linux/include
Damien Le Moal 737eb78e82 block: Delay default elevator initialization
When elevator_init_mq() is called from blk_mq_init_allocated_queue(),
the only information known about the device is the number of hardware
queues as the block device scan by the device driver is not completed
yet for most drivers. The device type and elevator required features
are not set yet, preventing to correctly select the default elevator
most suitable for the device.

This currently affects all multi-queue zoned block devices which default
to the "none" elevator instead of the required "mq-deadline" elevator.
These drives currently include host-managed SMR disks connected to a
smartpqi HBA and null_blk block devices with zoned mode enabled.
Upcoming NVMe Zoned Namespace devices will also be affected.

Fix this by adding the boolean elevator_init argument to
blk_mq_init_allocated_queue() to control the execution of
elevator_init_mq(). Two cases exist:
1) elevator_init = false is used for calls to
   blk_mq_init_allocated_queue() within blk_mq_init_queue(). In this
   case, a call to elevator_init_mq() is added to __device_add_disk(),
   resulting in the delayed initialization of the queue elevator
   after the device driver finished probing the device information. This
   effectively allows elevator_init_mq() access to more information
   about the device.
2) elevator_init = true preserves the current behavior of initializing
   the elevator directly from blk_mq_init_allocated_queue(). This case
   is used for the special request based DM devices where the device
   gendisk is created before the queue initialization and device
   information (e.g. queue limits) is already known when the queue
   initialization is executed.

Additionally, to make sure that the elevator initialization is never
done while requests are in-flight (there should be none when the device
driver calls device_add_disk()), freeze and quiesce the device request
queue before calling blk_mq_init_sched() in elevator_init_mq().

Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05 19:52:34 -06:00
..
acpi It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
asm-generic asm-generic: fix -Wtype-limits compiler warnings 2019-08-03 07:02:01 -07:00
clocksource
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2019-07-08 20:57:08 -07:00
drm drm/fb-helper: Instanciate shadow FB if configured in device's mode_config 2019-08-01 15:01:35 +02:00
dt-bindings ARM: Device-tree updates 2019-07-19 17:19:24 -07:00
keys request_key improvements 2019-07-08 19:19:37 -07:00
kvm
linux block: Delay default elevator initialization 2019-09-05 19:52:34 -06:00
math-emu
media media updates for v5.3-rc1 2019-07-09 09:47:22 -07:00
misc powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
net tcp: be more careful in tcp_fragment() 2019-07-21 20:41:24 -07:00
pcmcia It's been a relatively busy cycle for docs: 2019-07-09 12:34:26 -07:00
ras
rdma RDMA/devices: Remove the lock around remove_client_context 2019-08-01 11:44:48 -04:00
scsi scsi: fcoe: Embed fc_rport_priv in fcoe_rport structure 2019-07-29 21:12:35 -04:00
soc Merge branch 'pdf_fixes_v1' of https://git.linuxtv.org/mchehab/experimental into mauro 2019-07-22 13:51:20 -06:00
sound SPDX fixes for 5.3-rc2 2019-07-28 10:00:06 -07:00
target
trace writeback: don't access page->mapping directly in track_foreign_dirty TP 2019-08-30 19:54:28 -06:00
uapi virtio, vhost: bugfixes 2019-07-29 11:34:12 -07:00
vdso
video drm main pull request for v5.3-rc1 (sans mm changes) 2019-07-15 19:04:27 -07:00
xen xen: avoid link error on ARM 2019-07-31 08:14:12 +02:00
Kbuild kbuild: add net/netfilter/nf_tables_offload.h to header-test blacklist. 2019-07-21 11:43:43 -07:00