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![Andrea Righi](/assets/img/avatar_default.png)
The timer callback used to evaluate if the latency is exceeded can be
executed after the corresponding disk has been released, causing the
following NULL pointer dereference:
[ 119.987108] BUG: kernel NULL pointer dereference, address: 0000000000000098
[ 119.987617] #PF: supervisor read access in kernel mode
[ 119.987971] #PF: error_code(0x0000) - not-present page
[ 119.988325] PGD 7c4a4067 P4D 7c4a4067 PUD 7bf63067 PMD 0
[ 119.988697] Oops: 0000 [#1] SMP NOPTI
[ 119.988959] CPU: 1 PID: 9353 Comm: cloud-init Not tainted 5.15-rc5+arighi #rc5+arighi
[ 119.989520] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[ 119.990055] RIP: 0010:wb_timer_fn+0x44/0x3c0
[ 119.990376] Code: 41 8b 9c 24 98 00 00 00 41 8b 94 24 b8 00 00 00 41 8b 84 24 d8 00 00 00 4d 8b 74 24 28 01 d3 01 c3 49 8b 44 24 60 48 8b 40 78 <4c> 8b b8 98 00 00 00 4d 85 f6 0f 84 c4 00 00 00 49 83 7c 24 30 00
[ 119.991578] RSP: 0000:ffffb5f580957da8 EFLAGS: 00010246
[ 119.991937] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
[ 119.992412] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88f476d7f780
[ 119.992895] RBP: ffffb5f580957dd0 R08: 0000000000000000 R09: 0000000000000000
[ 119.993371] R10: 0000000000000004 R11: 0000000000000002 R12: ffff88f476c84500
[ 119.993847] R13: ffff88f4434390c0 R14: 0000000000000000 R15: ffff88f4bdc98c00
[ 119.994323] FS: 00007fb90bcd9c00(0000) GS:ffff88f4bdc80000(0000) knlGS:0000000000000000
[ 119.994952] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 119.995380] CR2: 0000000000000098 CR3: 000000007c0d6000 CR4: 00000000000006e0
[ 119.995906] Call Trace:
[ 119.996130] ? blk_stat_free_callback_rcu+0x30/0x30
[ 119.996505] blk_stat_timer_fn+0x138/0x140
[ 119.996830] call_timer_fn+0x2b/0x100
[ 119.997136] __run_timers.part.0+0x1d1/0x240
[ 119.997470] ? kvm_clock_get_cycles+0x11/0x20
[ 119.997826] ? ktime_get+0x3e/0xa0
[ 119.998110] ? native_apic_msr_write+0x2c/0x30
[ 119.998456] ? lapic_next_event+0x20/0x30
[ 119.998779] ? clockevents_program_event+0x94/0xf0
[ 119.999150] run_timer_softirq+0x2a/0x50
[ 119.999465] __do_softirq+0xcb/0x26f
[ 119.999764] irq_exit_rcu+0x8c/0xb0
[ 120.000057] sysvec_apic_timer_interrupt+0x43/0x90
[ 120.000429] ? asm_sysvec_apic_timer_interrupt+0xa/0x20
[ 120.000836] asm_sysvec_apic_timer_interrupt+0x12/0x20
In this case simply return from the timer callback (no action
required) to prevent the NULL pointer dereference.
BugLink: https://bugs.launchpad.net/bugs/1947557
Link: https://lore.kernel.org/linux-mm/YWRNVTk9N8K0RMst@arighi-desktop/
Fixes: 34dbad5d26
("blk-stat: convert to callback-based statistics reporting")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Link: https://lore.kernel.org/r/YW6N2qXpBU3oc50q@arighi-desktop
Signed-off-by: Jens Axboe <axboe@kernel.dk>
858 lines
20 KiB
C
858 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* buffered writeback throttling. loosely based on CoDel. We can't drop
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* packets for IO scheduling, so the logic is something like this:
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*
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* - Monitor latencies in a defined window of time.
