linux/block, branch v3.7-rc5

block: Add blk_rq_pos(rq) to sort rq when plushing

2012-10-25T19:58:17Z

My workload is a raid5 which had 16 disks. And used our filesystem to write using direct-io mode. I used the blktrace to find those message: 8,16 0 6647 2.453665504 2579 M W 7493152 + 8 [md0_raid5] 8,16 0 6648 2.453672411 2579 Q W 7493160 + 8 [md0_raid5] 8,16 0 6649 2.453672606 2579 M W 7493160 + 8 [md0_raid5] 8,16 0 6650 2.453679255 2579 Q W 7493168 + 8 [md0_raid5] 8,16 0 6651 2.453679441 2579 M W 7493168 + 8 [md0_raid5] 8,16 0 6652 2.453685948 2579 Q W 7493176 + 8 [md0_raid5] 8,16 0 6653 2.453686149 2579 M W 7493176 + 8 [md0_raid5] 8,16 0 6654 2.453693074 2579 Q W 7493184 + 8 [md0_raid5] 8,16 0 6655 2.453693254 2579 M W 7493184 + 8 [md0_raid5] 8,16 0 6656 2.453704290 2579 Q W 7493192 + 8 [md0_raid5] 8,16 0 6657 2.453704482 2579 M W 7493192 + 8 [md0_raid5] 8,16 0 6658 2.453715016 2579 Q W 7493200 + 8 [md0_raid5] 8,16 0 6659 2.453715247 2579 M W 7493200 + 8 [md0_raid5] 8,16 0 6660 2.453721730 2579 Q W 7493208 + 8 [md0_raid5] 8,16 0 6661 2.453721974 2579 M W 7493208 + 8 [md0_raid5] 8,16 0 6662 2.453728202 2579 Q W 7493216 + 8 [md0_raid5] 8,16 0 6663 2.453728436 2579 M W 7493216 + 8 [md0_raid5] 8,16 0 6664 2.453734782 2579 Q W 7493224 + 8 [md0_raid5] 8,16 0 6665 2.453735019 2579 M W 7493224 + 8 [md0_raid5] 8,16 0 6666 2.453741401 2579 Q W 7493232 + 8 [md0_raid5] 8,16 0 6667 2.453741632 2579 M W 7493232 + 8 [md0_raid5] 8,16 0 6668 2.453748148 2579 Q W 7493240 + 8 [md0_raid5] 8,16 0 6669 2.453748386 2579 M W 7493240 + 8 [md0_raid5] 8,16 0 6670 2.453851843 2579 I W 7493144 + 104 [md0_raid5] 8,16 0 0 2.453853661 0 m N cfq2579 insert_request 8,16 0 6671 2.453854064 2579 I W 7493120 + 24 [md0_raid5] 8,16 0 0 2.453854439 0 m N cfq2579 insert_request 8,16 0 6672 2.453854793 2579 U N [md0_raid5] 2 8,16 0 0 2.453855513 0 m N cfq2579 Not idling.st->count:1 8,16 0 0 2.453855927 0 m N cfq2579 dispatch_insert 8,16 0 0 2.453861771 0 m N cfq2579 dispatched a request 8,16 0 0 2.453862248 0 m N cfq2579 activate rq,drv=1 8,16 0 6673 2.453862332 2579 D W 7493120 + 24 [md0_raid5] 8,16 0 0 2.453865957 0 m N cfq2579 Not idling.st->count:1 8,16 0 0 2.453866269 0 m N cfq2579 dispatch_insert 8,16 0 0 2.453866707 0 m N cfq2579 dispatched a request 8,16 0 0 2.453867061 0 m N cfq2579 activate rq,drv=2 8,16 0 6674 2.453867145 2579 D W 7493144 + 104 [md0_raid5] 8,16 0 6675 2.454147608 0 C W 7493120 + 24 [0] 8,16 0 0 2.454149357 0 m N cfq2579 complete rqnoidle 0 8,16 0 6676 2.454791505 0 C W 7493144 + 104 [0] 8,16 0 0 2.454794803 0 m N cfq2579 complete rqnoidle 0 8,16 0 0 2.454795160 0 m N cfq schedule dispatch From above messages,we can find rq[W 7493144 + 104] and rq[W 7493120 + 24] do not merge. Because the bio order is: 8,16 0 6638 2.453619407 2579 Q W 7493144 + 8 [md0_raid5] 8,16 0 6639 2.453620460 2579 G W 7493144 + 8 [md0_raid5] 8,16 0 6640 2.453639311 2579 Q W 7493120 + 8 [md0_raid5] 8,16 0 6641 2.453639842 2579 G W 7493120 + 8 [md0_raid5] The bio(7493144) first and bio(7493120) later.So the subsequent bios will be divided into two parts. When flushing plug-list,because elv_attempt_insert_merge only support backmerge,not supporting frontmerge. So rq[7493120 + 24] can't merge with rq[7493144 + 104]. From my test,i found those situation can count 25% in our system. Using this patch, there is no this situation. Signed-off-by: Jianpeng Ma CC:Shaohua Li Signed-off-by: Jens Axboe

