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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
de7180ff90
DM cache now defaults to passing discards down to the origin device. User may disable this using the "no_discard_passdown" feature when creating the cache device. If the cache's underlying origin device doesn't support discards then passdown is disabled (with warning). Similarly, if the underlying origin device's max_discard_sectors is less than a cache block discard passdown will be disabled (this is required because sizing of the cache internal discard bitset depends on it). Signed-off-by: Mike Snitzer <snitzer@redhat.com>
3584 lines
85 KiB
C
3584 lines
85 KiB
C
/*
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* Copyright (C) 2012 Red Hat. All rights reserved.
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*
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* This file is released under the GPL.
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*/
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#include "dm.h"
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#include "dm-bio-prison-v2.h"
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#include "dm-bio-record.h"
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#include "dm-cache-metadata.h"
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#include <linux/dm-io.h>
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#include <linux/dm-kcopyd.h>
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#include <linux/jiffies.h>
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#include <linux/init.h>
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#include <linux/mempool.h>
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#include <linux/module.h>
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#include <linux/rwsem.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#define DM_MSG_PREFIX "cache"
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DECLARE_DM_KCOPYD_THROTTLE_WITH_MODULE_PARM(cache_copy_throttle,
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"A percentage of time allocated for copying to and/or from cache");
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/*----------------------------------------------------------------*/
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/*
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* Glossary:
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*
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* oblock: index of an origin block
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* cblock: index of a cache block
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* promotion: movement of a block from origin to cache
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* demotion: movement of a block from cache to origin
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* migration: movement of a block between the origin and cache device,
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* either direction
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*/
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/*----------------------------------------------------------------*/
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struct io_tracker {
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spinlock_t lock;
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/*
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* Sectors of in-flight IO.
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*/
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sector_t in_flight;
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/*
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* The time, in jiffies, when this device became idle (if it is
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* indeed idle).
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*/
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unsigned long idle_time;
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unsigned long last_update_time;
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};
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static void iot_init(struct io_tracker *iot)
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{
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spin_lock_init(&iot->lock);
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iot->in_flight = 0ul;
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iot->idle_time = 0ul;
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iot->last_update_time = jiffies;
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}
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static bool __iot_idle_for(struct io_tracker *iot, unsigned long jifs)
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{
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if (iot->in_flight)
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return false;
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return time_after(jiffies, iot->idle_time + jifs);
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}
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static bool iot_idle_for(struct io_tracker *iot, unsigned long jifs)
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{
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bool r;
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unsigned long flags;
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spin_lock_irqsave(&iot->lock, flags);
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r = __iot_idle_for(iot, jifs);
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spin_unlock_irqrestore(&iot->lock, flags);
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return r;
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}
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static void iot_io_begin(struct io_tracker *iot, sector_t len)
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{
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unsigned long flags;
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spin_lock_irqsave(&iot->lock, flags);
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iot->in_flight += len;
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spin_unlock_irqrestore(&iot->lock, flags);
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}
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static void __iot_io_end(struct io_tracker *iot, sector_t len)
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{
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if (!len)
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return;
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iot->in_flight -= len;
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if (!iot->in_flight)
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iot->idle_time = jiffies;
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}
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static void iot_io_end(struct io_tracker *iot, sector_t len)
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{
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unsigned long flags;
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spin_lock_irqsave(&iot->lock, flags);
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__iot_io_end(iot, len);
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spin_unlock_irqrestore(&iot->lock, flags);
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}
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/*----------------------------------------------------------------*/
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/*
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* Represents a chunk of future work. 'input' allows continuations to pass
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* values between themselves, typically error values.
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*/
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struct continuation {
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struct work_struct ws;
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blk_status_t input;
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};
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static inline void init_continuation(struct continuation *k,
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void (*fn)(struct work_struct *))
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{
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INIT_WORK(&k->ws, fn);
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k->input = 0;
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}
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static inline void queue_continuation(struct workqueue_struct *wq,
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struct continuation *k)
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{
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queue_work(wq, &k->ws);
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}
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/*----------------------------------------------------------------*/
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/*
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* The batcher collects together pieces of work that need a particular
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* operation to occur before they can proceed (typically a commit).
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*/
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struct batcher {
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/*
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* The operation that everyone is waiting for.
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*/
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blk_status_t (*commit_op)(void *context);
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void *commit_context;
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/*
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* This is how bios should be issued once the commit op is complete
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* (accounted_request).
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*/
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void (*issue_op)(struct bio *bio, void *context);
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void *issue_context;
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/*
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* Queued work gets put on here after commit.
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*/
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struct workqueue_struct *wq;
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spinlock_t lock;
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struct list_head work_items;
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struct bio_list bios;
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struct work_struct commit_work;
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bool commit_scheduled;
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};
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static void __commit(struct work_struct *_ws)
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{
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struct batcher *b = container_of(_ws, struct batcher, commit_work);
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blk_status_t r;
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unsigned long flags;
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struct list_head work_items;
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struct work_struct *ws, *tmp;
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struct continuation *k;
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struct bio *bio;
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struct bio_list bios;
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INIT_LIST_HEAD(&work_items);
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bio_list_init(&bios);
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/*
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* We have to grab these before the commit_op to avoid a race
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* condition.
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*/
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spin_lock_irqsave(&b->lock, flags);
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list_splice_init(&b->work_items, &work_items);
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bio_list_merge(&bios, &b->bios);
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bio_list_init(&b->bios);
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b->commit_scheduled = false;
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spin_unlock_irqrestore(&b->lock, flags);
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r = b->commit_op(b->commit_context);
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list_for_each_entry_safe(ws, tmp, &work_items, entry) {
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k = container_of(ws, struct continuation, ws);
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k->input = r;
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INIT_LIST_HEAD(&ws->entry); /* to avoid a WARN_ON */
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queue_work(b->wq, ws);
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}
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while ((bio = bio_list_pop(&bios))) {
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if (r) {
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bio->bi_status = r;
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bio_endio(bio);
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} else
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b->issue_op(bio, b->issue_context);
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}
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}
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static void batcher_init(struct batcher *b,
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blk_status_t (*commit_op)(void *),
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void *commit_context,
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void (*issue_op)(struct bio *bio, void *),
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void *issue_context,
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struct workqueue_struct *wq)
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{
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b->commit_op = commit_op;
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b->commit_context = commit_context;
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b->issue_op = issue_op;
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b->issue_context = issue_context;
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b->wq = wq;
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spin_lock_init(&b->lock);
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INIT_LIST_HEAD(&b->work_items);
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bio_list_init(&b->bios);
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INIT_WORK(&b->commit_work, __commit);
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b->commit_scheduled = false;
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}
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static void async_commit(struct batcher *b)
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{
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queue_work(b->wq, &b->commit_work);
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}
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static void continue_after_commit(struct batcher *b, struct continuation *k)
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{
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unsigned long flags;
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bool commit_scheduled;
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spin_lock_irqsave(&b->lock, flags);
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commit_scheduled = b->commit_scheduled;
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list_add_tail(&k->ws.entry, &b->work_items);
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spin_unlock_irqrestore(&b->lock, flags);
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if (commit_scheduled)
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async_commit(b);
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}
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/*
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* Bios are errored if commit failed.
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*/
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static void issue_after_commit(struct batcher *b, struct bio *bio)
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{
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unsigned long flags;
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bool commit_scheduled;
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spin_lock_irqsave(&b->lock, flags);
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commit_scheduled = b->commit_scheduled;
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bio_list_add(&b->bios, bio);
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spin_unlock_irqrestore(&b->lock, flags);
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if (commit_scheduled)
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async_commit(b);
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}
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/*
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* Call this if some urgent work is waiting for the commit to complete.
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*/
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static void schedule_commit(struct batcher *b)
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{
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bool immediate;
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unsigned long flags;
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spin_lock_irqsave(&b->lock, flags);
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immediate = !list_empty(&b->work_items) || !bio_list_empty(&b->bios);
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b->commit_scheduled = true;
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spin_unlock_irqrestore(&b->lock, flags);
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if (immediate)
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async_commit(b);
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}
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/*
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* There are a couple of places where we let a bio run, but want to do some
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* work before calling its endio function. We do this by temporarily
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* changing the endio fn.
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*/
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struct dm_hook_info {
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bio_end_io_t *bi_end_io;
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};
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static void dm_hook_bio(struct dm_hook_info *h, struct bio *bio,
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bio_end_io_t *bi_end_io, void *bi_private)
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{
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h->bi_end_io = bio->bi_end_io;
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bio->bi_end_io = bi_end_io;
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bio->bi_private = bi_private;
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}
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static void dm_unhook_bio(struct dm_hook_info *h, struct bio *bio)
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{
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bio->bi_end_io = h->bi_end_io;
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}
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/*----------------------------------------------------------------*/
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#define MIGRATION_POOL_SIZE 128
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#define COMMIT_PERIOD HZ
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#define MIGRATION_COUNT_WINDOW 10
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/*
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* The block size of the device holding cache data must be
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* between 32KB and 1GB.
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*/
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#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (32 * 1024 >> SECTOR_SHIFT)
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#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
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enum cache_metadata_mode {
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CM_WRITE, /* metadata may be changed */
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CM_READ_ONLY, /* metadata may not be changed */
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CM_FAIL
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};
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enum cache_io_mode {
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/*
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* Data is written to cached blocks only. These blocks are marked
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* dirty. If you lose the cache device you will lose data.
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* Potential performance increase for both reads and writes.
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*/
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CM_IO_WRITEBACK,
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/*
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* Data is written to both cache and origin. Blocks are never
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* dirty. Potential performance benfit for reads only.
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*/
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CM_IO_WRITETHROUGH,
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/*
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* A degraded mode useful for various cache coherency situations
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* (eg, rolling back snapshots). Reads and writes always go to the
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* origin. If a write goes to a cached oblock, then the cache
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* block is invalidated.
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*/
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CM_IO_PASSTHROUGH
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};
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struct cache_features {
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enum cache_metadata_mode mode;
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enum cache_io_mode io_mode;
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unsigned metadata_version;
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bool discard_passdown:1;
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};
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struct cache_stats {
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atomic_t read_hit;
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atomic_t read_miss;
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atomic_t write_hit;
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atomic_t write_miss;
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atomic_t demotion;
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atomic_t promotion;
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atomic_t writeback;
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atomic_t copies_avoided;
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atomic_t cache_cell_clash;
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atomic_t commit_count;
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atomic_t discard_count;
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};
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struct cache {
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struct dm_target *ti;
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spinlock_t lock;
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/*
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* Fields for converting from sectors to blocks.
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*/
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int sectors_per_block_shift;
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sector_t sectors_per_block;
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struct dm_cache_metadata *cmd;
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/*
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* Metadata is written to this device.
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*/
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struct dm_dev *metadata_dev;
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/*
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* The slower of the two data devices. Typically a spindle.
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*/
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struct dm_dev *origin_dev;
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/*
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* The faster of the two data devices. Typically an SSD.
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*/
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struct dm_dev *cache_dev;
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/*
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* Size of the origin device in _complete_ blocks and native sectors.
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*/
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dm_oblock_t origin_blocks;
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sector_t origin_sectors;
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/*
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* Size of the cache device in blocks.
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*/
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dm_cblock_t cache_size;
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/*
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* Invalidation fields.
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*/
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spinlock_t invalidation_lock;
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struct list_head invalidation_requests;
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sector_t migration_threshold;
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wait_queue_head_t migration_wait;
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atomic_t nr_allocated_migrations;
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/*
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* The number of in flight migrations that are performing
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* background io. eg, promotion, writeback.
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*/
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atomic_t nr_io_migrations;
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struct bio_list deferred_bios;
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struct rw_semaphore quiesce_lock;
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struct dm_target_callbacks callbacks;
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/*
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* origin_blocks entries, discarded if set.
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*/
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dm_dblock_t discard_nr_blocks;
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unsigned long *discard_bitset;
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uint32_t discard_block_size; /* a power of 2 times sectors per block */
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/*
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* Rather than reconstructing the table line for the status we just
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* save it and regurgitate.
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*/
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unsigned nr_ctr_args;
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const char **ctr_args;
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struct dm_kcopyd_client *copier;
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struct work_struct deferred_bio_worker;
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struct work_struct migration_worker;
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struct workqueue_struct *wq;
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struct delayed_work waker;
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struct dm_bio_prison_v2 *prison;
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/*
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* cache_size entries, dirty if set
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*/
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unsigned long *dirty_bitset;
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atomic_t nr_dirty;
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unsigned policy_nr_args;
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struct dm_cache_policy *policy;
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/*
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* Cache features such as write-through.
