- 根目录:
- 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_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_FLUSH_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 bio_list holds; /* bios are waiting until suspend */
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;
int leg_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)
{
struct mirror_set *ms = m->ms;
struct mirror *m0 = &(ms->mirror[0]);
atomic_set(&ms->default_mirror, m - m0);
}
static struct mirror *get_valid_mirror(struct mirror_set *ms)
{
struct mirror *m;
for (m = ms->mirror; m < ms->mirror + ms->nr_mirrors; m++)
if (!atomic_read(&m->error_count))
return m;
return NULL;
}
/* fail_mirror
* @m: mirror device to fail
* @error_type: one of the enum's, DM_RAID1_*_ERROR
*
* If errors are being handled, record the type of
* error encountered for this device. If this type
* of error has already been recorded, we can return;
* otherwise, we must signal userspace by triggering
* an event. Additionally, if the device is the
* primary device, we must choose a new primary, but
* only if the mirror is in-sync.
*
* This function must not block.
*/
static void fail_mirror(struct mirror *m, enum dm_raid1_error error_type)
{
struct mirror_set *ms = m->ms;
struct mirror *new;
ms->leg_failure = 1;
/*
* error_count is used for nothing more than a
* simple way to tell if a device has encountered
* errors.
*/
atomic_inc(&m->error_count);
if (test_and_set_bit(error_type, &m->error_type))
return;
if (!errors_handled(ms))
return;
if (m != get_default_mirror(ms))
goto out;
if (!ms->in_sync) {
/*
* Better to issue requests to same failing device
* than to risk returning corrupt data.
*/
DMERR("Primary mirror (%s) failed while out-of-sync: "
"Reads may fail.", m->dev->name);
goto out;
}
new = get_valid_mirror(ms);
if (new)
set_default_mirror(new);
else
DMWARN("All sides of mirror have failed.");
out:
schedule_work(&ms->trigger_event);
}
static int mirror_flush(struct dm_target *ti)
{
struct mirror_set *ms = ti->private;
unsigned long error_bits;
unsigned int i;
struct dm_io_region io[ms->nr_mirrors];
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE_FLUSH,
.mem.type = DM_IO_KMEM,
.mem.ptr.addr = NULL,
.client = ms->io_client,
};
for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++) {
io[i].bdev = m->dev->bdev;
io[i].sector = 0;
io[i].count = 0;
}
error_bits = -1;
dm_io(&io_req, ms->nr_mirrors, io, &error_bits);
if (unlikely(error_bits != 0)) {
for (i = 0; i < ms->nr_mirrors; i++)
if (test_bit(i, &error_bits))
fail_mirror(ms->mirror + i,
DM_RAID1_FLUSH_ERROR);
return -EIO;
}
return 0;
}
/*-----------------------------------------------------------------
* Recovery.
*
* When a mirror is first activated we may find that some regions
* are in the no-sync state. We have to recover these by
* recopying from the default mirror to all the others.
*---------------------------------------------------------------*/
static void recovery_complete(int read_err, unsigned long write_err,
void *context)
{
struct dm_region *reg = context;
struct mirror_set *ms = dm_rh_region_context(reg);
int m, bit = 0;
if (read_err) {
/* Read error means the failure of default mirror. */
DMERR_LIMIT("Unable to read primary mirror during recovery");
fail_mirror(get_default_mirror(ms), DM_RAID1_SYNC_ERROR);
}
if (write_err) {
DMERR_LIMIT("Write error during recovery (error = 0x%lx)",
write_err);
/*
* Bits correspond to devices (excluding default mirror).
* The default mirror cannot change during recovery.
*/
for (m = 0; m < ms->nr_mirrors; m++) {
if (&ms->mirror[m] == get_default_mirror(ms))
continue;
if (test_bit(bit, &write_err))
fail_mirror(ms->mirror + m,
DM_RAID1_SYNC_ERROR);
bit++;
}
}
dm_rh_recovery_end(reg, !(read_err || write_err));
}
static int recover(struct mirror_set *ms, struct dm_region *reg)
{
int r;
unsigned i;
struct dm_io_region from, to[DM_KCOPYD_MAX_REGIONS], *dest;
struct mirror *m;
unsigned long flags = 0;
region_t key = dm_rh_get_region_key(reg);
sector_t region_size = dm_rh_get_region_size(ms->rh);
/* fill in the source */
m = get_default_mirror(ms);
from.bdev = m->dev->bdev;
from.sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
if (key == (ms->nr_regions - 1)) {
/*
* The final region may be smaller than
* region_size.
