diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index 0b9cf5cf24c9..d92bdf3b079a 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -50,6 +50,84 @@ static const struct file_operations tracefs_file_operations = {
.llseek = noop_llseek,
};
+static struct tracefs_dir_ops {
+ int (*mkdir)(const char *name);
+ int (*rmdir)(const char *name);
+} tracefs_ops;
+
+static char *get_dname(struct dentry *dentry)
+{
+ const char *dname;
+ char *name;
+ int len = dentry->d_name.len;
+
+ dname = dentry->d_name.name;
+ name = kmalloc(len + 1, GFP_KERNEL);
+ if (!name)
+ return NULL;
+ memcpy(name, dname, len);
+ name[len] = 0;
+ return name;
+}
+
+static int tracefs_syscall_mkdir(struct inode *inode, struct dentry *dentry, umode_t mode)
+{
+ char *name;
+ int ret;
+
+ name = get_dname(dentry);
+ if (!name)
+ return -ENOMEM;
+
+ /*
+ * The mkdir call can call the generic functions that create
+ * the files within the tracefs system. It is up to the individual
+ * mkdir routine to handle races.
+ */
+ mutex_unlock(&inode->i_mutex);
+ ret = tracefs_ops.mkdir(name);
+ mutex_lock(&inode->i_mutex);
+
+ kfree(name);
+
+ return ret;
+}
+
+static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry)
+{
+ char *name;
+ int ret;
+
+ name = get_dname(dentry);
+ if (!name)
+ return -ENOMEM;
+
+ /*
+ * The rmdir call can call the generic functions that create
+ * the files within the tracefs system. It is up to the individual
+ * rmdir routine to handle races.
+ * This time we need to unlock not only the parent (inode) but
+ * also the directory that is being deleted.
+ */
+ mutex_unlock(&inode->i_mutex);
+ mutex_unlock(&dentry->d_inode->i_mutex);
+
+ ret = tracefs_ops.rmdir(name);
+
+ mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock(&dentry->d_inode->i_mutex);
+
+ kfree(name);
+
+ return ret;
+}
+
+static const struct inode_operations tracefs_dir_inode_operations = {
+ .lookup = simple_lookup,
+ .mkdir = tracefs_syscall_mkdir,
+ .rmdir = tracefs_syscall_rmdir,
+};
+
static struct inode *tracefs_get_inode(struct super_block *sb)
{
struct inode *inode = new_inode(sb);
@@ -334,6 +412,31 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
return end_creating(dentry);
}
+static struct dentry *__create_dir(const char *name, struct dentry *parent,
+ const struct inode_operations *ops)
+{
+ struct dentry *dentry = start_creating(name, parent);
+ struct inode *inode;
+
+ if (IS_ERR(dentry))
+ return NULL;
+
+ inode = tracefs_get_inode(dentry->d_sb);
+ if (unlikely(!inode))
+ return failed_creating(dentry);
+
+ inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
+ inode->i_op = ops;
+ inode->i_fop = &simple_dir_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);
+ return end_creating(dentry);
+}
+
/**
* tracefs_create_dir - create a directory in the tracefs filesystem
* @name: a pointer to a string containing the name of the directory to
@@ -353,26 +456,44 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
*/
struct dentry *tracefs_create_dir(const char *name, struct dentry *parent)
{
- struct dentry *dentry = start_creating(name, parent);
- struct inode *inode;
+ return __create_dir(name, parent, &simple_dir_inode_operations);
+}
- if (IS_ERR(dentry))
+/**
+ * tracefs_create_instance_dir - create the tracing instances directory
+ * @name: The name of the instances directory to create
+ * @parent: The parent directory that the instances directory will exist
+ * @mkdir: The function to call when a mkdir is performed.
+ * @rmdir: The function to call when a rmdir is performed.
+ *
+ * Only one instances directory is allowed.
+ *
+ * The instances directory is special as it allows for mkdir and rmdir to
+ * to be done by userspace. When a mkdir or rmdir is performed, the inode
+ * locks are released and the methhods passed in (@mkdir and @rmdir) are
+ * called without locks and with the name of the directory being created
+ * within the instances directory.
+ *
+ * Returns the dentry of the instances directory.
