Date: Thu, 21 May 2009 16:01:00 -0400 From: Theodore Ts'o Subject: 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" Cc: krh@redhat.com Cc: stefanr@s5r6.in-berlin.de Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Al Viro --- drivers/ieee1394/dv1394.c | 5 +++-- drivers/ieee1394/ieee1394_core.h | 6 +++++- fs/char_dev.c | 14 +++++++++++++- include/linux/cdev.h | 2 ++ include/linux/fs.h | 1 - 5 files changed, 23 insertions(+), 5 deletions(-) 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 @@ 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; } 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 #include #include +#include #include #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; 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 @@ 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); 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 @@ 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; 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 inode { struct block_device *i_bdev; struct cdev *i_cdev; }; - int i_cindex; __u32 i_generation; -- 1.6.0.6