Commit 2f512016 authored by Eric Dumazet's avatar Eric Dumazet Committed by Linus Torvalds

[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: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 503af334
......@@ -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)
......
......@@ -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);
......
......@@ -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? */
......
......@@ -533,7 +533,7 @@ static void proc_kill_inodes(struct proc_dir_entry *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;
struct inode * inode;
struct file_operations *fops;
......
......@@ -513,7 +513,7 @@ static void mark_files_ro(struct super_block *sb)
struct file *f;
file_list_lock();
list_for_each_entry(f, &sb->s_files, f_list) {
list_for_each_entry(f, &sb->s_files, f_u.fu_list) {
if (S_ISREG(f->f_dentry->d_inode->i_mode) && file_count(f))
f->f_mode &= ~FMODE_WRITE;
}
......
......@@ -574,7 +574,14 @@ struct file_ra_state {
#define RA_FLAG_INCACHE 0x02 /* file is already in cache */
struct file {
struct list_head f_list;
/*
* fu_list becomes invalid after file_free is called and queued via
* fu_rcuhead for RCU freeing
*/
union {
struct list_head fu_list;
struct rcu_head fu_rcuhead;
} f_u;
struct dentry *f_dentry;
struct vfsmount *f_vfsmnt;
struct file_operations *f_op;
......@@ -598,7 +605,6 @@ struct file {
spinlock_t f_ep_lock;
#endif /* #ifdef CONFIG_EPOLL */
struct address_space *f_mapping;
struct rcu_head f_rcuhead;
};
extern spinlock_t files_lock;
#define file_list_lock() spin_lock(&files_lock);
......
......@@ -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
......
......@@ -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) {
......
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