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bcache: prevent crash on changing writeback_running 

Added a safeguard in the shutdown case. At least while not being
attached it is also possible to trigger a kernel bug by writing into
writeback_running. This change  adds the same check before trying to
wake up the thread for that case.

Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Stefan Bader 2015-11-29 18:44:49 -08:00 committed by Jens Axboe
parent d7076f2162
commit 8d16ce540c
1 changed files with 2 additions and 1 deletions
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3
drivers/md/bcache/writeback.h
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@ -63,7 +63,8 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
static inline void bch_writeback_queue(struct cached_dev *dc)
{
wake_up_process(dc->writeback_thread);
if (!IS_ERR_OR_NULL(dc->writeback_thread))
wake_up_process(dc->writeback_thread);
}
static inline void bch_writeback_add(struct cached_dev *dc)