From 2f51201662b28dbf8c15fb7eb972bc51c6cc3fa5 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Sun, 30 Oct 2005 15:02:16 -0800 Subject: [PATCH] reduce sizeof(struct file) Now that RCU applied on 'struct file' seems stable, we can place f_rcuhead in a memory location that is not anymore used at call_rcu(&f->f_rcuhead, file_free_rcu) time, to reduce the size of this critical kernel object. The trick I used is to move f_rcuhead and f_list in an union called f_u The callers are changed so that f_rcuhead becomes f_u.fu_rcuhead and f_list becomes f_u.f_list Signed-off-by: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/fs.h | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'include/linux/fs.h') diff --git a/include/linux/fs.h b/include/linux/fs.h index f83d997c558..6d6226732c9 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -574,7 +574,14 @@ struct file_ra_state { #define RA_FLAG_INCACHE 0x02 /* file is already in cache */ struct file { - struct list_head f_list; + /* + * fu_list becomes invalid after file_free is called and queued via + * fu_rcuhead for RCU freeing + */ + union { + struct list_head fu_list; + struct rcu_head fu_rcuhead; + } f_u; struct dentry *f_dentry; struct vfsmount *f_vfsmnt; struct file_operations *f_op; @@ -598,7 +605,6 @@ struct file { spinlock_t f_ep_lock; #endif /* #ifdef CONFIG_EPOLL */ struct address_space *f_mapping; - struct rcu_head f_rcuhead; }; extern spinlock_t files_lock; #define file_list_lock() spin_lock(&files_lock); -- cgit v1.2.3