[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>

2 files changed, 2 insertions, 2 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d50d7a782cf5..bb62838be496 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1609,7 +1609,7 @@ static inline void flush_unauthorized_files(struct files_struct * files)
 
         if (tty) {
                 file_list_lock();
-                file = list_entry(tty->tty_files.next, typeof(*file), f_list);
+                file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
                 if (file) {
                         /* Revalidate access to controlling tty.
                            Use inode_has_perm on the tty inode directly rather
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 7a387fec2a0c..fdc382389720 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -914,7 +914,7 @@ static void sel_remove_bools(struct dentry *de)
 
         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 dentry * dentry = filp->f_dentry;
 
                 if (dentry->d_parent != de) {