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*/
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struct cache_features features;
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struct cache_stats stats;
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bool need_tick_bio:1;
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bool sized:1;
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bool invalidate:1;
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bool commit_requested:1;
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bool loaded_mappings:1;
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bool loaded_discards:1;
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struct rw_semaphore background_work_lock;
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struct batcher committer;
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struct work_struct commit_ws;
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struct io_tracker tracker;
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mempool_t migration_pool;
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struct bio_set bs;
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};
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struct per_bio_data {
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bool tick:1;
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unsigned req_nr:2;
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struct dm_bio_prison_cell_v2 *cell;
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struct dm_hook_info hook_info;
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sector_t len;
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};
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struct dm_cache_migration {
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struct continuation k;
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struct cache *cache;
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struct policy_work *op;
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struct bio *overwrite_bio;
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struct dm_bio_prison_cell_v2 *cell;
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dm_cblock_t invalidate_cblock;
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dm_oblock_t invalidate_oblock;
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};
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/*----------------------------------------------------------------*/
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static bool writethrough_mode(struct cache *cache)
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{
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return cache->features.io_mode == CM_IO_WRITETHROUGH;
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}
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static bool writeback_mode(struct cache *cache)
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{
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return cache->features.io_mode == CM_IO_WRITEBACK;
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}
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static inline bool passthrough_mode(struct cache *cache)
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{
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return unlikely(cache->features.io_mode == CM_IO_PASSTHROUGH);
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}
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/*----------------------------------------------------------------*/
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static void wake_deferred_bio_worker(struct cache *cache)
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{
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queue_work(cache->wq, &cache->deferred_bio_worker);
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}
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static void wake_migration_worker(struct cache *cache)
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{
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if (passthrough_mode(cache))
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return;
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queue_work(cache->wq, &cache->migration_worker);
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}
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|
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/*----------------------------------------------------------------*/
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static struct dm_bio_prison_cell_v2 *alloc_prison_cell(struct cache *cache)
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{
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return dm_bio_prison_alloc_cell_v2(cache->prison, GFP_NOWAIT);
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}
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static void free_prison_cell(struct cache *cache, struct dm_bio_prison_cell_v2 *cell)
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{
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dm_bio_prison_free_cell_v2(cache->prison, cell);
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}
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static struct dm_cache_migration *alloc_migration(struct cache *cache)
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{
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struct dm_cache_migration *mg;
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mg = mempool_alloc(&cache->migration_pool, GFP_NOWAIT);
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if (!mg)
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return NULL;
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memset(mg, 0, sizeof(*mg));
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mg->cache = cache;
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atomic_inc(&cache->nr_allocated_migrations);
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return mg;
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}
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static void free_migration(struct dm_cache_migration *mg)
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{
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struct cache *cache = mg->cache;
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|
|
if (atomic_dec_and_test(&cache->nr_allocated_migrations))
|
|
wake_up(&cache->migration_wait);
|
|
|
|
mempool_free(mg, &cache->migration_pool);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static inline dm_oblock_t oblock_succ(dm_oblock_t b)
|
|
{
|
|
return to_oblock(from_oblock(b) + 1ull);
|
|
}
|
|
|
|
static void build_key(dm_oblock_t begin, dm_oblock_t end, struct dm_cell_key_v2 *key)
|
|
{
|
|
key->virtual = 0;
|
|
key->dev = 0;
|
|
key->block_begin = from_oblock(begin);
|
|
key->block_end = from_oblock(end);
|
|
}
|
|
|
|
/*
|
|
* We have two lock levels. Level 0, which is used to prevent WRITEs, and
|
|
* level 1 which prevents *both* READs and WRITEs.
|
|
*/
|
|
#define WRITE_LOCK_LEVEL 0
|
|
#define READ_WRITE_LOCK_LEVEL 1
|
|
|
|
static unsigned lock_level(struct bio *bio)
|
|
{
|
|
return bio_data_dir(bio) == WRITE ?
|
|
WRITE_LOCK_LEVEL :
|
|
READ_WRITE_LOCK_LEVEL;
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Per bio data
|
|
*--------------------------------------------------------------*/
|
|
|
|
static struct per_bio_data *get_per_bio_data(struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
|
|
BUG_ON(!pb);
|
|
return pb;
|
|
}
|
|
|
|
static struct per_bio_data *init_per_bio_data(struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
pb->tick = false;
|
|
pb->req_nr = dm_bio_get_target_bio_nr(bio);
|
|
pb->cell = NULL;
|
|
pb->len = 0;
|
|
|
|
return pb;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void defer_bio(struct cache *cache, struct bio *bio)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
bio_list_add(&cache->deferred_bios, bio);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
|
|
wake_deferred_bio_worker(cache);
|
|
}
|
|
|
|
static void defer_bios(struct cache *cache, struct bio_list *bios)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
bio_list_merge(&cache->deferred_bios, bios);
|
|
bio_list_init(bios);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
|
|
wake_deferred_bio_worker(cache);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static bool bio_detain_shared(struct cache *cache, dm_oblock_t oblock, struct bio *bio)
|
|
{
|
|
bool r;
|
|
struct per_bio_data *pb;
|
|
struct dm_cell_key_v2 key;
|
|
dm_oblock_t end = to_oblock(from_oblock(oblock) + 1ULL);
|
|
struct dm_bio_prison_cell_v2 *cell_prealloc, *cell;
|
|
|
|
cell_prealloc = alloc_prison_cell(cache); /* FIXME: allow wait if calling from worker */
|
|
if (!cell_prealloc) {
|
|
defer_bio(cache, bio);
|
|
return false;
|
|
}
|
|
|
|
build_key(oblock, end, &key);
|
|
r = dm_cell_get_v2(cache->prison, &key, lock_level(bio), bio, cell_prealloc, &cell);
|
|
if (!r) {
|
|
/*
|
|
* Failed to get the lock.
|
|
*/
|
|
free_prison_cell(cache, cell_prealloc);
|
|
return r;
|
|
}
|
|
|
|
if (cell != cell_prealloc)
|
|
free_prison_cell(cache, cell_prealloc);
|
|
|
|
pb = get_per_bio_data(bio);
|
|
pb->cell = cell;
|
|
|
|
return r;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static bool is_dirty(struct cache *cache, dm_cblock_t b)
|
|
{
|
|
return test_bit(from_cblock(b), cache->dirty_bitset);
|
|
}
|
|
|
|
static void set_dirty(struct cache *cache, dm_cblock_t cblock)
|
|
{
|
|
if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset)) {
|
|
atomic_inc(&cache->nr_dirty);
|
|
policy_set_dirty(cache->policy, cblock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* These two are called when setting after migrations to force the policy
|
|
* and dirty bitset to be in sync.
|
|
*/
|
|
static void force_set_dirty(struct cache *cache, dm_cblock_t cblock)
|
|
{
|
|
if (!test_and_set_bit(from_cblock(cblock), cache->dirty_bitset))
|
|
atomic_inc(&cache->nr_dirty);
|
|
policy_set_dirty(cache->policy, cblock);
|
|
}
|
|
|
|
static void force_clear_dirty(struct cache *cache, dm_cblock_t cblock)
|
|
{
|
|
if (test_and_clear_bit(from_cblock(cblock), cache->dirty_bitset)) {
|
|
if (atomic_dec_return(&cache->nr_dirty) == 0)
|
|
dm_table_event(cache->ti->table);
|
|
}
|
|
|
|
policy_clear_dirty(cache->policy, cblock);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static bool block_size_is_power_of_two(struct cache *cache)
|
|
{
|
|
return cache->sectors_per_block_shift >= 0;
|
|
}
|
|
|
|
/* gcc on ARM generates spurious references to __udivdi3 and __umoddi3 */
|
|
#if defined(CONFIG_ARM) && __GNUC__ == 4 && __GNUC_MINOR__ <= 6
|
|
__always_inline
|
|
#endif
|
|
static dm_block_t block_div(dm_block_t b, uint32_t n)
|
|
{
|
|
do_div(b, n);
|
|
|
|
return b;
|
|
}
|
|
|
|
static dm_block_t oblocks_per_dblock(struct cache *cache)
|
|
{
|
|
dm_block_t oblocks = cache->discard_block_size;
|
|
|
|
if (block_size_is_power_of_two(cache))
|
|
oblocks >>= cache->sectors_per_block_shift;
|
|
else
|
|
oblocks = block_div(oblocks, cache->sectors_per_block);
|
|
|
|
return oblocks;
|
|
}
|
|
|
|
static dm_dblock_t oblock_to_dblock(struct cache *cache, dm_oblock_t oblock)
|
|
{
|
|
return to_dblock(block_div(from_oblock(oblock),
|
|
oblocks_per_dblock(cache)));
|
|
}
|
|
|
|
static void set_discard(struct cache *cache, dm_dblock_t b)
|
|
{
|
|
unsigned long flags;
|
|
|
|
BUG_ON(from_dblock(b) >= from_dblock(cache->discard_nr_blocks));
|
|
atomic_inc(&cache->stats.discard_count);
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
set_bit(from_dblock(b), cache->discard_bitset);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
}
|
|
|
|
static void clear_discard(struct cache *cache, dm_dblock_t b)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
clear_bit(from_dblock(b), cache->discard_bitset);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
}
|
|
|
|
static bool is_discarded(struct cache *cache, dm_dblock_t b)
|
|
{
|
|
int r;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
r = test_bit(from_dblock(b), cache->discard_bitset);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
static bool is_discarded_oblock(struct cache *cache, dm_oblock_t b)
|
|
{
|
|
int r;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
r = test_bit(from_dblock(oblock_to_dblock(cache, b)),
|
|
cache->discard_bitset);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Remapping
|
|
*--------------------------------------------------------------*/
|
|
static void remap_to_origin(struct cache *cache, struct bio *bio)
|
|
{
|
|
bio_set_dev(bio, cache->origin_dev->bdev);
|
|
}
|
|
|
|
static void remap_to_cache(struct cache *cache, struct bio *bio,
|
|
dm_cblock_t cblock)
|
|
{
|
|
sector_t bi_sector = bio->bi_iter.bi_sector;
|
|
sector_t block = from_cblock(cblock);
|
|
|
|
bio_set_dev(bio, cache->cache_dev->bdev);
|
|
if (!block_size_is_power_of_two(cache))
|
|
bio->bi_iter.bi_sector =
|
|
(block * cache->sectors_per_block) +
|
|
sector_div(bi_sector, cache->sectors_per_block);
|
|
else
|
|
bio->bi_iter.bi_sector =
|
|
(block << cache->sectors_per_block_shift) |
|
|
(bi_sector & (cache->sectors_per_block - 1));
|
|
}
|
|
|
|
static void check_if_tick_bio_needed(struct cache *cache, struct bio *bio)
|
|
{
|
|
unsigned long flags;
|
|
struct per_bio_data *pb;
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
if (cache->need_tick_bio && !op_is_flush(bio->bi_opf) &&
|
|
bio_op(bio) != REQ_OP_DISCARD) {
|
|
pb = get_per_bio_data(bio);
|
|
pb->tick = true;
|
|
cache->need_tick_bio = false;
|
|
}
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
}
|
|
|
|
static void __remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
|
|
dm_oblock_t oblock, bool bio_has_pbd)
|
|
{
|
|
if (bio_has_pbd)
|
|
check_if_tick_bio_needed(cache, bio);
|
|
remap_to_origin(cache, bio);
|
|
if (bio_data_dir(bio) == WRITE)
|
|
clear_discard(cache, oblock_to_dblock(cache, oblock));
|
|
}
|
|
|
|
static void remap_to_origin_clear_discard(struct cache *cache, struct bio *bio,
|
|
dm_oblock_t oblock)
|
|
{
|
|
// FIXME: check_if_tick_bio_needed() is called way too much through this interface
|
|
__remap_to_origin_clear_discard(cache, bio, oblock, true);
|
|
}
|
|
|
|
static void remap_to_cache_dirty(struct cache *cache, struct bio *bio,
|
|
dm_oblock_t oblock, dm_cblock_t cblock)
|
|
{
|
|
check_if_tick_bio_needed(cache, bio);
|
|
remap_to_cache(cache, bio, cblock);
|
|
if (bio_data_dir(bio) == WRITE) {
|
|
set_dirty(cache, cblock);
|
|
clear_discard(cache, oblock_to_dblock(cache, oblock));
|
|
}
|
|
}
|
|
|
|
static dm_oblock_t get_bio_block(struct cache *cache, struct bio *bio)
|
|
{
|
|
sector_t block_nr = bio->bi_iter.bi_sector;
|
|
|
|
if (!block_size_is_power_of_two(cache))
|
|
(void) sector_div(block_nr, cache->sectors_per_block);
|
|
else
|
|
block_nr >>= cache->sectors_per_block_shift;
|
|
|
|
return to_oblock(block_nr);
|
|
}
|
|
|
|
static bool accountable_bio(struct cache *cache, struct bio *bio)
|
|
{
|
|
return bio_op(bio) != REQ_OP_DISCARD;
|
|
}
|
|
|
|
static void accounted_begin(struct cache *cache, struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb;
|
|
|
|
if (accountable_bio(cache, bio)) {
|
|
pb = get_per_bio_data(bio);
|
|
pb->len = bio_sectors(bio);
|
|
iot_io_begin(&cache->tracker, pb->len);
|
|
}
|
|
}
|
|
|
|
static void accounted_complete(struct cache *cache, struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
iot_io_end(&cache->tracker, pb->len);
|
|
}
|
|
|
|
static void accounted_request(struct cache *cache, struct bio *bio)
|
|
{
|
|
accounted_begin(cache, bio);
|
|
generic_make_request(bio);
|
|
}
|
|
|
|
static void issue_op(struct bio *bio, void *context)
|
|
{
|
|
struct cache *cache = context;
|
|
accounted_request(cache, bio);
|
|
}
|
|
|
|
/*
|
|
* When running in writethrough mode we need to send writes to clean blocks
|
|
* to both the cache and origin devices. Clone the bio and send them in parallel.
