diff options
| author | Dongsheng Yang <dongsheng.yang@easystack.cn> | 2020-12-08 00:39:15 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-12-07 13:25:16 -0700 |
| commit | df4ad53242158f9f1f97daf4feddbb4f8b77f080 (patch) | |
| tree | 254fd64b672dcea3498c8ddc46e61fa57d8e0a78 /drivers/md | |
| parent | 733c15bd3a944b8eeaacdddf061759b6a83dd3f4 (diff) | |
bcache: fix race between setting bdev state to none and new write request direct to backing
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>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/bcache/super.c | 9 | ||||
| -rw-r--r-- | 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 46a00134a36a..b1a6ba9a5adb 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1114,9 +1114,6 @@ 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)); @@ -1130,12 +1127,6 @@ 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; } |