OpenCloudOS-Kernel/drivers/md/dm-raid1.c

1898 lines
44 KiB
C
Raw Normal View History

/*
* Copyright (C) 2003 Sistina Software Limited.
*
* This file is released under the GPL.
*/
#include "dm.h"
#include "dm-bio-list.h"
#include "dm-bio-record.h"
#include "dm-io.h"
#include "dm-log.h"
#include "kcopyd.h"
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/log2.h>
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
#include <linux/hardirq.h>
#define DM_MSG_PREFIX "raid1"
#define DM_IO_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);
/*-----------------------------------------------------------------
* Region hash
*
* The mirror splits itself up into discrete regions. Each
* region can be in one of three states: clean, dirty,
* nosync. There is no need to put clean regions in the hash.
*
* In addition to being present in the hash table a region _may_
* be present on one of three lists.
*
* clean_regions: Regions on this list have no io pending to
* them, they are in sync, we are no longer interested in them,
* they are dull. rh_update_states() will remove them from the
* hash table.
*
* quiesced_regions: These regions have been spun down, ready
* for recovery. rh_recovery_start() will remove regions from
* this list and hand them to kmirrord, which will schedule the
* recovery io with kcopyd.
*
* recovered_regions: Regions that kcopyd has successfully
* recovered. rh_update_states() will now schedule any delayed
* io, up the recovery_count, and remove the region from the
* hash.
*
* There are 2 locks:
* A rw spin lock 'hash_lock' protects just the hash table,
* this is never held in write mode from interrupt context,
* which I believe means that we only have to disable irqs when
* doing a write lock.
*
* An ordinary spin lock 'region_lock' that protects the three
* lists in the region_hash, with the 'state', 'list' and
* 'bhs_delayed' fields of the regions. This is used from irq
* context, so all other uses will have to suspend local irqs.
*---------------------------------------------------------------*/
struct mirror_set;
struct region_hash {
struct mirror_set *ms;
uint32_t region_size;
unsigned region_shift;
/* holds persistent region state */
struct dirty_log *log;
/* hash table */
rwlock_t hash_lock;
mempool_t *region_pool;
unsigned int mask;
unsigned int nr_buckets;
struct list_head *buckets;
spinlock_t region_lock;
atomic_t recovery_in_flight;
struct semaphore recovery_count;
struct list_head clean_regions;
struct list_head quiesced_regions;
struct list_head recovered_regions;
struct list_head failed_recovered_regions;
};
enum {
RH_CLEAN,
RH_DIRTY,
RH_NOSYNC,
RH_RECOVERING
};
struct region {
struct region_hash *rh; /* FIXME: can we get rid of this ? */
region_t key;
int state;
struct list_head hash_list;
struct list_head list;
atomic_t pending;
struct bio_list delayed_bios;
};
/*-----------------------------------------------------------------
* Mirror set structures.
*---------------------------------------------------------------*/
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
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;
struct region_hash rh;
struct kcopyd_client *kcopyd_client;
uint64_t features;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
spinlock_t lock; /* protects the lists */
struct bio_list reads;
struct bio_list writes;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
struct bio_list failures;
struct dm_io_client *io_client;
mempool_t *read_record_pool;
/* recovery */
region_t nr_regions;
int in_sync;
int log_failure;
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
atomic_t suspend;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
atomic_t default_mirror; /* Default mirror */
struct workqueue_struct *kmirrord_wq;
struct work_struct kmirrord_work;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
struct work_struct trigger_event;
unsigned int nr_mirrors;
struct mirror mirror[0];
};
/*
* Conversion fns
*/
static inline region_t bio_to_region(struct region_hash *rh, struct bio *bio)
{
return (bio->bi_sector - rh->ms->ti->begin) >> rh->region_shift;
}
static inline sector_t region_to_sector(struct region_hash *rh, region_t region)
{
return region << rh->region_shift;
}
static void wake(struct mirror_set *ms)
{
queue_work(ms->kmirrord_wq, &ms->kmirrord_work);
}
/* FIXME move this */
static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw);
#define MIN_REGIONS 64
#define MAX_RECOVERY 1
static int rh_init(struct region_hash *rh, struct mirror_set *ms,
struct dirty_log *log, uint32_t region_size,
region_t nr_regions)
{
unsigned int nr_buckets, max_buckets;
size_t i;
/*
* Calculate a suitable number of buckets for our hash
* table.
