@@ -62,6 +62,35 @@ enum {
#define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1)
+/*
+ * eventfs_inode reference count management.
+ *
+ * NOTE! We count only references from dentries, in the
+ * form 'dentry->d_fsdata'. There are also references from
+ * directory inodes ('ti->private'), but the dentry reference
+ * count is always a superset of the inode reference count.
+ */
+static void release_ei(struct kref *ref)
+{
+ struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref);
+ kfree(ei->entry_attrs);
+ kfree_const(ei->name);
+ kfree_rcu(ei, rcu);
+}
+
+static inline void put_ei(struct eventfs_inode *ei)
+{
+ if (ei)
+ kref_put(&ei->kref, release_ei);
+}
+
+static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei)
+{
+ if (ei)
+ kref_get(&ei->kref);
+ return ei;
+}
+
static struct dentry *eventfs_root_lookup(struct inode *dir,
struct dentry *dentry,
unsigned int flags);
@@ -289,7 +318,8 @@ static void update_inode_attr(struct dentry *dentry, struct inode *inode,
* directory. The inode.i_private pointer will point to @data in the open()
* call.
*/
-static struct dentry *lookup_file(struct dentry *dentry,
+static struct dentry *lookup_file(struct eventfs_inode *parent_ei,
+ struct dentry *dentry,
umode_t mode,
struct eventfs_attr *attr,
void *data,
@@ -302,7 +332,7 @@ static struct dentry *lookup_file(struct dentry *dentry,
mode |= S_IFREG;
if (WARN_ON_ONCE(!S_ISREG(mode)))
- return NULL;
+ return ERR_PTR(-EIO);
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
@@ -321,9 +351,12 @@ static struct dentry *lookup_file(struct dentry *dentry,
ti = get_tracefs(inode);
ti->flags |= TRACEFS_EVENT_INODE;
+ // Files have their parent's ei as their fsdata
+ dentry->d_fsdata = get_ei(parent_ei);
+
d_add(dentry, inode);
fsnotify_create(dentry->d_parent->d_inode, dentry);
- return dentry;
+ return NULL;
};
/**
@@ -359,22 +392,29 @@ static struct dentry *lookup_dir_entry(struct dentry *dentry,
/* Only directories have ti->private set to an ei, not files */
ti->private = ei;
- dentry->d_fsdata = ei;
- ei->dentry = dentry; // Remove me!
+ dentry->d_fsdata = get_ei(ei);
inc_nlink(inode);
d_add(dentry, inode);
inc_nlink(dentry->d_parent->d_inode);
fsnotify_mkdir(dentry->d_parent->d_inode, dentry);
- return dentry;
+ return NULL;
}
-static void free_ei(struct eventfs_inode *ei)
+static inline struct eventfs_inode *alloc_ei(const char *name)
{
- kfree_const(ei->name);
- kfree(ei->d_children);
- kfree(ei->entry_attrs);
- kfree(ei);
+ struct eventfs_inode *ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+
+ if (!ei)
+ return NULL;
+
+ ei->name = kstrdup_const(name, GFP_KERNEL);
+ if (!ei->name) {
+ kfree(ei);
+ return NULL;
+ }
+ kref_init(&ei->kref);
+ return ei;
}
/**
@@ -385,39 +425,13 @@ static void free_ei(struct eventfs_inode *ei)
*/
void eventfs_d_release(struct dentry *dentry)
{
- struct eventfs_inode *ei;
- int i;
-
- mutex_lock(&eventfs_mutex);
-
- ei = dentry->d_fsdata;
- if (!ei)
- 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 if (ei->is_freed) {
- free_ei(ei);
- } else {
- ei->dentry = NULL;
- }
-
- dentry->d_fsdata = NULL;
- out:
- mutex_unlock(&eventfs_mutex);
+ put_ei(dentry->d_fsdata);
}
/**
* lookup_file_dentry - create a dentry for a file of an eventfs_inode
* @ei: the eventfs_inode that the file will be created under
- * @idx: the index into the d_children[] of the @ei
+ * @idx: the index into the entry_attrs[] 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.