block: remove CONFIG_EXPERIMENTAL

2012-10-23T20:30:34Z

This config item has not carried much meaning for a while now and is almost always enabled by default. As agreed during the Linux kernel summit, remove it. CC: Jens Axboe Signed-off-by: Kees Cook Signed-off-by: Jens Axboe

blkcg: stop iteration early if root_rl is the only request list

2012-10-22T20:00:26Z

__blk_queue_next_rl() finds next request list based on blkg_list while skipping root_blkg in the list. OTOH, root_rl is special as it may exist even without root_blkg. Though the later part of the function handles such a case correctly, exiting early is good for readability of the code. Signed-off-by: Jun'ichi Nomura Cc: Tejun Heo Acked-by: Vivek Goyal Signed-off-by: Jens Axboe

blkcg: Fix use-after-free of q->root_blkg and q->root_rl.blkg

2012-10-22T20:00:26Z

blk_put_rl() does not call blkg_put() for q->root_rl because we don't take request list reference on q->root_blkg. However, if root_blkg is once attached then detached (freed), blk_put_rl() is confused by the bogus pointer in q->root_blkg. For example, with !CONFIG_BLK_DEV_THROTTLING && CONFIG_CFQ_GROUP_IOSCHED, switching IO scheduler from cfq to deadline will cause system stall after the following warning with 3.6: > WARNING: at /work/build/linux/block/blk-cgroup.h:250 > blk_put_rl+0x4d/0x95() > Modules linked in: bridge stp llc sunrpc acpi_cpufreq freq_table mperf > ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 > Pid: 0, comm: swapper/0 Not tainted 3.6.0 #1 > Call Trace: > [] warn_slowpath_common+0x85/0x9d > [] warn_slowpath_null+0x1a/0x1c > [] blk_put_rl+0x4d/0x95 > [] __blk_put_request+0xc3/0xcb > [] blk_finish_request+0x232/0x23f > [] ? blk_end_bidi_request+0x34/0x5d > [] blk_end_bidi_request+0x42/0x5d > [] blk_end_request+0x10/0x12 > [] scsi_io_completion+0x207/0x4d5 > [] scsi_finish_command+0xfa/0x103 > [] scsi_softirq_done+0xff/0x108 > [] blk_done_softirq+0x8d/0xa1 > [] ? > generic_smp_call_function_single_interrupt+0x9f/0xd7 > [] __do_softirq+0x102/0x213 > [] ? lock_release_holdtime+0xb6/0xbb > [] ? raise_softirq_irqoff+0x9/0x3d > [] call_softirq+0x1c/0x30 > [] do_softirq+0x4b/0xa3 > [] irq_exit+0x53/0xd5 > [] smp_call_function_single_interrupt+0x34/0x36 > [] call_function_single_interrupt+0x6f/0x80 > [] ? mwait_idle+0x94/0xcd > [] ? mwait_idle+0x8b/0xcd > [] cpu_idle+0xbb/0x114 > [] rest_init+0xc1/0xc8 > [] ? csum_partial_copy_generic+0x16c/0x16c > [] start_kernel+0x3d4/0x3e1 > [] ? kernel_init+0x1f7/0x1f7 > [] x86_64_start_reservations+0xb8/0xbd > [] x86_64_start_kernel+0x101/0x110 This patch clears q->root_blkg and q->root_rl.blkg when root blkg is destroyed. Signed-off-by: Jun'ichi Nomura Acked-by: Vivek Goyal Acked-by: Tejun Heo Cc: stable@kernel.org Signed-off-by: Jens Axboe