*/
from.count = ms->ti->len & (region_size - 1);
if (!from.count)
from.count = region_size;
} else
from.count = region_size;
/* fill in the destinations */
for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
if (&ms->mirror[i] == get_default_mirror(ms))
continue;
m = ms->mirror + i;
dest->bdev = m->dev->bdev;
dest->sector = m->offset + dm_rh_region_to_sector(ms->rh, key);
dest->count = from.count;
dest++;
}
/* hand to kcopyd */
if (!errors_handled(ms))
set_bit(DM_KCOPYD_IGNORE_ERROR, &flags);
r = dm_kcopyd_copy(ms->kcopyd_client, &from, ms->nr_mirrors - 1, to,
flags, recovery_complete, reg);
return r;
}
static void do_recovery(struct mirror_set *ms)
{
struct dm_region *reg;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
int r;
/*
* Start quiescing some regions.
*/
dm_rh_recovery_prepare(ms->rh);
/*
* Copy any already quiesced regions.
*/
while ((reg = dm_rh_recovery_start(ms->rh))) {
r = recover(ms, reg);
if (r)
dm_rh_recovery_end(reg, 0);
}
/*
* Update the in sync flag.
*/
if (!ms->in_sync &&
(log->type->get_sync_count(log) == ms->nr_regions)) {
/* the sync is complete */
dm_table_event(ms->ti->table);
ms->in_sync = 1;
}
}
/*-----------------------------------------------------------------
* Reads
*---------------------------------------------------------------*/
static struct mirror *choose_mirror(struct mirror_set *ms, sector_t sector)
{
struct mirror *m = get_default_mirror(ms);
do {
if (likely(!atomic_read(&m->error_count)))
return m;
if (m-- == ms->mirror)
m += ms->nr_mirrors;
} while (m != get_default_mirror(ms));
return NULL;
}
static int default_ok(struct mirror *m)
{
struct mirror *default_mirror = get_default_mirror(m->ms);
return !atomic_read(&default_mirror->error_count);
}
static int mirror_available(struct mirror_set *ms, struct bio *bio)
{
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
region_t region = dm_rh_bio_to_region(ms->rh, bio);
if (log->type->in_sync(log, region, 0))
return choose_mirror(ms, bio->bi_sector) ? 1 : 0;
return 0;
}
/*
* remap a buffer to a particular mirror.
*/
static sector_t map_sector(struct mirror *m, struct bio *bio)
{
if (unlikely(!bio->bi_size))
return 0;
return m->offset + dm_target_offset(m->ms->ti, bio->bi_sector);
}
static void map_bio(struct mirror *m, struct bio *bio)
{
bio->bi_bdev = m->dev->bdev;
bio->bi_sector = map_sector(m, bio);
}
static void map_region(struct dm_io_region *io, struct mirror *m,
struct bio *bio)
{
io->bdev = m->dev->bdev;
io->sector = map_sector(m, bio);
io->count = bio->bi_size >> 9;
}
static void hold_bio(struct mirror_set *ms, struct bio *bio)
{
/*
* Lock is required to avoid race condition during suspend
* process.
*/
spin_lock_irq(&ms->lock);
if (atomic_read(&ms->suspend)) {
spin_unlock_irq(&ms->lock);
/*
* If device is suspended, complete the bio.
*/
if (dm_noflush_suspending(ms->ti))
bio_endio(bio, DM_ENDIO_REQUEUE);
else
bio_endio(bio, -EIO);
return;
}
/*
* Hold bio until the suspend is complete.
