sysfs: merge sysfs_elem_bin_attr into sysfs_elem_attr

3124eb1679 ("sysfs: merge regular and bin file handling") folded bin
file handling into regular file handling.  Among other things, bin
file now shares the same open path including sysfs_open_dirent
association using sysfs_dirent->s_attr.open.  This is buggy because
->s_bin_attr lives in the same union and doesn't have the field.  This
bug doesn't trigger because sysfs_elem_bin_attr doesn't have an active
field at the conflicting position.  It does have a field "buffers" but
it isn't used anymore.

This patch collapses sysfs_elem_bin_attr into sysfs_elem_attr so that
the bin_attr is accessed through ->s_attr.bin_attr which lives with
->s_attr.attr in an anonymous union.  The code paths already assume
bin_attr contains attr as the first element, so this doesn't add any
more assumptions while making it explicit that the two types are
handled together.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/sysfs/file.c

@@ -154,7 +154,7 @@ static ssize_t sysfs_bin_read(struct file *file, char __user *userbuf,
 			      size_t bytes, loff_t *off)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr;
+	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
 	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
 	loff_t size = file_inode(file)->i_size;
 	int count = min_t(size_t, bytes, PAGE_SIZE);
@@ -236,7 +236,7 @@ static int flush_write_buffer(struct sysfs_open_file *of, char *buf, loff_t off,
 	}
 
 	if (sysfs_is_bin(of->sd)) {
-		struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr;
+		struct bin_attribute *battr = of->sd->s_attr.bin_attr;
 
 		rc = -EIO;
 		if (battr->write)
@@ -466,7 +466,7 @@ static const struct vm_operations_struct sysfs_bin_vm_ops = {
 static int sysfs_bin_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct sysfs_open_file *of = sysfs_of(file);
-	struct bin_attribute *battr = of->sd->s_bin_attr.bin_attr;
+	struct bin_attribute *battr = of->sd->s_attr.bin_attr;
 	struct kobject *kobj = of->sd->s_parent->s_dir.kobj;
 	int rc;
 
@@ -618,7 +618,7 @@ static int sysfs_open_file(struct inode *inode, struct file *file)
 		return -ENODEV;
 
 	if (sysfs_is_bin(attr_sd)) {
-		struct bin_attribute *battr = attr_sd->s_bin_attr.bin_attr;
+		struct bin_attribute *battr = attr_sd->s_attr.bin_attr;
 
 		has_read = battr->read || battr->mmap;
 		has_write = battr->write || battr->mmap;

fs/sysfs/inode.c

@@ -258,7 +258,7 @@ static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
 		inode->i_fop = &sysfs_file_operations;
 		break;
 	case SYSFS_KOBJ_BIN_ATTR:
-		bin_attr = sd->s_bin_attr.bin_attr;
+		bin_attr = sd->s_attr.bin_attr;
 		inode->i_size = bin_attr->size;
 		inode->i_fop = &sysfs_bin_operations;
 		break;

fs/sysfs/sysfs.h

@@ -29,15 +29,13 @@ struct sysfs_elem_symlink {
 };
 
 struct sysfs_elem_attr {
-	struct attribute	*attr;
+	union {
+		struct attribute	*attr;
+		struct bin_attribute	*bin_attr;
+	};
 	struct sysfs_open_dirent *open;
 };
 
-struct sysfs_elem_bin_attr {
-	struct bin_attribute	*bin_attr;
-	struct hlist_head	buffers;
-};
-
 struct sysfs_inode_attrs {
 	struct iattr	ia_iattr;
 	void		*ia_secdata;
@@ -74,7 +72,6 @@ struct sysfs_dirent {
 		struct sysfs_elem_dir		s_dir;
 		struct sysfs_elem_symlink	s_symlink;
 		struct sysfs_elem_attr		s_attr;
-		struct sysfs_elem_bin_attr	s_bin_attr;
 	};
 
 	unsigned short		s_flags;