Unverified Commit b47e42d1 authored by Christian Brauner's avatar Christian Brauner
Browse files

super: use common iterator (Part 2) 

Use a common iterator for all callbacks. We could go for something even
more elaborate (advance step-by-step similar to iov_iter) but I really
don't think this is warranted.

Link: https://lore.kernel.org/r/20250329-work-freeze-v2-5-a47af37ecc3d@kernel.org


Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 29924765

fs/super.c

+39 −9
Original line number Diff line number Diff line
@@ -887,21 +887,46 @@ void drop_super_exclusive(struct super_block *sb) 
}

EXPORT_SYMBOL(drop_super_exclusive);



void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl)

enum super_iter_flags_t {

	SUPER_ITER_EXCL		= (1U << 0),

	SUPER_ITER_UNLOCKED	= (1U << 1),

	SUPER_ITER_REVERSE	= (1U << 2),

};



static inline struct super_block *first_super(enum super_iter_flags_t flags)

{

	if (flags & SUPER_ITER_REVERSE)

		return list_last_entry(&super_blocks, struct super_block, s_list);

	return list_first_entry(&super_blocks, struct super_block, s_list);

}



static inline struct super_block *next_super(struct super_block *sb,

					     enum super_iter_flags_t flags)

{

	if (flags & SUPER_ITER_REVERSE)

		return list_prev_entry(sb, s_list);

	return list_next_entry(sb, s_list);

}



static void __iterate_supers(void (*f)(struct super_block *, void *), void *arg,

			     enum super_iter_flags_t flags)

{

	struct super_block *sb, *p = NULL;

	bool excl = flags & SUPER_ITER_EXCL;



	spin_lock(&sb_lock);

	list_for_each_entry(sb, &super_blocks, s_list) {

		bool locked;

	guard(spinlock)(&sb_lock);



	for (sb = first_super(flags);

	     !list_entry_is_head(sb, &super_blocks, s_list);

	     sb = next_super(sb, flags)) {

		if (super_flags(sb, SB_DYING))

			continue;

		sb->s_count++;

		spin_unlock(&sb_lock);



		locked = super_lock(sb, excl);

		if (locked) {

		if (flags & SUPER_ITER_UNLOCKED) {

			f(sb, arg);

		} else if (super_lock(sb, excl)) {

			f(sb, arg);

			super_unlock(sb, excl);

		}
@@ -913,7 +938,11 @@ void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool e 
	}

	if (p)

		__put_super(p);

	spin_unlock(&sb_lock);

}



void iterate_supers(void (*f)(struct super_block *, void *), void *arg)

{

	__iterate_supers(f, arg, 0);

}



/**
@@ -1097,7 +1126,8 @@ static void do_emergency_remount_callback(struct super_block *sb, void *unused) 


static void do_emergency_remount(struct work_struct *work)

{

	__iterate_supers(do_emergency_remount_callback, NULL, true);

	__iterate_supers(do_emergency_remount_callback, NULL,

			 SUPER_ITER_EXCL | SUPER_ITER_REVERSE);

	kfree(work);

	printk("Emergency Remount complete\n");

}
@@ -1124,7 +1154,7 @@ static void do_thaw_all_callback(struct super_block *sb, void *unused) 


static void do_thaw_all(struct work_struct *work)

{

	__iterate_supers(do_thaw_all_callback, NULL, true);

	__iterate_supers(do_thaw_all_callback, NULL, SUPER_ITER_EXCL);

	kfree(work);

	printk(KERN_WARNING "Emergency Thaw complete\n");

}

include/linux/fs.h

+1 −5
Original line number Diff line number Diff line
@@ -3515,11 +3515,7 @@ extern void put_filesystem(struct file_system_type *fs); 
extern struct file_system_type *get_fs_type(const char *name);

extern void drop_super(struct super_block *sb);

extern void drop_super_exclusive(struct super_block *sb);

void __iterate_supers(void (*f)(struct super_block *, void *), void *arg, bool excl);

static inline void iterate_supers(void (*f)(struct super_block *, void *), void *arg)

{

	__iterate_supers(f, arg, false);

}

extern void iterate_supers(void (*f)(struct super_block *, void *), void *arg);

extern void iterate_supers_type(struct file_system_type *,

			        void (*)(struct super_block *, void *), void *);