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* Merge branch 'for-3.18/core' of git://git.kernel.dk/linux-blockLinus Torvalds2014-10-181-177/+187
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull core block layer changes from Jens Axboe: "This is the core block IO pull request for 3.18. Apart from the new and improved flush machinery for blk-mq, this is all mostly bug fixes and cleanups. - blk-mq timeout updates and fixes from Christoph. - Removal of REQ_END, also from Christoph. We pass it through the ->queue_rq() hook for blk-mq instead, freeing up one of the request bits. The space was overly tight on 32-bit, so Martin also killed REQ_KERNEL since it's no longer used. - blk integrity updates and fixes from Martin and Gu Zheng. - Update to the flush machinery for blk-mq from Ming Lei. Now we have a per hardware context flush request, which both cleans up the code should scale better for flush intensive workloads on blk-mq. - Improve the error printing, from Rob Elliott. - Backing device improvements and cleanups from Tejun. - Fixup of a misplaced rq_complete() tracepoint from Hannes. - Make blk_get_request() return error pointers, fixing up issues where we NULL deref when a device goes bad or missing. From Joe Lawrence. - Prep work for drastically reducing the memory consumption of dm devices from Junichi Nomura. This allows creating clone bio sets without preallocating a lot of memory. - Fix a blk-mq hang on certain combinations of queue depths and hardware queues from me. - Limit memory consumption for blk-mq devices for crash dump scenarios and drivers that use crazy high depths (certain SCSI shared tag setups). We now just use a single queue and limited depth for that" * 'for-3.18/core' of git://git.kernel.dk/linux-block: (58 commits) block: Remove REQ_KERNEL blk-mq: allocate cpumask on the home node bio-integrity: remove the needless fail handle of bip_slab creating block: include func name in __get_request prints block: make blk_update_request print prefix match ratelimited prefix blk-merge: don't compute bi_phys_segments from bi_vcnt for cloned bio block: fix alignment_offset math that assumes io_min is a power-of-2 blk-mq: Make bt_clear_tag() easier to read blk-mq: fix potential hang if rolling wakeup depth is too high block: add bioset_create_nobvec() block: use bio_clone_fast() in blk_rq_prep_clone() block: misplaced rq_complete tracepoint sd: Honor block layer integrity handling flags block: Replace strnicmp with strncasecmp block: Add T10 Protection Information functions block: Don't merge requests if integrity flags differ block: Integrity checksum flag block: Relocate bio integrity flags block: Add a disk flag to block integrity profile block: Add prefix to block integrity profile flags ...
| * blk-mq: allocate cpumask on the home nodeJens Axboe2014-10-131-1/+2
| | | | | | | | | | | | | | | | All other allocs are done on the specific node, somehow the cpumask for hw queue runs was missed. Fix that by using zalloc_cpumask_var_node() in blk_mq_init_queue(). Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: support per-distpatch_queue flush machineryMing Lei2014-09-251-26/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch supports to run one single flush machinery for each blk-mq dispatch queue, so that: - current init_request and exit_request callbacks can cover flush request too, then the buggy copying way of initializing flush request's pdu can be fixed - flushing performance gets improved in case of multi hw-queue In fio sync write test over virtio-blk(4 hw queues, ioengine=sync, iodepth=64, numjobs=4, bs=4K), it is observed that througput gets increased a lot over my test environment: - throughput: +70% in case of virtio-blk over null_blk - throughput: +30% in case of virtio-blk over SSD image The multi virtqueue feature isn't merged to QEMU yet, and patches for the feature can be found in below tree: git://kernel.ubuntu.com/ming/qemu.git v2.1.0-mq.4 And simply passing 'num_queues=4 vectors=5' should be enough to enable multi queue(quad queue) feature for QEMU virtio-blk. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: introduce 'blk_mq_ctx' parameter to blk_get_flush_queueMing Lei2014-09-251-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds 'blk_mq_ctx' parameter to blk_get_flush_queue(), so that this function can find the corresponding blk_flush_queue bound with current mq context since the flush queue will become per hw-queue. For legacy queue, the parameter can be simply 'NULL'. For multiqueue case, the parameter should be set as the context from which the related request is originated. With this context info, the hw queue and related flush queue can be found easily. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: remove blk_init_flush() and its pairMing Lei2014-09-251-1/+2
| | | | | | | | | | | | | | | | Now mission of the two helpers is over, and just call blk_alloc_flush_queue() and blk_free_flush_queue() directly. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: introduce blk_flush_queue to drive flush machineryMing Lei2014-09-251-4/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces 'struct blk_flush_queue' and puts all flush machinery related fields into this structure, so that - flush implementation details aren't exposed to driver - it is easy to convert to per dispatch-queue flush machinery This patch is basically a mechanical replacement. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: introduce blk_init_flush and its pairMing Lei2014-09-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | These two temporary functions are introduced for holding flush initialization and de-initialization, so that we can introduce 'flush queue' easier in the following patch. And once 'flush queue' and its allocation/free functions are ready, they will be removed for sake of code readability. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: allocate flush_rq in blk_mq_init_flush()Ming Lei2014-09-251-10/+6
