Revert "sysfs: Kill nlink counting."

This reverts commit 524b6c5b39b931311dfe5a2f5abae2f5c9731676.

It has shown to break userspace tools, which is not acceptable.

Reported-by: Jiri Slaby <jslaby@suse.cz>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/sysfs/dir.c

@@ -91,6 +91,9 @@ static int sysfs_link_sibling(struct sysfs_dirent *sd)
 	struct rb_node **node = &sd->s_parent->s_dir.children.rb_node;
 	struct rb_node *parent = NULL;
 
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs++;
+
 	while (*node) {
 		struct sysfs_dirent *pos;
 		int result;
@@ -123,6 +126,9 @@ static int sysfs_link_sibling(struct sysfs_dirent *sd)
  */
 static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
 {
+	if (sysfs_type(sd) == SYSFS_DIR)
+		sd->s_parent->s_dir.subdirs--;
+
 	rb_erase(&sd->s_rb, &sd->s_parent->s_dir.children);
 }
 

fs/sysfs/inode.c

@@ -217,6 +217,9 @@ static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
 					    iattrs->ia_secdata,
 					    iattrs->ia_secdata_len);
 	}
+
+	if (sysfs_type(sd) == SYSFS_DIR)
+		set_nlink(inode, sd->s_dir.subdirs + 2);
 }
 
 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)

fs/sysfs/sysfs.h

@@ -19,6 +19,7 @@ struct sysfs_open_dirent;
 struct sysfs_elem_dir {
 	struct kobject		*kobj;
 
+	unsigned long		subdirs;
 	/* children rbtree starts here and goes through sd->s_rb */
 	struct rb_root		children;
 };