sysfs, kernfs: add kernfs_ops->seq_{start|next|stop}()
kernfs_ops currently only supports single_open() behavior which is
pretty restrictive. Add optional callbacks ->seq_{start|next|stop}()
which, when implemented, are invoked for seq_file traversal. This
allows full seq_file functionality for kernfs users. This currently
doesn't have any user and doesn't change any behavior.
v2: Refreshed on top of the updated "sysfs, kernfs: prepare read path
for kernfs".
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 9852450..74e3478 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -146,6 +146,7 @@
static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
{
struct sysfs_open_file *of = sf->private;
+ const struct kernfs_ops *ops;
/*
* @of->mutex nests outside active ref and is just to ensure that
@@ -155,26 +156,42 @@
if (!sysfs_get_active(of->sd))
return ERR_PTR(-ENODEV);
- /*
- * The same behavior and code as single_open(). Returns !NULL if
- * pos is at the beginning; otherwise, NULL.
- */
- return NULL + !*ppos;
+ ops = kernfs_ops(of->sd);
+ if (ops->seq_start) {
+ return ops->seq_start(sf, ppos);
+ } else {
+ /*
+ * The same behavior and code as single_open(). Returns
+ * !NULL if pos is at the beginning; otherwise, NULL.
+ */
+ return NULL + !*ppos;
+ }
}
static void *kernfs_seq_next(struct seq_file *sf, void *v, loff_t *ppos)
{
- /*
- * The same behavior and code as single_open(), always terminate
- * after the initial read.
- */
- ++*ppos;
- return NULL;
+ struct sysfs_open_file *of = sf->private;
+ const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+ if (ops->seq_next) {
+ return ops->seq_next(sf, v, ppos);
+ } else {
+ /*
+ * The same behavior and code as single_open(), always
+ * terminate after the initial read.
+ */
+ ++*ppos;
+ return NULL;
+ }
}
static void kernfs_seq_stop(struct seq_file *sf, void *v)
{
struct sysfs_open_file *of = sf->private;
+ const struct kernfs_ops *ops = kernfs_ops(of->sd);
+
+ if (ops->seq_stop)
+ ops->seq_stop(sf, v);
sysfs_put_active(of->sd);
mutex_unlock(&of->mutex);