| | | | | | | | | | | | | | | | It is reasonable to allocate flush req in blk_mq_init_flush(). Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: handle failure path for initializing hctxMing Lei2014-09-251-45/+69
| | | | | | | | | | | | | | | | | | | | Failure of initializing one hctx isn't handled, so this patch introduces blk_mq_init_hctx() and its pair to handle it explicitly. Also this patch makes code cleaner. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: fix blk_abort_request on blk-mqChristoph Hellwig2014-09-221-1/+1
| | | | | | | | | | | | | | | | Signed-off-by: Christoph Hellwig <hch@lst.de> Moved blk_mq_rq_timed_out() definition to the private blk-mq.h header. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: limit memory consumption if a crash dump is activeJens Axboe2014-09-221-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's not uncommon for crash dump kernels to be limited to 128MB or something low in that area. This is normally not a problem for devices as we don't use that much memory, but for some shared SCSI setups with huge queue depths, it can potentially fill most of memory with tons of request allocations. blk-mq does scale back when it fails to allocate memory, but it scales back just enough so that blk-mq succeeds. This could still leave the system with not enough memory to make any real progress. Check if we are in a kdump environment and limit the hardware queues and tag depth. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: remove unnecessary blk_clear_rq_complete()Ming Lei2014-09-221-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch removes two unnecessary blk_clear_rq_complete(), the REQ_ATOM_COMPLETE flag is cleared inside blk_mq_start_request(), so: - The blk_clear_rq_complete() in blk_flush_restore_request() needn't because the request will be freed later, and clearing it here may open a small race window with timeout. - The blk_clear_rq_complete() in blk_mq_requeue_request() isn't necessary too, even though REQ_ATOM_STARTED is cleared in __blk_mq_requeue_request(), in theory it still may cause a small race window with timeout since the two clear_bit() may be reordered. Signed-off-by: Ming Lei <ming.lei@canoical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: pass a reserved argument to the timeout handlerChristoph Hellwig2014-09-221-3/+3
| | | | | | | | | | | | | | | | | | Allow blk-mq to pass an argument to the timeout handler to indicate if we're timing out a reserved or regular command. For many drivers those need to be handled different. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: unshared timeout handlerChristoph Hellwig2014-09-221-16/+37
| | | | | | | | | | | | | | | | | | Duplicate the (small) timeout handler in blk-mq so that we can pass arguments more easily to the driver timeout handler. This enables the next patch. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: fix and simplify tag iteration for the timeout handlerChristoph Hellwig2014-09-221-60/+25
| | | | | | | | | | | | | | | | | | | | | | | | Don't do a kmalloc from timer to handle timeouts, chances are we could be under heavy load or similar and thus just miss out on the timeouts. Fortunately it is very easy to just iterate over all in use tags, and doing this properly actually cleans up the blk_mq_busy_iter API as well, and prepares us for the next patch by passing a reserved argument to the iterator. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: rename blk_mq_end_io to blk_mq_end_requestChristoph Hellwig2014-09-221-8/+8
| | | | | | | | | | | | | | | | | | Now that we've changed the driver API on the submission side use the opportunity to fix up the name on the completion side to fit into the general scheme. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: call blk_mq_start_request from ->queue_rqChristoph Hellwig2014-09-221-7/+6
| | | | | | | | | | | | | | | | | | | | | | | | When we call blk_mq_start_request from the core blk-mq code before calling into ->queue_rq there is a racy window where the timeout handler can hit before we've fully set up the driver specific part of the command. Move the call to blk_mq_start_request into the driver so the driver can start the request only once it is fully set up. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: remove REQ_ENDChristoph Hellwig2014-09-221-17/+5
| | | | | | | | | | | | | | | | | | | | Pass an explicit parameter for the last request in a batch to ->queue_rq instead of using a request flag. Besides being a cleaner and non-stateful interface this is also required for the next patch, which fixes the blk-mq I/O submission code to not start a time too early. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * Merge branch 'for-linus' into for-3.18/coreJens Axboe2014-09-221-11/+17
| |\ | | | | | | | | | | | | Moving patches from for-linus to 3.18 instead, pull in this changes that will go to Linus today.
