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authorEric Wheeler <git@linux.ewheeler.net>2016-02-27 01:39:06 +0300
committerJens Axboe <axboe@fb.com>2016-03-08 19:17:30 +0300
commit07cc6ef8edc47f8b4fc1e276d31127a0a5863d4d (patch)
treef70c53b8aa72129040a75222086ed6590d63bd3e /drivers/md
parent08095e70783f1d8296f858d37a9e1878f5da0623 (diff)
downloadlinux-07cc6ef8edc47f8b4fc1e276d31127a0a5863d4d.tar.xz
bcache: fix race of writeback thread starting before complete initialization
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> Cc: <stable@vger.kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/bcache/super.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 8d0ead98eb6e..b411c73bfeb3 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);