*/
max_buckets = nr_regions >> 6;
for (nr_buckets = 128u; nr_buckets < max_buckets; nr_buckets <<= 1)
;
nr_buckets >>= 1;
rh->ms = ms;
rh->log = log;
rh->region_size = region_size;
rh->region_shift = ffs(region_size) - 1;
rwlock_init(&rh->hash_lock);
rh->mask = nr_buckets - 1;
rh->nr_buckets = nr_buckets;
rh->buckets = vmalloc(nr_buckets * sizeof(*rh->buckets));
if (!rh->buckets) {
DMERR("unable to allocate region hash memory");
return -ENOMEM;
}
for (i = 0; i < nr_buckets; i++)
INIT_LIST_HEAD(rh->buckets + i);
spin_lock_init(&rh->region_lock);
sema_init(&rh->recovery_count, 0);
atomic_set(&rh->recovery_in_flight, 0);
INIT_LIST_HEAD(&rh->clean_regions);
INIT_LIST_HEAD(&rh->quiesced_regions);
INIT_LIST_HEAD(&rh->recovered_regions);
INIT_LIST_HEAD(&rh->failed_recovered_regions);
rh->region_pool = mempool_create_kmalloc_pool(MIN_REGIONS,
sizeof(struct region));
if (!rh->region_pool) {
vfree(rh->buckets);
rh->buckets = NULL;
return -ENOMEM;
}
return 0;
}
static void rh_exit(struct region_hash *rh)
{
unsigned int h;
struct region *reg, *nreg;
BUG_ON(!list_empty(&rh->quiesced_regions));
for (h = 0; h < rh->nr_buckets; h++) {
list_for_each_entry_safe(reg, nreg, rh->buckets + h, hash_list) {
BUG_ON(atomic_read(&reg->pending));
mempool_free(reg, rh->region_pool);
}
}
if (rh->log)
dm_destroy_dirty_log(rh->log);
if (rh->region_pool)
mempool_destroy(rh->region_pool);
vfree(rh->buckets);
}
#define RH_HASH_MULT 2654435387U
static inline unsigned int rh_hash(struct region_hash *rh, region_t region)
{
return (unsigned int) ((region * RH_HASH_MULT) >> 12) & rh->mask;
}
static struct region *__rh_lookup(struct region_hash *rh, region_t region)
{
struct region *reg;
list_for_each_entry (reg, rh->buckets + rh_hash(rh, region), hash_list)
if (reg->key == region)
return reg;
return NULL;
}
static void __rh_insert(struct region_hash *rh, struct region *reg)
{
unsigned int h = rh_hash(rh, reg->key);
list_add(&reg->hash_list, rh->buckets + h);
}
static struct region *__rh_alloc(struct region_hash *rh, region_t region)
{
struct region *reg, *nreg;
read_unlock(&rh->hash_lock);
[PATCH] dm: Fix deadlock under high i/o load in raid1 setup. On an nForce4-equipped machine with two SATA disk in raid1 setup using dmraid, we experienced frequent deadlock of the system under high i/o load. 'cat /dev/zero > ~/zero' was the most reliable way to reproduce them: Randomly after a few GB, 'cp' would be left in 'D' state along with kjournald and kmirrord. The functions cp and kjournald were blocked in did vary, but kmirrord's wchan always pointed to 'mempool_alloc()'. We've seen this pattern on 2.6.15 and 2.6.17 kernels. http://lkml.org/lkml/2005/4/20/142 indicates that this problem has been around even before. So much for the facts, here's my interpretation: mempool_alloc() first tries to atomically allocate the requested memory, or falls back to hand out preallocated chunks from the mempool. If both fail, it puts the calling process (kmirrord in this case) on a private waitqueue until somebody refills the pool. Where the only 'somebody' is kmirrord itself, so we have a deadlock. I worked around this problem by falling back to a (blocking) kmalloc when before kmirrord would have ended up on the waitqueue. This defeats part of the benefits of using the mempool, but at least keeps the system running. And it could be done with a two-line change. Note that mempool_alloc() clears the GFP_NOIO flag internally, and only uses it to decide whether to wait or return an error if immediate allocation fails, so the attached patch doesn't change behaviour in the non-deadlocking case. Path is against current git (2.6.18-rc4), but should apply to earlier versions as well. I've tested on 2.6.15, where this patch makes the difference between random lockup and a stable system. Signed-off-by: Daniel Kobras <kobras@linux.de> Acked-by: Alasdair G Kergon <agk@redhat.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-27 16:23:24 +08:00