@@ -434,17 +448,11 @@ lookup_file_dentry(struct dentry *dentry,
const struct file_operations *fops)
{
struct eventfs_attr *attr = NULL;
- struct dentry **e_dentry = &ei->d_children[idx];
if (ei->entry_attrs)
attr = &ei->entry_attrs[idx];
- dentry->d_fsdata = ei; // NOTE: ei of _parent_
- lookup_file(dentry, mode, attr, data, fops);
-
- *e_dentry = dentry; // Remove me
-
- return dentry;
+ return lookup_file(ei, dentry, mode, attr, data, fops);
}
/**
@@ -465,6 +473,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
struct tracefs_inode *ti;
struct eventfs_inode *ei;
const char *name = dentry->d_name.name;
+ struct dentry *result = NULL;
ti = get_tracefs(dir);
if (!(ti->flags & TRACEFS_EVENT_INODE))
@@ -481,7 +490,7 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
continue;
if (ei_child->is_freed)
goto out;
- lookup_dir_entry(dentry, ei, ei_child);
+ result = lookup_dir_entry(dentry, ei, ei_child);
goto out;
}
@@ -498,12 +507,12 @@ static struct dentry *eventfs_root_lookup(struct inode *dir,
if (entry->callback(name, &mode, &data, &fops) <= 0)
goto out;
- lookup_file_dentry(dentry, ei, i, mode, data, fops);
+ result = lookup_file_dentry(dentry, ei, i, mode, data, fops);
goto out;
}
out:
mutex_unlock(&eventfs_mutex);
- return NULL;
+ return result;
}
/*
@@ -653,25 +662,10 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
if (!parent)
return ERR_PTR(-EINVAL);
- ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+ ei = alloc_ei(name);
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 = kcalloc(size, sizeof(*ei->d_children), 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;
@@ -685,7 +679,7 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode
/* Was the parent freed? */
if (list_empty(&ei->list)) {
- free_ei(ei);
+ put_ei(ei);
ei = NULL;
}
return ei;
@@ -720,28 +714,20 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
if (IS_ERR(dentry))
return ERR_CAST(dentry);
- ei = kzalloc(sizeof(*ei), GFP_KERNEL);
+ ei = alloc_ei(name);
if (!ei)
- goto fail_ei;
+ goto fail;
inode = tracefs_get_inode(dentry->d_sb);
if (unlikely(!inode))
goto fail;
- if (size) {
- ei->d_children = kcalloc(size, sizeof(*ei->d_children), GFP_KERNEL);
- if (!ei->d_children)
- goto fail;
- }
-
- ei->dentry = dentry;
+ // Note: we have a ref to the dentry from tracefs_start_creating()
+ ei->events_dir = dentry;
ei->entries = entries;
ei->nr_entries = size;
ei->is_events = 1;
ei->data = data;
- ei->name = kstrdup_const(name, GFP_KERNEL);
- if (!ei->name)
- goto fail;
/* Save the ownership of this directory */
uid = d_inode(dentry->d_parent)->i_uid;
@@ -772,7 +758,7 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
inode->i_op = &eventfs_root_dir_inode_operations;
inode->i_fop = &eventfs_file_operations;
- dentry->d_fsdata = ei;
+ dentry->d_fsdata = get_ei(ei);
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inc_nlink(inode);
@@ -784,72 +770,11 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry
return ei;
fail:
- kfree(ei->d_children);
- kfree(ei);
- fail_ei:
+ put_ei(ei);
tracefs_failed_creating(dentry);
return ERR_PTR(-ENOMEM);
}
-static LLIST_HEAD(free_list);
-
-static void eventfs_workfn(struct work_struct *work)
-{
- struct eventfs_inode *ei, *tmp;
- struct llist_node *llnode;
-
- llnode = llist_del_all(&free_list);
- llist_for_each_entry_safe(ei, tmp, llnode, llist) {
- /* This dput() matches the dget() from unhook_dentry() */
- for (int i = 0; i < ei->nr_entries; i++) {
- if (ei->d_children[i])
- dput(ei->d_children[i]);
- }
- /* This should only get here if it had a dentry */
- if (!WARN_ON_ONCE(!ei->dentry))
- dput(ei->dentry);
- }
-}
-
-static DECLARE_WORK(eventfs_work, eventfs_workfn);
-
-static void free_rcu_ei(struct rcu_head *head)
-{
- struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu);
-
- if (ei->dentry) {
- /* Do not free the ei until all references of dentry are gone */
- if (llist_add(&ei->llist, &free_list))
- queue_work(system_unbound_wq, &eventfs_work);
- return;
- }
-
- /* If the ei doesn't have a dentry, neither should its children */
- for (int i = 0; i < ei->nr_entries; i++) {
- WARN_ON_ONCE(ei->d_children[i]);
- }
-
- free_ei(ei);
-}
-
-static void unhook_dentry(struct dentry *dentry)
-{
- if (!dentry)
- return;
- /*
- * Need to add a reference to the dentry that is expected by
- * simple_recursive_removal(), which will include a dput().
