From 887554ab96588de2917b6c8c73e552da082e5368 Mon Sep 17 00:00:00 2001
From: Mingzhe Zou <mingzhe.zou@easystack.cn>
Date: Fri, 11 Feb 2022 14:39:15 +0800
Subject: [PATCH] bcache: fixup multiple threads crash
Git-commit: 887554ab96588de2917b6c8c73e552da082e5368
Patch-mainline: v5.18-rc1
References: git-fixes

When multiple threads to check btree nodes in parallel, the main
thread wait for all threads to stop or CACHE_SET_IO_DISABLE flag:

wait_event_interruptible(check_state->wait,
                         atomic_read(&check_state->started) == 0 ||
                         test_bit(CACHE_SET_IO_DISABLE, &c->flags));

However, the bch_btree_node_read and bch_btree_node_read_done
maybe call bch_cache_set_error, then the CACHE_SET_IO_DISABLE
will be set. If the flag already set, the main thread return
error. At the same time, maybe some threads still running and
read NULL pointer, the kernel will crash.

This patch change the event wait condition, the main thread must
wait for all threads to stop.

Fixes: 8e7102273f597 ("bcache: make bch_btree_check() to be multithreaded")
Signed-off-by: Mingzhe Zou <mingzhe.zou@easystack.cn>
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Coly Li <colyli@suse.de>

---
 drivers/md/bcache/btree.c     | 6 ++++--
 drivers/md/bcache/writeback.c | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 88c573eeb598..ad9f16689419 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -2060,9 +2060,11 @@ int bch_btree_check(struct cache_set *c)
 		}
 	}
 
+	/*
+	 * Must wait for all threads to stop.
+	 */
 	wait_event_interruptible(check_state->wait,
-				 atomic_read(&check_state->started) == 0 ||
-				  test_bit(CACHE_SET_IO_DISABLE, &c->flags));
+				 atomic_read(&check_state->started) == 0);
 
 	for (i = 0; i < check_state->total_threads; i++) {
 		if (check_state->infos[i].result) {
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 176461f89f46..9ee0005874cd 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -1001,9 +1001,11 @@ void bch_sectors_dirty_init(struct bcache_device *d)
 		}
 	}
 
+	/*
+	 * Must wait for all threads to stop.
+	 */
 	wait_event_interruptible(state->wait,
-		 atomic_read(&state->started) == 0 ||
-		 test_bit(CACHE_SET_IO_DISABLE, &c->flags));
+		 atomic_read(&state->started) == 0);
 
 out:
 	kfree(state);
-- 
2.35.3