|
|
*/
|
|
static void remap_to_origin_and_cache(struct cache *cache, struct bio *bio,
|
|
dm_oblock_t oblock, dm_cblock_t cblock)
|
|
{
|
|
struct bio *origin_bio = bio_clone_fast(bio, GFP_NOIO, &cache->bs);
|
|
|
|
BUG_ON(!origin_bio);
|
|
|
|
bio_chain(origin_bio, bio);
|
|
/*
|
|
* Passing false to __remap_to_origin_clear_discard() skips
|
|
* all code that might use per_bio_data (since clone doesn't have it)
|
|
*/
|
|
__remap_to_origin_clear_discard(cache, origin_bio, oblock, false);
|
|
submit_bio(origin_bio);
|
|
|
|
remap_to_cache(cache, bio, cblock);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Failure modes
|
|
*--------------------------------------------------------------*/
|
|
static enum cache_metadata_mode get_cache_mode(struct cache *cache)
|
|
{
|
|
return cache->features.mode;
|
|
}
|
|
|
|
static const char *cache_device_name(struct cache *cache)
|
|
{
|
|
return dm_device_name(dm_table_get_md(cache->ti->table));
|
|
}
|
|
|
|
static void notify_mode_switch(struct cache *cache, enum cache_metadata_mode mode)
|
|
{
|
|
const char *descs[] = {
|
|
"write",
|
|
"read-only",
|
|
"fail"
|
|
};
|
|
|
|
dm_table_event(cache->ti->table);
|
|
DMINFO("%s: switching cache to %s mode",
|
|
cache_device_name(cache), descs[(int)mode]);
|
|
}
|
|
|
|
static void set_cache_mode(struct cache *cache, enum cache_metadata_mode new_mode)
|
|
{
|
|
bool needs_check;
|
|
enum cache_metadata_mode old_mode = get_cache_mode(cache);
|
|
|
|
if (dm_cache_metadata_needs_check(cache->cmd, &needs_check)) {
|
|
DMERR("%s: unable to read needs_check flag, setting failure mode.",
|
|
cache_device_name(cache));
|
|
new_mode = CM_FAIL;
|
|
}
|
|
|
|
if (new_mode == CM_WRITE && needs_check) {
|
|
DMERR("%s: unable to switch cache to write mode until repaired.",
|
|
cache_device_name(cache));
|
|
if (old_mode != new_mode)
|
|
new_mode = old_mode;
|
|
else
|
|
new_mode = CM_READ_ONLY;
|
|
}
|
|
|
|
/* Never move out of fail mode */
|
|
if (old_mode == CM_FAIL)
|
|
new_mode = CM_FAIL;
|
|
|
|
switch (new_mode) {
|
|
case CM_FAIL:
|
|
case CM_READ_ONLY:
|
|
dm_cache_metadata_set_read_only(cache->cmd);
|
|
break;
|
|
|
|
case CM_WRITE:
|
|
dm_cache_metadata_set_read_write(cache->cmd);
|
|
break;
|
|
}
|
|
|
|
cache->features.mode = new_mode;
|
|
|
|
if (new_mode != old_mode)
|
|
notify_mode_switch(cache, new_mode);
|
|
}
|
|
|
|
static void abort_transaction(struct cache *cache)
|
|
{
|
|
const char *dev_name = cache_device_name(cache);
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return;
|
|
|
|
if (dm_cache_metadata_set_needs_check(cache->cmd)) {
|
|
DMERR("%s: failed to set 'needs_check' flag in metadata", dev_name);
|
|
set_cache_mode(cache, CM_FAIL);
|
|
}
|
|
|
|
DMERR_LIMIT("%s: aborting current metadata transaction", dev_name);
|
|
if (dm_cache_metadata_abort(cache->cmd)) {
|
|
DMERR("%s: failed to abort metadata transaction", dev_name);
|
|
set_cache_mode(cache, CM_FAIL);
|
|
}
|
|
}
|
|
|
|
static void metadata_operation_failed(struct cache *cache, const char *op, int r)
|
|
{
|
|
DMERR_LIMIT("%s: metadata operation '%s' failed: error = %d",
|
|
cache_device_name(cache), op, r);
|
|
abort_transaction(cache);
|
|
set_cache_mode(cache, CM_READ_ONLY);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void load_stats(struct cache *cache)
|
|
{
|
|
struct dm_cache_statistics stats;
|
|
|
|
dm_cache_metadata_get_stats(cache->cmd, &stats);
|
|
atomic_set(&cache->stats.read_hit, stats.read_hits);
|
|
atomic_set(&cache->stats.read_miss, stats.read_misses);
|
|
atomic_set(&cache->stats.write_hit, stats.write_hits);
|
|
atomic_set(&cache->stats.write_miss, stats.write_misses);
|
|
}
|
|
|
|
static void save_stats(struct cache *cache)
|
|
{
|
|
struct dm_cache_statistics stats;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return;
|
|
|
|
stats.read_hits = atomic_read(&cache->stats.read_hit);
|
|
stats.read_misses = atomic_read(&cache->stats.read_miss);
|
|
stats.write_hits = atomic_read(&cache->stats.write_hit);
|
|
stats.write_misses = atomic_read(&cache->stats.write_miss);
|
|
|
|
dm_cache_metadata_set_stats(cache->cmd, &stats);
|
|
}
|
|
|
|
static void update_stats(struct cache_stats *stats, enum policy_operation op)
|
|
{
|
|
switch (op) {
|
|
case POLICY_PROMOTE:
|
|
atomic_inc(&stats->promotion);
|
|
break;
|
|
|
|
case POLICY_DEMOTE:
|
|
atomic_inc(&stats->demotion);
|
|
break;
|
|
|
|
case POLICY_WRITEBACK:
|
|
atomic_inc(&stats->writeback);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Migration processing
|
|
*
|
|
* Migration covers moving data from the origin device to the cache, or
|
|
* vice versa.
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void inc_io_migrations(struct cache *cache)
|
|
{
|
|
atomic_inc(&cache->nr_io_migrations);
|
|
}
|
|
|
|
static void dec_io_migrations(struct cache *cache)
|
|
{
|
|
atomic_dec(&cache->nr_io_migrations);
|
|
}
|
|
|
|
static bool discard_or_flush(struct bio *bio)
|
|
{
|
|
return bio_op(bio) == REQ_OP_DISCARD || op_is_flush(bio->bi_opf);
|
|
}
|
|
|
|
static void calc_discard_block_range(struct cache *cache, struct bio *bio,
|
|
dm_dblock_t *b, dm_dblock_t *e)
|
|
{
|
|
sector_t sb = bio->bi_iter.bi_sector;
|
|
sector_t se = bio_end_sector(bio);
|
|
|
|
*b = to_dblock(dm_sector_div_up(sb, cache->discard_block_size));
|
|
|
|
if (se - sb < cache->discard_block_size)
|
|
*e = *b;
|
|
else
|
|
*e = to_dblock(block_div(se, cache->discard_block_size));
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static void prevent_background_work(struct cache *cache)
|
|
{
|
|
lockdep_off();
|
|
down_write(&cache->background_work_lock);
|
|
lockdep_on();
|
|
}
|
|
|
|
static void allow_background_work(struct cache *cache)
|
|
{
|
|
lockdep_off();
|
|
up_write(&cache->background_work_lock);
|
|
lockdep_on();
|
|
}
|
|
|
|
static bool background_work_begin(struct cache *cache)
|
|
{
|
|
bool r;
|
|
|
|
lockdep_off();
|
|
r = down_read_trylock(&cache->background_work_lock);
|
|
lockdep_on();
|
|
|
|
return r;
|
|
}
|
|
|
|
static void background_work_end(struct cache *cache)
|
|
{
|
|
lockdep_off();
|
|
up_read(&cache->background_work_lock);
|
|
lockdep_on();
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static bool bio_writes_complete_block(struct cache *cache, struct bio *bio)
|
|
{
|
|
return (bio_data_dir(bio) == WRITE) &&
|
|
(bio->bi_iter.bi_size == (cache->sectors_per_block << SECTOR_SHIFT));
|
|
}
|
|
|
|
static bool optimisable_bio(struct cache *cache, struct bio *bio, dm_oblock_t block)
|
|
{
|
|
return writeback_mode(cache) &&
|
|
(is_discarded_oblock(cache, block) || bio_writes_complete_block(cache, bio));
|
|
}
|
|
|
|
static void quiesce(struct dm_cache_migration *mg,
|
|
void (*continuation)(struct work_struct *))
|
|
{
|
|
init_continuation(&mg->k, continuation);
|
|
dm_cell_quiesce_v2(mg->cache->prison, mg->cell, &mg->k.ws);
|
|
}
|
|
|
|
static struct dm_cache_migration *ws_to_mg(struct work_struct *ws)
|
|
{
|
|
struct continuation *k = container_of(ws, struct continuation, ws);
|
|
return container_of(k, struct dm_cache_migration, k);
|
|
}
|
|
|
|
static void copy_complete(int read_err, unsigned long write_err, void *context)
|
|
{
|
|
struct dm_cache_migration *mg = container_of(context, struct dm_cache_migration, k);
|
|
|
|
if (read_err || write_err)
|
|
mg->k.input = BLK_STS_IOERR;
|
|
|
|
queue_continuation(mg->cache->wq, &mg->k);
|
|
}
|
|
|
|
static void copy(struct dm_cache_migration *mg, bool promote)
|
|
{
|
|
struct dm_io_region o_region, c_region;
|
|
struct cache *cache = mg->cache;
|
|
|
|
o_region.bdev = cache->origin_dev->bdev;
|
|
o_region.sector = from_oblock(mg->op->oblock) * cache->sectors_per_block;
|
|
o_region.count = cache->sectors_per_block;
|
|
|
|
c_region.bdev = cache->cache_dev->bdev;
|
|
c_region.sector = from_cblock(mg->op->cblock) * cache->sectors_per_block;
|
|
c_region.count = cache->sectors_per_block;
|
|
|
|
if (promote)
|
|
dm_kcopyd_copy(cache->copier, &o_region, 1, &c_region, 0, copy_complete, &mg->k);
|
|
else
|
|
dm_kcopyd_copy(cache->copier, &c_region, 1, &o_region, 0, copy_complete, &mg->k);
|
|
}
|
|
|
|
static void bio_drop_shared_lock(struct cache *cache, struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
if (pb->cell && dm_cell_put_v2(cache->prison, pb->cell))
|
|
free_prison_cell(cache, pb->cell);
|
|
pb->cell = NULL;
|
|
}
|
|
|
|
static void overwrite_endio(struct bio *bio)
|
|
{
|
|
struct dm_cache_migration *mg = bio->bi_private;
|
|
struct cache *cache = mg->cache;
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
dm_unhook_bio(&pb->hook_info, bio);
|
|
|
|
if (bio->bi_status)
|
|
mg->k.input = bio->bi_status;
|
|
|
|
queue_continuation(cache->wq, &mg->k);
|
|
}
|
|
|
|
static void overwrite(struct dm_cache_migration *mg,
|
|
void (*continuation)(struct work_struct *))
|
|
{
|
|
struct bio *bio = mg->overwrite_bio;
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
dm_hook_bio(&pb->hook_info, bio, overwrite_endio, mg);
|
|
|
|
/*
|
|
* The overwrite bio is part of the copy operation, as such it does
|
|
* not set/clear discard or dirty flags.
|
|
*/
|
|
if (mg->op->op == POLICY_PROMOTE)
|
|
remap_to_cache(mg->cache, bio, mg->op->cblock);
|
|
else
|
|
remap_to_origin(mg->cache, bio);
|
|
|
|
init_continuation(&mg->k, continuation);
|
|
accounted_request(mg->cache, bio);
|
|
}
|
|
|
|
/*
|
|
* Migration steps:
|
|
*
|
|
* 1) exclusive lock preventing WRITEs
|
|
* 2) quiesce
|
|
* 3) copy or issue overwrite bio
|
|
* 4) upgrade to exclusive lock preventing READs and WRITEs
|
|
* 5) quiesce
|
|
* 6) update metadata and commit
|
|
* 7) unlock
|
|
*/
|
|
static void mg_complete(struct dm_cache_migration *mg, bool success)
|
|
{
|
|
struct bio_list bios;
|
|
struct cache *cache = mg->cache;
|
|
struct policy_work *op = mg->op;
|
|
dm_cblock_t cblock = op->cblock;
|
|
|
|
if (success)
|
|
update_stats(&cache->stats, op->op);
|
|
|
|
switch (op->op) {
|
|
case POLICY_PROMOTE:
|
|
clear_discard(cache, oblock_to_dblock(cache, op->oblock));
|
|
policy_complete_background_work(cache->policy, op, success);
|
|
|
|
if (mg->overwrite_bio) {
|
|
if (success)
|
|
force_set_dirty(cache, cblock);
|
|
else if (mg->k.input)
|
|
mg->overwrite_bio->bi_status = mg->k.input;
|
|
else
|
|
mg->overwrite_bio->bi_status = BLK_STS_IOERR;
|
|
bio_endio(mg->overwrite_bio);
|
|
} else {
|
|
if (success)
|
|
force_clear_dirty(cache, cblock);
|
|
dec_io_migrations(cache);
|
|
}
|
|
break;
|
|
|
|
case POLICY_DEMOTE:
|
|
/*
|
|
* We clear dirty here to update the nr_dirty counter.
|
|
*/
|
|
if (success)
|
|
force_clear_dirty(cache, cblock);
|
|
policy_complete_background_work(cache->policy, op, success);
|
|
dec_io_migrations(cache);
|
|
break;
|
|
|
|
case POLICY_WRITEBACK:
|
|
if (success)
|
|
force_clear_dirty(cache, cblock);
|
|
policy_complete_background_work(cache->policy, op, success);
|
|
dec_io_migrations(cache);
|
|
break;
|
|
}
|
|
|
|
bio_list_init(&bios);
|
|
if (mg->cell) {
|
|
if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
|
|
free_prison_cell(cache, mg->cell);
|
|
}
|
|
|
|
free_migration(mg);
|
|
defer_bios(cache, &bios);
|
|
wake_migration_worker(cache);
|
|
|
|
background_work_end(cache);
|
|
}
|
|
|
|
static void mg_success(struct work_struct *ws)
|
|
{
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
mg_complete(mg, mg->k.input == 0);
|
|
}
|
|
|
|
static void mg_update_metadata(struct work_struct *ws)
|
|
{
|
|
int r;
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
struct cache *cache = mg->cache;
|
|
struct policy_work *op = mg->op;
|
|
|
|
switch (op->op) {
|
|
case POLICY_PROMOTE:
|
|
r = dm_cache_insert_mapping(cache->cmd, op->cblock, op->oblock);
|
|
if (r) {
|
|
DMERR_LIMIT("%s: migration failed; couldn't insert mapping",
|
|
cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_insert_mapping", r);
|
|
|
|
mg_complete(mg, false);
|
|
return;
|
|
}
|
|
mg_complete(mg, true);
|
|
break;
|
|
|
|
case POLICY_DEMOTE:
|
|
r = dm_cache_remove_mapping(cache->cmd, op->cblock);
|
|
if (r) {
|
|
DMERR_LIMIT("%s: migration failed; couldn't update on disk metadata",
|
|
cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
|
|
|
|
mg_complete(mg, false);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* It would be nice if we only had to commit when a REQ_FLUSH
|
|
* comes through. But there's one scenario that we have to
|
|
* look out for:
|
|
*
|
|
* - vblock x in a cache block
|
|
* - domotion occurs
|
|
* - cache block gets reallocated and over written
|
|
* - crash
|
|
*
|
|
* When we recover, because there was no commit the cache will
|
|
* rollback to having the data for vblock x in the cache block.
|
|
* But the cache block has since been overwritten, so it'll end
|
|
* up pointing to data that was never in 'x' during the history
|
|
* of the device.
|
|
*
|
|
* To avoid this issue we require a commit as part of the
|
|
* demotion operation.
|
|
*/
|
|
init_continuation(&mg->k, mg_success);
|
|
continue_after_commit(&cache->committer, &mg->k);
|
|
schedule_commit(&cache->committer);
|
|
break;
|
|
|
|
case POLICY_WRITEBACK:
|
|
mg_complete(mg, true);
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void mg_update_metadata_after_copy(struct work_struct *ws)
|
|
{
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
|
|
/*
|
|
* Did the copy succeed?