| * \ Merge branch 'for-linus' into for-3.18/coreJens Axboe2014-09-111-33/+94
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A bit of churn on the for-linus side that would be nice to have in the core bits for 3.18, so pull it in to catch us up and make forward progress easier. Signed-off-by: Jens Axboe <axboe@fb.com> Conflicts: block/scsi_ioctl.c
| * | | block,scsi: fixup blk_get_request dead queue scenariosJoe Lawrence2014-08-281-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The blk_get_request function may fail in low-memory conditions or during device removal (even if __GFP_WAIT is set). To distinguish between these errors, modify the blk_get_request call stack to return the appropriate ERR_PTR. Verify that all callers check the return status and consider IS_ERR instead of a simple NULL pointer check. For consistency, make a similar change to the blk_mq_alloc_request leg of blk_get_request. It may fail if the queue is dead, or the caller was unwilling to wait. Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd] Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd] Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | | | blk-mq, percpu_ref: start q->mq_usage_counter in atomic modeTejun Heo2014-09-241-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk-mq uses percpu_ref for its usage counter which tracks the number of in-flight commands and used to synchronously drain the queue on freeze. percpu_ref shutdown takes measureable wallclock time as it involves a sched RCU grace period. This means that draining a blk-mq takes measureable wallclock time. One would think that this shouldn't matter as queue shutdown should be a rare event which takes place asynchronously w.r.t. userland. Unfortunately, SCSI probing involves synchronously setting up and then tearing down a lot of request_queues back-to-back for non-existent LUNs. This means that SCSI probing may take above ten seconds when scsi-mq is used. [ 0.949892] scsi host0: Virtio SCSI HBA [ 1.007864] scsi 0:0:0:0: Direct-Access QEMU QEMU HARDDISK 1.1. PQ: 0 ANSI: 5 [ 1.021299] scsi 0:0:1:0: Direct-Access QEMU QEMU HARDDISK 1.1. PQ: 0 ANSI: 5 [ 1.520356] tsc: Refined TSC clocksource calibration: 2491.910 MHz <stall> [ 16.186549] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 16.190478] sd 0:0:1:0: Attached scsi generic sg1 type 0 [ 16.194099] osd: LOADED open-osd 0.2.1 [ 16.203202] sd 0:0:0:0: [sda] 31457280 512-byte logical blocks: (16.1 GB/15.0 GiB) [ 16.208478] sd 0:0:0:0: [sda] Write Protect is off [ 16.211439] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 16.218771] sd 0:0:1:0: [sdb] 31457280 512-byte logical blocks: (16.1 GB/15.0 GiB) [ 16.223264] sd 0:0:1:0: [sdb] Write Protect is off [ 16.225682] sd 0:0:1:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA This is also the reason why request_queues start in bypass mode which is ended on blk_register_queue() as shutting down a fully functional queue also involves a RCU grace period and the queues for non-existent SCSI devices never reach registration. blk-mq basically needs to do the same thing - start the mq in a degraded mode which is faster to shut down and then make it fully functional only after the queue reaches registration. percpu_ref recently grew facilities to force atomic operation until explicitly switched to percpu mode, which can be used for this purpose. This patch makes blk-mq initialize q->mq_usage_counter in atomic mode and switch it to percpu mode only once blk_register_queue() is reached. Note that this issue was previously worked around by 0a30288da1ae ("blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe") for v3.17. The temp fix was reverted in preparation of adding persistent atomic mode to percpu_ref by 9eca80461a45 ("Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe""). This patch and the prerequisite percpu_ref changes will be merged during v3.18 devel cycle. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Christoph Hellwig <hch@infradead.org> Link: http://lkml.kernel.org/g/20140919113815.GA10791@lst.de Fixes: add703fda981 ("blk-mq: use percpu_ref for mq usage count") Reviewed-by: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Johannes Weiner <hannes@cmpxchg.org>
