fs: Remove i_cindex from struct inode
The only user of the i_cindex element in the inode structure is used
is by the firewire drivers. As part of an attempt to slim down the
inode structure to save memory --- since a typical Linux system will
have hundreds of thousands if not millions of inodes cached, a
reduction in the size inode has high leverage.
The firewire driver does not need i_cindex in any fast path, so it's
simple enough to calculate when it is needed, instead of wasting space
in the inode structure.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: krh@redhat.com
Cc: stefanr@s5r6.in-berlin.de
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/char_dev.c b/fs/char_dev.c
index 38f7122..b7c9d51 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -375,7 +375,6 @@
p = inode->i_cdev;
if (!p) {
inode->i_cdev = p = new;
- inode->i_cindex = idx;
list_add(&inode->i_devices, &p->list);
new = NULL;
} else if (!cdev_get(p))
@@ -405,6 +404,18 @@
return ret;
}
+int cdev_index(struct inode *inode)
+{
+ int idx;
+ struct kobject *kobj;
+
+ kobj = kobj_lookup(cdev_map, inode->i_rdev, &idx);
+ if (!kobj)
+ return -1;
+ kobject_put(kobj);
+ return idx;
+}
+
void cd_forget(struct inode *inode)
{
spin_lock(&cdev_lock);
@@ -557,6 +568,7 @@
EXPORT_SYMBOL(cdev_alloc);
EXPORT_SYMBOL(cdev_del);
EXPORT_SYMBOL(cdev_add);
+EXPORT_SYMBOL(cdev_index);
EXPORT_SYMBOL(register_chrdev);
EXPORT_SYMBOL(unregister_chrdev);
EXPORT_SYMBOL(directly_mappable_cdev_bdi);