sbitmap: remove unnecessary calculation of alloc_hint in __sbitmap_get_shallow

Updates to alloc_hint in the loop in __sbitmap_get_shallow() are mostly
pointless and equivalent to setting alloc_hint to zero (because
SB_NR_TO_BIT() considers only low sb->shift bits from alloc_hint). So
simplify the logic.

Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Kemeng Shi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>

Author: Kemeng Shi

lib/sbitmap.c

@@ -243,14 +243,15 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
 	int nr = -1;
 
 	index = SB_NR_TO_INDEX(sb, alloc_hint);
+	alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
 
 	for (i = 0; i < sb->map_nr; i++) {
 again:
 		nr = __sbitmap_get_word(&sb->map[index].word,
 					min_t(unsigned int,
 					      __map_depth(sb, index),
 					      shallow_depth),
-					SB_NR_TO_BIT(sb, alloc_hint), true);
+					alloc_hint, true);
 		if (nr != -1) {
 			nr += index << sb->shift;
 			break;
@@ -260,13 +261,9 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
 			goto again;
 
 		/* Jump to next index. */
-		index++;
-		alloc_hint = index << sb->shift;
-
-		if (index >= sb->map_nr) {
+		alloc_hint = 0;
+		if (++index >= sb->map_nr)
 			index = 0;
-			alloc_hint = 0;
-		}
 	}
 
 	return nr;