*/
bio_list_add(&ms->holds, bio);
spin_unlock_irq(&ms->lock);
}
/*-----------------------------------------------------------------
* Reads
*---------------------------------------------------------------*/
static void read_callback(unsigned long error, void *context)
{
struct bio *bio = context;
struct mirror *m;
m = bio_get_m(bio);
bio_set_m(bio, NULL);
if (likely(!error)) {
bio_endio(bio, 0);
return;
}
fail_mirror(m, DM_RAID1_READ_ERROR);
if (likely(default_ok(m)) || mirror_available(m->ms, bio)) {
DMWARN_LIMIT("Read failure on mirror device %s. "
"Trying alternative device.",
m->dev->name);
queue_bio(m->ms, bio, bio_rw(bio));
return;
}
DMERR_LIMIT("Read failure on mirror device %s. Failing I/O.",
m->dev->name);
bio_endio(bio, -EIO);
}
/* Asynchronous read. */
static void read_async_bio(struct mirror *m, struct bio *bio)
{
struct dm_io_region io;
struct dm_io_request io_req = {
.bi_rw = READ,
.mem.type = DM_IO_BVEC,
.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
.notify.fn = read_callback,
.notify.context = bio,
.client = m->ms->io_client,
};
map_region(&io, m, bio);
bio_set_m(bio, m);
BUG_ON(dm_io(&io_req, 1, &io, NULL));
}
static inline int region_in_sync(struct mirror_set *ms, region_t region,
int may_block)
{
int state = dm_rh_get_state(ms->rh, region, may_block);
return state == DM_RH_CLEAN || state == DM_RH_DIRTY;
}
static void do_reads(struct mirror_set *ms, struct bio_list *reads)
{
region_t region;
struct bio *bio;
struct mirror *m;
while ((bio = bio_list_pop(reads))) {
region = dm_rh_bio_to_region(ms->rh, bio);
m = get_default_mirror(ms);
/*
* We can only read balance if the region is in sync.
*/
if (likely(region_in_sync(ms, region, 1)))
m = choose_mirror(ms, bio->bi_sector);
else if (m && atomic_read(&m->error_count))
m = NULL;
if (likely(m))
read_async_bio(m, bio);
else
bio_endio(bio, -EIO);
}
}
/*-----------------------------------------------------------------
* Writes.
*
* We do different things with the write io depending on the
* state of the region that it's in:
*
* SYNC: increment pending, use kcopyd to write to *all* mirrors
* RECOVERING: delay the io until recovery completes
* NOSYNC: increment pending, just write to the default mirror
*---------------------------------------------------------------*/
static void write_callback(unsigned long error, void *context)
{
unsigned i, ret = 0;
struct bio *bio = (struct bio *) context;
struct mirror_set *ms;
int should_wake = 0;
unsigned long flags;
ms = bio_get_m(bio)->ms;
bio_set_m(bio, NULL);
/*
* NOTE: We don't decrement the pending count here,
* instead it is done by the targets endio function.
* This way we handle both writes to SYNC and NOSYNC
* regions with the same code.
*/
if (likely(!error)) {
bio_endio(bio, ret);
return;
}
for (i = 0; i < ms->nr_mirrors; i++)
if (test_bit(i, &error))
fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
/*
* Need to raise event. Since raising
* events can block, we need to do it in
* the main thread.
*/
spin_lock_irqsave(&ms->lock, flags);
if (!ms->failures.head)
should_wake = 1;
bio_list_add(&ms->failures, bio);
spin_unlock_irqrestore(&ms->lock, flags);
if (should_wake)
wakeup_mirrord(ms);
}
static void do_write(struct mirror_set *ms, struct bio *bio)
{
unsigned int i;
struct dm_io_region io[ms->nr_mirrors], *dest = io;
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE | (bio->bi_rw & WRITE_FLUSH_FUA),
.mem.type = DM_IO_BVEC,
.mem.ptr.bvec = bio->bi_io_vec + bio->bi_idx,
.notify.fn = write_callback,
.notify.context = bio,
.client = ms->io_client,
};
if (bio->bi_rw & REQ_DISCARD) {
io_req.bi_rw |= REQ_DISCARD;
io_req.mem.type = DM_IO_KMEM;
io_req.mem.ptr.addr = NULL;
}
for (i = 0, m = ms->mirror; i < ms->nr_mirrors; i++, m++)
map_region(dest++, m, bio);
/*
* Use default mirror because we only need it to retrieve the reference
* to the mirror set in write_callback().
*/
bio_set_m(bio, get_default_mirror(ms));
BUG_ON(dm_io(&io_req, ms->nr_mirrors, io, NULL));
}
static void do_writes(struct mirror_set *ms, struct bio_list *writes)
{
int state;
struct bio *bio;
struct bio_list sync, nosync, recover, *this_list = NULL;
struct bio_list requeue;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
region_t region;
if (!writes->head)
return;
/*
* Classify each write.
