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From: Pavel Begunkov <asml.silence@gmail.com>
To: Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, Omar Sandoval <osandov@osandov.com>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH v2 4/4] sbitmap: simplify wrap check
Date: Sun, 22 Nov 2020 15:35:48 +0000	[thread overview]
Message-ID: <120b9b0870719675c91764822016597bdfa3ee15.1606058975.git.asml.silence@gmail.com> (raw)
In-Reply-To: <cover.1606058975.git.asml.silence@gmail.com>

__sbitmap_get_word() doesn't warp if it's starting from the beginning
(i.e. initial hint is 0). Instead of stashing the original hint just set
@wrap accordingly.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
 lib/sbitmap.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index c18b518a16ba..d693d9213ceb 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -97,9 +97,11 @@ EXPORT_SYMBOL_GPL(sbitmap_resize);
 static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 			      unsigned int hint, bool wrap)
 {
-	unsigned int orig_hint = hint;
 	int nr;
 
+	/* don't wrap if starting from 0 */
+	wrap = wrap && hint;
+
 	while (1) {
 		nr = find_next_zero_bit(word, depth, hint);
 		if (unlikely(nr >= depth)) {
@@ -108,8 +110,8 @@ static int __sbitmap_get_word(unsigned long *word, unsigned long depth,
 			 * offset to 0 in a failure case, so start from 0 to
 			 * exhaust the map.
 			 */
-			if (orig_hint && hint && wrap) {
-				hint = orig_hint = 0;
+			if (hint && wrap) {
+				hint = 0;
 				continue;
 			}
 			return -1;
-- 
2.24.0


  parent reply	other threads:[~2020-11-22 15:39 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-22 15:35 [PATCH v2 for-next 0/4] optimise sbitmap deferred clear Pavel Begunkov
2020-11-22 15:35 ` [PATCH v2 1/4] sbitmap: optimise sbitmap_deferred_clear() Pavel Begunkov
2020-11-24 14:11   ` John Garry
2020-11-24 15:01     ` Pavel Begunkov
2020-11-22 15:35 ` [PATCH v2 2/4] sbitmap: remove swap_lock Pavel Begunkov
2020-11-24 14:22   ` John Garry
2020-11-24 14:43     ` Pavel Begunkov
2020-11-26  2:46   ` Ming Lei
2020-11-26 13:44     ` Pavel Begunkov
2020-11-27  2:06       ` Ming Lei
2020-11-22 15:35 ` [PATCH v2 3/4] sbitmap: replace CAS with atomic and Pavel Begunkov
2020-11-22 15:35 ` Pavel Begunkov [this message]
2020-12-08  0:13 ` [PATCH v2 for-next 0/4] optimise sbitmap deferred clear Jens Axboe

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