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super: use common iterator (Part 2)

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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: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Christian Brauner
2025-03-29 09:42:18 +01:00
parent 2992476528
commit b47e42d10e
2 changed files with 40 additions and 14 deletions
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48
fs/super.c
View File

@@ -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");
}

6
include/linux/fs.h
View File

@@ -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 *);