diff options
| author | Eric Wheeler <git@linux.ewheeler.net> | 2016-02-26 14:39:06 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-12 09:08:53 -0700 |
| commit | b58e781068d9a5fd6b0ee77f595c3dbaa0d2b7aa (patch) | |
| tree | 0e598e2780aed5a4ce4a85d130d15423f900383e /drivers/md | |
| parent | 32bb1185093c67c2280e440685ebc6b23fd47743 (diff) | |
| download | lwn-b58e781068d9a5fd6b0ee77f595c3dbaa0d2b7aa.tar.gz lwn-b58e781068d9a5fd6b0ee77f595c3dbaa0d2b7aa.zip | |
bcache: fix race of writeback thread starting before complete initialization
commit 07cc6ef8edc47f8b4fc1e276d31127a0a5863d4d upstream.
The bch_writeback_thread might BUG_ON in read_dirty() if
dc->sb==BDEV_STATE_DIRTY and bch_sectors_dirty_init has not yet completed
its related initialization. This patch downs the dc->writeback_lock until
after initialization is complete, thus preventing bch_writeback_thread
from proceeding prematurely.
See this thread:
http://thread.gmane.org/gmane.linux.kernel.bcache.devel/3453
Signed-off-by: Eric Wheeler <bcache@linux.ewheeler.net>
Tested-by: Marc MERLIN <marc@merlins.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/md')
| -rw-r--r-- | drivers/md/bcache/super.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c index f3f98c3d7f67..6b07a0c8c729 100644 --- a/drivers/md/bcache/super.c +++ b/drivers/md/bcache/super.c @@ -1015,8 +1015,12 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c) */ atomic_set(&dc->count, 1); - if (bch_cached_dev_writeback_start(dc)) + /* Block writeback thread, but spawn it */ + down_write(&dc->writeback_lock); + if (bch_cached_dev_writeback_start(dc)) { + up_write(&dc->writeback_lock); return -ENOMEM; + } if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) { bch_sectors_dirty_init(dc); @@ -1028,6 +1032,9 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c) bch_cached_dev_run(dc); bcache_device_link(&dc->disk, c, "bdev"); + /* Allow the writeback thread to proceed */ + up_write(&dc->writeback_lock); + pr_info("Caching %s as %s on set %pU", bdevname(dc->bdev, buf), dc->disk.disk->disk_name, dc->disk.c->sb.set_uuid); |