bcache: do not collect data insert info created by write_moving

euleros/rtos inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4LOJ6
CVE: NA

--------------------------------

commit 6947676c374("bcache: add a framework to perform prefetch")
collects data insert info which includes device info got from bio.
However, bio created by write_moving here has no device info, causing
a null pointer dereference.

[ 1497.991768] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[ 1497.991869] PGD 0 P4D 0
[ 1497.991912] Oops: 0000 [#1] SMP PTI
[ 1497.991962] CPU: 2 PID: 733 Comm: kworker/2:3 Not tainted 4.19.90+ #33
[ 1497.992030] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
[ 1497.992137] Workqueue: bcache_gc write_moving [bcache]
[ 1497.992219] RIP: 0010:bch_data_insert+0x4c/0x140 [bcache]
...
[ 1497.993367] Call Trace:
[ 1497.993427]  ? cached_dev_read_error+0x140/0x140 [bcache]
[ 1497.993526]  write_moving+0x19e/0x1b0 [bcache]
[ 1497.993621]  process_one_work+0x1fd/0x440
[ 1497.993742]  worker_thread+0x34/0x410
[ 1497.993811]  kthread+0x121/0x140
[ 1497.993873]  ? process_one_work+0x440/0x440
[ 1497.993946]  ? kthread_create_worker_on_cpu+0x70/0x70
[ 1497.994043]  ret_from_fork+0x35/0x40
Signed-off-by: NLi Ruilin <liruilin4@huawei.com>
Review-by: NSong Chao <chao.song@huawei.com>
Review-by: NXu Wei <xuwei56@huawei.com>
Signed-off-by: NLi Ruilin <liruilin4@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>
Reviewed-by: NGuangxing Deng <dengguangxing@huawei.com>
Reviewed-by: Nchao song <chao.song@huawei.com>
Reviewed-by: Nchao song <chao.song@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/md/bcache/request.c

@@ -315,12 +315,14 @@ void bch_data_insert(struct closure *cl)
 	trace_bcache_write(op->c, op->inode, op->bio,
 			   op->writeback, op->bypass);
 
-	msg.offset = op->bio->bi_iter.bi_sector;
-	msg.length = op->bio->bi_iter.bi_size;
-	msg.type = ACACHE_INFO_CACHE_INSERT;
-	msg.dev = bio_dev(op->bio);
-	msg.start_time = ktime_get_ns();
-	save_circ_item(&msg);
+        if (op->bio->bi_disk) {
+		msg.offset = op->bio->bi_iter.bi_sector;
+		msg.length = op->bio->bi_iter.bi_size;
+		msg.type = ACACHE_INFO_CACHE_INSERT;
+		msg.dev = bio_dev(op->bio);
+		msg.start_time = ktime_get_ns();
+		save_circ_item(&msg);
+        }
 
 	bch_keylist_init(&op->insert_keys);
 	bio_get(op->bio);