|
|
*/
|
|
if (mg->k.input)
|
|
mg_complete(mg, false);
|
|
else
|
|
mg_update_metadata(ws);
|
|
}
|
|
|
|
static void mg_upgrade_lock(struct work_struct *ws)
|
|
{
|
|
int r;
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
|
|
/*
|
|
* Did the copy succeed?
|
|
*/
|
|
if (mg->k.input)
|
|
mg_complete(mg, false);
|
|
|
|
else {
|
|
/*
|
|
* Now we want the lock to prevent both reads and writes.
|
|
*/
|
|
r = dm_cell_lock_promote_v2(mg->cache->prison, mg->cell,
|
|
READ_WRITE_LOCK_LEVEL);
|
|
if (r < 0)
|
|
mg_complete(mg, false);
|
|
|
|
else if (r)
|
|
quiesce(mg, mg_update_metadata);
|
|
|
|
else
|
|
mg_update_metadata(ws);
|
|
}
|
|
}
|
|
|
|
static void mg_full_copy(struct work_struct *ws)
|
|
{
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
struct cache *cache = mg->cache;
|
|
struct policy_work *op = mg->op;
|
|
bool is_policy_promote = (op->op == POLICY_PROMOTE);
|
|
|
|
if ((!is_policy_promote && !is_dirty(cache, op->cblock)) ||
|
|
is_discarded_oblock(cache, op->oblock)) {
|
|
mg_upgrade_lock(ws);
|
|
return;
|
|
}
|
|
|
|
init_continuation(&mg->k, mg_upgrade_lock);
|
|
copy(mg, is_policy_promote);
|
|
}
|
|
|
|
static void mg_copy(struct work_struct *ws)
|
|
{
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
|
|
if (mg->overwrite_bio) {
|
|
/*
|
|
* No exclusive lock was held when we last checked if the bio
|
|
* was optimisable. So we have to check again in case things
|
|
* have changed (eg, the block may no longer be discarded).
|
|
*/
|
|
if (!optimisable_bio(mg->cache, mg->overwrite_bio, mg->op->oblock)) {
|
|
/*
|
|
* Fallback to a real full copy after doing some tidying up.
|
|
*/
|
|
bool rb = bio_detain_shared(mg->cache, mg->op->oblock, mg->overwrite_bio);
|
|
BUG_ON(rb); /* An exclussive lock must _not_ be held for this block */
|
|
mg->overwrite_bio = NULL;
|
|
inc_io_migrations(mg->cache);
|
|
mg_full_copy(ws);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* It's safe to do this here, even though it's new data
|
|
* because all IO has been locked out of the block.
|
|
*
|
|
* mg_lock_writes() already took READ_WRITE_LOCK_LEVEL
|
|
* so _not_ using mg_upgrade_lock() as continutation.
|
|
*/
|
|
overwrite(mg, mg_update_metadata_after_copy);
|
|
|
|
} else
|
|
mg_full_copy(ws);
|
|
}
|
|
|
|
static int mg_lock_writes(struct dm_cache_migration *mg)
|
|
{
|
|
int r;
|
|
struct dm_cell_key_v2 key;
|
|
struct cache *cache = mg->cache;
|
|
struct dm_bio_prison_cell_v2 *prealloc;
|
|
|
|
prealloc = alloc_prison_cell(cache);
|
|
if (!prealloc) {
|
|
DMERR_LIMIT("%s: alloc_prison_cell failed", cache_device_name(cache));
|
|
mg_complete(mg, false);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* Prevent writes to the block, but allow reads to continue.
|
|
* Unless we're using an overwrite bio, in which case we lock
|
|
* everything.
|
|
*/
|
|
build_key(mg->op->oblock, oblock_succ(mg->op->oblock), &key);
|
|
r = dm_cell_lock_v2(cache->prison, &key,
|
|
mg->overwrite_bio ? READ_WRITE_LOCK_LEVEL : WRITE_LOCK_LEVEL,
|
|
prealloc, &mg->cell);
|
|
if (r < 0) {
|
|
free_prison_cell(cache, prealloc);
|
|
mg_complete(mg, false);
|
|
return r;
|
|
}
|
|
|
|
if (mg->cell != prealloc)
|
|
free_prison_cell(cache, prealloc);
|
|
|
|
if (r == 0)
|
|
mg_copy(&mg->k.ws);
|
|
else
|
|
quiesce(mg, mg_copy);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int mg_start(struct cache *cache, struct policy_work *op, struct bio *bio)
|
|
{
|
|
struct dm_cache_migration *mg;
|
|
|
|
if (!background_work_begin(cache)) {
|
|
policy_complete_background_work(cache->policy, op, false);
|
|
return -EPERM;
|
|
}
|
|
|
|
mg = alloc_migration(cache);
|
|
if (!mg) {
|
|
policy_complete_background_work(cache->policy, op, false);
|
|
background_work_end(cache);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
mg->op = op;
|
|
mg->overwrite_bio = bio;
|
|
|
|
if (!bio)
|
|
inc_io_migrations(cache);
|
|
|
|
return mg_lock_writes(mg);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* invalidation processing
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void invalidate_complete(struct dm_cache_migration *mg, bool success)
|
|
{
|
|
struct bio_list bios;
|
|
struct cache *cache = mg->cache;
|
|
|
|
bio_list_init(&bios);
|
|
if (dm_cell_unlock_v2(cache->prison, mg->cell, &bios))
|
|
free_prison_cell(cache, mg->cell);
|
|
|
|
if (!success && mg->overwrite_bio)
|
|
bio_io_error(mg->overwrite_bio);
|
|
|
|
free_migration(mg);
|
|
defer_bios(cache, &bios);
|
|
|
|
background_work_end(cache);
|
|
}
|
|
|
|
static void invalidate_completed(struct work_struct *ws)
|
|
{
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
invalidate_complete(mg, !mg->k.input);
|
|
}
|
|
|
|
static int invalidate_cblock(struct cache *cache, dm_cblock_t cblock)
|
|
{
|
|
int r = policy_invalidate_mapping(cache->policy, cblock);
|
|
if (!r) {
|
|
r = dm_cache_remove_mapping(cache->cmd, cblock);
|
|
if (r) {
|
|
DMERR_LIMIT("%s: invalidation failed; couldn't update on disk metadata",
|
|
cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_remove_mapping", r);
|
|
}
|
|
|
|
} else if (r == -ENODATA) {
|
|
/*
|
|
* Harmless, already unmapped.
|
|
*/
|
|
r = 0;
|
|
|
|
} else
|
|
DMERR("%s: policy_invalidate_mapping failed", cache_device_name(cache));
|
|
|
|
return r;
|
|
}
|
|
|
|
static void invalidate_remove(struct work_struct *ws)
|
|
{
|
|
int r;
|
|
struct dm_cache_migration *mg = ws_to_mg(ws);
|
|
struct cache *cache = mg->cache;
|
|
|
|
r = invalidate_cblock(cache, mg->invalidate_cblock);
|
|
if (r) {
|
|
invalidate_complete(mg, false);
|
|
return;
|
|
}
|
|
|
|
init_continuation(&mg->k, invalidate_completed);
|
|
continue_after_commit(&cache->committer, &mg->k);
|
|
remap_to_origin_clear_discard(cache, mg->overwrite_bio, mg->invalidate_oblock);
|
|
mg->overwrite_bio = NULL;
|
|
schedule_commit(&cache->committer);
|
|
}
|
|
|
|
static int invalidate_lock(struct dm_cache_migration *mg)
|
|
{
|
|
int r;
|
|
struct dm_cell_key_v2 key;
|
|
struct cache *cache = mg->cache;
|
|
struct dm_bio_prison_cell_v2 *prealloc;
|
|
|
|
prealloc = alloc_prison_cell(cache);
|
|
if (!prealloc) {
|
|
invalidate_complete(mg, false);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
build_key(mg->invalidate_oblock, oblock_succ(mg->invalidate_oblock), &key);
|
|
r = dm_cell_lock_v2(cache->prison, &key,
|
|
READ_WRITE_LOCK_LEVEL, prealloc, &mg->cell);
|
|
if (r < 0) {
|
|
free_prison_cell(cache, prealloc);
|
|
invalidate_complete(mg, false);
|
|
return r;
|
|
}
|
|
|
|
if (mg->cell != prealloc)
|
|
free_prison_cell(cache, prealloc);
|
|
|
|
if (r)
|
|
quiesce(mg, invalidate_remove);
|
|
|
|
else {
|
|
/*
|
|
* We can't call invalidate_remove() directly here because we
|
|
* might still be in request context.
|
|
*/
|
|
init_continuation(&mg->k, invalidate_remove);
|
|
queue_work(cache->wq, &mg->k.ws);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int invalidate_start(struct cache *cache, dm_cblock_t cblock,
|
|
dm_oblock_t oblock, struct bio *bio)
|
|
{
|
|
struct dm_cache_migration *mg;
|
|
|
|
if (!background_work_begin(cache))
|
|
return -EPERM;
|
|
|
|
mg = alloc_migration(cache);
|
|
if (!mg) {
|
|
background_work_end(cache);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
mg->overwrite_bio = bio;
|
|
mg->invalidate_cblock = cblock;
|
|
mg->invalidate_oblock = oblock;
|
|
|
|
return invalidate_lock(mg);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* bio processing
|
|
*--------------------------------------------------------------*/
|
|
|
|
enum busy {
|
|
IDLE,
|
|
BUSY
|
|
};
|
|
|
|
static enum busy spare_migration_bandwidth(struct cache *cache)
|
|
{
|
|
bool idle = iot_idle_for(&cache->tracker, HZ);
|
|
sector_t current_volume = (atomic_read(&cache->nr_io_migrations) + 1) *
|
|
cache->sectors_per_block;
|
|
|
|
if (idle && current_volume <= cache->migration_threshold)
|
|
return IDLE;
|
|
else
|
|
return BUSY;
|
|
}
|
|
|
|
static void inc_hit_counter(struct cache *cache, struct bio *bio)
|
|
{
|
|
atomic_inc(bio_data_dir(bio) == READ ?
|
|
&cache->stats.read_hit : &cache->stats.write_hit);
|
|
}
|
|
|
|
static void inc_miss_counter(struct cache *cache, struct bio *bio)
|
|
{
|
|
atomic_inc(bio_data_dir(bio) == READ ?
|
|
&cache->stats.read_miss : &cache->stats.write_miss);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static int map_bio(struct cache *cache, struct bio *bio, dm_oblock_t block,
|
|
bool *commit_needed)
|
|
{
|
|
int r, data_dir;
|
|
bool rb, background_queued;
|
|
dm_cblock_t cblock;
|
|
|
|
*commit_needed = false;
|
|
|
|
rb = bio_detain_shared(cache, block, bio);
|
|
if (!rb) {
|
|
/*
|
|
* An exclusive lock is held for this block, so we have to
|
|
* wait. We set the commit_needed flag so the current
|
|
* transaction will be committed asap, allowing this lock
|
|
* to be dropped.
|
|
*/
|
|
*commit_needed = true;
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
|
|
data_dir = bio_data_dir(bio);
|
|
|
|
if (optimisable_bio(cache, bio, block)) {
|
|
struct policy_work *op = NULL;
|
|
|
|
r = policy_lookup_with_work(cache->policy, block, &cblock, data_dir, true, &op);
|
|
if (unlikely(r && r != -ENOENT)) {
|
|
DMERR_LIMIT("%s: policy_lookup_with_work() failed with r = %d",
|
|
cache_device_name(cache), r);
|
|
bio_io_error(bio);
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
|
|
if (r == -ENOENT && op) {
|
|
bio_drop_shared_lock(cache, bio);
|
|
BUG_ON(op->op != POLICY_PROMOTE);
|
|
mg_start(cache, op, bio);
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
} else {
|
|
r = policy_lookup(cache->policy, block, &cblock, data_dir, false, &background_queued);
|
|
if (unlikely(r && r != -ENOENT)) {
|
|
DMERR_LIMIT("%s: policy_lookup() failed with r = %d",
|
|
cache_device_name(cache), r);
|
|
bio_io_error(bio);
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
|
|
if (background_queued)
|
|
wake_migration_worker(cache);
|
|
}
|
|
|
|
if (r == -ENOENT) {
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
/*
|
|
* Miss.
|
|
*/
|
|
inc_miss_counter(cache, bio);
|
|
if (pb->req_nr == 0) {
|
|
accounted_begin(cache, bio);
|
|
remap_to_origin_clear_discard(cache, bio, block);
|
|
} else {
|
|
/*
|
|
* This is a duplicate writethrough io that is no
|
|
* longer needed because the block has been demoted.
|
|
*/
|
|
bio_endio(bio);
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
} else {
|
|
/*
|
|
* Hit.
|
|
*/
|
|
inc_hit_counter(cache, bio);
|
|
|
|
/*
|
|
* Passthrough always maps to the origin, invalidating any
|
|
* cache blocks that are written to.
|
|
*/
|
|
if (passthrough_mode(cache)) {
|
|
if (bio_data_dir(bio) == WRITE) {
|
|
bio_drop_shared_lock(cache, bio);
|
|
atomic_inc(&cache->stats.demotion);
|
|
invalidate_start(cache, cblock, block, bio);
|
|
} else
|
|
remap_to_origin_clear_discard(cache, bio, block);
|
|
} else {
|
|
if (bio_data_dir(bio) == WRITE && writethrough_mode(cache) &&
|
|
!is_dirty(cache, cblock)) {
|
|
remap_to_origin_and_cache(cache, bio, block, cblock);
|
|
accounted_begin(cache, bio);
|
|
} else
|
|
remap_to_cache_dirty(cache, bio, block, cblock);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* dm core turns FUA requests into a separate payload and FLUSH req.
|
|
*/
|
|
if (bio->bi_opf & REQ_FUA) {
|
|
/*
|
|
* issue_after_commit will call accounted_begin a second time. So
|
|
* we call accounted_complete() to avoid double accounting.
