sysfs: make sysfs_dirent->s_element a union

Make sd->s_element a union of sysfs_elem_{dir|symlink|attr|bin_attr}
and rename it to s_elem.  This is to achieve...

* some level of type checking : changing symlink to point to
  sysfs_dirent instead of kobject is much safer and less painful now.
* easier / standardized dereferencing
* allow sysfs_elem_* to contain more than one entry

Where possible, pointer is obtained by directly deferencing from sd
instead of going through other entities.  This reduces dependencies to
dentry, inode and kobject.  to_attr() and to_bin_attr() are unused now
and removed.

This is in preparation of object reference simplification.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 7 deletions

diff --git a/fs/sysfs/bin.c b/fs/sysfs/bin.c
index 606267a36275..67a0d5030c96 100644
--- a/fs/sysfs/bin.c
+++ b/fs/sysfs/bin.c
@@ -23,7 +23,8 @@
 static int
 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
 {
-        struct bin_attribute * attr = to_bin_attr(dentry);
+        struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
         struct kobject * kobj = to_kobj(dentry->d_parent);
 
         if (!attr->read)
@@ -65,7 +66,8 @@ read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
 static int
 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
 {
-        struct bin_attribute *attr = to_bin_attr(dentry);
+        struct sysfs_dirent *attr_sd = dentry->d_fsdata;
+        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
         struct kobject *kobj = to_kobj(dentry->d_parent);
 
         if (!attr->write)
@@ -101,9 +103,9 @@ static ssize_t write(struct file *file, const char __user *userbuf,
 
 static int mmap(struct file *file, struct vm_area_struct *vma)
 {
-        struct dentry *dentry = file->f_path.dentry;
-        struct bin_attribute *attr = to_bin_attr(dentry);
-        struct kobject *kobj = to_kobj(dentry->d_parent);
+        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
+        struct kobject *kobj = to_kobj(file->f_path.dentry->d_parent);
 
         if (!attr->mmap)
                 return -EINVAL;
@@ -114,7 +116,8 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
 static int open(struct inode * inode, struct file * file)
 {
         struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
-        struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
+        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
         int error = -EINVAL;
 
         if (!kobj || !attr)
@@ -150,7 +153,8 @@ static int open(struct inode * inode, struct file * file)
 static int release(struct inode * inode, struct file * file)
 {
         struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
-        struct bin_attribute * attr = to_bin_attr(file->f_path.dentry);
+        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
+        struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
         u8 * buffer = file->private_data;
 
         kobject_put(kobj);