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* - If the minimum latency in the above window exceeds some target, increment
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* scaling step and scale down queue depth by a factor of 2x. The monitoring
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* window is then shrunk to 100 / sqrt(scaling step + 1).
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* - For any window where we don't have solid data on what the latencies
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* look like, retain status quo.
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* - If latencies look good, decrement scaling step.
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* - If we're only doing writes, allow the scaling step to go negative. This
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* will temporarily boost write performance, snapping back to a stable
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* scaling step of 0 if reads show up or the heavy writers finish. Unlike
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* positive scaling steps where we shrink the monitoring window, a negative
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* scaling step retains the default step==0 window size.
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*
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* Copyright (C) 2016 Jens Axboe
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*
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*/
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#include <linux/kernel.h>
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#include <linux/blk_types.h>
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#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/swap.h>
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#include "blk-wbt.h"
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#include "blk-rq-qos.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/wbt.h>
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static inline void wbt_clear_state(struct request *rq)
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{
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rq->wbt_flags = 0;
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}
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static inline enum wbt_flags wbt_flags(struct request *rq)
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{
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return rq->wbt_flags;
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}
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static inline bool wbt_is_tracked(struct request *rq)
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{
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return rq->wbt_flags & WBT_TRACKED;
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}
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static inline bool wbt_is_read(struct request *rq)
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{
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return rq->wbt_flags & WBT_READ;
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}
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enum {
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/*
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* Default setting, we'll scale up (to 75% of QD max) or down (min 1)
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* from here depending on device stats
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*/
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RWB_DEF_DEPTH = 16,
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/*
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* 100msec window
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*/
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RWB_WINDOW_NSEC = 100 * 1000 * 1000ULL,
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/*
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* Disregard stats, if we don't meet this minimum
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*/
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RWB_MIN_WRITE_SAMPLES = 3,
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/*
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* If we have this number of consecutive windows with not enough
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* information to scale up or down, scale up.
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*/
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RWB_UNKNOWN_BUMP = 5,
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};
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static inline bool rwb_enabled(struct rq_wb *rwb)
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{
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return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT &&
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rwb->wb_normal != 0;
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}
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static void wb_timestamp(struct rq_wb *rwb, unsigned long *var)
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{
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if (rwb_enabled(rwb)) {
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const unsigned long cur = jiffies;
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if (cur != *var)
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*var = cur;
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}
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}
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/*
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* If a task was rate throttled in balance_dirty_pages() within the last
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* second or so, use that to indicate a higher cleaning rate.
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*/
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static bool wb_recent_wait(struct rq_wb *rwb)
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{
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struct bdi_writeback *wb = &rwb->rqos.q->disk->bdi->wb;
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return time_before(jiffies, wb->dirty_sleep + HZ);
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}
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static inline struct rq_wait *get_rq_wait(struct rq_wb *rwb,
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enum wbt_flags wb_acct)
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{
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if (wb_acct & WBT_KSWAPD)
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return &rwb->rq_wait[WBT_RWQ_KSWAPD];
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else if (wb_acct & WBT_DISCARD)
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return &rwb->rq_wait[WBT_RWQ_DISCARD];
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return &rwb->rq_wait[WBT_RWQ_BG];
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}
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static void rwb_wake_all(struct rq_wb *rwb)
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{
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int i;
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for (i = 0; i < WBT_NUM_RWQ; i++) {
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struct rq_wait *rqw = &rwb->rq_wait[i];
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if (wq_has_sleeper(&rqw->wait))
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wake_up_all(&rqw->wait);
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}
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}
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static void wbt_rqw_done(struct rq_wb *rwb, struct rq_wait *rqw,
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enum wbt_flags wb_acct)
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{
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int inflight, limit;
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inflight = atomic_dec_return(&rqw->inflight);
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/*
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* wbt got disabled with IO in flight. Wake up any potential
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* waiters, we don't have to do more than that.
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*/
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if (unlikely(!rwb_enabled(rwb))) {
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rwb_wake_all(rwb);
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return;
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}
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/*
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* For discards, our limit is always the background. For writes, if
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* the device does write back caching, drop further down before we
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* wake people up.