|
|
*/
|
|
accounted_complete(cache, bio);
|
|
issue_after_commit(&cache->committer, bio);
|
|
*commit_needed = true;
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
|
|
return DM_MAPIO_REMAPPED;
|
|
}
|
|
|
|
static bool process_bio(struct cache *cache, struct bio *bio)
|
|
{
|
|
bool commit_needed;
|
|
|
|
if (map_bio(cache, bio, get_bio_block(cache, bio), &commit_needed) == DM_MAPIO_REMAPPED)
|
|
generic_make_request(bio);
|
|
|
|
return commit_needed;
|
|
}
|
|
|
|
/*
|
|
* A non-zero return indicates read_only or fail_io mode.
|
|
*/
|
|
static int commit(struct cache *cache, bool clean_shutdown)
|
|
{
|
|
int r;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return -EINVAL;
|
|
|
|
atomic_inc(&cache->stats.commit_count);
|
|
r = dm_cache_commit(cache->cmd, clean_shutdown);
|
|
if (r)
|
|
metadata_operation_failed(cache, "dm_cache_commit", r);
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* Used by the batcher.
|
|
*/
|
|
static blk_status_t commit_op(void *context)
|
|
{
|
|
struct cache *cache = context;
|
|
|
|
if (dm_cache_changed_this_transaction(cache->cmd))
|
|
return errno_to_blk_status(commit(cache, false));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static bool process_flush_bio(struct cache *cache, struct bio *bio)
|
|
{
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
if (!pb->req_nr)
|
|
remap_to_origin(cache, bio);
|
|
else
|
|
remap_to_cache(cache, bio, 0);
|
|
|
|
issue_after_commit(&cache->committer, bio);
|
|
return true;
|
|
}
|
|
|
|
static bool process_discard_bio(struct cache *cache, struct bio *bio)
|
|
{
|
|
dm_dblock_t b, e;
|
|
|
|
// FIXME: do we need to lock the region? Or can we just assume the
|
|
// user wont be so foolish as to issue discard concurrently with
|
|
// other IO?
|
|
calc_discard_block_range(cache, bio, &b, &e);
|
|
while (b != e) {
|
|
set_discard(cache, b);
|
|
b = to_dblock(from_dblock(b) + 1);
|
|
}
|
|
|
|
if (cache->features.discard_passdown) {
|
|
remap_to_origin(cache, bio);
|
|
generic_make_request(bio);
|
|
} else
|
|
bio_endio(bio);
|
|
|
|
return false;
|
|
}
|
|
|
|
static void process_deferred_bios(struct work_struct *ws)
|
|
{
|
|
struct cache *cache = container_of(ws, struct cache, deferred_bio_worker);
|
|
|
|
unsigned long flags;
|
|
bool commit_needed = false;
|
|
struct bio_list bios;
|
|
struct bio *bio;
|
|
|
|
bio_list_init(&bios);
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
bio_list_merge(&bios, &cache->deferred_bios);
|
|
bio_list_init(&cache->deferred_bios);
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
|
|
while ((bio = bio_list_pop(&bios))) {
|
|
if (bio->bi_opf & REQ_PREFLUSH)
|
|
commit_needed = process_flush_bio(cache, bio) || commit_needed;
|
|
|
|
else if (bio_op(bio) == REQ_OP_DISCARD)
|
|
commit_needed = process_discard_bio(cache, bio) || commit_needed;
|
|
|
|
else
|
|
commit_needed = process_bio(cache, bio) || commit_needed;
|
|
}
|
|
|
|
if (commit_needed)
|
|
schedule_commit(&cache->committer);
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Main worker loop
|
|
*--------------------------------------------------------------*/
|
|
|
|
static void requeue_deferred_bios(struct cache *cache)
|
|
{
|
|
struct bio *bio;
|
|
struct bio_list bios;
|
|
|
|
bio_list_init(&bios);
|
|
bio_list_merge(&bios, &cache->deferred_bios);
|
|
bio_list_init(&cache->deferred_bios);
|
|
|
|
while ((bio = bio_list_pop(&bios))) {
|
|
bio->bi_status = BLK_STS_DM_REQUEUE;
|
|
bio_endio(bio);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We want to commit periodically so that not too much
|
|
* unwritten metadata builds up.
|
|
*/
|
|
static void do_waker(struct work_struct *ws)
|
|
{
|
|
struct cache *cache = container_of(to_delayed_work(ws), struct cache, waker);
|
|
|
|
policy_tick(cache->policy, true);
|
|
wake_migration_worker(cache);
|
|
schedule_commit(&cache->committer);
|
|
queue_delayed_work(cache->wq, &cache->waker, COMMIT_PERIOD);
|
|
}
|
|
|
|
static void check_migrations(struct work_struct *ws)
|
|
{
|
|
int r;
|
|
struct policy_work *op;
|
|
struct cache *cache = container_of(ws, struct cache, migration_worker);
|
|
enum busy b;
|
|
|
|
for (;;) {
|
|
b = spare_migration_bandwidth(cache);
|
|
|
|
r = policy_get_background_work(cache->policy, b == IDLE, &op);
|
|
if (r == -ENODATA)
|
|
break;
|
|
|
|
if (r) {
|
|
DMERR_LIMIT("%s: policy_background_work failed",
|
|
cache_device_name(cache));
|
|
break;
|
|
}
|
|
|
|
r = mg_start(cache, op, NULL);
|
|
if (r)
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*----------------------------------------------------------------
|
|
* Target methods
|
|
*--------------------------------------------------------------*/
|
|
|
|
/*
|
|
* This function gets called on the error paths of the constructor, so we
|
|
* have to cope with a partially initialised struct.
|
|
*/
|
|
static void destroy(struct cache *cache)
|
|
{
|
|
unsigned i;
|
|
|
|
mempool_exit(&cache->migration_pool);
|
|
|
|
if (cache->prison)
|
|
dm_bio_prison_destroy_v2(cache->prison);
|
|
|
|
if (cache->wq)
|
|
destroy_workqueue(cache->wq);
|
|
|
|
if (cache->dirty_bitset)
|
|
free_bitset(cache->dirty_bitset);
|
|
|
|
if (cache->discard_bitset)
|
|
free_bitset(cache->discard_bitset);
|
|
|
|
if (cache->copier)
|
|
dm_kcopyd_client_destroy(cache->copier);
|
|
|
|
if (cache->cmd)
|
|
dm_cache_metadata_close(cache->cmd);
|
|
|
|
if (cache->metadata_dev)
|
|
dm_put_device(cache->ti, cache->metadata_dev);
|
|
|
|
if (cache->origin_dev)
|
|
dm_put_device(cache->ti, cache->origin_dev);
|
|
|
|
if (cache->cache_dev)
|
|
dm_put_device(cache->ti, cache->cache_dev);
|
|
|
|
if (cache->policy)
|
|
dm_cache_policy_destroy(cache->policy);
|
|
|
|
for (i = 0; i < cache->nr_ctr_args ; i++)
|
|
kfree(cache->ctr_args[i]);
|
|
kfree(cache->ctr_args);
|
|
|
|
bioset_exit(&cache->bs);
|
|
|
|
kfree(cache);
|
|
}
|
|
|
|
static void cache_dtr(struct dm_target *ti)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
|
|
destroy(cache);
|
|
}
|
|
|
|
static sector_t get_dev_size(struct dm_dev *dev)
|
|
{
|
|
return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Construct a cache device mapping.
|
|
*
|
|
* cache <metadata dev> <cache dev> <origin dev> <block size>
|
|
* <#feature args> [<feature arg>]*
|
|
* <policy> <#policy args> [<policy arg>]*
|
|
*
|
|
* metadata dev : fast device holding the persistent metadata
|
|
* cache dev : fast device holding cached data blocks
|
|
* origin dev : slow device holding original data blocks
|
|
* block size : cache unit size in sectors
|
|
*
|
|
* #feature args : number of feature arguments passed
|
|
* feature args : writethrough. (The default is writeback.)
|
|
*
|
|
* policy : the replacement policy to use
|
|
* #policy args : an even number of policy arguments corresponding
|
|
* to key/value pairs passed to the policy
|
|
* policy args : key/value pairs passed to the policy
|
|
* E.g. 'sequential_threshold 1024'
|
|
* See cache-policies.txt for details.
|
|
*
|
|
* Optional feature arguments are:
|
|
* writethrough : write through caching that prohibits cache block
|
|
* content from being different from origin block content.
|
|
* Without this argument, the default behaviour is to write
|
|
* back cache block contents later for performance reasons,
|
|
* so they may differ from the corresponding origin blocks.
|
|
*/
|
|
struct cache_args {
|
|
struct dm_target *ti;
|
|
|
|
struct dm_dev *metadata_dev;
|
|
|
|
struct dm_dev *cache_dev;
|
|
sector_t cache_sectors;
|
|
|
|
struct dm_dev *origin_dev;
|
|
sector_t origin_sectors;
|
|
|
|
uint32_t block_size;
|
|
|
|
const char *policy_name;
|
|
int policy_argc;
|
|
const char **policy_argv;
|
|
|
|
struct cache_features features;
|
|
};
|
|
|
|
static void destroy_cache_args(struct cache_args *ca)
|
|
{
|
|
if (ca->metadata_dev)
|
|
dm_put_device(ca->ti, ca->metadata_dev);
|
|
|
|
if (ca->cache_dev)
|
|
dm_put_device(ca->ti, ca->cache_dev);
|
|
|
|
if (ca->origin_dev)
|
|
dm_put_device(ca->ti, ca->origin_dev);
|
|
|
|
kfree(ca);
|
|
}
|
|
|
|
static bool at_least_one_arg(struct dm_arg_set *as, char **error)
|
|
{
|
|
if (!as->argc) {
|
|
*error = "Insufficient args";
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static int parse_metadata_dev(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
int r;
|
|
sector_t metadata_dev_size;
|
|
char b[BDEVNAME_SIZE];
|
|
|
|
if (!at_least_one_arg(as, error))
|
|
return -EINVAL;
|
|
|
|
r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
|
|
&ca->metadata_dev);
|
|
if (r) {
|
|
*error = "Error opening metadata device";
|
|
return r;
|
|
}
|
|
|
|
metadata_dev_size = get_dev_size(ca->metadata_dev);
|
|
if (metadata_dev_size > DM_CACHE_METADATA_MAX_SECTORS_WARNING)
|
|
DMWARN("Metadata device %s is larger than %u sectors: excess space will not be used.",
|
|
bdevname(ca->metadata_dev->bdev, b), THIN_METADATA_MAX_SECTORS);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
int r;
|
|
|
|
if (!at_least_one_arg(as, error))
|
|
return -EINVAL;
|
|
|
|
r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
|
|
&ca->cache_dev);
|
|
if (r) {
|
|
*error = "Error opening cache device";
|
|
return r;
|
|
}
|
|
ca->cache_sectors = get_dev_size(ca->cache_dev);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
int r;
|
|
|
|
if (!at_least_one_arg(as, error))
|
|
return -EINVAL;
|
|
|
|
r = dm_get_device(ca->ti, dm_shift_arg(as), FMODE_READ | FMODE_WRITE,
|
|
&ca->origin_dev);
|
|
if (r) {
|
|
*error = "Error opening origin device";
|
|
return r;
|
|
}
|
|
|
|
ca->origin_sectors = get_dev_size(ca->origin_dev);
|
|
if (ca->ti->len > ca->origin_sectors) {
|
|
*error = "Device size larger than cached device";
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int parse_block_size(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
unsigned long block_size;
|
|
|
|
if (!at_least_one_arg(as, error))
|
|
return -EINVAL;
|
|
|
|
if (kstrtoul(dm_shift_arg(as), 10, &block_size) || !block_size ||
|
|
block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
|
|
block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
|
|
block_size & (DATA_DEV_BLOCK_SIZE_MIN_SECTORS - 1)) {
|
|
*error = "Invalid data block size";
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (block_size > ca->cache_sectors) {
|
|
*error = "Data block size is larger than the cache device";
|
|
return -EINVAL;
|
|
}
|
|
|
|
ca->block_size = block_size;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void init_features(struct cache_features *cf)
|
|
{
|
|
cf->mode = CM_WRITE;
|
|
cf->io_mode = CM_IO_WRITEBACK;
|
|
cf->metadata_version = 1;
|
|
cf->discard_passdown = true;
|
|
}
|
|
|
|
static int parse_features(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
static const struct dm_arg _args[] = {
|
|
{0, 3, "Invalid number of cache feature arguments"},
|
|
};
|
|
|
|
int r, mode_ctr = 0;
|
|
unsigned argc;
|
|
const char *arg;
|
|
struct cache_features *cf = &ca->features;
|
|
|
|
init_features(cf);
|
|
|
|
r = dm_read_arg_group(_args, as, &argc, error);
|
|
if (r)
|
|
return -EINVAL;
|
|
|
|
while (argc--) {
|
|
arg = dm_shift_arg(as);
|
|
|
|
if (!strcasecmp(arg, "writeback")) {
|
|
cf->io_mode = CM_IO_WRITEBACK;
|
|
mode_ctr++;
|
|
}
|
|
|
|
else if (!strcasecmp(arg, "writethrough")) {
|
|
cf->io_mode = CM_IO_WRITETHROUGH;
|
|
mode_ctr++;
|
|
}
|
|
|
|
else if (!strcasecmp(arg, "passthrough")) {
|
|
cf->io_mode = CM_IO_PASSTHROUGH;
|
|
mode_ctr++;
|
|
}
|
|
|
|
else if (!strcasecmp(arg, "metadata2"))
|
|
cf->metadata_version = 2;
|
|
|
|
else if (!strcasecmp(arg, "no_discard_passdown"))
|
|
cf->discard_passdown = false;
|
|
|
|
else {
|
|
*error = "Unrecognised cache feature requested";
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
if (mode_ctr > 1) {
|
|
*error = "Duplicate cache io_mode features requested";
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int parse_policy(struct cache_args *ca, struct dm_arg_set *as,
|
|
char **error)
|
|
{
|
|
static const struct dm_arg _args[] = {
|
|
{0, 1024, "Invalid number of policy arguments"},
|
|
};
|
|
|
|
int r;
|
|
|
|
if (!at_least_one_arg(as, error))
|
|
return -EINVAL;
|
|
|
|
ca->policy_name = dm_shift_arg(as);
|
|
|
|
r = dm_read_arg_group(_args, as, &ca->policy_argc, error);
|
|
if (r)
|
|
return -EINVAL;
|
|
|
|
ca->policy_argv = (const char **)as->argv;
|
|
dm_consume_args(as, ca->policy_argc);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int parse_cache_args(struct cache_args *ca, int argc, char **argv,
|
|
char **error)
|
|
{
|
|
int r;
|
|
struct dm_arg_set as;
|
|
|
|
as.argc = argc;
|
|
as.argv = argv;
|
|
|
|
r = parse_metadata_dev(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
r = parse_cache_dev(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
r = parse_origin_dev(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
r = parse_block_size(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
r = parse_features(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
r = parse_policy(ca, &as, error);
|
|
if (r)
|
|
return r;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static struct kmem_cache *migration_cache;
|
|
|
|
#define NOT_CORE_OPTION 1
|
|
|
|
static int process_config_option(struct cache *cache, const char *key, const char *value)
|
|
{
|
|
unsigned long tmp;
|
|
|
|
if (!strcasecmp(key, "migration_threshold")) {
|
|
if (kstrtoul(value, 10, &tmp))
|
|
return -EINVAL;
|
|
|
|
cache->migration_threshold = tmp;
|
|
return 0;
|
|
}
|
|
|
|
return NOT_CORE_OPTION;
|
|
}
|
|
|
|
static int set_config_value(struct cache *cache, const char *key, const char *value)
|
|
{
|
|
int r = process_config_option(cache, key, value);
|
|
|
|
if (r == NOT_CORE_OPTION)
|
|
r = policy_set_config_value(cache->policy, key, value);
|
|
|
|
if (r)
|
|
DMWARN("bad config value for %s: %s", key, value);
|
|
|
|
return r;
|
|
}
|
|
|
|
static int set_config_values(struct cache *cache, int argc, const char **argv)
|
|
{
|
|
int r = 0;
|
|
|
|
if (argc & 1) {
|
|
DMWARN("Odd number of policy arguments given but they should be <key> <value> pairs.");
|
|
return -EINVAL;
|
|
}
|
|
|
|
while (argc) {
|
|
r = set_config_value(cache, argv[0], argv[1]);
|
|
if (r)
|
|
break;
|
|
|
|
argc -= 2;
|
|
argv += 2;
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
static int create_cache_policy(struct cache *cache, struct cache_args *ca,
|
|
char **error)
|
|
{
|
|
struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
|
|
cache->cache_size,
|
|
cache->origin_sectors,
|
|
cache->sectors_per_block);
|
|
if (IS_ERR(p)) {
|
|
*error = "Error creating cache's policy";
|
|
return PTR_ERR(p);
|
|
}
|
|
cache->policy = p;
|
|
BUG_ON(!cache->policy);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We want the discard block size to be at least the size of the cache
|
|
* block size and have no more than 2^14 discard blocks across the origin.
