-static int do_sb_start_write(struct super_block *sb, int level, bool wait,
- unsigned long ip)
-{
- if (wait)
- rwsem_acquire_read(&sb->s_writers.lock_map[level-1], 0, 0, ip);
-retry:
- if (unlikely(sb->s_writers.frozen >= level)) {
- if (!wait)
- return 0;
- wait_event(sb->s_writers.wait_unfrozen,
- sb->s_writers.frozen < level);
- }
-
- percpu_counter_inc(&sb->s_writers.counter[level-1]);
- /*
- * Make sure counter is updated before we check for frozen.
- * freeze_super() first sets frozen and then checks the counter.
- */
- smp_mb();
- if (unlikely(sb->s_writers.frozen >= level)) {
- __sb_end_write(sb, level);
- goto retry;
- }
-
- if (!wait)
- rwsem_acquire_read(&sb->s_writers.lock_map[level-1], 0, 1, ip);
- return 1;
-}
-