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*/
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if (wb_acct & WBT_DISCARD)
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limit = rwb->wb_background;
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else if (rwb->wc && !wb_recent_wait(rwb))
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limit = 0;
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else
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limit = rwb->wb_normal;
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/*
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* Don't wake anyone up if we are above the normal limit.
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*/
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if (inflight && inflight >= limit)
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return;
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if (wq_has_sleeper(&rqw->wait)) {
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int diff = limit - inflight;
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if (!inflight || diff >= rwb->wb_background / 2)
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wake_up_all(&rqw->wait);
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}
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}
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static void __wbt_done(struct rq_qos *rqos, enum wbt_flags wb_acct)
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{
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struct rq_wb *rwb = RQWB(rqos);
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struct rq_wait *rqw;
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if (!(wb_acct & WBT_TRACKED))
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return;
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rqw = get_rq_wait(rwb, wb_acct);
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wbt_rqw_done(rwb, rqw, wb_acct);
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}
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/*
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* Called on completion of a request. Note that it's also called when
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* a request is merged, when the request gets freed.
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*/
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static void wbt_done(struct rq_qos *rqos, struct request *rq)
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{
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struct rq_wb *rwb = RQWB(rqos);
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if (!wbt_is_tracked(rq)) {
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if (rwb->sync_cookie == rq) {
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rwb->sync_issue = 0;
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rwb->sync_cookie = NULL;
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}
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if (wbt_is_read(rq))
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wb_timestamp(rwb, &rwb->last_comp);
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} else {
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WARN_ON_ONCE(rq == rwb->sync_cookie);
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__wbt_done(rqos, wbt_flags(rq));
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}
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wbt_clear_state(rq);
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}
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static inline bool stat_sample_valid(struct blk_rq_stat *stat)
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{
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/*
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* We need at least one read sample, and a minimum of
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* RWB_MIN_WRITE_SAMPLES. We require some write samples to know
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* that it's writes impacting us, and not just some sole read on
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* a device that is in a lower power state.
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*/
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return (stat[READ].nr_samples >= 1 &&
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stat[WRITE].nr_samples >= RWB_MIN_WRITE_SAMPLES);
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}
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static u64 rwb_sync_issue_lat(struct rq_wb *rwb)
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{
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u64 now, issue = READ_ONCE(rwb->sync_issue);
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if (!issue || !rwb->sync_cookie)
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return 0;
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now = ktime_to_ns(ktime_get());
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return now - issue;
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}
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enum {
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LAT_OK = 1,
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LAT_UNKNOWN,
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LAT_UNKNOWN_WRITES,
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LAT_EXCEEDED,
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};
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static int latency_exceeded(struct rq_wb *rwb, struct blk_rq_stat *stat)
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{
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struct backing_dev_info *bdi = rwb->rqos.q->disk->bdi;
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struct rq_depth *rqd = &rwb->rq_depth;
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u64 thislat;
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/*
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* If our stored sync issue exceeds the window size, or it
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* exceeds our min target AND we haven't logged any entries,
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* flag the latency as exceeded. wbt works off completion latencies,
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* but for a flooded device, a single sync IO can take a long time
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* to complete after being issued. If this time exceeds our
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* monitoring window AND we didn't see any other completions in that
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* window, then count that sync IO as a violation of the latency.
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*/
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thislat = rwb_sync_issue_lat(rwb);
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if (thislat > rwb->cur_win_nsec ||
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(thislat > rwb->min_lat_nsec && !stat[READ].nr_samples)) {
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trace_wbt_lat(bdi, thislat);
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return LAT_EXCEEDED;
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}
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/*
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* No read/write mix, if stat isn't valid
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*/
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if (!stat_sample_valid(stat)) {
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/*
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* If we had writes in this stat window and the window is
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* current, we're only doing writes. If a task recently
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* waited or still has writes in flights, consider us doing
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* just writes as well.
