linux-kernel - bcache: unlock new_nodes[i]->write_lock in btree_gc

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Message-ID: <f4a66326-5ac5-7089-a570-0e02ad3093fa@huawei.com>
Date:   Wed, 15 Apr 2020 19:42:03 +0800
From:   Zhiqiang Liu <liuzhiqiang26@...wei.com>
To:     <colyli@...e.de>, <kmo@...erainc.com>,
        <linux-bcache@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     "wubo (T)" <wubo40@...wei.com>,
        Mingfangsen <mingfangsen@...wei.com>,
        Yanxiaodan <yanxiaodan@...wei.com>,
        linfeilong <linfeilong@...wei.com>
Subject: bcache: unlock new_nodes[i]->write_lock in btree_gc_coalesce

From: Zhiqiang Liu <liuzhiqiang26@...wei.com>

coccicheck reports:
  drivers/md//bcache/btree.c:1538:1-7: preceding lock on line 1417

After obtaining new_nodes[i]->write_lock, we may go to out_nocoalesce
tag without releasing lock. Here, we add a new tag
'out_unlock_nocoalesce' before out_nocoalesce tag to release
new_nodes[i]->write_lock.

Fixes: 2a285686c1 ("bcache: btree locking rework")
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@...wei.com>
---
 drivers/md/bcache/btree.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index fa872df4e770..cad8b0b97e33 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
 			if (__set_blocks(n1, n1->keys + n2->keys,
 					 block_bytes(b->c)) >
 			    btree_blocks(new_nodes[i]))
-				goto out_nocoalesce;
+				goto out_unlock_nocoalesce;

 			keys = n2->keys;
 			/* Take the key of the node we're getting rid of */
@@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,

 		if (__bch_keylist_realloc(&keylist,
 					  bkey_u64s(&new_nodes[i]->key)))
-			goto out_nocoalesce;
+			goto out_unlock_nocoalesce;

 		bch_btree_node_write(new_nodes[i], &cl);
 		bch_keylist_add(&keylist, &new_nodes[i]->key);
@@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
 	/* Invalidated our iterator */
 	return -EINTR;

+out_unlock_nocoalesce:
+	for (i = 0; i < nodes; i++)
+		mutex_unlock(&new_nodes[i]->write_lock);
+
 out_nocoalesce:
 	closure_sync(&cl);

-- 
2.19.1