*/
bio_list_init(&sync);
bio_list_init(&nosync);
bio_list_init(&recover);
bio_list_init(&requeue);
while ((bio = bio_list_pop(writes))) {
if ((bio->bi_rw & REQ_FLUSH) ||
(bio->bi_rw & REQ_DISCARD)) {
bio_list_add(&sync, bio);
continue;
}
region = dm_rh_bio_to_region(ms->rh, bio);
if (log->type->is_remote_recovering &&
log->type->is_remote_recovering(log, region)) {
bio_list_add(&requeue, bio);
continue;
}
state = dm_rh_get_state(ms->rh, region, 1);
switch (state) {
case DM_RH_CLEAN:
case DM_RH_DIRTY:
this_list = &sync;
break;
case DM_RH_NOSYNC:
this_list = &nosync;
break;
case DM_RH_RECOVERING:
this_list = &recover;
break;
}
bio_list_add(this_list, bio);
}
/*
* Add bios that are delayed due to remote recovery
* back on to the write queue
*/
if (unlikely(requeue.head)) {
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->writes, &requeue);
spin_unlock_irq(&ms->lock);
delayed_wake(ms);
}
/*
* Increment the pending counts for any regions that will
* be written to (writes to recover regions are going to
* be delayed).
*/
dm_rh_inc_pending(ms->rh, &sync);
dm_rh_inc_pending(ms->rh, &nosync);
/*
* If the flush fails on a previous call and succeeds here,
* we must not reset the log_failure variable. We need
* userspace interaction to do that.
*/
ms->log_failure = dm_rh_flush(ms->rh) ? 1 : ms->log_failure;
/*
* Dispatch io.
*/
if (unlikely(ms->log_failure) && errors_handled(ms)) {
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->failures, &sync);
spin_unlock_irq(&ms->lock);
wakeup_mirrord(ms);
} else
while ((bio = bio_list_pop(&sync)))
do_write(ms, bio);
while ((bio = bio_list_pop(&recover)))
dm_rh_delay(ms->rh, bio);
while ((bio = bio_list_pop(&nosync))) {
if (unlikely(ms->leg_failure) && errors_handled(ms)) {
spin_lock_irq(&ms->lock);
bio_list_add(&ms->failures, bio);
spin_unlock_irq(&ms->lock);
wakeup_mirrord(ms);
} else {
map_bio(get_default_mirror(ms), bio);
generic_make_request(bio);
}
}
}
static void do_failures(struct mirror_set *ms, struct bio_list *failures)
{
struct bio *bio;
if (likely(!failures->head))
return;
/*
* If the log has failed, unattempted writes are being
* put on the holds list. We can't issue those writes
* until a log has been marked, so we must store them.
*
* If a 'noflush' suspend is in progress, we can requeue
* the I/O's to the core. This give userspace a chance
* to reconfigure the mirror, at which point the core
* will reissue the writes. If the 'noflush' flag is
* not set, we have no choice but to return errors.
*
* Some writes on the failures list may have been
* submitted before the log failure and represent a
* failure to write to one of the devices. It is ok
* for us to treat them the same and requeue them
* as well.
*/
while ((bio = bio_list_pop(failures))) {
if (!ms->log_failure) {
ms->in_sync = 0;
dm_rh_mark_nosync(ms->rh, bio);
}
/*
* If all the legs are dead, fail the I/O.
* If we have been told to handle errors, hold the bio
* and wait for userspace to deal with the problem.
* Otherwise pretend that the I/O succeeded. (This would
* be wrong if the failed leg returned after reboot and
* got replicated back to the good legs.)