nreg = mempool_alloc(rh->region_pool, GFP_ATOMIC);
if (unlikely(!nreg))
nreg = kmalloc(sizeof(struct region), GFP_NOIO);
nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
RH_CLEAN : RH_NOSYNC;
nreg->rh = rh;
nreg->key = region;
INIT_LIST_HEAD(&nreg->list);
atomic_set(&nreg->pending, 0);
bio_list_init(&nreg->delayed_bios);
write_lock_irq(&rh->hash_lock);
reg = __rh_lookup(rh, region);
if (reg)
/* we lost the race */
mempool_free(nreg, rh->region_pool);
else {
__rh_insert(rh, nreg);
if (nreg->state == RH_CLEAN) {
spin_lock(&rh->region_lock);
list_add(&nreg->list, &rh->clean_regions);
spin_unlock(&rh->region_lock);
}
reg = nreg;
}
write_unlock_irq(&rh->hash_lock);
read_lock(&rh->hash_lock);
return reg;
}
static inline struct region *__rh_find(struct region_hash *rh, region_t region)
{
struct region *reg;
reg = __rh_lookup(rh, region);
if (!reg)
reg = __rh_alloc(rh, region);
return reg;
}
static int rh_state(struct region_hash *rh, region_t region, int may_block)
{
int r;
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_lookup(rh, region);
read_unlock(&rh->hash_lock);
if (reg)
return reg->state;
/*
* The region wasn't in the hash, so we fall back to the
* dirty log.
*/
r = rh->log->type->in_sync(rh->log, region, may_block);
/*
* Any error from the dirty log (eg. -EWOULDBLOCK) gets
* taken as a RH_NOSYNC
*/
return r == 1 ? RH_CLEAN : RH_NOSYNC;
}
static inline int rh_in_sync(struct region_hash *rh,
region_t region, int may_block)
{
int state = rh_state(rh, region, may_block);
return state == RH_CLEAN || state == RH_DIRTY;
}
static void dispatch_bios(struct mirror_set *ms, struct bio_list *bio_list)
{
struct bio *bio;
while ((bio = bio_list_pop(bio_list))) {
queue_bio(ms, bio, WRITE);
}
}
static void complete_resync_work(struct region *reg, int success)
{
struct region_hash *rh = reg->rh;
rh->log->type->set_region_sync(rh->log, reg->key, success);
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
/*
* Dispatch the bios before we call 'wake_up_all'.
* This is important because if we are suspending,
* we want to know that recovery is complete and
* the work queue is flushed. If we wake_up_all
* before we dispatch_bios (queue bios and call wake()),
* then we risk suspending before the work queue
* has been properly flushed.
*/
dispatch_bios(rh->ms, &reg->delayed_bios);
if (atomic_dec_and_test(&rh->recovery_in_flight))
wake_up_all(&_kmirrord_recovery_stopped);
up(&rh->recovery_count);
}
static void rh_update_states(struct region_hash *rh)
{
struct region *reg, *next;
LIST_HEAD(clean);
LIST_HEAD(recovered);
LIST_HEAD(failed_recovered);
/*
* Quickly grab the lists.
*/
write_lock_irq(&rh->hash_lock);
spin_lock(&rh->region_lock);
if (!list_empty(&rh->clean_regions)) {
list_splice(&rh->clean_regions, &clean);
INIT_LIST_HEAD(&rh->clean_regions);
list_for_each_entry(reg, &clean, list)
list_del(&reg->hash_list);
}
if (!list_empty(&rh->recovered_regions)) {
list_splice(&rh->recovered_regions, &recovered);
INIT_LIST_HEAD(&rh->recovered_regions);
list_for_each_entry (reg, &recovered, list)
list_del(&reg->hash_list);
}
if (!list_empty(&rh->failed_recovered_regions)) {
list_splice(&rh->failed_recovered_regions, &failed_recovered);
INIT_LIST_HEAD(&rh->failed_recovered_regions);
list_for_each_entry(reg, &failed_recovered, list)
list_del(&reg->hash_list);
}
spin_unlock(&rh->region_lock);
write_unlock_irq(&rh->hash_lock);
/*
* All the regions on the recovered and clean lists have
* now been pulled out of the system, so no need to do
* any more locking.