|
|
*/
|
|
#define MAX_DISCARD_BLOCKS (1 << 14)
|
|
|
|
static bool too_many_discard_blocks(sector_t discard_block_size,
|
|
sector_t origin_size)
|
|
{
|
|
(void) sector_div(origin_size, discard_block_size);
|
|
|
|
return origin_size > MAX_DISCARD_BLOCKS;
|
|
}
|
|
|
|
static sector_t calculate_discard_block_size(sector_t cache_block_size,
|
|
sector_t origin_size)
|
|
{
|
|
sector_t discard_block_size = cache_block_size;
|
|
|
|
if (origin_size)
|
|
while (too_many_discard_blocks(discard_block_size, origin_size))
|
|
discard_block_size *= 2;
|
|
|
|
return discard_block_size;
|
|
}
|
|
|
|
static void set_cache_size(struct cache *cache, dm_cblock_t size)
|
|
{
|
|
dm_block_t nr_blocks = from_cblock(size);
|
|
|
|
if (nr_blocks > (1 << 20) && cache->cache_size != size)
|
|
DMWARN_LIMIT("You have created a cache device with a lot of individual cache blocks (%llu)\n"
|
|
"All these mappings can consume a lot of kernel memory, and take some time to read/write.\n"
|
|
"Please consider increasing the cache block size to reduce the overall cache block count.",
|
|
(unsigned long long) nr_blocks);
|
|
|
|
cache->cache_size = size;
|
|
}
|
|
|
|
static int is_congested(struct dm_dev *dev, int bdi_bits)
|
|
{
|
|
struct request_queue *q = bdev_get_queue(dev->bdev);
|
|
return bdi_congested(q->backing_dev_info, bdi_bits);
|
|
}
|
|
|
|
static int cache_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
|
|
{
|
|
struct cache *cache = container_of(cb, struct cache, callbacks);
|
|
|
|
return is_congested(cache->origin_dev, bdi_bits) ||
|
|
is_congested(cache->cache_dev, bdi_bits);
|
|
}
|
|
|
|
#define DEFAULT_MIGRATION_THRESHOLD 2048
|
|
|
|
static int cache_create(struct cache_args *ca, struct cache **result)
|
|
{
|
|
int r = 0;
|
|
char **error = &ca->ti->error;
|
|
struct cache *cache;
|
|
struct dm_target *ti = ca->ti;
|
|
dm_block_t origin_blocks;
|
|
struct dm_cache_metadata *cmd;
|
|
bool may_format = ca->features.mode == CM_WRITE;
|
|
|
|
cache = kzalloc(sizeof(*cache), GFP_KERNEL);
|
|
if (!cache)
|
|
return -ENOMEM;
|
|
|
|
cache->ti = ca->ti;
|
|
ti->private = cache;
|
|
ti->num_flush_bios = 2;
|
|
ti->flush_supported = true;
|
|
|
|
ti->num_discard_bios = 1;
|
|
ti->discards_supported = true;
|
|
|
|
ti->per_io_data_size = sizeof(struct per_bio_data);
|
|
|
|
cache->features = ca->features;
|
|
if (writethrough_mode(cache)) {
|
|
/* Create bioset for writethrough bios issued to origin */
|
|
r = bioset_init(&cache->bs, BIO_POOL_SIZE, 0, 0);
|
|
if (r)
|
|
goto bad;
|
|
}
|
|
|
|
cache->callbacks.congested_fn = cache_is_congested;
|
|
dm_table_add_target_callbacks(ti->table, &cache->callbacks);
|
|
|
|
cache->metadata_dev = ca->metadata_dev;
|
|
cache->origin_dev = ca->origin_dev;
|
|
cache->cache_dev = ca->cache_dev;
|
|
|
|
ca->metadata_dev = ca->origin_dev = ca->cache_dev = NULL;
|
|
|
|
origin_blocks = cache->origin_sectors = ca->origin_sectors;
|
|
origin_blocks = block_div(origin_blocks, ca->block_size);
|
|
cache->origin_blocks = to_oblock(origin_blocks);
|
|
|
|
cache->sectors_per_block = ca->block_size;
|
|
if (dm_set_target_max_io_len(ti, cache->sectors_per_block)) {
|
|
r = -EINVAL;
|
|
goto bad;
|
|
}
|
|
|
|
if (ca->block_size & (ca->block_size - 1)) {
|
|
dm_block_t cache_size = ca->cache_sectors;
|
|
|
|
cache->sectors_per_block_shift = -1;
|
|
cache_size = block_div(cache_size, ca->block_size);
|
|
set_cache_size(cache, to_cblock(cache_size));
|
|
} else {
|
|
cache->sectors_per_block_shift = __ffs(ca->block_size);
|
|
set_cache_size(cache, to_cblock(ca->cache_sectors >> cache->sectors_per_block_shift));
|
|
}
|
|
|
|
r = create_cache_policy(cache, ca, error);
|
|
if (r)
|
|
goto bad;
|
|
|
|
cache->policy_nr_args = ca->policy_argc;
|
|
cache->migration_threshold = DEFAULT_MIGRATION_THRESHOLD;
|
|
|
|
r = set_config_values(cache, ca->policy_argc, ca->policy_argv);
|
|
if (r) {
|
|
*error = "Error setting cache policy's config values";
|
|
goto bad;
|
|
}
|
|
|
|
cmd = dm_cache_metadata_open(cache->metadata_dev->bdev,
|
|
ca->block_size, may_format,
|
|
dm_cache_policy_get_hint_size(cache->policy),
|
|
ca->features.metadata_version);
|
|
if (IS_ERR(cmd)) {
|
|
*error = "Error creating metadata object";
|
|
r = PTR_ERR(cmd);
|
|
goto bad;
|
|
}
|
|
cache->cmd = cmd;
|
|
set_cache_mode(cache, CM_WRITE);
|
|
if (get_cache_mode(cache) != CM_WRITE) {
|
|
*error = "Unable to get write access to metadata, please check/repair metadata.";
|
|
r = -EINVAL;
|
|
goto bad;
|
|
}
|
|
|
|
if (passthrough_mode(cache)) {
|
|
bool all_clean;
|
|
|
|
r = dm_cache_metadata_all_clean(cache->cmd, &all_clean);
|
|
if (r) {
|
|
*error = "dm_cache_metadata_all_clean() failed";
|
|
goto bad;
|
|
}
|
|
|
|
if (!all_clean) {
|
|
*error = "Cannot enter passthrough mode unless all blocks are clean";
|
|
r = -EINVAL;
|
|
goto bad;
|
|
}
|
|
|
|
policy_allow_migrations(cache->policy, false);
|
|
}
|
|
|
|
spin_lock_init(&cache->lock);
|
|
bio_list_init(&cache->deferred_bios);
|
|
atomic_set(&cache->nr_allocated_migrations, 0);
|
|
atomic_set(&cache->nr_io_migrations, 0);
|
|
init_waitqueue_head(&cache->migration_wait);
|
|
|
|
r = -ENOMEM;
|
|
atomic_set(&cache->nr_dirty, 0);
|
|
cache->dirty_bitset = alloc_bitset(from_cblock(cache->cache_size));
|
|
if (!cache->dirty_bitset) {
|
|
*error = "could not allocate dirty bitset";
|
|
goto bad;
|
|
}
|
|
clear_bitset(cache->dirty_bitset, from_cblock(cache->cache_size));
|
|
|
|
cache->discard_block_size =
|
|
calculate_discard_block_size(cache->sectors_per_block,
|
|
cache->origin_sectors);
|
|
cache->discard_nr_blocks = to_dblock(dm_sector_div_up(cache->origin_sectors,
|
|
cache->discard_block_size));
|
|
cache->discard_bitset = alloc_bitset(from_dblock(cache->discard_nr_blocks));
|
|
if (!cache->discard_bitset) {
|
|
*error = "could not allocate discard bitset";
|
|
goto bad;
|
|
}
|
|
clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
|
|
|
|
cache->copier = dm_kcopyd_client_create(&dm_kcopyd_throttle);
|
|
if (IS_ERR(cache->copier)) {
|
|
*error = "could not create kcopyd client";
|
|
r = PTR_ERR(cache->copier);
|
|
goto bad;
|
|
}
|
|
|
|
cache->wq = alloc_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM, 0);
|
|
if (!cache->wq) {
|
|
*error = "could not create workqueue for metadata object";
|
|
goto bad;
|
|
}
|
|
INIT_WORK(&cache->deferred_bio_worker, process_deferred_bios);
|
|
INIT_WORK(&cache->migration_worker, check_migrations);
|
|
INIT_DELAYED_WORK(&cache->waker, do_waker);
|
|
|
|
cache->prison = dm_bio_prison_create_v2(cache->wq);
|
|
if (!cache->prison) {
|
|
*error = "could not create bio prison";
|
|
goto bad;
|
|
}
|
|
|
|
r = mempool_init_slab_pool(&cache->migration_pool, MIGRATION_POOL_SIZE,
|
|
migration_cache);
|
|
if (r) {
|
|
*error = "Error creating cache's migration mempool";
|
|
goto bad;
|
|
}
|
|
|
|
cache->need_tick_bio = true;
|
|
cache->sized = false;
|
|
cache->invalidate = false;
|
|
cache->commit_requested = false;
|
|
cache->loaded_mappings = false;
|
|
cache->loaded_discards = false;
|
|
|
|
load_stats(cache);
|
|
|
|
atomic_set(&cache->stats.demotion, 0);
|
|
atomic_set(&cache->stats.promotion, 0);
|
|
atomic_set(&cache->stats.copies_avoided, 0);
|
|
atomic_set(&cache->stats.cache_cell_clash, 0);
|
|
atomic_set(&cache->stats.commit_count, 0);
|
|
atomic_set(&cache->stats.discard_count, 0);
|
|
|
|
spin_lock_init(&cache->invalidation_lock);
|
|
INIT_LIST_HEAD(&cache->invalidation_requests);
|
|
|
|
batcher_init(&cache->committer, commit_op, cache,
|
|
issue_op, cache, cache->wq);
|
|
iot_init(&cache->tracker);
|
|
|
|
init_rwsem(&cache->background_work_lock);
|
|
prevent_background_work(cache);
|
|
|
|
*result = cache;
|
|
return 0;
|
|
bad:
|
|
destroy(cache);
|
|
return r;
|
|
}
|
|
|
|
static int copy_ctr_args(struct cache *cache, int argc, const char **argv)
|
|
{
|
|
unsigned i;
|
|
const char **copy;
|
|
|
|
copy = kcalloc(argc, sizeof(*copy), GFP_KERNEL);
|
|
if (!copy)
|
|
return -ENOMEM;
|
|
for (i = 0; i < argc; i++) {
|
|
copy[i] = kstrdup(argv[i], GFP_KERNEL);
|
|
if (!copy[i]) {
|
|
while (i--)
|
|
kfree(copy[i]);
|
|
kfree(copy);
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
|
|
cache->nr_ctr_args = argc;
|
|
cache->ctr_args = copy;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cache_ctr(struct dm_target *ti, unsigned argc, char **argv)
|
|
{
|
|
int r = -EINVAL;
|
|
struct cache_args *ca;
|
|
struct cache *cache = NULL;
|
|
|
|
ca = kzalloc(sizeof(*ca), GFP_KERNEL);
|
|
if (!ca) {
|
|
ti->error = "Error allocating memory for cache";
|
|
return -ENOMEM;
|
|
}
|
|
ca->ti = ti;
|
|
|
|
r = parse_cache_args(ca, argc, argv, &ti->error);
|
|
if (r)
|
|
goto out;
|
|
|
|
r = cache_create(ca, &cache);
|
|
if (r)
|
|
goto out;
|
|
|
|
r = copy_ctr_args(cache, argc - 3, (const char **)argv + 3);
|
|
if (r) {
|
|
destroy(cache);
|
|
goto out;
|
|
}
|
|
|
|
ti->private = cache;
|
|
out:
|
|
destroy_cache_args(ca);
|
|
return r;
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static int cache_map(struct dm_target *ti, struct bio *bio)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
|
|
int r;
|
|
bool commit_needed;
|
|
dm_oblock_t block = get_bio_block(cache, bio);
|
|
|
|
init_per_bio_data(bio);
|
|
if (unlikely(from_oblock(block) >= from_oblock(cache->origin_blocks))) {
|
|
/*
|
|
* This can only occur if the io goes to a partial block at
|
|
* the end of the origin device. We don't cache these.
