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Diffstat (limited to 'fs/tracefs/inode.c')
-rw-r--r--fs/tracefs/inode.c151
1 files changed, 136 insertions, 15 deletions
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)