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*/
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if (stat[WRITE].nr_samples || wb_recent_wait(rwb) ||
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wbt_inflight(rwb))
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return LAT_UNKNOWN_WRITES;
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return LAT_UNKNOWN;
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}
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/*
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* If the 'min' latency exceeds our target, step down.
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*/
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if (stat[READ].min > rwb->min_lat_nsec) {
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trace_wbt_lat(bdi, stat[READ].min);
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trace_wbt_stat(bdi, stat);
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return LAT_EXCEEDED;
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}
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if (rqd->scale_step)
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trace_wbt_stat(bdi, stat);
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return LAT_OK;
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}
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static void rwb_trace_step(struct rq_wb *rwb, const char *msg)
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{
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struct backing_dev_info *bdi = rwb->rqos.q->disk->bdi;
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struct rq_depth *rqd = &rwb->rq_depth;
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trace_wbt_step(bdi, msg, rqd->scale_step, rwb->cur_win_nsec,
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rwb->wb_background, rwb->wb_normal, rqd->max_depth);
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}
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static void calc_wb_limits(struct rq_wb *rwb)
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{
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if (rwb->min_lat_nsec == 0) {
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rwb->wb_normal = rwb->wb_background = 0;
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} else if (rwb->rq_depth.max_depth <= 2) {
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rwb->wb_normal = rwb->rq_depth.max_depth;
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rwb->wb_background = 1;
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} else {
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rwb->wb_normal = (rwb->rq_depth.max_depth + 1) / 2;
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rwb->wb_background = (rwb->rq_depth.max_depth + 3) / 4;
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}
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}
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static void scale_up(struct rq_wb *rwb)
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{
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if (!rq_depth_scale_up(&rwb->rq_depth))
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return;
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calc_wb_limits(rwb);
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rwb->unknown_cnt = 0;
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rwb_wake_all(rwb);
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rwb_trace_step(rwb, tracepoint_string("scale up"));
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}
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static void scale_down(struct rq_wb *rwb, bool hard_throttle)
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{
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if (!rq_depth_scale_down(&rwb->rq_depth, hard_throttle))
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return;
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calc_wb_limits(rwb);
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rwb->unknown_cnt = 0;
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rwb_trace_step(rwb, tracepoint_string("scale down"));
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}
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static void rwb_arm_timer(struct rq_wb *rwb)
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{
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struct rq_depth *rqd = &rwb->rq_depth;
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if (rqd->scale_step > 0) {
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/*
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* We should speed this up, using some variant of a fast
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* integer inverse square root calculation. Since we only do
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* this for every window expiration, it's not a huge deal,
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* though.
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*/
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rwb->cur_win_nsec = div_u64(rwb->win_nsec << 4,
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int_sqrt((rqd->scale_step + 1) << 8));
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} else {
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/*
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* For step < 0, we don't want to increase/decrease the
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* window size.
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*/
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rwb->cur_win_nsec = rwb->win_nsec;
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}
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blk_stat_activate_nsecs(rwb->cb, rwb->cur_win_nsec);
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}
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static void wb_timer_fn(struct blk_stat_callback *cb)
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{
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struct rq_wb *rwb = cb->data;
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struct rq_depth *rqd = &rwb->rq_depth;
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unsigned int inflight = wbt_inflight(rwb);
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int status;
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if (!rwb->rqos.q->disk)
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return;
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status = latency_exceeded(rwb, cb->stat);
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trace_wbt_timer(rwb->rqos.q->disk->bdi, status, rqd->scale_step,
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inflight);
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/*
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* If we exceeded the latency target, step down. If we did not,
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* step one level up. If we don't know enough to say either exceeded
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* or ok, then don't do anything.
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*/
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switch (status) {
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case LAT_EXCEEDED:
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scale_down(rwb, true);
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break;
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case LAT_OK:
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scale_up(rwb);
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break;
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case LAT_UNKNOWN_WRITES:
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/*
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* We started a the center step, but don't have a valid
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* read/write sample, but we do have writes going on.
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* Allow step to go negative, to increase write perf.
