kernfs: add kernfs_ops->open/release() callbacks
Add ->open/release() methods to kernfs_ops. ->open() is called when
the file is opened and ->release() when the file is either released or
severed. These callbacks can be used, for example, to manage
persistent caching objects over multiple seq_file iterations.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index afd4e5a..a9b11b8 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -46,6 +46,7 @@ enum kernfs_node_flag {
KERNFS_SUICIDAL = 0x0400,
KERNFS_SUICIDED = 0x0800,
KERNFS_EMPTY_DIR = 0x1000,
+ KERNFS_HAS_RELEASE = 0x2000,
};
/* @flags for kernfs_create_root() */
@@ -175,6 +176,7 @@ struct kernfs_open_file {
/* published fields */
struct kernfs_node *kn;
struct file *file;
+ struct seq_file *seq_file;
void *priv;
/* private fields, do not use outside kernfs proper */
@@ -186,11 +188,19 @@ struct kernfs_open_file {
size_t atomic_write_len;
bool mmapped:1;
+ bool released:1;
const struct vm_operations_struct *vm_ops;
};
struct kernfs_ops {
/*
+ * Optional open/release methods. Both are called with
+ * @of->seq_file populated.
+ */
+ int (*open)(struct kernfs_open_file *of);
+ void (*release)(struct kernfs_open_file *of);
+
+ /*
* Read is handled by either seq_file or raw_read().
*
* If seq_show() is present, seq_file path is active. Other seq