d_fsdata;
+ if (!ef)
+ goto out;
+
+ /*
+ * If ef 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)ef & 1))
+ goto out;
+
+ dentry->d_fsdata = NULL;
+ ef->dentry = NULL;
+out:
+ mutex_unlock(&eventfs_mutex);
+}
+
+/**
+ * eventfs_post_create_dir - post create dir routine
+ * @ef: eventfs_file 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_file *ef)
+{
+ struct eventfs_file *ef_child;
+ struct tracefs_inode *ti;
+
+ /* srcu lock already held */
+ /* fill parent-child relation */
+ list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list,
+ srcu_read_lock_held(&eventfs_srcu)) {
+ ef_child->d_parent = ef->dentry;
+ }
+
+ ti = get_tracefs(ef->dentry->d_inode);
+ ti->private = ef->ei;
+}
+
+/**
+ * create_dentry - helper function to create dentry
+ * @ef: eventfs_file of file or directory to create
+ * @parent: parent dentry
+ * @lookup: true if called from lookup routine
+ *
+ * Used to create a dentry for file/dir, executes post dentry creation routine
+ */
+static struct dentry *
+create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup)
+{
+ bool invalidate = false;
+ struct dentry *dentry;
+
+ mutex_lock(&eventfs_mutex);
+ if (ef->is_freed) {
+ mutex_unlock(&eventfs_mutex);
+ return NULL;
+ }
+ if (ef->dentry) {
+ dentry = ef->dentry;
+ /* On dir open, up the ref count */
+ if (!lookup)
+ dget(dentry);
+ mutex_unlock(&eventfs_mutex);
+ return dentry;
+ }
+ mutex_unlock(&eventfs_mutex);
+
+ if (!lookup)
+ inode_lock(parent->d_inode);
+
+ if (ef->ei)
+ dentry = create_dir(ef->name, parent, ef->data);
+ else
+ dentry = create_file(ef->name, ef->mode, parent,
+ ef->data, ef->fop);
+
+ if (!lookup)
+ inode_unlock(parent->d_inode);
+
+ mutex_lock(&eventfs_mutex);
+ if (IS_ERR_OR_NULL(dentry)) {
+ /* If the ef was already updated get it */
+ dentry = ef->dentry;
+ if (dentry && !lookup)
+ dget(dentry);
+ mutex_unlock(&eventfs_mutex);
+ return dentry;
+ }
+
+ if (!ef->dentry && !ef->is_freed) {
+ ef->dentry = dentry;
+ if (ef->ei)
+ eventfs_post_create_dir(ef);
+ dentry->d_fsdata = ef;
+ } else {
+ /* A race here, should try again (unless freed) */
+ invalidate = true;
+ }
+ mutex_unlock(&eventfs_mutex);
+ if (invalidate)
+ d_invalidate(dentry);
+
+ if (lookup || invalidate)
+ dput(dentry);
+
+ return invalidate ? NULL : dentry;
+}
+
+static bool match_event_file(struct eventfs_file *ef, const char *name)
+{
+ bool ret;
+
+ mutex_lock(&eventfs_mutex);
+ ret = !ef->is_freed && strcmp(ef->name, name) == 0;
+ mutex_unlock(&eventfs_mutex);
+
+ return ret;
+}
+
+/**
+ * eventfs_root_lookup - lookup routine to create file/dir
+ * @dir: in which a lookup is being done
+ * @dentry: file/dir dentry
+ * @flags: to pass as flags parameter to simple lookup
+ *
+ * Used to create a dynamic file/dir within @dir. Use the eventfs_inode
+ * list of meta data to find the information needed to create the file/dir.
