Commit eee5cc27 authored by Al Viro's avatar Al Viro
Browse files

get rid of s_files and files_lock 



The only thing we need it for is alt-sysrq-r (emergency remount r/o)
and these days we can do just as well without going through the
list of files.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 8b61e74f

fs/file_table.c

+0 −125
Original line number Diff line number Diff line
@@ -36,8 +36,6 @@ struct files_stat_struct files_stat = { 
	.max_files = NR_FILE

};



DEFINE_STATIC_LGLOCK(files_lglock);



/* SLAB cache for file structures */

static struct kmem_cache *filp_cachep __read_mostly;
@@ -134,7 +132,6 @@ struct file *get_empty_filp(void) 
		return ERR_PTR(error);

	}



	INIT_LIST_HEAD(&f->f_u.fu_list);

	atomic_long_set(&f->f_count, 1);

	rwlock_init(&f->f_owner.lock);

	spin_lock_init(&f->f_lock);
@@ -304,7 +301,6 @@ void fput(struct file *file) 
	if (atomic_long_dec_and_test(&file->f_count)) {

		struct task_struct *task = current;



		file_sb_list_del(file);

		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {

			init_task_work(&file->f_u.fu_rcuhead, ____fput);

			if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
@@ -333,7 +329,6 @@ void __fput_sync(struct file *file) 
{

	if (atomic_long_dec_and_test(&file->f_count)) {

		struct task_struct *task = current;

		file_sb_list_del(file);

		BUG_ON(!(task->flags & PF_KTHREAD));

		__fput(file);

	}
@@ -345,129 +340,10 @@ void put_filp(struct file *file) 
{

	if (atomic_long_dec_and_test(&file->f_count)) {

		security_file_free(file);

		file_sb_list_del(file);

		file_free(file);

	}

}



static inline int file_list_cpu(struct file *file)

{

#ifdef CONFIG_SMP

	return file->f_sb_list_cpu;

#else

	return smp_processor_id();

#endif

}



/* helper for file_sb_list_add to reduce ifdefs */

static inline void __file_sb_list_add(struct file *file, struct super_block *sb)

{

	struct list_head *list;

#ifdef CONFIG_SMP

	int cpu;

	cpu = smp_processor_id();

	file->f_sb_list_cpu = cpu;

	list = per_cpu_ptr(sb->s_files, cpu);

#else

	list = &sb->s_files;

#endif

	list_add(&file->f_u.fu_list, list);

}



/**

 * file_sb_list_add - add a file to the sb's file list

 * @file: file to add

 * @sb: sb to add it to

 *

 * Use this function to associate a file with the superblock of the inode it

 * refers to.

 */

void file_sb_list_add(struct file *file, struct super_block *sb)

{

	if (likely(!(file->f_mode & FMODE_WRITE)))

		return;

	if (!S_ISREG(file_inode(file)->i_mode))

		return;

	lg_local_lock(&files_lglock);

	__file_sb_list_add(file, sb);

	lg_local_unlock(&files_lglock);

}



/**

 * file_sb_list_del - remove a file from the sb's file list

 * @file: file to remove

 * @sb: sb to remove it from

 *

 * Use this function to remove a file from its superblock.

 */

void file_sb_list_del(struct file *file)

{

	if (!list_empty(&file->f_u.fu_list)) {

		lg_local_lock_cpu(&files_lglock, file_list_cpu(file));

		list_del_init(&file->f_u.fu_list);

		lg_local_unlock_cpu(&files_lglock, file_list_cpu(file));

	}

}



#ifdef CONFIG_SMP



/*

 * These macros iterate all files on all CPUs for a given superblock.

 * files_lglock must be held globally.

 */

#define do_file_list_for_each_entry(__sb, __file)		\

{								\

	int i;							\

	for_each_possible_cpu(i) {				\

		struct list_head *list;				\

		list = per_cpu_ptr((__sb)->s_files, i);		\

		list_for_each_entry((__file), list, f_u.fu_list)



#define while_file_list_for_each_entry				\

	}							\

}



#else



#define do_file_list_for_each_entry(__sb, __file)		\

{								\

	struct list_head *list;					\

	list = &(sb)->s_files;					\

	list_for_each_entry((__file), list, f_u.fu_list)



#define while_file_list_for_each_entry				\

}



#endif



/**

 *	mark_files_ro - mark all files read-only

 *	@sb: superblock in question

 *

 *	All files are marked read-only.  We don't care about pending

 *	delete files so this should be used in 'force' mode only.

