From: Dongsheng Yang dongsheng.yang@easystack.cn
mainline inclusion from v5.11-rc1 commit df4ad53242158f9f1f97daf4feddbb4f8b77f080 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I59A5L?from=project-issue CVE: N/A
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There is a race condition in detaching as below: A. detaching B. Write request (1) writing back (2) write back done, set bdev state to clean. (3) cached_dev_put() and schedule_work(&dc->detach); (4) write data [0 - 4K] directly into backing and ack to user. (5) power-failure...
When we restart this bcache device, this bdev is clean but not detached, and read [0 - 4K], we will get unexpected old data from cache device.
To fix this problem, set the bdev state to none when we writeback done in detaching, and then if power-failure happened as above, the data in cache will not be used in next bcache device starting, it's detached, we will read the correct data from backing derectly.
Signed-off-by: Dongsheng Yang dongsheng.yang@easystack.cn Signed-off-by: Coly Li colyli@suse.de Signed-off-by: Jens Axboe axboe@kernel.dk Reviewed-by: Jason Yan yanaijie@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- drivers/md/bcache/super.c | 9 --------- drivers/md/bcache/writeback.c | 9 +++++++++ 2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index 81f1cc5b3499..b7d9d1b79ac2 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1151,9 +1151,6 @@ static void cancel_writeback_rate_update_dwork(struct cached_dev *dc) static void cached_dev_detach_finish(struct work_struct *w) { struct cached_dev *dc = container_of(w, struct cached_dev, detach); - struct closure cl; - - closure_init_stack(&cl);
BUG_ON(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)); BUG_ON(refcount_read(&dc->count)); @@ -1167,12 +1164,6 @@ static void cached_dev_detach_finish(struct work_struct *w) dc->writeback_thread = NULL; }
- memset(&dc->sb.set_uuid, 0, 16); - SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE); - - bch_write_bdev_super(dc, &cl); - closure_sync(&cl); - mutex_lock(&bch_register_lock);
calc_cached_dev_sectors(dc->disk.c); diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 3c74996978da..a129e4d2707c 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -705,6 +705,15 @@ static int bch_writeback_thread(void *arg) * bch_cached_dev_detach(). */ if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags)) { + struct closure cl; + + closure_init_stack(&cl); + memset(&dc->sb.set_uuid, 0, 16); + SET_BDEV_STATE(&dc->sb, BDEV_STATE_NONE); + + bch_write_bdev_super(dc, &cl); + closure_sync(&cl); + up_write(&dc->writeback_lock); break; }