Merge branch 'for-3.7/core' of git://git.kernel.dk/linux-block

2012-10-11T00:04:23Z

Pull block IO update from Jens Axboe: "Core block IO bits for 3.7. Not a huge round this time, it contains: - First series from Kent cleaning up and generalizing bio allocation and freeing. - WRITE_SAME support from Martin. - Mikulas patches to prevent O_DIRECT crashes when someone changes the block size of a device. - Make bio_split() work on data-less bio's (like trim/discards). - A few other minor fixups." Fixed up silent semantic mis-merge as per Mikulas Patocka and Andrew Morton. It is due to the VM no longer using a prio-tree (see commit 6b2dbba8b6ac: "mm: replace vma prio_tree with an interval tree"). So make set_blocksize() use mapping_mapped() instead of open-coding the internal VM knowledge that has changed. * 'for-3.7/core' of git://git.kernel.dk/linux-block: (26 commits) block: makes bio_split support bio without data scatterlist: refactor the sg_nents scatterlist: add sg_nents fs: fix include/percpu-rwsem.h export error percpu-rw-semaphore: fix documentation typos fs/block_dev.c:1644:5: sparse: symbol 'blkdev_mmap' was not declared blockdev: turn a rw semaphore into a percpu rw semaphore Fix a crash when block device is read and block size is changed at the same time block: fix request_queue->flags initialization block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue() block: ioctl to zero block ranges block: Make blkdev_issue_zeroout use WRITE SAME block: Implement support for WRITE SAME block: Consolidate command flag and queue limit checks for merges block: Clean up special command handling logic block/blk-tag.c: Remove useless kfree block: remove the duplicated setting for congestion_threshold block: reject invalid queue attribute values block: Add bio_clone_bioset(), bio_clone_kmalloc() block: Consolidate bio_alloc_bioset(), bio_kmalloc() ...

Merge branch 'for-3.7-hierarchy' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2012-10-02T17:52:28Z

Pull cgroup hierarchy update from Tejun Heo: "Currently, different cgroup subsystems handle nested cgroups completely differently. There's no consistency among subsystems and the behaviors often are outright broken. People at least seem to agree that the broken hierarhcy behaviors need to be weeded out if any progress is gonna be made on this front and that the fallouts from deprecating the broken behaviors should be acceptable especially given that the current behaviors don't make much sense when nested. This patch makes cgroup emit warning messages if cgroups for subsystems with broken hierarchy behavior are nested to prepare for fixing them in the future. This was put in a separate branch because more related changes were expected (didn't make it this round) and the memory cgroup wanted to pull in this and make changes on top." * 'for-3.7-hierarchy' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: mark subsystems with broken hierarchy support and whine if cgroups are nested for them

Merge branch 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

2012-10-02T16:54:49Z

Pull workqueue changes from Tejun Heo: "This is workqueue updates for v3.7-rc1. A lot of activities this round including considerable API and behavior cleanups. * delayed_work combines a timer and a work item. The handling of the timer part has always been a bit clunky leading to confusing cancelation API with weird corner-case behaviors. delayed_work is updated to use new IRQ safe timer and cancelation now works as expected. * Another deficiency of delayed_work was lack of the counterpart of mod_timer() which led to cancel+queue combinations or open-coded timer+work usages. mod_delayed_work[_on]() are added. These two delayed_work changes make delayed_work provide interface and behave like timer which is executed with process context. * A work item could be executed concurrently on multiple CPUs, which is rather unintuitive and made flush_work() behavior confusing and half-broken under certain circumstances. This problem doesn't exist for non-reentrant workqueues. While non-reentrancy check isn't free, the overhead is incurred only when a work item bounces across different CPUs and even in simulated pathological scenario the overhead isn't too high. All workqueues are made non-reentrant. This removes the distinction between flush_[delayed_]work() and flush_[delayed_]_work_sync(). The former is now as strong as the latter and the specified work item is guaranteed to have finished execution of any previous queueing on return. * In addition to the various bug fixes, Lai redid and simplified CPU hotplug handling significantly. * Joonsoo introduced system_highpri_wq and used it during CPU hotplug. There are two merge commits - one to pull in IRQ safe timer from tip/timers/core and the other to pull in CPU hotplug fixes from wq/for-3.6-fixes as Lai's hotplug restructuring depended on them." Fixed a number of trivial conflicts, but the more interesting conflicts were silent ones where the deprecated interfaces had been used by new code in the merge window, and thus didn't cause any real data conflicts. Tejun pointed out a few of them, I fixed a couple more. * 'for-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: (46 commits) workqueue: remove spurious WARN_ON_ONCE(in_irq()) from try_to_grab_pending() workqueue: use cwq_set_max_active() helper for workqueue_set_max_active() workqueue: introduce cwq_set_max_active() helper for thaw_workqueues() workqueue: remove @delayed from cwq_dec_nr_in_flight() workqueue: fix possible stall on try_to_grab_pending() of a delayed work item workqueue: use hotcpu_notifier() for workqueue_cpu_down_callback() workqueue: use __cpuinit instead of __devinit for cpu callbacks workqueue: rename manager_mutex to assoc_mutex workqueue: WORKER_REBIND is no longer necessary for idle rebinding workqueue: WORKER_REBIND is no longer necessary for busy rebinding workqueue: reimplement idle worker rebinding workqueue: deprecate __cancel_delayed_work() workqueue: reimplement cancel_delayed_work() using try_to_grab_pending() workqueue: use mod_delayed_work() instead of __cancel + queue workqueue: use irqsafe timer for delayed_work workqueue: clean up delayed_work initializers and add missing one workqueue: make deferrable delayed_work initializer names consistent workqueue: cosmetic whitespace updates for macro definitions workqueue: deprecate system_nrt[_freezable]_wq workqueue: deprecate flush[_delayed]_work_sync() ...