 */

void mark_files_ro(struct super_block *sb)

{

	struct file *f;



	lg_global_lock(&files_lglock);

	do_file_list_for_each_entry(sb, f) {

		if (!file_count(f))

			continue;

		if (!(f->f_mode & FMODE_WRITE))

			continue;

		spin_lock(&f->f_lock);

		f->f_mode &= ~FMODE_WRITE;

		spin_unlock(&f->f_lock);

		if (file_check_writeable(f) != 0)

			continue;

		__mnt_drop_write(f->f_path.mnt);

		file_release_write(f);

	} while_file_list_for_each_entry;

	lg_global_unlock(&files_lglock);

}



void __init files_init(unsigned long mempages)

{ 

	unsigned long n;
@@ -483,6 +359,5 @@ void __init files_init(unsigned long mempages) 
	n = (mempages * (PAGE_SIZE / 1024)) / 10;

	files_stat.max_files = max_t(unsigned long, n, NR_FILE);

	files_defer_init();

	lg_lock_init(&files_lglock, "files_lglock");

	percpu_counter_init(&nr_files, 0);

}

fs/internal.h

+0 −3
Original line number Diff line number Diff line
@@ -73,9 +73,6 @@ extern void chroot_fs_refs(const struct path *, const struct path *); 
/*

 * file_table.c

 */

extern void file_sb_list_add(struct file *f, struct super_block *sb);

extern void file_sb_list_del(struct file *f);

extern void mark_files_ro(struct super_block *);

extern struct file *get_empty_filp(void);



/*

fs/open.c

+0 −2
Original line number Diff line number Diff line
@@ -685,7 +685,6 @@ static int do_dentry_open(struct file *f, 
	}



	f->f_mapping = inode->i_mapping;

	file_sb_list_add(f, inode->i_sb);



	if (unlikely(f->f_mode & FMODE_PATH)) {

		f->f_op = &empty_fops;
@@ -724,7 +723,6 @@ static int do_dentry_open(struct file *f, 


cleanup_all:

	fops_put(f->f_op);

	file_sb_list_del(f);

	if (f->f_mode & FMODE_WRITE) {

		put_write_access(inode);

		if (!special_file(inode->i_mode)) {

fs/super.c

+2 −13
Original line number Diff line number Diff line
@@ -140,9 +140,6 @@ static void destroy_super(struct super_block *s) 
	int i;

	list_lru_destroy(&s->s_dentry_lru);

	list_lru_destroy(&s->s_inode_lru);

#ifdef CONFIG_SMP

	free_percpu(s->s_files);

#endif

	for (i = 0; i < SB_FREEZE_LEVELS; i++)

		percpu_counter_destroy(&s->s_writers.counter[i]);

	security_sb_free(s);
@@ -172,15 +169,6 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags) 
	if (security_sb_alloc(s))

		goto fail;



#ifdef CONFIG_SMP

	s->s_files = alloc_percpu(struct list_head);

	if (!s->s_files)

		goto fail;

	for_each_possible_cpu(i)

		INIT_LIST_HEAD(per_cpu_ptr(s->s_files, i));

#else

	INIT_LIST_HEAD(&s->s_files);

#endif

	for (i = 0; i < SB_FREEZE_LEVELS; i++) {

		if (percpu_counter_init(&s->s_writers.counter[i], 0) < 0)

			goto fail;
@@ -722,7 +710,8 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force) 
	   make sure there are no rw files opened */

	if (remount_ro) {

		if (force) {

			mark_files_ro(sb);

			sb->s_readonly_remount = 1;

			smp_wmb();

		} else {

			retval = sb_prepare_remount_readonly(sb);

			if (retval)

include/linux/fs.h

+0 −13
Original line number Diff line number Diff line
@@ -764,12 +764,7 @@ static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index) 
#define FILE_MNT_WRITE_RELEASED	2



struct file {

	/*

	 * fu_list becomes invalid after file_free is called and queued via

	 * fu_rcuhead for RCU freeing

	 */

	union {

		struct list_head	fu_list;

		struct llist_node	fu_llist;

		struct rcu_head 	fu_rcuhead;

	} f_u;
@@ -783,9 +778,6 @@ struct file { 
	 * Must not be taken from IRQ context.

	 */

	spinlock_t		f_lock;

#ifdef CONFIG_SMP

	int			f_sb_list_cpu;

#endif

	atomic_long_t		f_count;

	unsigned int 		f_flags;

	fmode_t			f_mode;
@@ -1264,11 +1256,6 @@ struct super_block { 


	struct list_head	s_inodes;	/* all inodes */

	struct hlist_bl_head	s_anon;		/* anonymous dentries for (nfs) exporting */

#ifdef CONFIG_SMP

	struct list_head __percpu *s_files;

#else

	struct list_head	s_files;

#endif

	struct list_head	s_mounts;	/* list of mounts; _not_ for fs use */

	struct block_device	*s_bdev;

	struct backing_dev_info *s_bdi;