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*/
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scale_up(rwb);
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break;
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case LAT_UNKNOWN:
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if (++rwb->unknown_cnt < RWB_UNKNOWN_BUMP)
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break;
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/*
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* We get here when previously scaled reduced depth, and we
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* currently don't have a valid read/write sample. For that
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* case, slowly return to center state (step == 0).
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*/
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if (rqd->scale_step > 0)
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scale_up(rwb);
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else if (rqd->scale_step < 0)
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scale_down(rwb, false);
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break;
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default:
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break;
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}
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/*
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* Re-arm timer, if we have IO in flight
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*/
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if (rqd->scale_step || inflight)
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rwb_arm_timer(rwb);
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}
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static void wbt_update_limits(struct rq_wb *rwb)
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{
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struct rq_depth *rqd = &rwb->rq_depth;
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rqd->scale_step = 0;
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rqd->scaled_max = false;
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rq_depth_calc_max_depth(rqd);
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calc_wb_limits(rwb);
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rwb_wake_all(rwb);
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}
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u64 wbt_get_min_lat(struct request_queue *q)
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{
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struct rq_qos *rqos = wbt_rq_qos(q);
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if (!rqos)
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return 0;
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return RQWB(rqos)->min_lat_nsec;
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}
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void wbt_set_min_lat(struct request_queue *q, u64 val)
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{
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struct rq_qos *rqos = wbt_rq_qos(q);
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|
if (!rqos)
|
|
return;
|
|
RQWB(rqos)->min_lat_nsec = val;
|
|
RQWB(rqos)->enable_state = WBT_STATE_ON_MANUAL;
|
|
wbt_update_limits(RQWB(rqos));
|
|
}
|
|
|
|
|
|
static bool close_io(struct rq_wb *rwb)
|
|
{
|
|
const unsigned long now = jiffies;
|
|
|
|
return time_before(now, rwb->last_issue + HZ / 10) ||
|
|
time_before(now, rwb->last_comp + HZ / 10);
|
|
}
|
|
|
|
#define REQ_HIPRIO (REQ_SYNC | REQ_META | REQ_PRIO)
|
|
|
|
static inline unsigned int get_limit(struct rq_wb *rwb, unsigned long rw)
|
|
{
|
|
unsigned int limit;
|
|
|
|
/*
|
|
* If we got disabled, just return UINT_MAX. This ensures that
|
|
* we'll properly inc a new IO, and dec+wakeup at the end.
|
|
*/
|
|
if (!rwb_enabled(rwb))
|
|
return UINT_MAX;
|
|
|
|
if ((rw & REQ_OP_MASK) == REQ_OP_DISCARD)
|
|
return rwb->wb_background;
|
|
|
|
/*
|
|
* At this point we know it's a buffered write. If this is
|
|
* kswapd trying to free memory, or REQ_SYNC is set, then
|
|
* it's WB_SYNC_ALL writeback, and we'll use the max limit for
|
|
* that. If the write is marked as a background write, then use
|
|
* the idle limit, or go to normal if we haven't had competing
|
|
* IO for a bit.
|
|
*/
|
|
if ((rw & REQ_HIPRIO) || wb_recent_wait(rwb) || current_is_kswapd())
|
|
limit = rwb->rq_depth.max_depth;
|
|
else if ((rw & REQ_BACKGROUND) || close_io(rwb)) {
|
|
/*
|
|
* If less than 100ms since we completed unrelated IO,
|
|
* limit us to half the depth for background writeback.
