linux-kernel - [PATCH] btrfs: Use refcount_t instead of atomic_t for mmap

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Message-ID: <20250429072033.3382-1-liubo03@inspur.com>
Date: Tue, 29 Apr 2025 03:20:33 -0400
From: Bo Liu <liubo03@...pur.com>
To: <clm@...com>, <josef@...icpanda.com>, <dsterba@...e.com>
CC: <linux-btrfs@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Bo Liu
	<liubo03@...pur.com>
Subject: [PATCH] btrfs: Use refcount_t instead of atomic_t for mmap_count

Use an API that resembles more the actual use of mmap_count.
Found by cocci:
fs/btrfs/bio.c:153:5-24: WARNING: atomic_dec_and_test variation before object free at line 155

Signed-off-by: Bo Liu <liubo03@...pur.com>
---
 fs/btrfs/bio.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index a3ee9a976f6f..353c61936cd6 100644
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -23,7 +23,7 @@ static mempool_t btrfs_failed_bio_pool;
 struct btrfs_failed_bio {
 	struct btrfs_bio *bbio;
 	int num_copies;
-	atomic_t repair_count;
+	refcount_t repair_count;
 };
 
 /* Is this a data path I/O that needs storage layer checksum and repair? */
@@ -150,7 +150,7 @@ static int prev_repair_mirror(struct btrfs_failed_bio *fbio, int cur_mirror)
 
 static void btrfs_repair_done(struct btrfs_failed_bio *fbio)
 {
-	if (atomic_dec_and_test(&fbio->repair_count)) {
+	if (refcount_dec_and_test(&fbio->repair_count)) {
 		btrfs_bio_end_io(fbio->bbio, fbio->bbio->bio.bi_status);
 		mempool_free(fbio, &btrfs_failed_bio_pool);
 	}
@@ -235,10 +235,10 @@ static struct btrfs_failed_bio *repair_one_sector(struct btrfs_bio *failed_bbio,
 		fbio = mempool_alloc(&btrfs_failed_bio_pool, GFP_NOFS);
 		fbio->bbio = failed_bbio;
 		fbio->num_copies = num_copies;
-		atomic_set(&fbio->repair_count, 1);
+		refcount_set(&fbio->repair_count, 1);
 	}
 
-	atomic_inc(&fbio->repair_count);
+	refcount_inc(&fbio->repair_count);
 
 	repair_bio = bio_alloc_bioset(NULL, 1, REQ_OP_READ, GFP_NOFS,
 				      &btrfs_repair_bioset);
-- 
2.31.1