* | | | percpu_ref: add PERCPU_REF_INIT_* flagsTejun Heo2014-09-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | With the recent addition of percpu_ref_reinit(), percpu_ref now can be used as a persistent switch which can be turned on and off repeatedly where turning off maps to killing the ref and waiting for it to drain; however, there currently isn't a way to initialize a percpu_ref in its off (killed and drained) state, which can be inconvenient for certain persistent switch use cases. Similarly, percpu_ref_switch_to_atomic/percpu() allow dynamic selection of operation mode; however, currently a newly initialized percpu_ref is always in percpu mode making it impossible to avoid the latency overhead of switching to atomic mode. This patch adds @flags to percpu_ref_init() and implements the following flags. * PERCPU_REF_INIT_ATOMIC : start ref in atomic mode * PERCPU_REF_INIT_DEAD : start ref killed and drained These flags should be able to serve the above two use cases. v2: target_core_tpg.c conversion was missing. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org>
* | | | Revert "blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during ↵Tejun Heo2014-09-241-10/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | probe" This reverts commit 0a30288da1aec914e158c2d7a3482a85f632750f, which was a temporary fix for SCSI blk-mq stall issue. The following patches will fix the issue properly by introducing atomic mode to percpu_ref. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@lst.de>
* | | | Merge branch 'for-linus' of ↵Tejun Heo2014-09-241-43/+119
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block into for-3.18 This is to receive 0a30288da1ae ("blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe") which implements __percpu_ref_kill_expedited() to work around SCSI blk-mq stall. The commit reverted and patches to implement proper fix will be added. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@lst.de>
| * | | | blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probeTejun Heo2014-09-241-1/+10
| | |_|/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk-mq uses percpu_ref for its usage counter which tracks the number of in-flight commands and used to synchronously drain the queue on freeze. percpu_ref shutdown takes measureable wallclock time as it involves a sched RCU grace period. This means that draining a blk-mq takes measureable wallclock time. One would think that this shouldn't matter as queue shutdown should be a rare event which takes place asynchronously w.r.t. userland. Unfortunately, SCSI probing involves synchronously setting up and then tearing down a lot of request_queues back-to-back for non-existent LUNs. This means that SCSI probing may take more than ten seconds when scsi-mq is used. This will be properly fixed by implementing a mechanism to keep q->mq_usage_counter in atomic mode till genhd registration; however, that involves rather big updates to percpu_ref which is difficult to apply late in the devel cycle (v3.17-rc6 at the moment). As a stop-gap measure till the proper fix can be implemented in the next cycle, this patch introduces __percpu_ref_kill_expedited() and makes blk_mq_freeze_queue() use it. This is heavy-handed but should work for testing the experimental SCSI blk-mq implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Christoph Hellwig <hch@infradead.org> Link: http://lkml.kernel.org/g/20140919113815.GA10791@lst.de Fixes: add703fda981 ("blk-mq: use percpu_ref for mq usage count") Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Tested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | blk-mq: use blk_mq_start_hw_queues() when running requeue workJens Axboe2014-09-221-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When requests are retried due to hw or sw resource shortages, we often stop the associated hardware queue. So ensure that we restart the queues when running the requeue work, otherwise the queue run will be a no-op. Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | blk-mq: fix potential oops on out-of-memory in __blk_mq_alloc_rq_maps()Jens Axboe2014-09-221-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | __blk_mq_alloc_rq_maps() can be invoked multiple times, if we scale back the queue depth if we are low on memory. So don't clear set->tags when we fail, this is handled directly in the parent function, blk_mq_alloc_tag_set(). Reported-by: Robert Elliott <Elliott@hp.