|
|
* Just remap to the origin and carry on.
|
|
*/
|
|
remap_to_origin(cache, bio);
|
|
accounted_begin(cache, bio);
|
|
return DM_MAPIO_REMAPPED;
|
|
}
|
|
|
|
if (discard_or_flush(bio)) {
|
|
defer_bio(cache, bio);
|
|
return DM_MAPIO_SUBMITTED;
|
|
}
|
|
|
|
r = map_bio(cache, bio, block, &commit_needed);
|
|
if (commit_needed)
|
|
schedule_commit(&cache->committer);
|
|
|
|
return r;
|
|
}
|
|
|
|
static int cache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *error)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
unsigned long flags;
|
|
struct per_bio_data *pb = get_per_bio_data(bio);
|
|
|
|
if (pb->tick) {
|
|
policy_tick(cache->policy, false);
|
|
|
|
spin_lock_irqsave(&cache->lock, flags);
|
|
cache->need_tick_bio = true;
|
|
spin_unlock_irqrestore(&cache->lock, flags);
|
|
}
|
|
|
|
bio_drop_shared_lock(cache, bio);
|
|
accounted_complete(cache, bio);
|
|
|
|
return DM_ENDIO_DONE;
|
|
}
|
|
|
|
static int write_dirty_bitset(struct cache *cache)
|
|
{
|
|
int r;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return -EINVAL;
|
|
|
|
r = dm_cache_set_dirty_bits(cache->cmd, from_cblock(cache->cache_size), cache->dirty_bitset);
|
|
if (r)
|
|
metadata_operation_failed(cache, "dm_cache_set_dirty_bits", r);
|
|
|
|
return r;
|
|
}
|
|
|
|
static int write_discard_bitset(struct cache *cache)
|
|
{
|
|
unsigned i, r;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return -EINVAL;
|
|
|
|
r = dm_cache_discard_bitset_resize(cache->cmd, cache->discard_block_size,
|
|
cache->discard_nr_blocks);
|
|
if (r) {
|
|
DMERR("%s: could not resize on-disk discard bitset", cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_discard_bitset_resize", r);
|
|
return r;
|
|
}
|
|
|
|
for (i = 0; i < from_dblock(cache->discard_nr_blocks); i++) {
|
|
r = dm_cache_set_discard(cache->cmd, to_dblock(i),
|
|
is_discarded(cache, to_dblock(i)));
|
|
if (r) {
|
|
metadata_operation_failed(cache, "dm_cache_set_discard", r);
|
|
return r;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int write_hints(struct cache *cache)
|
|
{
|
|
int r;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY)
|
|
return -EINVAL;
|
|
|
|
r = dm_cache_write_hints(cache->cmd, cache->policy);
|
|
if (r) {
|
|
metadata_operation_failed(cache, "dm_cache_write_hints", r);
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* returns true on success
|
|
*/
|
|
static bool sync_metadata(struct cache *cache)
|
|
{
|
|
int r1, r2, r3, r4;
|
|
|
|
r1 = write_dirty_bitset(cache);
|
|
if (r1)
|
|
DMERR("%s: could not write dirty bitset", cache_device_name(cache));
|
|
|
|
r2 = write_discard_bitset(cache);
|
|
if (r2)
|
|
DMERR("%s: could not write discard bitset", cache_device_name(cache));
|
|
|
|
save_stats(cache);
|
|
|
|
r3 = write_hints(cache);
|
|
if (r3)
|
|
DMERR("%s: could not write hints", cache_device_name(cache));
|
|
|
|
/*
|
|
* If writing the above metadata failed, we still commit, but don't
|
|
* set the clean shutdown flag. This will effectively force every
|
|
* dirty bit to be set on reload.
|
|
*/
|
|
r4 = commit(cache, !r1 && !r2 && !r3);
|
|
if (r4)
|
|
DMERR("%s: could not write cache metadata", cache_device_name(cache));
|
|
|
|
return !r1 && !r2 && !r3 && !r4;
|
|
}
|
|
|
|
static void cache_postsuspend(struct dm_target *ti)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
|
|
prevent_background_work(cache);
|
|
BUG_ON(atomic_read(&cache->nr_io_migrations));
|
|
|
|
cancel_delayed_work(&cache->waker);
|
|
flush_workqueue(cache->wq);
|
|
WARN_ON(cache->tracker.in_flight);
|
|
|
|
/*
|
|
* If it's a flush suspend there won't be any deferred bios, so this
|
|
* call is harmless.
|
|
*/
|
|
requeue_deferred_bios(cache);
|
|
|
|
if (get_cache_mode(cache) == CM_WRITE)
|
|
(void) sync_metadata(cache);
|
|
}
|
|
|
|
static int load_mapping(void *context, dm_oblock_t oblock, dm_cblock_t cblock,
|
|
bool dirty, uint32_t hint, bool hint_valid)
|
|
{
|
|
int r;
|
|
struct cache *cache = context;
|
|
|
|
if (dirty) {
|
|
set_bit(from_cblock(cblock), cache->dirty_bitset);
|
|
atomic_inc(&cache->nr_dirty);
|
|
} else
|
|
clear_bit(from_cblock(cblock), cache->dirty_bitset);
|
|
|
|
r = policy_load_mapping(cache->policy, oblock, cblock, dirty, hint, hint_valid);
|
|
if (r)
|
|
return r;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The discard block size in the on disk metadata is not
|
|
* neccessarily the same as we're currently using. So we have to
|
|
* be careful to only set the discarded attribute if we know it
|
|
* covers a complete block of the new size.
|
|
*/
|
|
struct discard_load_info {
|
|
struct cache *cache;
|
|
|
|
/*
|
|
* These blocks are sized using the on disk dblock size, rather
|
|
* than the current one.
|
|
*/
|
|
dm_block_t block_size;
|
|
dm_block_t discard_begin, discard_end;
|
|
};
|
|
|
|
static void discard_load_info_init(struct cache *cache,
|
|
struct discard_load_info *li)
|
|
{
|
|
li->cache = cache;
|
|
li->discard_begin = li->discard_end = 0;
|
|
}
|
|
|
|
static void set_discard_range(struct discard_load_info *li)
|
|
{
|
|
sector_t b, e;
|
|
|
|
if (li->discard_begin == li->discard_end)
|
|
return;
|
|
|
|
/*
|
|
* Convert to sectors.
|
|
*/
|
|
b = li->discard_begin * li->block_size;
|
|
e = li->discard_end * li->block_size;
|
|
|
|
/*
|
|
* Then convert back to the current dblock size.
|
|
*/
|
|
b = dm_sector_div_up(b, li->cache->discard_block_size);
|
|
sector_div(e, li->cache->discard_block_size);
|
|
|
|
/*
|
|
* The origin may have shrunk, so we need to check we're still in
|
|
* bounds.
|
|
*/
|
|
if (e > from_dblock(li->cache->discard_nr_blocks))
|
|
e = from_dblock(li->cache->discard_nr_blocks);
|
|
|
|
for (; b < e; b++)
|
|
set_discard(li->cache, to_dblock(b));
|
|
}
|
|
|
|
static int load_discard(void *context, sector_t discard_block_size,
|
|
dm_dblock_t dblock, bool discard)
|
|
{
|
|
struct discard_load_info *li = context;
|
|
|
|
li->block_size = discard_block_size;
|
|
|
|
if (discard) {
|
|
if (from_dblock(dblock) == li->discard_end)
|
|
/*
|
|
* We're already in a discard range, just extend it.
|
|
*/
|
|
li->discard_end = li->discard_end + 1ULL;
|
|
|
|
else {
|
|
/*
|
|
* Emit the old range and start a new one.
|
|
*/
|
|
set_discard_range(li);
|
|
li->discard_begin = from_dblock(dblock);
|
|
li->discard_end = li->discard_begin + 1ULL;
|
|
}
|
|
} else {
|
|
set_discard_range(li);
|
|
li->discard_begin = li->discard_end = 0;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static dm_cblock_t get_cache_dev_size(struct cache *cache)
|
|
{
|
|
sector_t size = get_dev_size(cache->cache_dev);
|
|
(void) sector_div(size, cache->sectors_per_block);
|
|
return to_cblock(size);
|
|
}
|
|
|
|
static bool can_resize(struct cache *cache, dm_cblock_t new_size)
|
|
{
|
|
if (from_cblock(new_size) > from_cblock(cache->cache_size)) {
|
|
if (cache->sized) {
|
|
DMERR("%s: unable to extend cache due to missing cache table reload",
|
|
cache_device_name(cache));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We can't drop a dirty block when shrinking the cache.
|
|
*/
|
|
while (from_cblock(new_size) < from_cblock(cache->cache_size)) {
|
|
new_size = to_cblock(from_cblock(new_size) + 1);
|
|
if (is_dirty(cache, new_size)) {
|
|
DMERR("%s: unable to shrink cache; cache block %llu is dirty",
|
|
cache_device_name(cache),
|
|
(unsigned long long) from_cblock(new_size));
|
|
return false;
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
static int resize_cache_dev(struct cache *cache, dm_cblock_t new_size)
|
|
{
|
|
int r;
|
|
|
|
r = dm_cache_resize(cache->cmd, new_size);
|
|
if (r) {
|
|
DMERR("%s: could not resize cache metadata", cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_resize", r);
|
|
return r;
|
|
}
|
|
|
|
set_cache_size(cache, new_size);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int cache_preresume(struct dm_target *ti)
|
|
{
|
|
int r = 0;
|
|
struct cache *cache = ti->private;
|
|
dm_cblock_t csize = get_cache_dev_size(cache);
|
|
|
|
/*
|
|
* Check to see if the cache has resized.
|
|
*/
|
|
if (!cache->sized) {
|
|
r = resize_cache_dev(cache, csize);
|
|
if (r)
|
|
return r;
|
|
|
|
cache->sized = true;
|
|
|
|
} else if (csize != cache->cache_size) {
|
|
if (!can_resize(cache, csize))
|
|
return -EINVAL;
|
|
|
|
r = resize_cache_dev(cache, csize);
|
|
if (r)
|
|
return r;
|
|
}
|
|
|
|
if (!cache->loaded_mappings) {
|
|
r = dm_cache_load_mappings(cache->cmd, cache->policy,
|
|
load_mapping, cache);
|
|
if (r) {
|
|
DMERR("%s: could not load cache mappings", cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_load_mappings", r);
|
|
return r;
|
|
}
|
|
|
|
cache->loaded_mappings = true;
|
|
}
|
|
|
|
if (!cache->loaded_discards) {
|
|
struct discard_load_info li;
|
|
|
|
/*
|
|
* The discard bitset could have been resized, or the
|
|
* discard block size changed. To be safe we start by
|
|
* setting every dblock to not discarded.
