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From: chengming.zhou@linux.dev
To: axboe@kernel.dk, osandov@fb.com, ming.lei@redhat.com,
	kbusch@kernel.org, krisman@suse.de
Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
	zhouchengming@bytedance.com
Subject: [PATCH 2/6] sbitmap: fix round-robin non-wrap find with hint > 0
Date: Thu, 20 Jul 2023 17:45:51 +0800	[thread overview]
Message-ID: <20230720094555.1397621-3-chengming.zhou@linux.dev> (raw)
In-Reply-To: <20230720094555.1397621-1-chengming.zhou@linux.dev>

From: Chengming Zhou <zhouchengming@bytedance.com>

If we have alloc_hint > 0 and don't wrap, we need to recheck
sb->map[index] with hint == 0 to exhaust the map.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
---
 lib/sbitmap.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 5ed6c2adf58e..ccb96d1f92ba 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -192,10 +192,18 @@ static int sbitmap_find_bit(struct sbitmap *sb,
 			    unsigned int alloc_hint,
 			    bool wrap)
 {
+	unsigned int map_nr = sb->map_nr;
 	unsigned int i;
 	int nr = -1;
 
-	for (i = 0; i < sb->map_nr; i++) {
+	/*
+	 * If we have alloc_hint > 0 and don't wrap, we need to
+	 * recheck sb->map[index] with hint == 0 to exhaust the map.
+	 */
+	if (alloc_hint && !wrap)
+		map_nr += 1;
+
+	for (i = 0; i < map_nr; i++) {
 		nr = sbitmap_find_bit_in_word(&sb->map[index],
 					      min_t(unsigned int,
 						    __map_depth(sb, index),
-- 
2.41.0


  parent reply	other threads:[~2023-07-20  9:49 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-20  9:45 [PATCH 0/6] sbitmap: fix offset hint wrap and some optimizations chengming.zhou
2023-07-20  9:45 ` [PATCH 1/6] sbitmap: fix hint wrap in the failure case chengming.zhou
2023-07-20 19:06   ` Gabriel Krisman Bertazi
2023-07-21  3:51     ` Chengming Zhou
2023-07-20  9:45 ` chengming.zhou [this message]
2023-07-20  9:45 ` [PATCH 3/6] sbitmap: don't loop twice in find_next_zero_bit() chengming.zhou
2023-07-20  9:45 ` [PATCH 4/6] sbitmap: remove offset wrap logic when finding bit in word chengming.zhou
2023-07-20  9:45 ` [PATCH 5/6] sbitmap: wake_index doesn't need to be atomic_t chengming.zhou
2023-07-20  9:45 ` [PATCH 6/6] sbitmap: check ws_active before check waitqueues chengming.zhou

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