*/
if (!get_valid_mirror(ms))
bio_endio(bio, -EIO);
else if (errors_handled(ms))
hold_bio(ms, bio);
else
bio_endio(bio, 0);
}
}
static void trigger_event(struct work_struct *work)
{
struct mirror_set *ms =
container_of(work, struct mirror_set, trigger_event);
dm_table_event(ms->ti->table);
}
/*-----------------------------------------------------------------
* kmirrord
*---------------------------------------------------------------*/
static void do_mirror(struct work_struct *work)
{
struct mirror_set *ms = container_of(work, struct mirror_set,
kmirrord_work);
struct bio_list reads, writes, failures;
unsigned long flags;
spin_lock_irqsave(&ms->lock, flags);
reads = ms->reads;
writes = ms->writes;
failures = ms->failures;
bio_list_init(&ms->reads);
bio_list_init(&ms->writes);
bio_list_init(&ms->failures);
spin_unlock_irqrestore(&ms->lock, flags);
dm_rh_update_states(ms->rh, errors_handled(ms));
do_recovery(ms);
do_reads(ms, &reads);
do_writes(ms, &writes);
do_failures(ms, &failures);
}
/*-----------------------------------------------------------------
* Target functions
*---------------------------------------------------------------*/
static struct mirror_set *alloc_context(unsigned int nr_mirrors,
uint32_t region_size,
struct dm_target *ti,
struct dm_dirty_log *dl)
{
size_t len;
struct mirror_set *ms = NULL;
len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
ms = kzalloc(len, GFP_KERNEL);
if (!ms) {
ti->error = "Cannot allocate mirror context";
return NULL;
}
spin_lock_init(&ms->lock);
bio_list_init(&ms->reads);
bio_list_init(&ms->writes);
bio_list_init(&ms->failures);
bio_list_init(&ms->holds);
ms->ti = ti;
ms->nr_mirrors = nr_mirrors;
ms->nr_regions = dm_sector_div_up(ti->len, region_size);
ms->in_sync = 0;
ms->log_failure = 0;
ms->leg_failure = 0;
atomic_set(&ms->suspend, 0);
atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
ms->read_record_pool = mempool_create_slab_pool(MIN_READ_RECORDS,
_dm_raid1_read_record_cache);
if (!ms->read_record_pool) {
ti->error = "Error creating mirror read_record_pool";
kfree(ms);
return NULL;
}
ms->io_client = dm_io_client_create();
if (IS_ERR(ms->io_client)) {
ti->error = "Error creating dm_io client";
mempool_destroy(ms->read_record_pool);
kfree(ms);
return NULL;
}
ms->rh = dm_region_hash_create(ms, dispatch_bios, wakeup_mirrord,
wakeup_all_recovery_waiters,
ms->ti->begin, MAX_RECOVERY,
dl, region_size, ms->nr_regions);
if (IS_ERR(ms->rh)) {
ti->error = "Error creating dirty region hash";
dm_io_client_destroy(ms->io_client);
mempool_destroy(ms->read_record_pool);
kfree(ms);
return NULL;
}
return ms;
}
static void free_context(struct mirror_set *ms, struct dm_target *ti,
unsigned int m)
{
while (m--)
dm_put_device(ti, ms->mirror[m].dev);
dm_io_client_destroy(ms->io_client);
dm_region_hash_destroy(ms->rh);
mempool_destroy(ms->read_record_pool);
kfree(ms);
}
static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
unsigned int mirror, char **argv)
{
unsigned long long offset;
if (sscanf(argv[1], "%llu", &offset) != 1) {
ti->error = "Invalid offset";
return -EINVAL;
}
if (dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
&ms->mirror[mirror].dev)) {
ti->error = "Device lookup failure";
return -ENXIO;
}
ms->mirror[mirror].ms = ms;
atomic_set(&(ms->mirror[mirror].error_count), 0);
ms->mirror[mirror].error_type = 0;
ms->mirror[mirror].offset = offset;
return 0;
}
/*
* Create dirty log: log_type #log_params <log_params>
*/
static struct dm_dirty_log *create_dirty_log(struct dm_target *ti,
unsigned argc, char **argv,
unsigned *args_used)
{
unsigned param_count;
struct dm_dirty_log *dl;
if (argc < 2) {
ti->error = "Insufficient mirror log arguments";
return NULL;
}
if (sscanf(argv[1], "%u", ¶m_count) != 1) {
ti->error = "Invalid mirror log argument count";
return NULL;
}
*args_used = 2 + param_count;
if (argc < *args_used) {
ti->error = "Insufficient mirror log arguments";
return NULL;
}
dl = dm_dirty_log_create(argv[0], ti, mirror_flush, param_count,
argv + 2);
if (!dl) {
ti->error = "Error creating mirror dirty log";
return NULL;
}
return dl;
}
static int parse_features(struct mirror_set *ms, unsigned argc, char **argv,
unsigned *args_used)
{
unsigned num_features;
struct dm_target *ti = ms->ti;
*args_used = 0;
if (!argc)
return 0;
if (sscanf(argv[0], "%u", &num_features) != 1) {
ti->error = "Invalid number of features";
return -EINVAL;
}
argc--;
argv++;
(*args_used)++;
if (num_features > argc) {
ti->error = "Not enough arguments to support feature count";
return -EINVAL;
}
if (!strcmp("handle_errors", argv[0]))
ms->features |= DM_RAID1_HANDLE_ERRORS;
else {
ti->error = "Unrecognised feature requested";
return -EINVAL;
}
(*args_used)++;
return 0;
}
/*
* Construct a mirror mapping:
*
* log_type #log_params <log_params>
* #mirrors [mirror_path offset]{2,}
* [#features <features>]
*
* log_type is "core" or "disk"
* #log_params is between 1 and 3
*
* If present, features must be "handle_errors".