|
|
*/
|
|
limit = rwb->wb_background;
|
|
} else
|
|
limit = rwb->wb_normal;
|
|
|
|
return limit;
|
|
}
|
|
|
|
struct wbt_wait_data {
|
|
struct rq_wb *rwb;
|
|
enum wbt_flags wb_acct;
|
|
unsigned long rw;
|
|
};
|
|
|
|
static bool wbt_inflight_cb(struct rq_wait *rqw, void *private_data)
|
|
{
|
|
struct wbt_wait_data *data = private_data;
|
|
return rq_wait_inc_below(rqw, get_limit(data->rwb, data->rw));
|
|
}
|
|
|
|
static void wbt_cleanup_cb(struct rq_wait *rqw, void *private_data)
|
|
{
|
|
struct wbt_wait_data *data = private_data;
|
|
wbt_rqw_done(data->rwb, rqw, data->wb_acct);
|
|
}
|
|
|
|
/*
|
|
* Block if we will exceed our limit, or if we are currently waiting for
|
|
* the timer to kick off queuing again.
|
|
*/
|
|
static void __wbt_wait(struct rq_wb *rwb, enum wbt_flags wb_acct,
|
|
unsigned long rw)
|
|
{
|
|
struct rq_wait *rqw = get_rq_wait(rwb, wb_acct);
|
|
struct wbt_wait_data data = {
|
|
.rwb = rwb,
|
|
.wb_acct = wb_acct,
|
|
.rw = rw,
|
|
};
|
|
|
|
rq_qos_wait(rqw, &data, wbt_inflight_cb, wbt_cleanup_cb);
|
|
}
|
|
|
|
static inline bool wbt_should_throttle(struct bio *bio)
|
|
{
|
|
switch (bio_op(bio)) {
|
|
case REQ_OP_WRITE:
|
|
/*
|
|
* Don't throttle WRITE_ODIRECT
|
|
*/
|
|
if ((bio->bi_opf & (REQ_SYNC | REQ_IDLE)) ==
|
|
(REQ_SYNC | REQ_IDLE))
|
|
return false;
|
|
fallthrough;
|
|
case REQ_OP_DISCARD:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
static enum wbt_flags bio_to_wbt_flags(struct rq_wb *rwb, struct bio *bio)
|
|
{
|
|
enum wbt_flags flags = 0;
|
|
|
|
if (!rwb_enabled(rwb))
|
|
return 0;
|
|
|
|
if (bio_op(bio) == REQ_OP_READ) {
|
|
flags = WBT_READ;
|
|
} else if (wbt_should_throttle(bio)) {
|
|
if (current_is_kswapd())
|
|
flags |= WBT_KSWAPD;
|
|
if (bio_op(bio) == REQ_OP_DISCARD)
|
|
flags |= WBT_DISCARD;
|
|
flags |= WBT_TRACKED;
|
|
}
|
|
return flags;
|
|
}
|
|
|
|
static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
enum wbt_flags flags = bio_to_wbt_flags(rwb, bio);
|
|
__wbt_done(rqos, flags);
|
|
}
|
|
|
|
/*
|
|
* May sleep, if we have exceeded the writeback limits. Caller can pass
|
|
* in an irq held spinlock, if it holds one when calling this function.
|
|
* If we do sleep, we'll release and re-grab it.
|
|
*/
|
|
static void wbt_wait(struct rq_qos *rqos, struct bio *bio)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
enum wbt_flags flags;
|
|
|
|
flags = bio_to_wbt_flags(rwb, bio);
|
|
if (!(flags & WBT_TRACKED)) {
|
|
if (flags & WBT_READ)
|
|
wb_timestamp(rwb, &rwb->last_issue);
|
|
return;
|
|
}
|
|
|
|
__wbt_wait(rwb, flags, bio->bi_opf);
|
|
|
|
if (!blk_stat_is_active(rwb->cb))
|
|
rwb_arm_timer(rwb);
|
|
}
|
|
|
|
static void wbt_track(struct rq_qos *rqos, struct request *rq, struct bio *bio)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
rq->wbt_flags |= bio_to_wbt_flags(rwb, bio);
|
|
}
|
|
|
|
static void wbt_issue(struct rq_qos *rqos, struct request *rq)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
if (!rwb_enabled(rwb))
|
|
return;
|
|
|
|
/*
|
|
* Track sync issue, in case it takes a long time to complete. Allows us
|
|
* to react quicker, if a sync IO takes a long time to complete. Note
|
|
* that this is just a hint. The request can go away when it completes,
|
|
* so it's important we never dereference it. We only use the address to
|
|
* compare with, which is why we store the sync_issue time locally.
