[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>
diff --git a/fs/file_table.c b/fs/file_table.c
index 86ec8ae..4dc2055 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -56,13 +56,13 @@
static inline void file_free_rcu(struct rcu_head *head)
{
- struct file *f = container_of(head, struct file, f_rcuhead);
+ struct file *f = container_of(head, struct file, f_u.fu_rcuhead);
kmem_cache_free(filp_cachep, f);
}
static inline void file_free(struct file *f)
{
- call_rcu(&f->f_rcuhead, file_free_rcu);
+ call_rcu(&f->f_u.fu_rcuhead, file_free_rcu);
}
/* Find an unused file structure and return a pointer to it.
@@ -95,7 +95,7 @@
f->f_gid = current->fsgid;
rwlock_init(&f->f_owner.lock);
/* f->f_version: 0 */
- INIT_LIST_HEAD(&f->f_list);
+ INIT_LIST_HEAD(&f->f_u.fu_list);
return f;
over:
@@ -225,15 +225,15 @@
if (!list)
return;
file_list_lock();
- list_move(&file->f_list, list);
+ list_move(&file->f_u.fu_list, list);
file_list_unlock();
}
void file_kill(struct file *file)
{
- if (!list_empty(&file->f_list)) {
+ if (!list_empty(&file->f_u.fu_list)) {
file_list_lock();
- list_del_init(&file->f_list);
+ list_del_init(&file->f_u.fu_list);
file_list_unlock();
}
}
@@ -245,7 +245,7 @@
/* Check that no files are currently opened for writing. */
file_list_lock();
list_for_each(p, &sb->s_files) {
- struct file *file = list_entry(p, struct file, f_list);
+ struct file *file = list_entry(p, struct file, f_u.fu_list);
struct inode *inode = file->f_dentry->d_inode;
/* File with pending delete? */