Hi Guys, Recently there are several reports about loop partition scanning failure[1][2]. For loop, the root cause is one ABBA and one AA lock dependency issue, and the two are fixed by patch 2 and patch 3 each. Another reason is from the trylock in blkdev_reread_part(), which may cause partition scanning failure too sometimes when another task is holding the bd_mutex. In the discussion[1], both Tejun and Christoph suggests to replace the trylock with mutex_lock in blkdev_reread_part(), also Christoph suggests to export blkdev_reread_part. Following the discussion, this patchset exports blkdev_reread_part(), and introduces __blkdev_reread_part() for fixing loop's AA lock issue. Then ioctl_by_bdev(BLKRRPART) in loop, nbd and dasd is replaced with blkdev_reread_part(). In the last patch, trylock in blkdev_reread_part() is replaced with mutex_lock, and some analysis is provided about the conversion. V1: - introduce __blkdev_reread_part(), and use lockdep_assert_held()(1/7) - replace lo_open_mutex with atomic reference count, plus freezing queue(2/7) - add comment about detecting release path(3/7) - remove dead code in dasd(7/7) block/ioctl.c | 37 +++++++++++++++++++++++++---- drivers/block/loop.c | 49 +++++++++++++++++++++++++++++---------- drivers/block/loop.h | 2 +- drivers/block/nbd.c | 2 +- drivers/s390/block/dasd_genhd.c | 20 ++++------------ include/linux/fs.h | 3 +++ 6 files changed, 79 insertions(+), 34 deletions(-) [1], https://lkml.org/lkml/2015/1/26/137 [2], https://lkml.org/lkml/2015/3/31/888 Thanks, Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
