user/sven/linux.git/block/elevator.c, branch v4.14.328

elevator: lookup mq vs non-mq elevators

2018-12-21T13:13:10Z

[ Upstream commit 2527d99789e248576ac8081530cd4fd88730f8c7 ] If an IO scheduler is selected via elevator= and it doesn't match the driver in question wrt blk-mq support, then we fail to boot. The elevator= parameter is deprecated and only supported for non-mq devices. Augment the elevator lookup API so that we pass in if we're looking for an mq capable scheduler or not, so that we only ever return a valid type for the queue in question. Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=196695 Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin

block: fix warning when I/O elevator is changed as request_queue is being removed

2017-08-28T16:52:44Z

There is a race between changing I/O elevator and request_queue removal which can trigger the warning in kobject_add_internal. A program can use sysfs to request a change of elevator at the same time another task is unregistering the request_queue the elevator would be attached to. The elevator's kobject will then attempt to be connected to the request_queue in the object tree when the request_queue has just been removed from sysfs. This triggers the warning in kobject_add_internal as the request_queue no longer has a sysfs directory: kobject_add_internal failed for iosched (error: -2 parent: queue) ------------[ cut here ]------------ WARNING: CPU: 3 PID: 14075 at lib/kobject.c:244 kobject_add_internal+0x103/0x2d0 To fix this warning, we can check the QUEUE_FLAG_REGISTERED flag when changing the elevator and use the request_queue's sysfs_lock to serialize between clearing the flag and the elevator testing the flag. Signed-off-by: David Jeffery Tested-by: Ming Lei Reviewed-by: Ming Lei Signed-off-by: Jens Axboe

block: Add fallthrough markers to switch statements

2017-06-21T17:46:07Z

This patch suppresses gcc 7 warnings about falling through in switch statements when building with W=1. From the gcc documentation: The -Wimplicit-fallthrough=3 warning is enabled by -Wextra. See also https://gcc.gnu.org/onlinedocs/gcc-7.1.0/gcc/Warning-Options.html. Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe

elevator: remove redundant warnings on IO scheduler switch

2017-05-10T13:40:04Z

We warn twice for switching to a scheduler, if that switch fails. As we also report the failure in the return value to the sysfs write, remove the dmesg induced failures. Keep the failure print for warning to switch to the kconfig selected IO scheduler, as we can't report errors for that in any other way. Signed-off-by: Jens Axboe

block: don't call blk_mq_quiesce_queue() after queue is frozen

2017-05-02T17:33:08Z

After queue is frozen, no request in this queue can be in use at all, so there can't be any .queue_rq() running on this queue. It isn't necessary to call blk_mq_quiesce_queue() any more, so remove it in both elevator_switch_mq() and blk_mq_update_nr_requests(). Cc: Bart Van Assche Signed-off-by: Ming Lei Fixed up the description a bit. Signed-off-by: Jens Axboe

block: Remove elevator_change()

2017-05-02T13:52:08Z

Since commit 84253394927c ("remove the mg_disk driver") removed the only caller of elevator_change(), also remove the elevator_change() function itself. Signed-off-by: Bart Van Assche Cc: Christoph Hellwig Cc: Markus Trippelsdorf Signed-off-by: Jens Axboe

