blk-iocost: use spin_lock_irqsave in adjust_inuse_and_calc_cost

In the Linux kernel, the following vulnerability has been resolved:

blk-iocost: use spin_lock_irqsave in adjust_inuse_and_calc_cost

adjust_inuse_and_calc_cost() use spin_lock_irq() and IRQ will be enabled
when unlock. DEADLOCK might happen if we have held other locks and disabled
IRQ before invoking it.

Fix it by using spin_lock_irqsave() instead, which can keep IRQ state
consistent with before when unlock.

================================
WARNING: inconsistent lock state
5.10.0-02758-g8e5f91fd772f #26 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
kworker/2:3/388 [HC0[0]:SC0[0]:HE0:SE1] takes:
ffff888118c00c28 (&bfqd->lock){?.-.}-{2:2}, at: spin_lock_irq
ffff888118c00c28 (&bfqd->lock){?.-.}-{2:2}, at: bfq_bio_merge+0x141/0x390
{IN-HARDIRQ-W} state was registered at:
__lock_acquire+0x3d7/0x1070
lock_acquire+0x197/0x4a0
__raw_spin_lock_irqsave
_raw_spin_lock_irqsave+0x3b/0x60
bfq_idle_slice_timer_body
bfq_idle_slice_timer+0x53/0x1d0
__run_hrtimer+0x477/0xa70
__hrtimer_run_queues+0x1c6/0x2d0
hrtimer_interrupt+0x302/0x9e0
local_apic_timer_interrupt
__sysvec_apic_timer_interrupt+0xfd/0x420
run_sysvec_on_irqstack_cond
sysvec_apic_timer_interrupt+0x46/0xa0
asm_sysvec_apic_timer_interrupt+0x12/0x20
irq event stamp: 837522
hardirqs last enabled at (837521): [<ffffffff84b9419d>] __raw_spin_unlock_irqrestore
hardirqs last enabled at (837521): [<ffffffff84b9419d>] _raw_spin_unlock_irqrestore+0x3d/0x40
hardirqs last disabled at (837522): [<ffffffff84b93fa3>] __raw_spin_lock_irq
hardirqs last disabled at (837522): [<ffffffff84b93fa3>] _raw_spin_lock_irq+0x43/0x50
softirqs last enabled at (835852): [<ffffffff84e00558>] __do_softirq+0x558/0x8ec
softirqs last disabled at (835845): [<ffffffff84c010ff>] asm_call_irq_on_stack+0xf/0x20

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&bfqd->lock);
<Interrupt>
lock(&bfqd->lock);

*** DEADLOCK ***

3 locks held by kworker/2:3/388:
#0: ffff888107af0f38 ((wq_completion)kthrotld){+.+.}-{0:0}, at: process_one_work+0x742/0x13f0
#1: ffff8881176bfdd8 ((work_completion)(&td->dispatch_work)){+.+.}-{0:0}, at: process_one_work+0x777/0x13f0
#2: ffff888118c00c28 (&bfqd->lock){?.-.}-{2:2}, at: spin_lock_irq
#2: ffff888118c00c28 (&bfqd->lock){?.-.}-{2:2}, at: bfq_bio_merge+0x141/0x390

stack backtrace:
CPU: 2 PID: 388 Comm: kworker/2:3 Not tainted 5.10.0-02758-g8e5f91fd772f #26
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Workqueue: kthrotld blk_throtl_dispatch_work_fn
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x107/0x167
print_usage_bug
valid_state
mark_lock_irq.cold+0x32/0x3a
mark_lock+0x693/0xbc0
mark_held_locks+0x9e/0xe0
__trace_hardirqs_on_caller
lockdep_hardirqs_on_prepare.part.0+0x151/0x360
trace_hardirqs_on+0x5b/0x180
__raw_spin_unlock_irq
_raw_spin_unlock_irq+0x24/0x40
spin_unlock_irq
adjust_inuse_and_calc_cost+0x4fb/0x970
ioc_rqos_merge+0x277/0x740
__rq_qos_merge+0x62/0xb0
rq_qos_merge
bio_attempt_back_merge+0x12c/0x4a0
blk_mq_sched_try_merge+0x1b6/0x4d0
bfq_bio_merge+0x24a/0x390
__blk_mq_sched_bio_merge+0xa6/0x460
blk_mq_sched_bio_merge
blk_mq_submit_bio+0x2e7/0x1ee0
__submit_bio_noacct_mq+0x175/0x3b0
submit_bio_noacct+0x1fb/0x270
blk_throtl_dispatch_work_fn+0x1ef/0x2b0
process_one_work+0x83e/0x13f0
process_scheduled_works
worker_thread+0x7e3/0xd80
kthread+0x353/0x470
ret_from_fork+0x1f/0x30