user/sven/linux.git/drivers/md, branch v3.12.13

md/raid5: Fix CPU hotplug callback registration

2014-02-22T21:32:29Z

commit 789b5e0315284463617e106baad360cb9e8db3ac upstream. Subsystems that want to register CPU hotplug callbacks, as well as perform initialization for the CPUs that are already online, often do it as shown below: get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); register_cpu_notifier(&foobar_cpu_notifier); put_online_cpus(); This is wrong, since it is prone to ABBA deadlocks involving the cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently with CPU hotplug operations). Interestingly, the raid5 code can actually prevent double initialization and hence can use the following simplified form of callback registration: register_cpu_notifier(&foobar_cpu_notifier); get_online_cpus(); for_each_online_cpu(cpu) init_cpu(cpu); put_online_cpus(); A hotplug operation that occurs between registering the notifier and calling get_online_cpus(), won't disrupt anything, because the code takes care to perform the memory allocations only once. So reorganize the code in raid5 this way to fix the deadlock with callback registration. Cc: linux-raid@vger.kernel.org Fixes: 36d1c6476be51101778882897b315bd928c8c7b5 Signed-off-by: Oleg Nesterov [Srivatsa: Fixed the unregister_cpu_notifier() deadlock, added the free_scratch_buffer() helper to condense code further and wrote the changelog.] Signed-off-by: Srivatsa S. Bhat Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

md/raid1: restore ability for check and repair to fix read errors.

2014-02-22T21:32:29Z

commit 1877db75589a895bbdc4c4c3f23558e57b521141 upstream. commit 30bc9b53878a9921b02e3b5bc4283ac1c6de102a md/raid1: fix bio handling problems in process_checks() Move the bio_reset() to a point before where BIO_UPTODATE is checked, so that check now always report that the bio is uptodate, even if it is not. This causes process_check() to sometimes treat read-errors as successful matches so the good data isn't written out. This patch preserves the flag until it is needed. Bug was introduced in 3.11, but backported to 3.10-stable (as it fixed an even worse bug). So suitable for any -stable since 3.10. Reported-and-tested-by: Michael Tokarev Fixed: 30bc9b53878a9921b02e3b5bc4283ac1c6de102a Signed-off-by: NeilBrown Signed-off-by: Greg Kroah-Hartman

dm sysfs: fix a module unload race

2014-02-13T21:50:22Z

commit 2995fa78e423d7193f3b57835f6c1c75006a0315 upstream. This reverts commit be35f48610 ("dm: wait until embedded kobject is released before destroying a device") and provides an improved fix. The kobject release code that calls the completion must be placed in a non-module file, otherwise there is a module unload race (if the process calling dm_kobject_release is preempted and the DM module unloaded after the completion is triggered, but before dm_kobject_release returns). To fix this race, this patch moves the completion code to dm-builtin.c which is always compiled directly into the kernel if BLK_DEV_DM is selected. The patch introduces a new dm_kobject_holder structure, its purpose is to keep the completion and kobject in one place, so that it can be accessed from non-module code without the need to export the layout of struct mapped_device to that code. Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman

dm space map metadata: fix bug in resizing of thin metadata

2014-02-13T21:50:18Z

commit fca028438fb903852beaf7c3fe1cd326651af57d upstream. This bug was introduced in commit 7e664b3dec431e ("dm space map metadata: fix extending the space map"). When extending a dm-thin metadata volume we: - Switch the space map into a simple bootstrap mode, which allocates all space linearly from the newly added space. - Add new bitmap entries for the new space - Increment the reference counts for those newly allocated bitmap entries - Commit changes to disk - Switch back out of bootstrap mode. But, the disk commit may allocate space itself, if so this fact will be lost when switching out of bootstrap mode. The bug exhibited itself as an error when the bitmap_root, with an erroneous ref count of 0, was subsequently decremented as part of a later disk commit. This would cause the disk commit to fail, and thinp to enter read_only mode. The metadata was not damaged (thin_check passed). The fix is to put the increments + commit into a loop, running until the commit has not allocated extra space. In practise this loop only runs twice. With this fix the following device mapper testsuite test passes: dmtest run --suite thin-provisioning -n thin_remove_works_after_resize Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm space map metadata: fix extending the space map

2014-02-13T21:50:18Z

commit 7e664b3dec431eebf0c5df5ff704d6197634cf35 upstream. When extending a metadata space map we should do the first commit whilst still in bootstrap mode -- a mode where all blocks get allocated in the new area. That way the commit overhead is allocated from the newly added space. Otherwise we risk running out of space. With this fix, and the previous commit "dm space map common: make sure new space is used during extend", the following device mapper testsuite test passes: dmtest run --suite thin-provisioning -n /resize_metadata_no_io/ Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm space map common: make sure new space is used during extend

2014-02-13T21:50:17Z

commit 12c91a5c2d2a8e8cc40a9552313e1e7b0a2d9ee3 upstream. When extending a low level space map we should update nr_blocks at the start so the new space is used for the index entries. Otherwise extend can fail, e.g.: sm_metadata_extend call sequence that fails: -> sm_ll_extend -> dm_tm_new_block -> dm_sm_new_block -> sm_bootstrap_new_block => returns -ENOSPC because smm->begin == smm->ll.nr_blocks Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm: wait until embedded kobject is released before destroying a device