*/
list_for_each_entry_safe (reg, next, &recovered, list) {
rh->log->type->clear_region(rh->log, reg->key);
complete_resync_work(reg, 1);
mempool_free(reg, rh->region_pool);
}
list_for_each_entry_safe(reg, next, &failed_recovered, list) {
complete_resync_work(reg, errors_handled(rh->ms) ? 0 : 1);
mempool_free(reg, rh->region_pool);
}
list_for_each_entry_safe(reg, next, &clean, list) {
rh->log->type->clear_region(rh->log, reg->key);
mempool_free(reg, rh->region_pool);
}
rh->log->type->flush(rh->log);
}
static void rh_inc(struct region_hash *rh, region_t region)
{
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
spin_lock_irq(&rh->region_lock);
atomic_inc(&reg->pending);
if (reg->state == RH_CLEAN) {
reg->state = RH_DIRTY;
list_del_init(&reg->list); /* take off the clean list */
spin_unlock_irq(&rh->region_lock);
rh->log->type->mark_region(rh->log, reg->key);
} else
spin_unlock_irq(&rh->region_lock);
read_unlock(&rh->hash_lock);
}
static void rh_inc_pending(struct region_hash *rh, struct bio_list *bios)
{
struct bio *bio;
for (bio = bios->head; bio; bio = bio->bi_next)
rh_inc(rh, bio_to_region(rh, bio));
}
static void rh_dec(struct region_hash *rh, region_t region)
{
unsigned long flags;
struct region *reg;
int should_wake = 0;
read_lock(&rh->hash_lock);
reg = __rh_lookup(rh, region);
read_unlock(&rh->hash_lock);
spin_lock_irqsave(&rh->region_lock, flags);
if (atomic_dec_and_test(&reg->pending)) {
[PATCH] drivers/md/dm-raid1.c: Fix inconsistent mirroring after interrupted recovery dm-mirror has potential data corruption problem: while on-disk log shows that all disk contents are in-sync, actual contents of the disks are not synchronized. This problem occurs if initial recovery (synching) is interrupted and resumed. Attached patch fixes this problem. Background: rh_dec() changes the region state from RH_NOSYNC (out-of-sync) to RH_CLEAN (in-sync), which results in the corresponding bit of clean_bits being set. This is harmful if on-disk log is used and the map is removed/suspended before the initial sync is completed. The clean_bits is written down to the on-disk log at the map removal, and, upon resume, it's read and copied to sync_bits. Since the recovery process refers to the sync_bits to find a region to be recovered, the region whose state was changed from RH_NOSYNC to RH_CLEAN is no longer recovered. If you haven't applied dm-raid1-read-balancing.patch proposed in dm-devel sometimes ago, the contents of the mirrored disk just corrupt silently. If you have, balanced read may get bogus data from out-of-sync disks. The patch keeps RH_NOSYNC state unchanged. It will be changed to RH_RECOVERING when recovery starts and get reclaimed when the recovery completes. So it doesn't leak the region hash entry. Description: Keep RH_NOSYNC state unchanged when I/O on the region completes. rh_dec() changes the region state from RH_NOSYNC (out-of-sync) to RH_CLEAN (in-sync), which results in the corresponding bit of clean_bits being set. This is harmful if on-disk log is used and the map is removed/suspended before the initial sync is completed. The clean_bits is written down to the on-disk log at the map removal, and, upon resume, it's read and copied to sync_bits. Since the recovery process refers to the sync_bits to find a region to be recovered, the region whose state was changed from RH_NOSYNC to RH_CLEAN is no longer recovered. If you haven't applied dm-raid1-read-balancing.patch proposed in dm-devel sometimes ago, the contents of the mirrored disk just corrupt silently. If you have, balanced read may get bogus data from out-of-sync disks. The RH_NOSYNC region will be changed to RH_RECOVERING when recovery starts on the region and get reclaimed when the recovery completes. So it doesn't leak the region hash entry. Alasdair said: I've analysed the relevant part of the state machine and I believe that the patch is correct. (Further work on this code is still needed - this patch has the side-effect of holding onto memory unnecessarily for long periods of time under certain workloads - but better that than corrupting data.) Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 17:17:47 +08:00
/*
* There is no pending I/O for this region.
* We can move the region to corresponding list for next action.