*/
static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
int r;
unsigned int nr_mirrors, m, args_used;
struct mirror_set *ms;
struct dm_dirty_log *dl;
dl = create_dirty_log(ti, argc, argv, &args_used);
if (!dl)
return -EINVAL;
argv += args_used;
argc -= args_used;
if (!argc || sscanf(argv[0], "%u", &nr_mirrors) != 1 ||
nr_mirrors < 2 || nr_mirrors > DM_KCOPYD_MAX_REGIONS + 1) {
ti->error = "Invalid number of mirrors";
dm_dirty_log_destroy(dl);
return -EINVAL;
}
argv++, argc--;
if (argc < nr_mirrors * 2) {
ti->error = "Too few mirror arguments";
dm_dirty_log_destroy(dl);
return -EINVAL;
}
ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
if (!ms) {
dm_dirty_log_destroy(dl);
return -ENOMEM;
}
/* Get the mirror parameter sets */
for (m = 0; m < nr_mirrors; m++) {
r = get_mirror(ms, ti, m, argv);
if (r) {
free_context(ms, ti, m);
return r;
}
argv += 2;
argc -= 2;
}
ti->private = ms;
ti->split_io = dm_rh_get_region_size(ms->rh);
ti->num_flush_requests = 1;
ti->num_discard_requests = 1;
ms->kmirrord_wq = alloc_workqueue("kmirrord",
WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
if (!ms->kmirrord_wq) {
DMERR("couldn't start kmirrord");
r = -ENOMEM;
goto err_free_context;
}
INIT_WORK(&ms->kmirrord_work, do_mirror);
init_timer(&ms->timer);
ms->timer_pending = 0;
INIT_WORK(&ms->trigger_event, trigger_event);
r = parse_features(ms, argc, argv, &args_used);
if (r)
goto err_destroy_wq;
argv += args_used;
argc -= args_used;
/*
* Any read-balancing addition depends on the
* DM_RAID1_HANDLE_ERRORS flag being present.
* This is because the decision to balance depends
* on the sync state of a region. If the above
* flag is not present, we ignore errors; and
* the sync state may be inaccurate.
*/
if (argc) {
ti->error = "Too many mirror arguments";
r = -EINVAL;
goto err_destroy_wq;
}
ms->kcopyd_client = dm_kcopyd_client_create();
if (IS_ERR(ms->kcopyd_client)) {
r = PTR_ERR(ms->kcopyd_client);
goto err_destroy_wq;
}
wakeup_mirrord(ms);
return 0;
err_destroy_wq:
destroy_workqueue(ms->kmirrord_wq);
err_free_context:
free_context(ms, ti, ms->nr_mirrors);
return r;
}
static void mirror_dtr(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
del_timer_sync(&ms->timer);
flush_workqueue(ms->kmirrord_wq);
flush_work_sync(&ms->trigger_event);
dm_kcopyd_client_destroy(ms->kcopyd_client);
destroy_workqueue(ms->kmirrord_wq);
free_context(ms, ti, ms->nr_mirrors);
}
/*
* Mirror mapping function
*/
static int mirror_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
int r, rw = bio_rw(bio);
struct mirror *m;
struct mirror_set *ms = ti->private;
struct dm_raid1_read_record *read_record = NULL;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
if (rw == WRITE) {
/* Save region for mirror_end_io() handler */
map_context->ll = dm_rh_bio_to_region(ms->rh, bio);
queue_bio(ms, bio, rw);
return DM_MAPIO_SUBMITTED;
}
r = log->type->in_sync(log, dm_rh_bio_to_region(ms->rh, bio), 0);
if (r < 0 && r != -EWOULDBLOCK)
return r;
/*
* If region is not in-sync queue the bio.