+ */
+struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
+ int (*mkdir)(const char *name),
+ int (*rmdir)(const char *name))
+{
+ struct dentry *dentry;
+
+ /* Only allow one instance of the instances directory. */
+ if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir))
return NULL;
- inode = tracefs_get_inode(dentry->d_sb);
- if (unlikely(!inode))
- return failed_creating(dentry);
+ dentry = __create_dir(name, parent, &tracefs_dir_inode_operations);
+ if (!dentry)
+ return NULL;
- inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
- inode->i_op = &simple_dir_inode_operations;
- inode->i_fop = &simple_dir_operations;
+ tracefs_ops.mkdir = mkdir;
+ tracefs_ops.rmdir = rmdir;
- /* 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);
- return end_creating(dentry);
+ return dentry;
}
static inline int tracefs_positive(struct dentry *dentry)
diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h
index 23e04ce21749..5b727a17beee 100644
--- a/include/linux/tracefs.h
+++ b/include/linux/tracefs.h
@@ -34,6 +34,10 @@ struct dentry *tracefs_create_dir(const char *name, struct dentry *parent);
void tracefs_remove(struct dentry *dentry);
void tracefs_remove_recursive(struct dentry *dentry);
+struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent,
+ int (*mkdir)(const char *name),
+ int (*rmdir)(const char *name));
+
bool tracefs_initialized(void);
#endif /* CONFIG_TRACING */
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b4aa936509d2..3c8913bac204 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6292,7 +6292,7 @@ static void free_trace_buffers(struct trace_array *tr)
#endif
}
-static int new_instance_create(const char *name)
+static int instance_mkdir(const char *name)
{
struct trace_array *tr;
int ret;
@@ -6362,7 +6362,7 @@ static int new_instance_create(const char *name)
}
-static int instance_delete(const char *name)
+static int instance_rmdir(const char *name)
{
struct trace_array *tr;
int found = 0;
@@ -6403,78 +6403,13 @@ static int instance_delete(const char *name)
return ret;
}
-static int instance_mkdir (struct inode *inode, struct dentry *dentry, umode_t mode)
-{
- struct dentry *parent;
- int ret;
-
- /* Paranoid: Make sure the parent is the "instances" directory */
- parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
- if (WARN_ON_ONCE(parent != trace_instance_dir))
- return -ENOENT;
-
- /*
- * The inode mutex is locked, but tracefs_create_dir() will also
- * take the mutex. As the instances directory can not be destroyed
- * or changed in any other way, it is safe to unlock it, and
- * let the dentry try. If two users try to make the same dir at
- * the same time, then the new_instance_create() will determine the
- * winner.
- */
- mutex_unlock(&inode->i_mutex);
-
- ret = new_instance_create(dentry->d_iname);
-
- mutex_lock(&inode->i_mutex);
-
- return ret;
-}
-
-static int instance_rmdir(struct inode *inode, struct dentry *dentry)
-{
- struct dentry *parent;
- int ret;
-
- /* Paranoid: Make sure the parent is the "instances" directory */
- parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias);
- if (WARN_ON_ONCE(parent != trace_instance_dir))
- return -ENOENT;
-
- /* The caller did a dget() on dentry */
- mutex_unlock(&dentry->d_inode->i_mutex);
-
- /*
- * The inode mutex is locked, but tracefs_create_dir() will also
- * take the mutex. As the instances directory can not be destroyed
- * or changed in any other way, it is safe to unlock it, and
- * let the dentry try. If two users try to make the same dir at
- * the same time, then the instance_delete() will determine the
- * winner.
- */
- mutex_unlock(&inode->i_mutex);
-
- ret = instance_delete(dentry->d_iname);
-
- mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
- mutex_lock(&dentry->d_inode->i_mutex);
-
- return ret;
-}
-
-static const struct inode_operations instance_dir_inode_operations = {
- .lookup = simple_lookup,
- .mkdir = instance_mkdir,
- .rmdir = instance_rmdir,
-};
-
static __init void create_trace_instances(struct dentry *d_tracer)
{
- trace_instance_dir = tracefs_create_dir("instances", d_tracer);
+ trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer,
+ instance_mkdir,
+ instance_rmdir);
if (WARN_ON(!trace_instance_dir))
return;
-
- /* Hijack the dir inode operations, to allow mkdir */
- trace_instance_dir->d_inode->i_op = &instance_dir_inode_operations;
}
static void