linux/block, branch v2.6.39

block: don't delay blk_run_queue_async

2011-05-18T10:24:03Z

Let's check a scenario: 1. blk_delay_queue(q, SCSI_QUEUE_DELAY); 2. blk_run_queue_async(); the second one will became a noop, because q->delay_work already has WORK_STRUCT_PENDING_BIT set, so the delayed work will still run after SCSI_QUEUE_DELAY. But blk_run_queue_async actually hopes the delayed work runs immediately. Fix this by doing a cancel on potentially pending delayed work before queuing an immediate run of the workqueue. Signed-off-by: Shaohua Li Signed-off-by: Jens Axboe

blk-throttle: Use task_subsys_state() to determine a task's blkio_cgroup

2011-05-16T13:24:08Z

Currentlly we first map the task to cgroup and then cgroup to blkio_cgroup. There is a more direct way to get to blkio_cgroup from task using task_subsys_state(). Use that. The real reason for the fix is that it also avoids a race in generic cgroup code. During remount/umount rebind_subsystems() is called and it can do following with and rcu protection. cgrp->subsys[i] = NULL; That means if somebody got hold of cgroup under rcu and then it tried to do cgroup->subsys[] to get to blkio_cgroup, it would get NULL which is wrong. I was running into this race condition with ltp running on a upstream derived kernel and that lead to crash. So ideally we should also fix cgroup generic code to wait for rcu grace period before setting pointer to NULL. Li Zefan is not very keen on introducing synchronize_wait() as he thinks it will slow down moun/remount/umount operations. So for the time being atleast fix the kernel crash by taking a more direct route to blkio_cgroup. One tester had reported a crash while running LTP on a derived kernel and with this fix crash is no more seen while the test has been running for over 6 days. Signed-off-by: Vivek Goyal Reviewed-by: Li Zefan Signed-off-by: Jens Axboe

block: don't propagate unlisted DISK_EVENTs to userland

2011-04-21T17:43:58Z

DISK_EVENT_MEDIA_CHANGE is used for both userland visible event and internal event for revalidation of removeable devices. Some legacy drivers don't implement proper event detection and continuously generate events under certain circumstances. For example, ide-cd generates media changed continuously if there's no media in the drive, which can lead to infinite loop of events jumping back and forth between the driver and userland event handler. This patch updates disk event infrastructure such that it never propagates events not listed in disk->events to userland. Those events are processed the same for internal purposes but uevent generation is suppressed. This also ensures that userland only gets events which are advertised in the @events sysfs node lowering risk of confusion. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

elevator: check for ELEVATOR_INSERT_SORT_MERGE in !elvpriv case too

2011-04-21T17:28:35Z

The sort insert is the one that goes to the IO scheduler. With the SORT_MERGE addition, we could bypass IO scheduler setup but still ask the IO scheduler to insert the request. This would cause an oops on switching IO schedulers through the sysfs interface, unless the disk just happened to be idle while it occured. Signed-off-by: Jens Axboe

block: Remove the extra check in queue_requests_store

2011-04-19T11:51:53Z

In queue_requests_store, the code looks like if (rl->count[BLK_RW_SYNC] >= q->nr_requests) { blk_set_queue_full(q, BLK_RW_SYNC); } else if (rl->count[BLK_RW_SYNC]+1 <= q->nr_requests) { blk_clear_queue_full(q, BLK_RW_SYNC); wake_up(&rl->wait[BLK_RW_SYNC]); } If we don't satify the situation of "if", we can get that rl->count[BLK_RW_SYNC} < q->nr_quests. It is the same as rl->count[BLK_RW_SYNC]+1 <= q->nr_requests. All the "else" should satisfy the "else if" check so it isn't needed actually. Signed-off-by: Tao Ma Signed-off-by: Jens Axboe

block, blk-sysfs: Fix an err return path in blk_register_queue()

2011-04-19T11:51:53Z

We do not call blk_trace_remove_sysfs() in err return path if kobject_add() fails. This path fixes it. Cc: stable@kernel.org Signed-off-by: Liu Yuan Signed-off-by: Jens Axboe

block: remove stale kerneldoc member from __blk_run_queue()

2011-04-19T11:34:14Z

We don't pass in a 'force_kblockd' anymore, get rid of the stsale comment. Reported-by: Mike Snitzer Signed-off-by: Jens Axboe

block: get rid of QUEUE_FLAG_REENTER

2011-04-19T11:32:46Z

We are currently using this flag to check whether it's safe to call into ->request_fn(). If it is set, we punt to kblockd. But we get a lot of false positives and excessive punts to kblockd, which hurts performance. The only real abuser of this infrastructure is SCSI. So export the async queue run and convert SCSI over to use that. There's room for improvement in that SCSI need not always use the async call, but this fixes our performance issue and they can fix that up in due time. Signed-off-by: Jens Axboe

cfq-iosched: read_lock() does not always imply rcu_read_lock()

2011-04-19T07:10:35Z

For some configurations of CONFIG_PREEMPT that is not true. So get rid of __call_for_each_cic() and always uses the explicitly rcu_read_lock() protected call_for_each_cic() instead. This fixes a potential bug related to IO scheduler removal or online switching. Thanks to Paul McKenney for clarifying this. Signed-off-by: Jens Axboe

block: kill blk_flush_plug_list() export

2011-04-18T20:06:57Z

With all drivers and file systems converted, we only have in-core use of this function. So remove the export. Reporteed-by: Christoph Hellwig Signed-off-by: Jens Axboe