Merge branch 'for-4.12/block' of git://git.kernel.dk/linux-block

2017-05-01T17:39:57Z

Pull block layer updates from Jens Axboe: - Add BFQ IO scheduler under the new blk-mq scheduling framework. BFQ was initially a fork of CFQ, but subsequently changed to implement fairness based on B-WF2Q+, a modified variant of WF2Q. BFQ is meant to be used on desktop type single drives, providing good fairness. From Paolo. - Add Kyber IO scheduler. This is a full multiqueue aware scheduler, using a scalable token based algorithm that throttles IO based on live completion IO stats, similary to blk-wbt. From Omar. - A series from Jan, moving users to separately allocated backing devices. This continues the work of separating backing device life times, solving various problems with hot removal. - A series of updates for lightnvm, mostly from Javier. Includes a 'pblk' target that exposes an open channel SSD as a physical block device. - A series of fixes and improvements for nbd from Josef. - A series from Omar, removing queue sharing between devices on mostly legacy drivers. This helps us clean up other bits, if we know that a queue only has a single device backing. This has been overdue for more than a decade. - Fixes for the blk-stats, and improvements to unify the stats and user windows. This both improves blk-wbt, and enables other users to register a need to receive IO stats for a device. From Omar. - blk-throttle improvements from Shaohua. This provides a scalable framework for implementing scalable priotization - particularly for blk-mq, but applicable to any type of block device. The interface is marked experimental for now. - Bucketized IO stats for IO polling from Stephen Bates. This improves efficiency of polled workloads in the presence of mixed block size IO. - A few fixes for opal, from Scott. - A few pulls for NVMe, including a lot of fixes for NVMe-over-fabrics. From a variety of folks, mostly Sagi and James Smart. - A series from Bart, improving our exposed info and capabilities from the blk-mq debugfs support. - A series from Christoph, cleaning up how handle WRITE_ZEROES. - A series from Christoph, cleaning up the block layer handling of how we track errors in a request. On top of being a nice cleanup, it also shrinks the size of struct request a bit. - Removal of mg_disk and hd (sorry Linus) by Christoph. The former was never used by platforms, and the latter has outlived it's usefulness. - Various little bug fixes and cleanups from a wide variety of folks. * 'for-4.12/block' of git://git.kernel.dk/linux-block: (329 commits) block: hide badblocks attribute by default blk-mq: unify hctx delay_work and run_work block: add kblock_mod_delayed_work_on() blk-mq: unify hctx delayed_run_work and run_work nbd: fix use after free on module unload MAINTAINERS: bfq: Add Paolo as maintainer for the BFQ I/O scheduler blk-mq-sched: alloate reserved tags out of normal pool mtip32xx: use runtime tag to initialize command header scsi: Implement blk_mq_ops.show_rq() blk-mq: Add blk_mq_ops.show_rq() blk-mq: Show operation, cmd_flags and rq_flags names blk-mq: Make blk_flags_show() callers append a newline character blk-mq: Move the "state" debugfs attribute one level down blk-mq: Unregister debugfs attributes earlier blk-mq: Only unregister hctxs for which registration succeeded blk-mq-debugfs: Rename functions for registering and unregistering the mq directory blk-mq: Let blk_mq_debugfs_register() look up the queue name blk-mq: Register /queue/mq after having registered /queue ide-pm: always pass 0 error to ide_complete_rq in ide_do_devset ide-pm: always pass 0 error to __blk_end_request_all ..

block: respect BLK_MQ_F_NO_SCHED

2017-04-19T20:15:43Z

If one driver claims that it doesn't support io scheduler via BLK_MQ_F_NO_SCHED, we should not allow to change and show the availabe io schedulers. This patch adds check to enhance this behaviour. Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

block: Make writeback throttling defaults consistent for SQ devices

2017-04-19T14:49:03Z

When CFQ is used as an elevator, it disables writeback throttling because they don't play well together. Later when a different elevator is chosen for the device, writeback throttling doesn't get enabled again as it should. Make sure CFQ enables writeback throttling (if it should be enabled by default) when we switch from it to another IO scheduler. Signed-off-by: Jan Kara Signed-off-by: Jens Axboe

blk-mq-sched: fix crash in switch error path

2017-04-07T14:56:48Z

In elevator_switch(), if blk_mq_init_sched() fails, we attempt to fall back to the original scheduler. However, at this point, we've already torn down the original scheduler's tags, so this causes a crash. Doing the fallback like the legacy elevator path is much harder for mq, so fix it by just falling back to none, instead. Signed-off-by: Omar Sandoval Signed-off-by: Jens Axboe