+ */
+static struct dentry *eventfs_root_lookup(struct inode *dir,
+ struct dentry *dentry,
+ unsigned int flags)
+{
+ struct tracefs_inode *ti;
+ struct eventfs_inode *ei;
+ struct eventfs_file *ef;
+ struct dentry *ret = NULL;
+ int idx;
+
+ ti = get_tracefs(dir);
+ if (!(ti->flags & TRACEFS_EVENT_INODE))
+ return NULL;
+
+ ei = ti->private;
+ idx = srcu_read_lock(&eventfs_srcu);
+ list_for_each_entry_srcu(ef, &ei->e_top_files, list,
+ srcu_read_lock_held(&eventfs_srcu)) {
+ if (!match_event_file(ef, dentry->d_name.name))
+ continue;
+ ret = simple_lookup(dir, dentry, flags);
+ create_dentry(ef, ef->d_parent, true);
+ break;
+ }
+ srcu_read_unlock(&eventfs_srcu, idx);
+ return ret;
+}
+
+/**
+ * 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 eventfs_inode *ei;
+ struct eventfs_file *ef;
+ struct dentry *dentry;
+ int idx;
+
+ ti = get_tracefs(inode);
+ if (!(ti->flags & TRACEFS_EVENT_INODE))
+ return -EINVAL;
+
+ ei = ti->private;
+ idx = srcu_read_lock(&eventfs_srcu);
+ list_for_each_entry_srcu(ef, &ei->e_top_files, list,
+ srcu_read_lock_held(&eventfs_srcu)) {
+ mutex_lock(&eventfs_mutex);
+ dentry = ef->dentry;
+ mutex_unlock(&eventfs_mutex);
+ if (dentry)
+ dput(dentry);
+ }
+ srcu_read_unlock(&eventfs_srcu, idx);
+ return dcache_dir_close(inode, file);
+}
+
+/**
+ * dcache_dir_open_wrapper - eventfs open wrapper
+ * @inode: not used
+ * @file: dir to be opened (to create its child)
+ *
+ * Used to dynamically create the file/dir within @file. @file is really a
+ * directory and all the files/dirs of the children within @file will be
+ * created. If any of the files/dirs have already been created, their
+ * reference count will be incremented.
+ */
+static int dcache_dir_open_wrapper(struct inode *inode, struct file *file)
+{
+ struct tracefs_inode *ti;
+ struct eventfs_inode *ei;
+ struct eventfs_file *ef;
+ struct dentry *dentry = file_dentry(file);
+ struct inode *f_inode = file_inode(file);
+ int idx;
+
+ ti = get_tracefs(f_inode);
+ if (!(ti->flags & TRACEFS_EVENT_INODE))
+ return -EINVAL;
+
+ ei = ti->private;
+ idx = srcu_read_lock(&eventfs_srcu);
+ list_for_each_entry_rcu(ef, &ei->e_top_files, list) {
+ create_dentry(ef, dentry, false);
+ }
+ srcu_read_unlock(&eventfs_srcu, idx);
+ return dcache_dir_open(inode, file);
+}
+
/**
* eventfs_prepare_ef - helper function to prepare eventfs_file
* @name: the name of the file/directory to create.
@@ -179,6 +487,7 @@ struct eventfs_file *eventfs_add_subsystem_dir(const char *name,
mutex_lock(&eventfs_mutex);
list_add_tail(&ef->list, &ei_parent->e_top_files);
+ ef->d_parent = parent;
mutex_unlock(&eventfs_mutex);
return ef;
}
@@ -206,6 +515,7 @@ struct eventfs_file *eventfs_add_dir(const char *name,
mutex_lock(&eventfs_mutex);
list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+ ef->d_parent = ef_parent->dentry;
mutex_unlock(&eventfs_mutex);
return ef;
}
@@ -254,6 +564,7 @@ int eventfs_add_events_file(const char *name, umode_t mode,
mutex_lock(&eventfs_mutex);
list_add_tail(&ef->list, &ei->e_top_files);
+ ef->d_parent = parent;
mutex_unlock(&eventfs_mutex);
return 0;
}
@@ -292,6 +603,7 @@ int eventfs_add_file(const char *name, umode_t mode,
mutex_lock(&eventfs_mutex);
list_add_tail(&ef->list, &ef_parent->ei->e_top_files);
+ ef->d_parent = ef_parent->dentry;
mutex_unlock(&eventfs_mutex);
return 0;
}
@@ -21,4 +21,6 @@ struct dentry *tracefs_start_creating(const char *name, struct dentry *parent);
struct dentry *tracefs_end_creating(struct dentry *dentry);
struct dentry *tracefs_failed_creating(struct dentry *dentry);
struct inode *tracefs_get_inode(struct super_block *sb);
+void eventfs_set_ef_status_free(struct dentry *dentry);
+
#endif /* _TRACEFS_INTERNAL_H */