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

[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

drivers/char/tty_io.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

fs/dquot.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

fs/file_table.c

+7 −7
Original line number Diff line number Diff line
@@ -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? */

fs/proc/generic.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

fs/super.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

	}