[PATCH 3/4] Provide per-file private data for bin sysfs files

[Thomas Schlichter]

For binary sysfs files, provide a per-file private field in struct bin_buffer.
To be easily accessible, it is located on head of the struct. Additionally add
a release() callback that may be used to e.g. free the private data on file
release.

Signed-off-by: Thomas Schlichter <thomas.schlichter@xxxxxx>
---
 fs/sysfs/bin.c        |   10 +++++++++-
 include/linux/sysfs.h |    3 +++
 2 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 60c702b..c0575a3 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -37,6 +37,7 @@
 static DEFINE_MUTEX(sysfs_bin_lock);
 
 struct bin_buffer {
+	void				*private;
 	struct mutex			mutex;
 	void				*buffer;
 	int				mmapped;
@@ -438,14 +439,21 @@ static int open(struct inode * inode, struct file * file)
 static int release(struct inode * inode, struct file * file)
 {
 	struct bin_buffer *bb = file->private_data;
+	struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+	struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
+	struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
+	int rc = 0;
 
+	if (attr->release)
+		rc = attr->release(kobj, attr, file);
+	
 	mutex_lock(&sysfs_bin_lock);
 	hlist_del(&bb->list);
 	mutex_unlock(&sysfs_bin_lock);
 
 	kfree(bb->buffer);
 	kfree(bb);
-	return 0;
+	return rc;
 }
 
 const struct file_operations bin_fops = {
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 9d68fed..751ea68 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -19,6 +19,7 @@
 
 struct kobject;
 struct module;
+struct file;
 
 /* FIXME
  * The *owner field is no longer used.
@@ -72,6 +73,8 @@ struct bin_attribute {
 			 char *, loff_t, size_t);
 	int (*mmap)(struct kobject *, struct bin_attribute *attr,
 		    struct vm_area_struct *vma);
+	int (*release)(struct kobject *, struct bin_attribute *attr,
+		      struct file *file);
 };
 
 struct sysfs_ops {
-- 
1.6.5.1


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