linux/drivers/md/dm-raid1.c
Mikulas Patocka 5528d17de1 dm raid1: fail writes if errors are not handled and log fails
If the mirror log fails when the handle_errors option was not selected
and there is no remaining valid mirror leg, writes return success even
though they weren't actually written to any device.  This patch
completes them with EIO instead.

This code path is taken:
do_writes:
	bio_list_merge(&ms->failures, &sync);
do_failures:
	if (!get_valid_mirror(ms)) (false)
	else if (errors_handled(ms)) (false)
	else bio_endio(bio, 0);

The logic in do_failures is based on presuming that the write was already
tried: if it succeeded at least on one leg (without handle_errors) it
is reported as success.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=555197

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2010-02-16 18:42:55 +00:00

1452 lines
34 KiB
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_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_BARRIER,
.mem.type = DM_IO_KMEM,
.mem.ptr.bvec = 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 + (bio->bi_sector - m->ms->ti->begin);
}
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)
{
/*
* If device is suspended, complete the bio.
*/
if (atomic_read(&ms->suspend)) {
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.
*/
spin_lock_irq(&ms->lock);
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_BARRIER),
.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,
};
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 (unlikely(bio_empty_barrier(bio))) {
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))
hold_bio(ms, bio);
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);
dm_table_unplug_all(ms->ti->table);
}
/*-----------------------------------------------------------------
* 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(DM_IO_PAGES);
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], offset, ti->len,
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", &param_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;
ms->kmirrord_wq = create_singlethread_workqueue("kmirrord");
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;
}
r = dm_kcopyd_client_create(DM_KCOPYD_PAGES, &ms->kcopyd_client);
if (r)
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_scheduled_work();
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 (likely(!bio_empty_barrier(bio)))
dm_rh_dec(ms->rh, map_context->ll);
return error;
}
if (error == -EOPNOTSUPP)
goto out;
if ((error == -EWOULDBLOCK) && bio_rw_flagged(bio, BIO_RW_AHEAD))
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);
/*
* 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);
/*
* Now set ms->suspend is set and the workqueue flushed, no more
* entries can be added to ms->hold list, so process it.
*
* Bios can still arrive concurrently with or after this
* presuspend function, but they cannot join 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);
}
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, 0},
.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");