lib/sbitmap: define swap_lock as raw_spinlock_t

When called from sbitmap_queue_get(), sbitmap_deferred_clear() may be run
with preempt disabled. In RT kernel, spin_lock() can sleep, then warning
of "BUG: sleeping function called from invalid context" can be triggered.

Fix it by replacing it with raw_spin_lock.

Cc: Yang Yang <[email protected]>
Fixes: 72d04bd ("sbitmap: fix io hung due to race on sbitmap_word::cleared")
Signed-off-by: Ming Lei <[email protected]>
Reviewed-by: Yang Yang <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: Ming Lei

include/linux/sbitmap.h

@@ -40,7 +40,7 @@ struct sbitmap_word {
 	/**
 	 * @swap_lock: serializes simultaneous updates of ->word and ->cleared
 	 */
-	spinlock_t swap_lock;
+	raw_spinlock_t swap_lock;
 } ____cacheline_aligned_in_smp;
 
 /**

lib/sbitmap.c

@@ -65,7 +65,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap_word *map,
 {
 	unsigned long mask, word_mask;
 
-	guard(spinlock_irqsave)(&map->swap_lock);
+	guard(raw_spinlock_irqsave)(&map->swap_lock);
 
 	if (!map->cleared) {
 		if (depth == 0)
@@ -136,7 +136,7 @@ int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,
 	}
 
 	for (i = 0; i < sb->map_nr; i++)
-		spin_lock_init(&sb->map[i].swap_lock);
+		raw_spin_lock_init(&sb->map[i].swap_lock);
 
 	return 0;
 }