[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 <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/dquot.c b/fs/dquot.c
index 05f3327d64a3..ea7644227a65 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -662,7 +662,7 @@ static void add_dquot_ref(struct super_block *sb, int type)
 restart:
         file_list_lock();
         list_for_each(p, &sb->s_files) {
-                struct file *filp = list_entry(p, struct file, f_list);
+                struct file *filp = list_entry(p, struct file, f_u.fu_list);
                 struct inode *inode = filp->f_dentry->d_inode;
                 if (filp->f_mode & FMODE_WRITE && dqinit_needed(inode, type)) {
                         struct dentry *dentry = dget(filp->f_dentry);