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | blk-mq: avoid infinite recursion with the FUA flagChristoph Hellwig2014-09-221-8/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We should not insert requests into the flush state machine from blk_mq_insert_request. All incoming flush requests come through blk_{m,s}q_make_request and are handled there, while blk_execute_rq_nowait should only be called for BLOCK_PC requests. All other callers deal with requests that already went through the flush statemchine and shouldn't be reinserted into it. Reported-by: Robert Elliott <Elliott@hp.com> Debugged-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | blk-mq: Avoid race condition with uninitialized requestsDavid Hildenbrand2014-09-221-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch should fix the bug reported in https://lkml.org/lkml/2014/9/11/249. We have to initialize at least the atomic_flags and the cmd_flags when allocating storage for the requests. Otherwise blk_mq_timeout_check() might dereference uninitialized pointers when racing with the creation of a request. Also move the reset of cmd_flags for the initializing code to the point where a request is freed. So we will never end up with pending flush request indicators that might trigger dereferences of invalid pointers in blk_mq_timeout_check(). Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Reported-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> Tested-by: Paulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | | blk-mq: request deadline must be visible before marking rq as startedJens Axboe2014-09-221-0/+6
| | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When we start the request, we set the deadline and flip the bits marking the request as started and non-complete. However, it's important that the deadline store is ordered before flipping the bits, otherwise we could have a small window where the request is marked started but with an invalid deadline. This can confuse the timeout handling. Suggested-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: scale depth and rq map appropriate if low on memoryJens Axboe2014-09-101-19/+69
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we are running in a kdump environment, resources are scarce. For some SCSI setups with a huge set of shared tags, we run out of memory allocating what the drivers is asking for. So implement a scale back logic to reduce the tag depth for those cases, allowing the driver to successfully load. We should extend this to detect low memory situations, and implement a sane fallback for those (1 queue, 64 tags, or something like that). Tested-by: Robert Elliott <elliott@hp.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: cleanup after blk_mq_init_rq_map failuresRobert Elliott2014-09-031-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In blk-mq.c blk_mq_alloc_tag_set, if: set->tags = kmalloc_node() succeeds, but one of the blk_mq_init_rq_map() calls fails, goto out_unwind; needs to free set->tags so the caller is not obligated to do so. None of the current callers (null_blk, virtio_blk, virtio_blk, or the forthcoming scsi-mq) do so. set->tags needs to be set to NULL after doing so, so other tag cleanup logic doesn't try to free a stale pointer later. Also set it to NULL in blk_mq_free_tag_set. Tested with error injection on the forthcoming scsi-mq + hpsa combination. Signed-off-by: Robert Elliott <elliott@hp.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | scsi-mq: fix requests that use a separate CDB bufferTony Battersby2014-08-221-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes code such as the following with scsi-mq enabled: rq = blk_get_request(...); blk_rq_set_block_pc(rq); rq->cmd = my_cmd_buffer; /* separate CDB buffer */ blk_execute_rq_nowait(...); Code like this appears in e.g. sg_start_req() in drivers/scsi/sg.c (for large CDBs only). Without this patch, scsi_mq_prep_fn() will set rq->cmd back to rq->__cmd, causing the wrong CDB to be sent to the device. Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: blk_mq_freeze_queue() should allow nestingTejun Heo2014-08-211-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | While converting to percpu_ref for freezing, add703fda981 ("blk-mq: use percpu_ref for mq usage count") incorrectly made blk_mq_freeze_queue() misbehave when freezing is nested due to percpu_ref_kill() being invoked on an already killed ref. Fix it by making blk_mq_freeze_queue() kill and kick the queue only for the outermost freeze attempt. All the nested ones can simply wait for the ref to reach zero. While at it, remove unnecessary @wake initialization from blk_mq_unfreeze_queue(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: correct a few wrong/bad commentsJens Axboe2014-08-211-3/+3