2014-02-13T21:50:17Z

commit be35f486108227e10fe5d96fd42fb2b344c59983 upstream. There may be other parts of the kernel holding a reference on the dm kobject. We must wait until all references are dropped before deallocating the mapped_device structure. The dm_kobject_release method signals that all references are dropped via completion. But dm_kobject_release doesn't free the kobject (which is embedded in the mapped_device structure). This is the sequence of operations: * when destroying a DM device, call kobject_put from dm_sysfs_exit * wait until all users stop using the kobject, when it happens the release method is called * the release method signals the completion and should return without delay * the dm device removal code that waits on the completion continues * the dm device removal code drops the dm_mod reference the device had * the dm device removal code frees the mapped_device structure that contains the kobject Using kobject this way should avoid the module unload race that was mentioned at the beginning of this thread: https://lkml.org/lkml/2014/1/4/83 Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm thin: fix set_pool_mode exposed pool operation races

2014-02-13T21:50:17Z

commit 8b64e881eb40ac8b9bfcbce068a97eef819044ee upstream. The pool mode must not be switched until after the corresponding pool process_* methods have been established. Otherwise, because set_pool_mode() isn't interlocked with the IO path for performance reasons, the IO path can end up executing process_* operations that don't match the mode. This patch eliminates problems like the following (as seen on really fast PCIe SSD storage when transitioning the pool's mode from PM_READ_ONLY to PM_WRITE): kernel: device-mapper: thin: 253:2: reached low water mark for data device: sending event. kernel: device-mapper: thin: 253:2: no free data space available. kernel: device-mapper: thin: 253:2: switching pool to read-only mode kernel: device-mapper: thin: 253:2: switching pool to write mode kernel: ------------[ cut here ]------------ kernel: WARNING: CPU: 11 PID: 7564 at drivers/md/dm-thin.c:995 handle_unserviceable_bio+0x146/0x160 [dm_thin_pool]() ... kernel: Workqueue: dm-thin do_worker [dm_thin_pool] kernel: 00000000000003e3 ffff880308831cc8 ffffffff8152ebcb 00000000000003e3 kernel: 0000000000000000 ffff880308831d08 ffffffff8104c46c ffff88032502a800 kernel: ffff880036409000 ffff88030ec7ce00 0000000000000001 00000000ffffffc3 kernel: Call Trace: kernel: [] dump_stack+0x49/0x5e kernel: [] warn_slowpath_common+0x8c/0xc0 kernel: [] warn_slowpath_null+0x1a/0x20 kernel: [] handle_unserviceable_bio+0x146/0x160 [dm_thin_pool] kernel: [] process_bio_read_only+0x136/0x180 [dm_thin_pool] kernel: [] process_deferred_bios+0xc5/0x230 [dm_thin_pool] kernel: [] do_worker+0x51/0x60 [dm_thin_pool] kernel: [] process_one_work+0x183/0x490 kernel: [] worker_thread+0x120/0x3a0 kernel: [] ? manage_workers+0x160/0x160 kernel: [] kthread+0xce/0xf0 kernel: [] ? kthread_freezable_should_stop+0x70/0x70 kernel: [] ret_from_fork+0x7c/0xb0 kernel: [] ? kthread_freezable_should_stop+0x70/0x70 kernel: ---[ end trace 3f00528e08ffa55c ]--- kernel: device-mapper: thin: pool mode is PM_WRITE not PM_READ_ONLY like expected!? dm-thin.c:995 was the WARN_ON_ONCE(get_pool_mode(pool) != PM_READ_ONLY); at the top of handle_unserviceable_bio(). And as the additional debugging I had conveys: the pool mode was _not_ PM_READ_ONLY like expected, it was already PM_WRITE, yet pool->process_bio was still set to process_bio_read_only(). Also, while fixing this up, reduce logging of redundant pool mode transitions by checking new_mode is different from old_mode. Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman

dm thin: initialize dm_thin_new_mapping returned by get_next_mapping

2014-02-13T21:50:17Z

commit 16961b042db8cc5cf75d782b4255193ad56e1d4f upstream. As additional members are added to the dm_thin_new_mapping structure care should be taken to make sure they get initialized before use. Signed-off-by: Mike Snitzer Acked-by: Joe Thornber Signed-off-by: Greg Kroah-Hartman

dm thin: fix discard support to a previously shared block

2014-02-13T21:50:17Z

commit 19fa1a6756ed9e92daa9537c03b47d6b55cc2316 upstream. If a snapshot is created and later deleted the origin dm_thin_device's snapshotted_time will have been updated to reflect the snapshot's creation time. The 'shared' flag in the dm_thin_lookup_result struct returned from dm_thin_find_block() is an approximation based on snapshotted_time -- this is done to avoid 0(n), or worse, time complexity. In this case, the shared flag would be true. But because the 'shared' flag reflects an approximation a block can be incorrectly assumed to be shared (e.g. false positive for 'shared' because the snapshot no longer exists). This could result in discards issued to a thin device not being passed down to the pool's underlying data device. To fix this we double check that a thin block is really still in-use after a mapping is removed using dm_pool_block_is_used(). If the reference count for a block is now zero the discard is allowed to be passed down. Also add a 'definitely_not_shared' member to the dm_thin_new_mapping structure -- reflects that the 'shared' flag in the response from dm_thin_find_block() can only be held as definitive if false is returned. Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1043527 Signed-off-by: Joe Thornber Signed-off-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman