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/drivers/ieee1394/dv1394.c b/drivers/ieee1394/dv1394.c
index 823a629..2cd00b5 100644
--- a/drivers/ieee1394/dv1394.c
+++ b/drivers/ieee1394/dv1394.c
@@ -1789,12 +1789,13 @@
} else {
/* look up the card by ID */
unsigned long flags;
+ int idx = ieee1394_file_to_instance(file);
spin_lock_irqsave(&dv1394_cards_lock, flags);
if (!list_empty(&dv1394_cards)) {
struct video_card *p;
list_for_each_entry(p, &dv1394_cards, list) {
- if ((p->id) == ieee1394_file_to_instance(file)) {
+ if ((p->id) == idx) {
video = p;
break;
}
@@ -1803,7 +1804,7 @@
spin_unlock_irqrestore(&dv1394_cards_lock, flags);
if (!video) {
- debug_printk("dv1394: OHCI card %d not found", ieee1394_file_to_instance(file));
+ debug_printk("dv1394: OHCI card %d not found", idx);
return -ENODEV;
}
diff --git a/drivers/ieee1394/ieee1394_core.h b/drivers/ieee1394/ieee1394_core.h
index 21d50f7..28b9f58 100644
--- a/drivers/ieee1394/ieee1394_core.h
+++ b/drivers/ieee1394/ieee1394_core.h
@@ -5,6 +5,7 @@
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/types.h>
+#include <linux/cdev.h>
#include <asm/atomic.h>
#include "hosts.h"
@@ -155,7 +156,10 @@
*/
static inline unsigned char ieee1394_file_to_instance(struct file *file)
{
- return file->f_path.dentry->d_inode->i_cindex;
+ int idx = cdev_index(file->f_path.dentry->d_inode);
+ if (idx < 0)
+ idx = 0;
+ return idx;
}
extern int hpsb_disable_irm;
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);
diff --git a/include/linux/cdev.h b/include/linux/cdev.h
index fb45919..f389e31 100644
--- a/include/linux/cdev.h
+++ b/include/linux/cdev.h
@@ -28,6 +28,8 @@
void cdev_del(struct cdev *);
+int cdev_index(struct inode *inode);
+
void cd_forget(struct inode *);
extern struct backing_dev_info directly_mappable_cdev_bdi;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e7833ef..bcd6370 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -751,7 +751,6 @@
struct block_device *i_bdev;
struct cdev *i_cdev;
};
- int i_cindex;
__u32 i_generation;