| | | | | | | | | | | | | | | | | | Just grammar or spelling errors, nothing major. Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: don't allow merges if turned off for the queueJens Axboe2014-08-211-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk-mq uses BLK_MQ_F_SHOULD_MERGE, as set by the driver at init time, to determine whether it should merge IO or not. However, this could also be disabled by the admin, if merging is switched off through sysfs. So check the general queue state as well before attempting to merge IO. Reported-by: Rob Elliott <Elliott@hp.com> Tested-by: Rob Elliott <Elliott@hp.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * | blk-mq: fix WARNING "percpu_ref_kill() called more than once!"Ming Lei2014-08-151-4/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | | | Before doing queue release, the queue has been freezed already by blk_cleanup_queue(), so needn't to freeze queue for deleting tag set. This patch fixes the WARNING of "percpu_ref_kill() called more than once!" which is triggered during unloading block driver. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* / percpu-refcount: add @gfp to percpu_ref_init()Tejun Heo2014-09-081-1/+2
|/ | | | | | | | | | | | | | | | | Percpu allocator now supports allocation mask. Add @gfp to percpu_ref_init() so that !GFP_KERNEL allocation masks can be used with percpu_refs too. This patch doesn't make any functional difference. v2: blk-mq conversion was missing. Updated. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kent Overstreet <koverstreet@google.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Jens Axboe <axboe@kernel.dk>
* blk-mq: use percpu_ref for mq usage countTejun Heo2014-07-011-39/+29
| | | | | | | | | | | | | | | | | | | | | | | | | Currently, blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism. This type of code has relatively high chance of subtle bugs which are extremely difficult to trigger and it's way too hairy to be open coded in blk-mq. percpu_ref can serve the same purpose after the recent changes. This patch replaces the open-coded per-cpu usage counting and draining mechanism with percpu_ref. blk_mq_queue_enter() performs tryget_live on the ref and exit() performs put. blk_mq_freeze_queue() kills the ref and waits until the reference count reaches zero. blk_mq_unfreeze_queue() revives the ref and wakes up the waiters. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Kent Overstreet <kmo@daterainc.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: collapse __blk_mq_drain_queue() into blk_mq_freeze_queue()Tejun Heo2014-07-011-14/+9
| | | | | | | | | | | | | Keeping __blk_mq_drain_queue() as a separate function doesn't buy us anything and it's gonna be further simplified. Let's flatten it into its caller. This patch doesn't make any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: decouble blk-mq freezing from generic bypassingTejun Heo2014-07-011-11/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk_mq freezing is entangled with generic bypassing which bypasses blkcg and io scheduler and lets IO requests fall through the block layer to the drivers in FIFO order. This allows forward progress on IOs with the advanced features disabled so that those features can be configured or altered without worrying about stalling IO which may lead to deadlock through memory allocation. However, generic bypassing doesn't quite fit blk-mq. blk-mq currently doesn't make use of blkcg or ioscheds and it maps bypssing to freezing, which blocks request processing and drains all the in-flight ones. This causes problems as bypassing assumes that request processing is online. blk-mq works around this by conditionally allowing request processing for the problem case - during queue initialization. Another weirdity is that except for during queue cleanup, bypassing started on the generic side prevents blk-mq from processing new requests but doesn't drain the in-flight ones. This shouldn't break anything but again highlights that something isn't quite right here. The root cause is conflating blk-mq freezing and generic bypassing which are two different mechanisms. The only intersecting purpose that they serve is during queue cleanup. Let's properly separate blk-mq freezing from generic bypassing and simply use it where necessary. * request_queue->mq_freeze_depth is added and blk_mq_[un]freeze_queue() now operate on this counter instead of ->bypass_depth. The replacement for QUEUE_FLAG_BYPASS isn't added but the counter is tested directly. This will be further updated by later changes. * blk_mq_drain_queue() is dropped and "__" prefix is dropped from blk_mq_freeze_queue(). Queue cleanup path now calls blk_mq_freeze_queue() directly. * blk_queue_enter()'s fast path condition is simplified to simply check @q->mq_freeze_depth. Previously, the condition was !blk_queue_dying(q) && (!blk_queue_bypass(q) || !blk_queue_init_done(q)) mq_freeze_depth is incremented right after dying is set and blk_queue_init_done() exception isn't necessary as blk-mq doesn't start frozen, which only leaves the blk_queue_bypass() test which can be replaced by @q->mq_freeze_depth test. This change simplifies the code and reduces confusion in the area. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* block, blk-mq: draining can't be skipped even if bypass_depth was non-zeroTejun Heo2014-07-011-5/+2
| | | | | | | | | | | | | | | | | | | | | | Currently, both blk_queue_bypass_start() and blk_mq_freeze_queue() skip queue draining if bypass_depth was already above zero. The assumption is that the one which bumped the bypass_depth should have performed draining already; however, there's nothing which prevents a new instance of bypassing/freezing from starting before the previous one finishes draining. The current code may allow the later bypassing/freezing instances to complete while there still are in-flight requests which haven't finished draining. Fix it by draining regardless of bypass_depth. We still skip draining from blk_queue_bypass_start() while the queue is initializing to avoid introducing excessive delays during boot. INIT_DONE setting is moved above the initial blk_queue_bypass_end() so that bypassing attempts can't slip inbetween. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix a memory ordering bug in blk_mq_queue_enter()Tejun Heo2014-07-011-1/+1
| | | | | | | | | | | | | | | | | | | | | blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism; unfortunately, it contains a subtle bug - smp_wmb() in blk_mq_queue_enter() doesn't prevent prevent the cpu from fetching @q->bypass_depth before incrementing @q->mq_usage_counter and if freezing happens inbetween the caller can slip through and freezing can be complete while there are active users. Use smp_mb() instead so that bypass_depth and mq_usage_counter modifications and tests are properly interlocked. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: blk_mq_start_hw_queue() should use blk_mq_run_hw_queue()Jens Axboe2014-06-251-1/+1
| | | | | | | | | | | | | | Currently it calls __blk_mq_run_hw_queue(), which depends on the CPU placement being correct. This means it's not possible to call blk_mq_start_hw_queues(q) from a context that is correct for all queues, leading to triggering the WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)); in __blk_mq_run_hw_queue(). Reported-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: merge blk_mq_drain_queue and __blk_mq_drain_queueChristoph Hellwig2014-06-131-7/+2
| | | | | Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: properly drain stopped queuesChristoph Hellwig2014-06-131-1/+1
| | | | | | | | | | | | | If we need to drain a queue we need to run all queues, even if they are marked stopped to make sure the driver has a chance to error out on all queued requests. This fixes surprise removal with scsi-mq. Reported-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: add timer in blk_mq_start_requestMing Lei2014-06-091-16/+1
| | | | | | | | | | | | | This way will become consistent with non-mq case, also avoid to update rq->deadline twice for mq. The comment said: "We do this early, to ensure we are on the right CPU.", but no percpu stuff is used in blk_add_timer(), so it isn't necessary. Even when inserting from plug list, there is no such guarantee at all. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: always initialize request->start_timeJens Axboe2014-06-091-3/+2
| | | | | | | | | | The blk-mq core only initializes this if io stats are enabled, since blk-mq only reads the field in that case. But drivers could potentially use it internally, so ensure that we always set it to the current time when the request is allocated. Reported-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: ->timeout should be cleared in blk_mq_rq_ctx_init()Jens Axboe2014-06-061-0/+2
| | | | | | | | | | It'll be used in blk_mq_start_request() to set a potential timeout for the request, so clear it to zero at alloc time to ensure that we know if someone has set it or not. Fixes random early timeouts on NVMe testing. Signed-off-by: Jens Axboe <axboe@fb.com>
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