linux/drivers/md, branch v3.16

dm cache: fix race affecting dirty block count

2014-08-01T16:25:22Z

nr_dirty is updated without locking, causing it to drift so that it is non-zero (either a small positive integer, or a very large one when an underflow occurs) even when there are no actual dirty blocks. This was due to a race between the workqueue and map function accessing nr_dirty in parallel without proper protection. People were seeing under runs due to a race on increment/decrement of nr_dirty, see: https://lkml.org/lkml/2014/6/3/648 Fix this by using an atomic_t for nr_dirty. Reported-by: roma1390@gmail.com Signed-off-by: Anssi Hannula Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org

dm bufio: fully initialize shrinker

2014-08-01T16:07:21Z

1d3d4437eae1 ("vmscan: per-node deferred work") added a flags field to struct shrinker assuming that all shrinkers were zero filled. The dm bufio shrinker is not zero filled, which leaves arbitrary kmalloc() data in flags. So far the only defined flags bit is SHRINKER_NUMA_AWARE. But there are proposed patches which add other bits to shrinker.flags (e.g. memcg awareness). Rather than simply initializing the shrinker, this patch uses kzalloc() when allocating the dm_bufio_client to ensure that the embedded shrinker and any other similar structures are zeroed. This fixes theoretical over aggressive shrinking of dm bufio objects. If the uninitialized dm_bufio_client.shrinker.flags contains SHRINKER_NUMA_AWARE then shrink_slab() would call the dm shrinker for each numa node rather than just once. This has been broken since 3.12. Signed-off-by: Greg Thelen Acked-by: Mikulas Patocka Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # v3.12+

Merge tag 'dm-3.16-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2014-07-18T16:25:05Z

Pull device mapper fixes from Mike Snitzer: "Fix the dm-thinp and dm-cache targets to disallow changing the data device's block size" * tag 'dm-3.16-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm cache metadata: do not allow the data block size to change dm thin metadata: do not allow the data block size to change

dm cache metadata: do not allow the data block size to change

2014-07-15T18:07:50Z

The block size for the dm-cache's data device must remained fixed for the life of the cache. Disallow any attempt to change the cache's data block size. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber Cc: stable@vger.kernel.org

dm thin metadata: do not allow the data block size to change

2014-07-15T18:05:26Z

The block size for the thin-pool's data device must remained fixed for the life of the thin-pool. Disallow any attempt to change the thin-pool's data block size. It should be noted that attempting to change the data block size via thin-pool table reload will be ignored as a side-effect of the thin-pool handover that the thin-pool target does during thin-pool table reload. Here is an example outcome of attempting to load a thin-pool table that reduced the thin-pool's data block size from 1024K to 512K. Before: kernel: device-mapper: thin: 253:4: growing the data device from 204800 to 409600 blocks After: kernel: device-mapper: thin metadata: changing the data block size (from 2048 to 1024) is not supported kernel: device-mapper: table: 253:4: thin-pool: Error creating metadata object kernel: device-mapper: ioctl: error adding target to table Signed-off-by: Mike Snitzer Acked-by: Joe Thornber Cc: stable@vger.kernel.org

Merge tag 'dm-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2014-07-11T16:33:36Z

Pull device mapper fixes from Mike Snitzer: - Fix DM multipath IO hang regression from 3.15 due to logic bug in multipath_busy. This impacted cable-pull testing and also the ability to boot with IPR SCSI on a POWER8 box. - Fix possible deadlock with deferred device removal by using a new dedicated workqueue rather than using the system workqueue. - Fix NULL pointer crash due to race condition in dm-io's wake up code for sync_io by using a completion. - Update dm-crypt and dm-zero author name following legal name change; this is important to Jana so I didn't see any reason to hold it back. * tag 'dm-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: dm mpath: fix IO hang due to logic bug in multipath_busy dm io: fix a race condition in the wake up code for sync_io dm crypt, dm zero: update author name following legal name change dm: allocate a special workqueue for deferred device removal

dm mpath: fix IO hang due to logic bug in multipath_busy

2014-07-10T20:44:15Z

Commit e80991773 ("dm mpath: push back requests instead of queueing") modified multipath_busy() to return true if !pg_ready(). pg_ready() checks the current state of the multipath device and may return false even if a new IO is needed to change the state. Bart Van Assche reported that he had multipath IO lockup when he was performing cable pull tests. Analysis showed that the multipath device had a single path group with both paths active, but that the path group itself was not active. During the multipath device state transitions 'queue_io' got set but nothing could clear it. Clearing 'queue_io' only happens in __choose_pgpath(), but it won't be called if multipath_busy() returns true due to pg_ready() returning false when 'queue_io' is set. As such the !pg_ready() check in multipath_busy() is wrong because new IO will not be sent to multipath target and the multipath state change won't happen. That results in multipath IO lockup. The intent of multipath_busy() is to avoid unnecessary cycles of dequeue + request_fn + requeue if it is known that the multipath device will requeue. Such "busy" situations would be: - path group is being activated - there is no path and the multipath is setup to requeue if no path Fix multipath_busy() to return "busy" early only for these specific situations. Reported-by: Bart Van Assche Tested-by: Bart Van Assche Signed-off-by: Jun'ichi Nomura Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # v3.15

dm io: fix a race condition in the wake up code for sync_io

2014-07-10T20:44:14Z

There's a race condition between the atomic_dec_and_test(&io->count) in dec_count() and the waking of the sync_io() thread. If the thread is spuriously woken immediately after the decrement it may exit, making the on stack io struct invalid, yet the dec_count could still be using it. Fix this race by using a completion in sync_io() and dec_count(). Reported-by: Minfei Huang Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Acked-by: Mikulas Patocka Cc: stable@vger.kernel.org

dm crypt, dm zero: update author name following legal name change

2014-07-10T20:44:14Z

Signed-off-by: Jana Saout Signed-off-by: Mike Snitzer

dm: allocate a special workqueue for deferred device removal

2014-07-10T20:44:13Z

The commit 2c140a246dc ("dm: allow remove to be deferred") introduced a deferred removal feature for the device mapper. When this feature is used (by passing a flag DM_DEFERRED_REMOVE to DM_DEV_REMOVE_CMD ioctl) and the user tries to remove a device that is currently in use, the device will be removed automatically in the future when the last user closes it. Device mapper used the system workqueue to perform deferred removals. However, some targets (dm-raid1, dm-mpath, dm-stripe) flush work items scheduled for the system workqueue from their destructor. If the destructor itself is called from the system workqueue during deferred removal, it introduces a possible deadlock - the workqueue tries to flush itself. Fix this possible deadlock by introducing a new workqueue for deferred removals. We allocate just one workqueue for all dm targets. The ability of dm targets to process IOs isn't dependent on deferred removal of unused targets, so a deadlock due to shared workqueue isn't possible. Also, cleanup local_init() to eliminate potential for returning success on failure. Signed-off-by: Mikulas Patocka Signed-off-by: Dan Carpenter Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org # 3.13+