*/
if (!r || (r == -EWOULDBLOCK)) {
if (rw == READA)
return -EWOULDBLOCK;
queue_bio(ms, bio, rw);
return DM_MAPIO_SUBMITTED;
}
/*
* The region is in-sync and we can perform reads directly.
* Store enough information so we can retry if it fails.
*/
m = choose_mirror(ms, bio->bi_sector);
if (unlikely(!m))
return -EIO;
read_record = mempool_alloc(ms->read_record_pool, GFP_NOIO);
if (likely(read_record)) {
dm_bio_record(&read_record->details, bio);
map_context->ptr = read_record;
read_record->m = m;
}
map_bio(m, bio);
return DM_MAPIO_REMAPPED;
}
static int mirror_end_io(struct dm_target *ti, struct bio *bio,
int error, union map_info *map_context)
{
int rw = bio_rw(bio);
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct mirror *m = NULL;
struct dm_bio_details *bd = NULL;
struct dm_raid1_read_record *read_record = map_context->ptr;
/*
* We need to dec pending if this was a write.
*/
if (rw == WRITE) {
if (!(bio->bi_rw & REQ_FLUSH))
dm_rh_dec(ms->rh, map_context->ll);
return error;
}
if (error == -EOPNOTSUPP)
goto out;
if ((error == -EWOULDBLOCK) && (bio->bi_rw & REQ_RAHEAD))
goto out;
if (unlikely(error)) {
if (!read_record) {
/*
* There wasn't enough memory to record necessary
* information for a retry or there was no other
* mirror in-sync.
*/
DMERR_LIMIT("Mirror read failed.");
return -EIO;
}
m = read_record->m;
DMERR("Mirror read failed from %s. Trying alternative device.",
m->dev->name);
fail_mirror(m, DM_RAID1_READ_ERROR);
/*
* A failed read is requeued for another attempt using an intact
* mirror.
*/
if (default_ok(m) || mirror_available(ms, bio)) {
bd = &read_record->details;
dm_bio_restore(bd, bio);
mempool_free(read_record, ms->read_record_pool);
map_context->ptr = NULL;
queue_bio(ms, bio, rw);
return 1;
}
DMERR("All replicated volumes dead, failing I/O");
}
out:
if (read_record) {
mempool_free(read_record, ms->read_record_pool);
map_context->ptr = NULL;
}
return error;
}
static void mirror_presuspend(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
struct bio_list holds;
struct bio *bio;
atomic_set(&ms->suspend, 1);
/*
* Process bios in the hold list to start recovery waiting
* for bios in the hold list. After the process, no bio has
* a chance to be added in the hold list because ms->suspend
* is set.
*/
spin_lock_irq(&ms->lock);
holds = ms->holds;
bio_list_init(&ms->holds);
spin_unlock_irq(&ms->lock);
while ((bio = bio_list_pop(&holds)))
hold_bio(ms, bio);
/*
* We must finish up all the work that we've
* generated (i.e. recovery work).
*/
dm_rh_stop_recovery(ms->rh);
wait_event(_kmirrord_recovery_stopped,
!dm_rh_recovery_in_flight(ms->rh));
if (log->type->presuspend && log->type->presuspend(log))
/* FIXME: need better error handling */
DMWARN("log presuspend failed");
/*
* Now that recovery is complete/stopped and the
* delayed bios are queued, we need to wait for
* the worker thread to complete. This way,
* we know that all of our I/O has been pushed.
