path: root/drivers/md/dm-raid1.c

/*
 * Copyright (C) 2003 Sistina Software Limited.
 * Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

#include "dm-bio-record.h"

#include <linux/init.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include <linux/device-mapper.h>
#include <linux/dm-io.h>
#include <linux/dm-dirty-log.h>
#include <linux/dm-kcopyd.h>
#include <linux/dm-region-hash.h>

#define DM_MSG_PREFIX "raid1"

#define MAX_RECOVERY 1	/* Maximum number of regions recovered in parallel. */
#define DM_IO_PAGES 64
#define DM_KCOPYD_PAGES 64

#define DM_RAID1_HANDLE_ERRORS 0x01
#define errors_handled(p)	((p)->features & DM_RAID1_HANDLE_ERRORS)

static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);

/*-----------------------------------------------------------------
 * Mirror set structures.
 *---------------------------------------------------------------*/
enum dm_raid1_error {
	DM_RAID1_WRITE_ERROR,
	DM_RAID1_SYNC_ERROR,
	DM_RAID1_READ_ERROR
};

struct mirror {
	struct mirror_set *ms;
	atomic_t error_count;
	unsigned long error_type;
	struct dm_dev *dev;
	sector_t offset;
};

struct mirror_set {
	struct dm_target *ti;
	struct list_head list;

	uint64_t features;

	spinlock_t lock;	/* protects the lists */
	struct bio_list reads;
	struct bio_list writes;
	struct bio_list failures;

	struct dm_region_hash *rh;
	struct dm_kcopyd_client *kcopyd_client;
	struct dm_io_client *io_client;
	mempool_t *read_record_pool;

	/* recovery */
	region_t nr_regions;
	int in_sync;
	int log_failure;
	atomic_t suspend;

	atomic_t default_mirror;	/* Default mirror */

	struct workqueue_struct *kmirrord_wq;
	struct work_struct kmirrord_work;
	struct timer_list timer;
	unsigned long timer_pending;

	struct work_struct trigger_event;

	unsigned nr_mirrors;
	struct mirror mirror[0];
};

static void wakeup_mirrord(void *context)
{
	struct mirror_set *ms = context;

	queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
}

static void delayed_wake_fn(unsigned long data)
{
	struct mirror_set *ms = (struct mirror_set *) data;

	clear_bit(0, &ms->timer_pending);
	wakeup_mirrord(ms);
}

static void delayed_wake(struct mirror_set *ms)
{
	if (test_and_set_bit(0, &ms->timer_pending))
		return;

	ms->timer.expires = jiffies + HZ / 5;
	ms->timer.data = (unsigned long) ms;
	ms->timer.function = delayed_wake_fn;
	add_timer(&ms->timer);
}

static void wakeup_all_recovery_waiters(void *context)
{
	wake_up_all(&_kmirrord_recovery_stopped);
}

static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
{
	unsigned long flags;
	int should_wake = 0;
	struct bio_list *bl;

	bl = (rw == WRITE) ? &ms->writes : &ms->reads;
	spin_lock_irqsave(&ms->lock, flags);
	should_wake = !(bl->head);
	bio_list_add(bl, bio);
	spin_unlock_irqrestore(&ms->lock, flags);

	if (should_wake)
		wakeup_mirrord(ms);
}

static void dispatch_bios(void *context, struct bio_list *bio_list)
{
	struct mirror_set *ms = context;
	struct bio *bio;

	while ((bio = bio_list_pop(bio_list)))
		queue_bio(ms, bio, WRITE);
}

#define MIN_READ_RECORDS 20
struct dm_raid1_read_record {
	struct mirror *m;
	struct dm_bio_details details;
};

static struct kmem_cache *_dm_raid1_read_record_cache;

/*
 * Every mirror should look like this one.
 */
#define DEFAULT_MIRROR 0

/*
 * This is yucky.  We squirrel the mirror struct away inside
 * bi_next for read/write buffers.  This is safe since the bh
 * doesn't get submitted to the lower levels of block layer.
 */
static struct mirror *bio_get_m(struct bio *bio)
{
	return (struct mirror *) bio->bi_next;
}

static void bio_set_m(struct bio *bio, struct mirror *m)
{
	bio->bi_next = (struct bio *) m;
}

static struct mirror *get_default_mirror(struct mirror_set *ms)
{
	return &ms->mirror[atomic_read(&ms->default_mirror)];
}

static void set_default_mirror(struct mirror *m)
{