s390/partitions: make partition detection independent from DASD ioctls

2012-09-26T13:45:05Z

In some usage scenarios it is desireable to work with disk images or virtualized DASD devices. One problem that prevents such applications is the partition detection in ibm.c. Currently it works only for devices that support the BIODASDINFO2 ioctl, in other words, it only works for devices that belong to the DASD device driver. The information gained from the BIODASDINFO2 ioctl is only for a small set of legacy cases abolutely necessary. All current VOL1, LNX1 and CMS1 type of disk labels can be interpreted correctly without this information, as long as the generic HDIO_GETGEO ioctl works and provides a correct disk geometry. This patch makes the ibm.c partition detection as independent as possible from the BIODASDINFO2 ioctl. Only the following two cases are still restricted to real DASDs: - An FBA DASD, or LDL formatted ECKD DASD without any disk label. - An old style LNX1 label (without large volume support) on a disk with inconsistent device geometry. Signed-off-by: Stefan Weinhuber Signed-off-by: Martin Schwidefsky

block: fix request_queue->flags initialization

2012-09-21T13:33:12Z

A queue newly allocated with blk_alloc_queue_node() has only QUEUE_FLAG_BYPASS set. For request-based drivers, blk_init_allocated_queue() is called and q->queue_flags is overwritten with QUEUE_FLAG_DEFAULT which doesn't include BYPASS even though the initial bypass is still in effect. In blk_init_allocated_queue(), or QUEUE_FLAG_DEFAULT to q->queue_flags instead of overwriting. Signed-off-by: Tejun Heo Cc: stable@vger.kernel.org Acked-by: Vivek Goyal Signed-off-by: Jens Axboe

block: lift the initial queue bypass mode on blk_register_queue() instead of blk_init_allocated_queue()

2012-09-21T13:32:57Z

b82d4b197c ("blkcg: make request_queue bypassing on allocation") made request_queues bypassed on allocation to avoid switching on and off bypass mode on a queue being initialized. Some drivers allocate and then destroy a lot of queues without fully initializing them and incurring bypass latency overhead on each of them could add upto significant overhead. Unfortunately, blk_init_allocated_queue() is never used by queues of bio-based drivers, which means that all bio-based driver queues are in bypass mode even after initialization and registration complete successfully. Due to the limited way request_queues are used by bio drivers, this problem is hidden pretty well but it shows up when blk-throttle is used in combination with a bio-based driver. Trying to configure (echoing to cgroupfs file) blk-throttle for a bio-based driver hangs indefinitely in blkg_conf_prep() waiting for bypass mode to end. This patch moves the initial blk_queue_bypass_end() call from blk_init_allocated_queue() to blk_register_queue() which is called for any userland-visible queues regardless of its type. I believe this is correct because I don't think there is any block driver which needs or wants working elevator and blk-cgroup on a queue which isn't visible to userland. If there are such users, we need a different solution. Signed-off-by: Tejun Heo Reported-by: Joseph Glanville Cc: stable@vger.kernel.org Acked-by: Vivek Goyal Signed-off-by: Jens Axboe