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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
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+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);
} 
+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);

/*
+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)) {
+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)
+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;