|
|
*/
|
|
if (wbt_is_read(rq) && !rwb->sync_issue) {
|
|
rwb->sync_cookie = rq;
|
|
rwb->sync_issue = rq->io_start_time_ns;
|
|
}
|
|
}
|
|
|
|
static void wbt_requeue(struct rq_qos *rqos, struct request *rq)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
if (!rwb_enabled(rwb))
|
|
return;
|
|
if (rq == rwb->sync_cookie) {
|
|
rwb->sync_issue = 0;
|
|
rwb->sync_cookie = NULL;
|
|
}
|
|
}
|
|
|
|
void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
|
|
{
|
|
struct rq_qos *rqos = wbt_rq_qos(q);
|
|
if (rqos)
|
|
RQWB(rqos)->wc = write_cache_on;
|
|
}
|
|
|
|
/*
|
|
* Enable wbt if defaults are configured that way
|
|
*/
|
|
void wbt_enable_default(struct request_queue *q)
|
|
{
|
|
struct rq_qos *rqos = wbt_rq_qos(q);
|
|
|
|
/* Throttling already enabled? */
|
|
if (rqos) {
|
|
if (RQWB(rqos)->enable_state == WBT_STATE_OFF_DEFAULT)
|
|
RQWB(rqos)->enable_state = WBT_STATE_ON_DEFAULT;
|
|
return;
|
|
}
|
|
|
|
/* Queue not registered? Maybe shutting down... */
|
|
if (!blk_queue_registered(q))
|
|
return;
|
|
|
|
if (queue_is_mq(q) && IS_ENABLED(CONFIG_BLK_WBT_MQ))
|
|
wbt_init(q);
|
|
}
|
|
EXPORT_SYMBOL_GPL(wbt_enable_default);
|
|
|
|
u64 wbt_default_latency_nsec(struct request_queue *q)
|
|
{
|
|
/*
|
|
* We default to 2msec for non-rotational storage, and 75msec
|
|
* for rotational storage.
|
|
*/
|
|
if (blk_queue_nonrot(q))
|
|
return 2000000ULL;
|
|
else
|
|
return 75000000ULL;
|
|
}
|
|
|
|
static int wbt_data_dir(const struct request *rq)
|
|
{
|
|
const int op = req_op(rq);
|
|
|
|
if (op == REQ_OP_READ)
|
|
return READ;
|
|
else if (op_is_write(op))
|
|
return WRITE;
|
|
|
|
/* don't account */
|
|
return -1;
|
|
}
|
|
|
|
static void wbt_queue_depth_changed(struct rq_qos *rqos)
|
|
{
|
|
RQWB(rqos)->rq_depth.queue_depth = blk_queue_depth(rqos->q);
|
|
wbt_update_limits(RQWB(rqos));
|
|
}
|
|
|
|
static void wbt_exit(struct rq_qos *rqos)
|
|
{
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
struct request_queue *q = rqos->q;
|
|
|
|
blk_stat_remove_callback(q, rwb->cb);
|
|
blk_stat_free_callback(rwb->cb);
|
|
kfree(rwb);
|
|
}
|
|
|
|
/*
|
|
* Disable wbt, if enabled by default.
