Commit 9fd5746f authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Al Viro
Browse files

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: default avatar"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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ebc1ac16

drivers/ieee1394/dv1394.c

+3 −2
Original line number Diff line number Diff line
@@ -1789,12 +1789,13 @@ static int dv1394_open(struct inode *inode, struct file *file) 
	} 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 @@ static int dv1394_open(struct inode *inode, struct file *file) 
		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;

		}

drivers/ieee1394/ieee1394_core.h

+5 −1
Original line number Diff line number Diff line
@@ -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 @@ void hpsb_packet_received(struct hpsb_host *host, quadlet_t *data, size_t size, 
 */

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;

fs/char_dev.c

+13 −1
Original line number Diff line number Diff line
@@ -375,7 +375,6 @@ static int chrdev_open(struct inode *inode, struct file *filp) 
		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 @@ static int chrdev_open(struct inode *inode, struct file *filp) 
	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_init); 
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);

include/linux/cdev.h

+2 −0
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ int cdev_add(struct cdev *, dev_t, unsigned); 


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;

include/linux/fs.h

+0 −1
Original line number Diff line number Diff line
@@ -751,7 +751,6 @@ struct inode { 
		struct block_device	*i_bdev;

		struct cdev		*i_cdev;

	};

	int			i_cindex;



	__u32			i_generation;

CRA Git | Maintained and supported by SUSTech CRA and CCSE