linux-kernel - [PATCH 3/4] sbitmap: rewrite sbitmap_find_bit_in

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Message-Id: <20221208220147.3315388-4-shikemeng@huaweicloud.com>
Date:   Fri,  9 Dec 2022 06:01:46 +0800
From:   Kemeng Shi <shikemeng@...weicloud.com>
To:     axboe@...nel.dk
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linfeilong@...wei.com, liuzhiqiang26@...wei.com
Subject: [PATCH 3/4] sbitmap: rewrite sbitmap_find_bit_in_index to reduce repeat code

Rewrite sbitmap_find_bit_in_index as following:
1. Rename sbitmap_find_bit_in_index to sbitmap_find_bit_in_word
2. Accept "struct sbitmap_word *" directly instead of accepting
"struct sbitmap *" and "int index" to get "struct sbitmap_word *".
3. Accept depth/shallow_depth and wrap for __sbitmap_get_word from caller
to support need of both __sbitmap_get_shallow and __sbitmap_get.

With helper function sbitmap_find_bit_in_word, we can remove repeat
code in __sbitmap_get_shallow to find bit considring deferred clear.

Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
---
 lib/sbitmap.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 11e75f4040fb..3f7e276a427d 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -167,15 +167,16 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 	return nr;
 }
 
-static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,
-				     unsigned int alloc_hint)
+static int sbitmap_find_bit_in_word(struct sbitmap_word *map,
+				    unsigned int depth,
+				    unsigned int alloc_hint,
+				    bool wrap)
 {
-	struct sbitmap_word *map = &sb->map[index];
 	int nr;
 
 	do {
-		nr = __sbitmap_get_word(&map->word, __map_depth(sb, index),
-					alloc_hint, !sb->round_robin);
+		nr = __sbitmap_get_word(&map->word, depth,
+					alloc_hint, wrap);
 		if (nr != -1)
 			break;
 		if (!sbitmap_deferred_clear(map))
@@ -203,7 +204,8 @@ static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint)
 		alloc_hint = 0;
 
 	for (i = 0; i < sb->map_nr; i++) {
-		nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);
+		nr = sbitmap_find_bit_in_word(&sb->map[index], __map_depth(sb, index),
+					      alloc_hint, !sb->round_robin);
 		if (nr != -1) {
 			nr += index << sb->shift;
 			break;
@@ -246,20 +248,17 @@ static int __sbitmap_get_shallow(struct sbitmap *sb,
 	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),
-					alloc_hint, true);
+		nr = sbitmap_find_bit_in_word(&sb->map[index],
+					      min_t(unsigned int,
+						    __map_depth(sb, index),
+						    shallow_depth),
+					      alloc_hint, true);
+
 		if (nr != -1) {
 			nr += index << sb->shift;
 			break;
 		}
 
-		if (sbitmap_deferred_clear(&sb->map[index]))
-			goto again;
-
 		/* Jump to next index. */
 		alloc_hint = 0;
 		if (++index >= sb->map_nr)
-- 
2.30.0