|
|
*/
|
|
void wbt_disable_default(struct request_queue *q)
|
|
{
|
|
struct rq_qos *rqos = wbt_rq_qos(q);
|
|
struct rq_wb *rwb;
|
|
if (!rqos)
|
|
return;
|
|
rwb = RQWB(rqos);
|
|
if (rwb->enable_state == WBT_STATE_ON_DEFAULT) {
|
|
blk_stat_deactivate(rwb->cb);
|
|
rwb->enable_state = WBT_STATE_OFF_DEFAULT;
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(wbt_disable_default);
|
|
|
|
#ifdef CONFIG_BLK_DEBUG_FS
|
|
static int wbt_curr_win_nsec_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%llu\n", rwb->cur_win_nsec);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_enabled_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%d\n", rwb->enable_state);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_id_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
|
|
seq_printf(m, "%u\n", rqos->id);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_inflight_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
int i;
|
|
|
|
for (i = 0; i < WBT_NUM_RWQ; i++)
|
|
seq_printf(m, "%d: inflight %d\n", i,
|
|
atomic_read(&rwb->rq_wait[i].inflight));
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_min_lat_nsec_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%lu\n", rwb->min_lat_nsec);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_unknown_cnt_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%u\n", rwb->unknown_cnt);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_normal_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%u\n", rwb->wb_normal);
|
|
return 0;
|
|
}
|
|
|
|
static int wbt_background_show(void *data, struct seq_file *m)
|
|
{
|
|
struct rq_qos *rqos = data;
|
|
struct rq_wb *rwb = RQWB(rqos);
|
|
|
|
seq_printf(m, "%u\n", rwb->wb_background);
|
|
return 0;
|
|
}
|
|
|
|
static const struct blk_mq_debugfs_attr wbt_debugfs_attrs[] = {
|
|
{"curr_win_nsec", 0400, wbt_curr_win_nsec_show},
|
|
{"enabled", 0400, wbt_enabled_show},
|
|
{"id", 0400, wbt_id_show},
|
|
{"inflight", 0400, wbt_inflight_show},
|
|
{"min_lat_nsec", 0400, wbt_min_lat_nsec_show},
|
|
{"unknown_cnt", 0400, wbt_unknown_cnt_show},
|
|
{"wb_normal", 0400, wbt_normal_show},
|
|
{"wb_background", 0400, wbt_background_show},
|
|
{},
|
|
};
|
|
#endif
|
|
|
|
static struct rq_qos_ops wbt_rqos_ops = {
|
|
.throttle = wbt_wait,
|
|
.issue = wbt_issue,
|
|
.track = wbt_track,
|
|
.requeue = wbt_requeue,
|
|
.done = wbt_done,
|
|
.cleanup = wbt_cleanup,
|
|
.queue_depth_changed = wbt_queue_depth_changed,
|
|
.exit = wbt_exit,
|
|
#ifdef CONFIG_BLK_DEBUG_FS
|
|
.debugfs_attrs = wbt_debugfs_attrs,
|
|
#endif
|
|
};
|
|
|
|
int wbt_init(struct request_queue *q)
|
|
{
|
|
struct rq_wb *rwb;
|
|
int i;
|
|
|
|
rwb = kzalloc(sizeof(*rwb), GFP_KERNEL);
|
|
if (!rwb)
|
|
return -ENOMEM;
|
|
|
|
rwb->cb = blk_stat_alloc_callback(wb_timer_fn, wbt_data_dir, 2, rwb);
|
|
if (!rwb->cb) {
|
|
kfree(rwb);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
for (i = 0; i < WBT_NUM_RWQ; i++)
|
|
rq_wait_init(&rwb->rq_wait[i]);
|
|
|
|
rwb->rqos.id = RQ_QOS_WBT;
|
|
rwb->rqos.ops = &wbt_rqos_ops;
|
|
rwb->rqos.q = q;
|
|
rwb->last_comp = rwb->last_issue = jiffies;
|
|
rwb->win_nsec = RWB_WINDOW_NSEC;
|
|
rwb->enable_state = WBT_STATE_ON_DEFAULT;
|
|
rwb->wc = 1;
|
|
rwb->rq_depth.default_depth = RWB_DEF_DEPTH;
|
|
|
|
/*
|
|
* Assign rwb and add the stats callback.
|
|
*/
|
|
rq_qos_add(q, &rwb->rqos);
|
|
blk_stat_add_callback(q, rwb->cb);
|
|
|
|
rwb->min_lat_nsec = wbt_default_latency_nsec(q);
|
|
|
|
wbt_queue_depth_changed(&rwb->rqos);
|
|
wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
|
|
|
|
return 0;
|
|
}
|