linux-kernel - [PATCH 1/2] dm-bufio: merge cache_put() into cache_put_and

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Message-ID: <20260111213821.94895-2-ebiggers@kernel.org>
Date: Sun, 11 Jan 2026 13:38:20 -0800
From: Eric Biggers <ebiggers@...nel.org>
To: dm-devel@...ts.linux.dev,
	Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>,
	Benjamin Marzinski <bmarzins@...hat.com>
Cc: Sami Tolvanen <samitolvanen@...gle.com>,
	linux-kernel@...r.kernel.org,
	Eric Biggers <ebiggers@...nel.org>
Subject: [PATCH 1/2] dm-bufio: merge cache_put() into cache_put_and_wake()

Merge cache_put() into its only caller, cache_put_and_wake().

Signed-off-by: Eric Biggers <ebiggers@...nel.org>
---
 drivers/md/dm-bufio.c | 32 ++++++++++----------------------
 1 file changed, 10 insertions(+), 22 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 5235f3e4924b..6e61982c9b92 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -367,12 +367,12 @@ struct dm_buffer {
  * It does *not* handle:
  *  - allocation/freeing of buffers.
  *  - IO
  *  - Eviction or cache sizing.
  *
- * cache_get() and cache_put() are threadsafe, you do not need to
- * protect these calls with a surrounding mutex.  All the other
+ * cache_get() and cache_put_and_wake() are threadsafe, you do not need
+ * to protect these calls with a surrounding mutex.  All the other
  * methods are not threadsafe; they do use locking primitives, but
  * only enough to ensure get/put are threadsafe.
  */
 
 struct buffer_tree {
@@ -617,28 +617,10 @@ static struct dm_buffer *cache_get(struct dm_buffer_cache *bc, sector_t block)
 	return b;
 }
 
 /*--------------*/
 
-/*
- * Returns true if the hold count hits zero.
- * threadsafe
- */
-static bool cache_put(struct dm_buffer_cache *bc, struct dm_buffer *b)
-{
-	bool r;
-
-	cache_read_lock(bc, b->block);
-	BUG_ON(!atomic_read(&b->hold_count));
-	r = atomic_dec_and_test(&b->hold_count);
-	cache_read_unlock(bc, b->block);
-
-	return r;
-}
-
-/*--------------*/
-
 typedef enum evict_result (*b_predicate)(struct dm_buffer *, void *);
 
 /*
  * Evicts a buffer based on a predicate.  The oldest buffer that
  * matches the predicate will be selected.  In addition to the
@@ -1743,16 +1725,22 @@ static void __check_watermark(struct dm_bufio_client *c,
  *--------------------------------------------------------------
  */
 
 static void cache_put_and_wake(struct dm_bufio_client *c, struct dm_buffer *b)
 {
+	bool wake;
+
+	cache_read_lock(&c->cache, b->block);
+	BUG_ON(!atomic_read(&b->hold_count));
+	wake = atomic_dec_and_test(&b->hold_count);
+	cache_read_unlock(&c->cache, b->block);
+
 	/*
 	 * Relying on waitqueue_active() is racey, but we sleep
 	 * with schedule_timeout anyway.
 	 */
-	if (cache_put(&c->cache, b) &&
-	    unlikely(waitqueue_active(&c->free_buffer_wait)))
+	if (wake && unlikely(waitqueue_active(&c->free_buffer_wait)))
 		wake_up(&c->free_buffer_wait);
 }
 
 /*
  * This assumes you have already checked the cache to see if the buffer
-- 
2.52.0