[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/drivers/char/tty_io.c b/drivers/char/tty_io.c
index f5649a337743..c586bfa852ee 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -809,7 +809,7 @@ static void do_tty_hangup(void *data)
         check_tty_count(tty, "do_tty_hangup");
         file_list_lock();
         /* This breaks for file handles being sent over AF_UNIX sockets ? */
-        list_for_each_entry(filp, &tty->tty_files, f_list) {
+        list_for_each_entry(filp, &tty->tty_files, f_u.fu_list) {
                 if (filp->f_op->write == redirected_tty_write)
                         cons_filp = filp;
                 if (filp->f_op->write != tty_write)