- */
- dget(dentry);
-
- /*
- * Also add a reference for the dput() in eventfs_workfn().
- * That is required as that dput() will free the ei after
- * the SRCU grace period is over.
- */
- dget(dentry);
-}
-
/**
* eventfs_remove_rec - remove eventfs dir or file from list
* @ei: eventfs_inode to be removed.
@@ -862,8 +787,6 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
{
struct eventfs_inode *ei_child;
- if (!ei)
- return;
/*
* Check recursion depth. It should never be greater than 3:
* 0 - events/
@@ -875,28 +798,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
return;
/* search for nested folders or files */
- list_for_each_entry_srcu(ei_child, &ei->children, list,
- lockdep_is_held(&eventfs_mutex)) {
- /* Children only have dentry if parent does */
- WARN_ON_ONCE(ei_child->dentry && !ei->dentry);
+ list_for_each_entry(ei_child, &ei->children, list)
eventfs_remove_rec(ei_child, level + 1);
- }
-
ei->is_freed = 1;
-
- for (int i = 0; i < ei->nr_entries; i++) {
- if (ei->d_children[i]) {
- /* Children only have dentry if parent does */
- WARN_ON_ONCE(!ei->dentry);
- unhook_dentry(ei->d_children[i]);
- }
- }
-
- unhook_dentry(ei->dentry);
-
- list_del_rcu(&ei->list);
- call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei);
+ list_del(&ei->list);
+ put_ei(ei);
}
/**
@@ -907,22 +814,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level)
*/
void eventfs_remove_dir(struct eventfs_inode *ei)
{
- struct dentry *dentry;
-
if (!ei)
return;
mutex_lock(&eventfs_mutex);
- dentry = ei->dentry;
eventfs_remove_rec(ei, 0);
mutex_unlock(&eventfs_mutex);
-
- /*
- * If any of the ei children has a dentry, then the ei itself
- * must have a dentry.
- */
- if (dentry)
- simple_recursive_removal(dentry, NULL);
}
/**
@@ -935,7 +832,11 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei)
{
struct dentry *dentry;
- dentry = ei->dentry;
+ dentry = ei->events_dir;
+ if (!dentry)
+ return;
+
+ ei->events_dir = NULL;
eventfs_remove_dir(ei);
/*
@@ -945,5 +846,6 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei)
* sticks around while the other ei->dentry are created
* and destroyed dynamically.
*/
+ d_invalidate(dentry);
dput(dentry);
}
@@ -35,8 +35,7 @@ struct eventfs_attr {
* @entries: the array of entries representing the files in the directory
* @name: the name of the directory to create
* @children: link list into the child eventfs_inode
- * @dentry: the dentry of the directory
- * @d_children: The array of dentries to represent the files when created
+ * @events_dir: the dentry of the events directory
* @entry_attrs: Saved mode and ownership of the @d_children
* @attr: Saved mode and ownership of eventfs_inode itself
* @data: The private data to pass to the callbacks
@@ -45,12 +44,12 @@ struct eventfs_attr {
* @nr_entries: The number of items in @entries
*/
struct eventfs_inode {
+ struct kref kref;
struct list_head list;
const struct eventfs_entry *entries;
const char *name;
struct list_head children;
- struct dentry *dentry; /* Check is_freed to access */
- struct dentry **d_children;
+ struct dentry *events_dir;
struct eventfs_attr *entry_attrs;
struct eventfs_attr attr;
void *data;