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[PATCH] reduce sizeof(struct file)

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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>
This commit is contained in:
Eric Dumazet 2005-10-30 15:02:16 -08:00 • committed by Linus Torvalds
parent 503af334ec
commit 2f51201662
8 changed files with 21 additions and 15 deletions
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14
fs/file_table.c
View file

@ -56,13 +56,13 @@ void filp_dtor(void * objp, struct kmem_cache_s *cachep, unsigned long dflags)
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 @@ struct file *get_empty_filp(void)
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 @@ void file_move(struct file *file, struct list_head *list)
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 @@ int fs_may_remount_ro(struct super_block *sb)
/* 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? */