linux/drivers/block/null_blk.c, branch v4.4

null_blk: use async queue restart helper

2015-12-28T20:07:09Z

If null_blk is run in NULL_IRQ_TIMER mode and with queue_mode NULL_Q_RQ, we need to restart the queue from the hrtimer interrupt. We can't directly invoke the request_fn from that context, so punt the queue run to async kblockd context. Tested-by: Rabin Vincent Signed-off-by: Jens Axboe

null_blk: fix use-after-free error

2015-12-22T17:42:48Z

blk_end_request_all may free request, so we need to save request_queue pointer before blk_end_request_all call. The problem was introduced in commit cf8ecc5a8455266f8d51 ("null_blk: guarantee device restart in all irq modes") and causes general protection fault with slab poisoning enabled. Fixes: cf8ecc5a8455266f8d51 ("null_blk: guarantee device restart in all irq modes") Signed-off-by: Mike Krinkin Reviewed-by: Ming Lei Signed-off-by: Jens Axboe

null_blk: Fix error path in module initialization

2015-12-08T20:47:34Z

Module couldn't release resource properly during the initialization. To fix this issue, we will clean up the proper resource before returning. Signed-off-by: Minfei Huang Signed-off-by: Jens Axboe

lightnvm: replace req queue with nvmdev for lld

2015-12-07T16:14:19Z

In the case where a request queue is passed to the low lever lightnvm device drive integration, the device driver might pass its admin commands through another queue. Instead pass nvm_dev, and let the low level drive the appropriate queue. Reported-by: Christoph Hellwig Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

null_blk: change type of completion_nsec to unsigned long

2015-12-01T17:52:12Z

This commit at least doubles the maximum value for completion_nsec. This helps in special cases where one wants/needs to emulate an extremely slow I/O (for example to spot bugs). Signed-off-by: Paolo Valente Signed-off-by: Arianna Avanzini Signed-off-by: Jens Axboe

null_blk: guarantee device restart in all irq modes

2015-12-01T17:52:10Z

In single-queue (block layer) mode,the function null_rq_prep_fn stops the device if alloc_cmd fails. Then, once stopped, the device must be restarted on the next command completion, so that the request(s) for which alloc_cmd failed can be requeued. Otherwise the device hangs. Unfortunately, device restart is currently performed only for delayed completions, i.e., in irqmode==2. This fact causes hangs, for the above reasons, with the other irqmodes in combination with single-queue block layer. This commits addresses this issue by making sure that, if stopped, the device is properly restarted for all irqmodes on completions. Signed-off-by: Paolo Valente Signed-off-by: Arianna AVanzini Signed-off-by: Jens Axboe

null_blk: set a separate timer for each command

2015-12-01T17:52:08Z

For the Timer IRQ mode (i.e., when command completions are delayed), there is one timer for each CPU. Each of these timers . has a completion queue associated with it, containing all the command completions to be executed when the timer fires; . is set, and a new completion-to-execute is inserted into its completion queue, every time the dispatch code for a new command happens to be executed on the CPU related to the timer. This implies that, if the dispatch of a new command happens to be executed on a CPU whose timer has already been set, but has not yet fired, then the timer is set again, to the completion time of the newly arrived command. When the timer eventually fires, all its queued completions are executed. This way of handling delayed command completions entails the following problem: if more than one command completion is inserted into the queue of a timer before the timer fires, then the expiration time for the timer is moved forward every time each of these completions is enqueued. As a consequence, only the last completion enqueued enjoys a correct execution time, while all previous completions are unjustly delayed until the last completion is executed (and at that time they are executed all together). Specifically, if all the above completions are enqueued almost at the same time, then the problem is negligible. On the opposite end, if every completion is enqueued a while after the previous completion was enqueued (in the extreme case, it is enqueued only right before the timer would have expired), then every enqueued completion, except for the last one, experiences an inflated delay, proportional to the number of completions enqueued after it. In the end, commands, and thus I/O requests, may be completed at an arbitrarily lower rate than the desired one. This commit addresses this issue by replacing per-CPU timers with per-command timers, i.e., by associating an individual timer with each command. Signed-off-by: Paolo Valente Signed-off-by: Arianna Avanzini Signed-off-by: Jens Axboe

null_blk: do not del gendisk with lightnvm

2015-11-19T22:15:56Z

The gendisk structure has not been initialized when using lightnvm. Make sure to not delete it upon exit. Also make sure that we use the appropriate disk_name at unregistration. Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

null_blk: use device addressing mode

2015-11-19T22:15:54Z

The linear addressing mode was removed in 7386af2. Make null_blk instead expose the ppa format geometry and support the generic addressing mode. Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe

null_blk: use ppa_cache pool

2015-11-19T22:15:53Z

Instead of using a page pool, we can save memory by only allocating room for 64 entries for the ppa command. Introduce a ppa_cache to allocate only the required memory for the ppa list. Signed-off-by: Matias Bjørling Signed-off-by: Jens Axboe