kernel/block, branch linux-4.3.y

block: ensure to split after potentially bouncing a bio

2016-02-19T22:28:23Z

commit 23688bf4f830a89866fd0ed3501e342a7360fe4f upstream. blk_queue_bio() does split then bounce, which makes the segment counting based on pages before bouncing and could go wrong. Move the split to after bouncing, like we do for blk-mq, and the we fix the issue of having the bio count for segments be wrong. Fixes: 54efd50bfd87 ("block: make generic_make_request handle arbitrarily sized bios") Tested-by: Artem S. Tashkinov Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: Always check queue limits for cloned requests

2016-02-19T22:28:22Z

commit bf4e6b4e757488dee1b6a581f49c7ac34cd217f8 upstream. When a cloned request is retried on other queues it always needs to be checked against the queue limits of that queue. Otherwise the calculations for nr_phys_segments might be wrong, leading to a crash in scsi_init_sgtable(). To clarify this the patch renames blk_rq_check_limits() to blk_cloned_rq_check_limits() and removes the symbol export, as the new function should only be used for cloned requests and never exported. Cc: Mike Snitzer Cc: Ewan Milne Cc: Jeff Moyer Signed-off-by: Hannes Reinecke Fixes: e2a60da74 ("block: Clean up special command handling logic") Acked-by: Mike Snitzer Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: fix segment split

2015-12-15T05:41:09Z

commit 578270bfbd2803dc7b0b03fbc2ac119efbc73195 upstream. Inside blk_bio_segment_split(), previous bvec pointer(bvprvp) always points to the iterator local variable, which is obviously wrong, so fix it by pointing to the local variable of 'bvprv'. Fixes: 5014c311baa2b(block: fix bogus compiler warnings in blk-merge.c) Reported-by: Michael Ellerman Reported-by: Mark Salter Tested-by: Laurent Dufour Tested-by: Mark Salter Signed-off-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: re-add discard_granularity and alignment checks

2015-10-28T00:12:58Z

In commit b49a087("block: remove split code in blkdev_issue_{discard,write_same}"), discard_granularity and alignment checks were removed. Ideally, with bio late splitting, the upper layers shouldn't need to depend on device's limits. Christoph reported a discard regression on the HGST Ultrastar SN100 NVMe device when mkfs.xfs. We have not found the root cause yet. This patch re-adds discard_granularity and alignment checks by reverting the related changes in commit b49a087. The good thing is now we can remove the 2G discard size cap and just use UINT_MAX to avoid bi_size overflow. Reviewed-by: Christoph Hellwig Tested-by: Christoph Hellwig Signed-off-by: Ming Lin Reviewed-by: Mike Snitzer Signed-off-by: Jens Axboe

block: don't release bdi while request_queue has live references

2015-10-15T15:53:28Z

bdi's are initialized in two steps, bdi_init() and bdi_register(), but destroyed in a single step by bdi_destroy() which, for a bdi embedded in a request_queue, is called during blk_cleanup_queue() which makes the queue invisible and starts the draining of remaining usages. A request_queue's user can access the congestion state of the embedded bdi as long as it holds a reference to the queue. As such, it may access the congested state of a queue which finished blk_cleanup_queue() but hasn't reached blk_release_queue() yet. Because the congested state was embedded in backing_dev_info which in turn is embedded in request_queue, accessing the congested state after bdi_destroy() was called was fine. The bdi was destroyed but the memory region for the congested state remained accessible till the queue got released. a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") changed the situation. Now, the root congested state which is expected to be pinned while request_queue remains accessible is separately reference counted and the base ref is put during bdi_destroy(). This means that the root congested state may go away prematurely while the queue is between bdi_dstroy() and blk_cleanup_queue(), which was detected by Andrey's KASAN tests. The root cause of this problem is that bdi doesn't distinguish the two steps of destruction, unregistration and release, and now the root congested state actually requires a separate release step. To fix the issue, this patch separates out bdi_unregister() and bdi_exit() from bdi_destroy(). bdi_unregister() is called from blk_cleanup_queue() and bdi_exit() from blk_release_queue(). bdi_destroy() is now just a simple wrapper calling the two steps back-to-back. While at it, the prototype of bdi_destroy() is moved right below bdi_setup_and_register() so that the counterpart operations are located together. Signed-off-by: Tejun Heo Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") Cc: stable@vger.kernel.org # v4.2+ Reported-and-tested-by: Andrey Konovalov Link: http://lkml.kernel.org/g/CAAeHK+zUJ74Zn17=rOyxacHU18SgCfC6bsYW=6kCY5GXJBwGfQ@mail.gmail.com Reviewed-by: Jan Kara Reviewed-by: Jeff Moyer Signed-off-by: Jens Axboe

blk-mq: fix use-after-free in blk_mq_free_tag_set()

