[PATCH 3/6] 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. Therefore this modified struct is exported in the
<linux/sysfs.h> header file. Additionally add a release() callback
that can be used to free the private data on file release.

Signed-off-by: Thomas Schlichter <thomas.schlichter@xxxxxx>
---
 fs/sysfs/bin.c        |   18 ++++++++----------
 include/linux/sysfs.h |   14 ++++++++++++++
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 60c702b..3647b7a 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -36,15 +36,6 @@
  */
 static DEFINE_MUTEX(sysfs_bin_lock);
 
-struct bin_buffer {
-	struct mutex			mutex;
-	void				*buffer;
-	int				mmapped;
-	const struct vm_operations_struct *vm_ops;
-	struct file			*file;
-	struct hlist_node		list;
-};
-
 static int
 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
 {
@@ -438,14 +429,21 @@ 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..bcad8ad 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -15,6 +15,7 @@
 #include <linux/compiler.h>
 #include <linux/errno.h>
 #include <linux/list.h>
+#include <linux/mutex.h>
 #include <asm/atomic.h>
 
 struct kobject;
@@ -60,8 +61,19 @@ struct attribute_group {
 
 #define attr_name(_attr) (_attr).attr.name
 
+struct file;
 struct vm_area_struct;
 
+struct bin_buffer {
+	struct mutex			mutex;
+	void				*buffer;
+	void				*private;
+	int				mmapped;
+	const struct vm_operations_struct *vm_ops;
+	struct file			*file;
+	struct hlist_node		list;
+};
+
 struct bin_attribute {
 	struct attribute	attr;
 	size_t			size;
@@ -72,6 +84,8 @@ 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


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