|
|
*/
|
|
clear_bitset(cache->discard_bitset, from_dblock(cache->discard_nr_blocks));
|
|
|
|
discard_load_info_init(cache, &li);
|
|
r = dm_cache_load_discards(cache->cmd, load_discard, &li);
|
|
if (r) {
|
|
DMERR("%s: could not load origin discards", cache_device_name(cache));
|
|
metadata_operation_failed(cache, "dm_cache_load_discards", r);
|
|
return r;
|
|
}
|
|
set_discard_range(&li);
|
|
|
|
cache->loaded_discards = true;
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
static void cache_resume(struct dm_target *ti)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
|
|
cache->need_tick_bio = true;
|
|
allow_background_work(cache);
|
|
do_waker(&cache->waker.work);
|
|
}
|
|
|
|
static void emit_flags(struct cache *cache, char *result,
|
|
unsigned maxlen, ssize_t *sz_ptr)
|
|
{
|
|
ssize_t sz = *sz_ptr;
|
|
struct cache_features *cf = &cache->features;
|
|
unsigned count = (cf->metadata_version == 2) + !cf->discard_passdown + 1;
|
|
|
|
DMEMIT("%u ", count);
|
|
|
|
if (cf->metadata_version == 2)
|
|
DMEMIT("metadata2 ");
|
|
|
|
if (writethrough_mode(cache))
|
|
DMEMIT("writethrough ");
|
|
|
|
else if (passthrough_mode(cache))
|
|
DMEMIT("passthrough ");
|
|
|
|
else if (writeback_mode(cache))
|
|
DMEMIT("writeback ");
|
|
|
|
else {
|
|
DMEMIT("unknown ");
|
|
DMERR("%s: internal error: unknown io mode: %d",
|
|
cache_device_name(cache), (int) cf->io_mode);
|
|
}
|
|
|
|
if (!cf->discard_passdown)
|
|
DMEMIT("no_discard_passdown ");
|
|
|
|
*sz_ptr = sz;
|
|
}
|
|
|
|
/*
|
|
* Status format:
|
|
*
|
|
* <metadata block size> <#used metadata blocks>/<#total metadata blocks>
|
|
* <cache block size> <#used cache blocks>/<#total cache blocks>
|
|
* <#read hits> <#read misses> <#write hits> <#write misses>
|
|
* <#demotions> <#promotions> <#dirty>
|
|
* <#features> <features>*
|
|
* <#core args> <core args>
|
|
* <policy name> <#policy args> <policy args>* <cache metadata mode> <needs_check>
|
|
*/
|
|
static void cache_status(struct dm_target *ti, status_type_t type,
|
|
unsigned status_flags, char *result, unsigned maxlen)
|
|
{
|
|
int r = 0;
|
|
unsigned i;
|
|
ssize_t sz = 0;
|
|
dm_block_t nr_free_blocks_metadata = 0;
|
|
dm_block_t nr_blocks_metadata = 0;
|
|
char buf[BDEVNAME_SIZE];
|
|
struct cache *cache = ti->private;
|
|
dm_cblock_t residency;
|
|
bool needs_check;
|
|
|
|
switch (type) {
|
|
case STATUSTYPE_INFO:
|
|
if (get_cache_mode(cache) == CM_FAIL) {
|
|
DMEMIT("Fail");
|
|
break;
|
|
}
|
|
|
|
/* Commit to ensure statistics aren't out-of-date */
|
|
if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
|
|
(void) commit(cache, false);
|
|
|
|
r = dm_cache_get_free_metadata_block_count(cache->cmd, &nr_free_blocks_metadata);
|
|
if (r) {
|
|
DMERR("%s: dm_cache_get_free_metadata_block_count returned %d",
|
|
cache_device_name(cache), r);
|
|
goto err;
|
|
}
|
|
|
|
r = dm_cache_get_metadata_dev_size(cache->cmd, &nr_blocks_metadata);
|
|
if (r) {
|
|
DMERR("%s: dm_cache_get_metadata_dev_size returned %d",
|
|
cache_device_name(cache), r);
|
|
goto err;
|
|
}
|
|
|
|
residency = policy_residency(cache->policy);
|
|
|
|
DMEMIT("%u %llu/%llu %llu %llu/%llu %u %u %u %u %u %u %lu ",
|
|
(unsigned)DM_CACHE_METADATA_BLOCK_SIZE,
|
|
(unsigned long long)(nr_blocks_metadata - nr_free_blocks_metadata),
|
|
(unsigned long long)nr_blocks_metadata,
|
|
(unsigned long long)cache->sectors_per_block,
|
|
(unsigned long long) from_cblock(residency),
|
|
(unsigned long long) from_cblock(cache->cache_size),
|
|
(unsigned) atomic_read(&cache->stats.read_hit),
|
|
(unsigned) atomic_read(&cache->stats.read_miss),
|
|
(unsigned) atomic_read(&cache->stats.write_hit),
|
|
(unsigned) atomic_read(&cache->stats.write_miss),
|
|
(unsigned) atomic_read(&cache->stats.demotion),
|
|
(unsigned) atomic_read(&cache->stats.promotion),
|
|
(unsigned long) atomic_read(&cache->nr_dirty));
|
|
|
|
emit_flags(cache, result, maxlen, &sz);
|
|
|
|
DMEMIT("2 migration_threshold %llu ", (unsigned long long) cache->migration_threshold);
|
|
|
|
DMEMIT("%s ", dm_cache_policy_get_name(cache->policy));
|
|
if (sz < maxlen) {
|
|
r = policy_emit_config_values(cache->policy, result, maxlen, &sz);
|
|
if (r)
|
|
DMERR("%s: policy_emit_config_values returned %d",
|
|
cache_device_name(cache), r);
|
|
}
|
|
|
|
if (get_cache_mode(cache) == CM_READ_ONLY)
|
|
DMEMIT("ro ");
|
|
else
|
|
DMEMIT("rw ");
|
|
|
|
r = dm_cache_metadata_needs_check(cache->cmd, &needs_check);
|
|
|
|
if (r || needs_check)
|
|
DMEMIT("needs_check ");
|
|
else
|
|
DMEMIT("- ");
|
|
|
|
break;
|
|
|
|
case STATUSTYPE_TABLE:
|
|
format_dev_t(buf, cache->metadata_dev->bdev->bd_dev);
|
|
DMEMIT("%s ", buf);
|
|
format_dev_t(buf, cache->cache_dev->bdev->bd_dev);
|
|
DMEMIT("%s ", buf);
|
|
format_dev_t(buf, cache->origin_dev->bdev->bd_dev);
|
|
DMEMIT("%s", buf);
|
|
|
|
for (i = 0; i < cache->nr_ctr_args - 1; i++)
|
|
DMEMIT(" %s", cache->ctr_args[i]);
|
|
if (cache->nr_ctr_args)
|
|
DMEMIT(" %s", cache->ctr_args[cache->nr_ctr_args - 1]);
|
|
}
|
|
|
|
return;
|
|
|
|
err:
|
|
DMEMIT("Error");
|
|
}
|
|
|
|
/*
|
|
* Defines a range of cblocks, begin to (end - 1) are in the range. end is
|
|
* the one-past-the-end value.
|
|
*/
|
|
struct cblock_range {
|
|
dm_cblock_t begin;
|
|
dm_cblock_t end;
|
|
};
|
|
|
|
/*
|
|
* A cache block range can take two forms:
|
|
*
|
|
* i) A single cblock, eg. '3456'
|
|
* ii) A begin and end cblock with a dash between, eg. 123-234
|
|
*/
|
|
static int parse_cblock_range(struct cache *cache, const char *str,
|
|
struct cblock_range *result)
|
|
{
|
|
char dummy;
|
|
uint64_t b, e;
|
|
int r;
|
|
|
|
/*
|
|
* Try and parse form (ii) first.
|
|
*/
|
|
r = sscanf(str, "%llu-%llu%c", &b, &e, &dummy);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (r == 2) {
|
|
result->begin = to_cblock(b);
|
|
result->end = to_cblock(e);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* That didn't work, try form (i).
|
|
*/
|
|
r = sscanf(str, "%llu%c", &b, &dummy);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (r == 1) {
|
|
result->begin = to_cblock(b);
|
|
result->end = to_cblock(from_cblock(result->begin) + 1u);
|
|
return 0;
|
|
}
|
|
|
|
DMERR("%s: invalid cblock range '%s'", cache_device_name(cache), str);
|
|
return -EINVAL;
|
|
}
|
|
|
|
static int validate_cblock_range(struct cache *cache, struct cblock_range *range)
|
|
{
|
|
uint64_t b = from_cblock(range->begin);
|
|
uint64_t e = from_cblock(range->end);
|
|
uint64_t n = from_cblock(cache->cache_size);
|
|
|
|
if (b >= n) {
|
|
DMERR("%s: begin cblock out of range: %llu >= %llu",
|
|
cache_device_name(cache), b, n);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (e > n) {
|
|
DMERR("%s: end cblock out of range: %llu > %llu",
|
|
cache_device_name(cache), e, n);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (b >= e) {
|
|
DMERR("%s: invalid cblock range: %llu >= %llu",
|
|
cache_device_name(cache), b, e);
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static inline dm_cblock_t cblock_succ(dm_cblock_t b)
|
|
{
|
|
return to_cblock(from_cblock(b) + 1);
|
|
}
|
|
|
|
static int request_invalidation(struct cache *cache, struct cblock_range *range)
|
|
{
|
|
int r = 0;
|
|
|
|
/*
|
|
* We don't need to do any locking here because we know we're in
|
|
* passthrough mode. There's is potential for a race between an
|
|
* invalidation triggered by an io and an invalidation message. This
|
|
* is harmless, we must not worry if the policy call fails.
|
|
*/
|
|
while (range->begin != range->end) {
|
|
r = invalidate_cblock(cache, range->begin);
|
|
if (r)
|
|
return r;
|
|
|
|
range->begin = cblock_succ(range->begin);
|
|
}
|
|
|
|
cache->commit_requested = true;
|
|
return r;
|
|
}
|
|
|
|
static int process_invalidate_cblocks_message(struct cache *cache, unsigned count,
|
|
const char **cblock_ranges)
|
|
{
|
|
int r = 0;
|
|
unsigned i;
|
|
struct cblock_range range;
|
|
|
|
if (!passthrough_mode(cache)) {
|
|
DMERR("%s: cache has to be in passthrough mode for invalidation",
|
|
cache_device_name(cache));
|
|
return -EPERM;
|
|
}
|
|
|
|
for (i = 0; i < count; i++) {
|
|
r = parse_cblock_range(cache, cblock_ranges[i], &range);
|
|
if (r)
|
|
break;
|
|
|
|
r = validate_cblock_range(cache, &range);
|
|
if (r)
|
|
break;
|
|
|
|
/*
|
|
* Pass begin and end origin blocks to the worker and wake it.
|
|
*/
|
|
r = request_invalidation(cache, &range);
|
|
if (r)
|
|
break;
|
|
}
|
|
|
|
return r;
|
|
}
|
|
|
|
/*
|
|
* Supports
|
|
* "<key> <value>"
|
|
* and
|
|
* "invalidate_cblocks [(<begin>)|(<begin>-<end>)]*
|
|
*
|
|
* The key migration_threshold is supported by the cache target core.
|
|
*/
|
|
static int cache_message(struct dm_target *ti, unsigned argc, char **argv,
|
|
char *result, unsigned maxlen)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
|
|
if (!argc)
|
|
return -EINVAL;
|
|
|
|
if (get_cache_mode(cache) >= CM_READ_ONLY) {
|
|
DMERR("%s: unable to service cache target messages in READ_ONLY or FAIL mode",
|
|
cache_device_name(cache));
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
if (!strcasecmp(argv[0], "invalidate_cblocks"))
|
|
return process_invalidate_cblocks_message(cache, argc - 1, (const char **) argv + 1);
|
|
|
|
if (argc != 2)
|
|
return -EINVAL;
|
|
|
|
return set_config_value(cache, argv[0], argv[1]);
|
|
}
|
|
|
|
static int cache_iterate_devices(struct dm_target *ti,
|
|
iterate_devices_callout_fn fn, void *data)
|
|
{
|
|
int r = 0;
|
|
struct cache *cache = ti->private;
|
|
|
|
r = fn(ti, cache->cache_dev, 0, get_dev_size(cache->cache_dev), data);
|
|
if (!r)
|
|
r = fn(ti, cache->origin_dev, 0, ti->len, data);
|
|
|
|
return r;
|
|
}
|
|
|
|
static bool origin_dev_supports_discard(struct block_device *origin_bdev)
|
|
{
|
|
struct request_queue *q = bdev_get_queue(origin_bdev);
|
|
|
|
return q && blk_queue_discard(q);
|
|
}
|
|
|
|
/*
|
|
* If discard_passdown was enabled verify that the origin device
|
|
* supports discards. Disable discard_passdown if not.
|
|
*/
|
|
static void disable_passdown_if_not_supported(struct cache *cache)
|
|
{
|
|
struct block_device *origin_bdev = cache->origin_dev->bdev;
|
|
struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
|
|
const char *reason = NULL;
|
|
char buf[BDEVNAME_SIZE];
|
|
|
|
if (!cache->features.discard_passdown)
|
|
return;
|
|
|
|
if (!origin_dev_supports_discard(origin_bdev))
|
|
reason = "discard unsupported";
|
|
|
|
else if (origin_limits->max_discard_sectors < cache->sectors_per_block)
|
|
reason = "max discard sectors smaller than a block";
|
|
|
|
if (reason) {
|
|
DMWARN("Origin device (%s) %s: Disabling discard passdown.",
|
|
bdevname(origin_bdev, buf), reason);
|
|
cache->features.discard_passdown = false;
|
|
}
|
|
}
|
|
|
|
static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
|
|
{
|
|
struct block_device *origin_bdev = cache->origin_dev->bdev;
|
|
struct queue_limits *origin_limits = &bdev_get_queue(origin_bdev)->limits;
|
|
|
|
if (!cache->features.discard_passdown) {
|
|
/* No passdown is done so setting own virtual limits */
|
|
limits->max_discard_sectors = min_t(sector_t, cache->discard_block_size * 1024,
|
|
cache->origin_sectors);
|
|
limits->discard_granularity = cache->discard_block_size << SECTOR_SHIFT;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* cache_iterate_devices() is stacking both origin and fast device limits
|
|
* but discards aren't passed to fast device, so inherit origin's limits.
|
|
*/
|
|
limits->max_discard_sectors = origin_limits->max_discard_sectors;
|
|
limits->max_hw_discard_sectors = origin_limits->max_hw_discard_sectors;
|
|
limits->discard_granularity = origin_limits->discard_granularity;
|
|
limits->discard_alignment = origin_limits->discard_alignment;
|
|
limits->discard_misaligned = origin_limits->discard_misaligned;
|
|
}
|
|
|
|
static void cache_io_hints(struct dm_target *ti, struct queue_limits *limits)
|
|
{
|
|
struct cache *cache = ti->private;
|
|
uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
|
|
|
|
/*
|
|
* If the system-determined stacked limits are compatible with the
|
|
* cache's blocksize (io_opt is a factor) do not override them.
|
|
*/
|
|
if (io_opt_sectors < cache->sectors_per_block ||
|
|
do_div(io_opt_sectors, cache->sectors_per_block)) {
|
|
blk_limits_io_min(limits, cache->sectors_per_block << SECTOR_SHIFT);
|
|
blk_limits_io_opt(limits, cache->sectors_per_block << SECTOR_SHIFT);
|
|
}
|
|
|
|
disable_passdown_if_not_supported(cache);
|
|
set_discard_limits(cache, limits);
|
|
}
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
static struct target_type cache_target = {
|
|
.name = "cache",
|
|
.version = {2, 1, 0},
|
|
.module = THIS_MODULE,
|
|
.ctr = cache_ctr,
|
|
.dtr = cache_dtr,
|
|
.map = cache_map,
|
|
.end_io = cache_end_io,
|
|
.postsuspend = cache_postsuspend,
|
|
.preresume = cache_preresume,
|
|
.resume = cache_resume,
|
|
.status = cache_status,
|
|
.message = cache_message,
|
|
.iterate_devices = cache_iterate_devices,
|
|
.io_hints = cache_io_hints,
|
|
};
|
|
|
|
static int __init dm_cache_init(void)
|
|
{
|
|
int r;
|
|
|
|
migration_cache = KMEM_CACHE(dm_cache_migration, 0);
|
|
if (!migration_cache)
|
|
return -ENOMEM;
|
|
|
|
r = dm_register_target(&cache_target);
|
|
if (r) {
|
|
DMERR("cache target registration failed: %d", r);
|
|
kmem_cache_destroy(migration_cache);
|
|
return r;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void __exit dm_cache_exit(void)
|
|
{
|
|
dm_unregister_target(&cache_target);
|
|
kmem_cache_destroy(migration_cache);
|
|
}
|
|
|
|
module_init(dm_cache_init);
|
|
module_exit(dm_cache_exit);
|
|
|
|
MODULE_DESCRIPTION(DM_NAME " cache target");
|
|
MODULE_AUTHOR("Joe Thornber <ejt@redhat.com>");
|
|
MODULE_LICENSE("GPL");
|