2015-10-15T14:45:58Z

tags is freed in blk_mq_free_rq_map() and should not be used after that. The problem doesn't manifest if CONFIG_CPUMASK_OFFSTACK is false because free_cpumask_var() is nop. tags->cpumask is allocated in blk_mq_init_tags() so it's natural to free cpumask in its counter part, blk_mq_free_tags(). Fixes: f26cdc8536ad ("blk-mq: Shared tag enhancements") Signed-off-by: Jun'ichi Nomura Cc: Keith Busch Reviewed-by: Jeff Moyer Signed-off-by: Jens Axboe

blk-mq: factor out a helper to iterate all tags for a request_queue

2015-10-01T08:10:57Z

And replace the blk_mq_tag_busy_iter with it - the driver use has been replaced with a new helper a while ago, and internal to the block we only need the new version. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe

blk-mq: fix racy updates of rq->errors

2015-10-01T08:10:55Z

blk_mq_complete_request may be a no-op if the request has already been completed by others means (e.g. a timeout or cancellation), but currently drivers have to set rq->errors before calling blk_mq_complete_request, which might leave us with the wrong error value. Add an error parameter to blk_mq_complete_request so that we can defer setting rq->errors until we known we won the race to complete the request. Signed-off-by: Christoph Hellwig Reviewed-by: Sagi Grimberg Signed-off-by: Jens Axboe

blk-mq: fix deadlock when reading cpu_list

2015-09-29T17:32:51Z

CPU hotplug handling for blk-mq (blk_mq_queue_reinit) acquires all_q_mutex in blk_mq_queue_reinit_notify() and then removes sysfs entries by blk_mq_sysfs_unregister(). Removing sysfs entry needs to be blocked until the active reference of the kernfs_node to be zero. On the other hand, reading blk_mq_hw_sysfs_cpu sysfs entry (e.g. /sys/block/nullb0/mq/0/cpu_list) acquires all_q_mutex in blk_mq_hw_sysfs_cpus_show(). If these happen at the same time, a deadlock can happen. Because one can wait for the active reference to be zero with holding all_q_mutex, and the other tries to acquire all_q_mutex with holding the active reference. The reason that all_q_mutex is acquired in blk_mq_hw_sysfs_cpus_show() is to avoid reading an imcomplete hctx->cpumask. Since reading sysfs entry for blk-mq needs to acquire q->sysfs_lock, we can avoid deadlock and reading an imcomplete hctx->cpumask by protecting q->sysfs_lock while hctx->cpumask is being updated. Signed-off-by: Akinobu Mita Reviewed-by: Ming Lei Cc: Ming Lei Cc: Wanpeng Li Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe

blk-mq: avoid inserting requests before establishing new mapping

2015-09-29T17:32:50Z

Notifier callbacks for CPU_ONLINE action can be run on the other CPU than the CPU which was just onlined. So it is possible for the process running on the just onlined CPU to insert request and run hw queue before establishing new mapping which is done by blk_mq_queue_reinit_notify(). This can cause a problem when the CPU has just been onlined first time since the request queue was initialized. At this time ctx->index_hw for the CPU, which is the index in hctx->ctxs[] for this ctx, is still zero before blk_mq_queue_reinit_notify() is called by notifier callbacks for CPU_ONLINE action. For example, there is a single hw queue (hctx) and two CPU queues (ctx0 for CPU0, and ctx1 for CPU1). Now CPU1 is just onlined and a request is inserted into ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is still zero. And then while running hw queue, flush_busy_ctxs() finds bit0 is set in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is ignored. Fix it by ensuring that new mapping is established before onlined cpu starts running. Signed-off-by: Akinobu Mita Reviewed-by: Ming Lei Cc: Jens Axboe Cc: Ming Lei Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe