diff options
| author | Coly Li <colyli@suse.de> | 2019-06-10 01:13:35 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-06-13 12:09:15 +0300 |
| commit | 1f0ffa67349c56ea54c03ccfd1e073c990e7411e (patch) | |
| tree | e3fecad087a9cdac7eba72f96da496a3f29f814e /drivers | |
| parent | 31b90956b124240aa8c63250243ae1a53585c5e2 (diff) | |
| download | linux-1f0ffa67349c56ea54c03ccfd1e073c990e7411e.tar.xz | |
bcache: only set BCACHE_DEV_WB_RUNNING when cached device attached
When people set a writeback percent via sysfs file,
/sys/block/bcache<N>/bcache/writeback_percent
current code directly sets BCACHE_DEV_WB_RUNNING to dc->disk.flags
and schedules kworker dc->writeback_rate_update.
If there is no cache set attached to, the writeback kernel thread is
not running indeed, running dc->writeback_rate_update does not make
sense and may cause NULL pointer deference when reference cache set
pointer inside update_writeback_rate().
This patch checks whether the cache set point (dc->disk.c) is NULL in
sysfs interface handler, and only set BCACHE_DEV_WB_RUNNING and
schedule dc->writeback_rate_update when dc->disk.c is not NULL (it
means the cache device is attached to a cache set).
This problem might be introduced from initial bcache commit, but
commit 3fd47bfe55b0 ("bcache: stop dc->writeback_rate_update properly")
changes part of the original code piece, so I add 'Fixes: 3fd47bfe55b0'
to indicate from which commit this patch can be applied.
Fixes: 3fd47bfe55b0 ("bcache: stop dc->writeback_rate_update properly")
Reported-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/md/bcache/sysfs.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 6cd44d3cf906..bfb437ffb13c 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -431,8 +431,13 @@ STORE(bch_cached_dev) bch_writeback_queue(dc); } + /* + * Only set BCACHE_DEV_WB_RUNNING when cached device attached to + * a cache set, otherwise it doesn't make sense. + */ if (attr == &sysfs_writeback_percent) - if (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)) + if ((dc->disk.c != NULL) && + (!test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags))) schedule_delayed_work(&dc->writeback_rate_update, dc->writeback_rate_update_seconds * HZ); |