*/
flush_workqueue(ms->kmirrord_wq);
}
static void mirror_postsuspend(struct dm_target *ti)
{
struct mirror_set *ms = ti->private;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
if (log->type->postsuspend && log->type->postsuspend(log))
/* FIXME: need better error handling */
DMWARN("log postsuspend failed");
}
static void mirror_resume(struct dm_target *ti)
{
struct mirror_set *ms = ti->private;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
atomic_set(&ms->suspend, 0);
if (log->type->resume && log->type->resume(log))
/* FIXME: need better error handling */
DMWARN("log resume failed");
dm_rh_start_recovery(ms->rh);
}
/*
* device_status_char
* @m: mirror device/leg we want the status of
*
* We return one character representing the most severe error
* we have encountered.
* A => Alive - No failures
* D => Dead - A write failure occurred leaving mirror out-of-sync
* S => Sync - A sychronization failure occurred, mirror out-of-sync
* R => Read - A read failure occurred, mirror data unaffected
*
* Returns: <char>
*/
static char device_status_char(struct mirror *m)
{
if (!atomic_read(&(m->error_count)))
return 'A';
return (test_bit(DM_RAID1_FLUSH_ERROR, &(m->error_type))) ? 'F' :
(test_bit(DM_RAID1_WRITE_ERROR, &(m->error_type))) ? 'D' :
(test_bit(DM_RAID1_SYNC_ERROR, &(m->error_type))) ? 'S' :
(test_bit(DM_RAID1_READ_ERROR, &(m->error_type))) ? 'R' : 'U';
}
static int mirror_status(struct dm_target *ti, status_type_t type,
char *result, unsigned int maxlen)
{
unsigned int m, sz = 0;
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
char buffer[ms->nr_mirrors + 1];
switch (type) {
case STATUSTYPE_INFO:
DMEMIT("%d ", ms->nr_mirrors);
for (m = 0; m < ms->nr_mirrors; m++) {
DMEMIT("%s ", ms->mirror[m].dev->name);
buffer[m] = device_status_char(&(ms->mirror[m]));
}
buffer[m] = '\0';
DMEMIT("%llu/%llu 1 %s ",
(unsigned long long)log->type->get_sync_count(log),
(unsigned long long)ms->nr_regions, buffer);
sz += log->type->status(log, type, result+sz, maxlen-sz);
break;
case STATUSTYPE_TABLE:
sz = log->type->status(log, type, result, maxlen);
DMEMIT("%d", ms->nr_mirrors);
for (m = 0; m < ms->nr_mirrors; m++)
DMEMIT(" %s %llu", ms->mirror[m].dev->name,
(unsigned long long)ms->mirror[m].offset);
if (ms->features & DM_RAID1_HANDLE_ERRORS)
DMEMIT(" 1 handle_errors");
}
return 0;
}
static int mirror_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct mirror_set *ms = ti->private;
int ret = 0;
unsigned i;
for (i = 0; !ret && i < ms->nr_mirrors; i++)
ret = fn(ti, ms->mirror[i].dev,
ms->mirror[i].offset, ti->len, data);
return ret;
}
static struct target_type mirror_target = {
.name = "mirror",
.version = {1, 12, 1},
.module = THIS_MODULE,
.ctr = mirror_ctr,
.dtr = mirror_dtr,
.map = mirror_map,
.end_io = mirror_end_io,
.presuspend = mirror_presuspend,
.postsuspend = mirror_postsuspend,
.resume = mirror_resume,
.status = mirror_status,
.iterate_devices = mirror_iterate_devices,
};
static int __init dm_mirror_init(void)
{
int r;
_dm_raid1_read_record_cache = KMEM_CACHE(dm_raid1_read_record, 0);
if (!_dm_raid1_read_record_cache) {
DMERR("Can't allocate dm_raid1_read_record cache");
r = -ENOMEM;
goto bad_cache;
}
r = dm_register_target(&mirror_target);
if (r < 0) {
DMERR("Failed to register mirror target");
goto bad_target;
}
return 0;
bad_target:
kmem_cache_destroy(_dm_raid1_read_record_cache);
bad_cache:
return r;
}
static void __exit dm_mirror_exit(void)
{
dm_unregister_target(&mirror_target);
kmem_cache_destroy(_dm_raid1_read_record_cache);
}
/* Module hooks */
module_init(dm_mirror_init);
module_exit(dm_mirror_exit);
MODULE_DESCRIPTION(DM_NAME " mirror target");
MODULE_AUTHOR("Joe Thornber");
MODULE_LICENSE("GPL");