* At this point, the region is not yet connected to any list.
*
* If the state is RH_NOSYNC, the region should be kept off
* from clean list.
* The hash entry for RH_NOSYNC will remain in memory
* until the region is recovered or the map is reloaded.
*/
/* do nothing for RH_NOSYNC */
if (reg->state == RH_RECOVERING) {
list_add_tail(&reg->list, &rh->quiesced_regions);
[PATCH] drivers/md/dm-raid1.c: Fix inconsistent mirroring after interrupted recovery dm-mirror has potential data corruption problem: while on-disk log shows that all disk contents are in-sync, actual contents of the disks are not synchronized. This problem occurs if initial recovery (synching) is interrupted and resumed. Attached patch fixes this problem. Background: rh_dec() changes the region state from RH_NOSYNC (out-of-sync) to RH_CLEAN (in-sync), which results in the corresponding bit of clean_bits being set. This is harmful if on-disk log is used and the map is removed/suspended before the initial sync is completed. The clean_bits is written down to the on-disk log at the map removal, and, upon resume, it's read and copied to sync_bits. Since the recovery process refers to the sync_bits to find a region to be recovered, the region whose state was changed from RH_NOSYNC to RH_CLEAN is no longer recovered. If you haven't applied dm-raid1-read-balancing.patch proposed in dm-devel sometimes ago, the contents of the mirrored disk just corrupt silently. If you have, balanced read may get bogus data from out-of-sync disks. The patch keeps RH_NOSYNC state unchanged. It will be changed to RH_RECOVERING when recovery starts and get reclaimed when the recovery completes. So it doesn't leak the region hash entry. Description: Keep RH_NOSYNC state unchanged when I/O on the region completes. rh_dec() changes the region state from RH_NOSYNC (out-of-sync) to RH_CLEAN (in-sync), which results in the corresponding bit of clean_bits being set. This is harmful if on-disk log is used and the map is removed/suspended before the initial sync is completed. The clean_bits is written down to the on-disk log at the map removal, and, upon resume, it's read and copied to sync_bits. Since the recovery process refers to the sync_bits to find a region to be recovered, the region whose state was changed from RH_NOSYNC to RH_CLEAN is no longer recovered. If you haven't applied dm-raid1-read-balancing.patch proposed in dm-devel sometimes ago, the contents of the mirrored disk just corrupt silently. If you have, balanced read may get bogus data from out-of-sync disks. The RH_NOSYNC region will be changed to RH_RECOVERING when recovery starts on the region and get reclaimed when the recovery completes. So it doesn't leak the region hash entry. Alasdair said: I've analysed the relevant part of the state machine and I believe that the patch is correct. (Further work on this code is still needed - this patch has the side-effect of holding onto memory unnecessarily for long periods of time under certain workloads - but better that than corrupting data.) Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 17:17:47 +08:00
} else if (reg->state == RH_DIRTY) {
reg->state = RH_CLEAN;
list_add(&reg->list, &rh->clean_regions);
}
should_wake = 1;
}
spin_unlock_irqrestore(&rh->region_lock, flags);
if (should_wake)
wake(rh->ms);
}
/*
* Starts quiescing a region in preparation for recovery.
*/
static int __rh_recovery_prepare(struct region_hash *rh)
{
int r;
struct region *reg;
region_t region;
/*
* Ask the dirty log what's next.
*/
r = rh->log->type->get_resync_work(rh->log, &region);
if (r <= 0)
return r;
/*
* Get this region, and start it quiescing by setting the
* recovering flag.
*/
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
read_unlock(&rh->hash_lock);
spin_lock_irq(&rh->region_lock);
reg->state = RH_RECOVERING;
/* Already quiesced ? */
if (atomic_read(&reg->pending))
list_del_init(&reg->list);
else
list_move(&reg->list, &rh->quiesced_regions);
spin_unlock_irq(&rh->region_lock);
return 1;
}
static void rh_recovery_prepare(struct region_hash *rh)
{
/* Extra reference to avoid race with rh_stop_recovery */
atomic_inc(&rh->recovery_in_flight);
while (!down_trylock(&rh->recovery_count)) {
atomic_inc(&rh->recovery_in_flight);
if (__rh_recovery_prepare(rh) <= 0) {
atomic_dec(&rh->recovery_in_flight);
up(&rh->recovery_count);
break;
}
}
/* Drop the extra reference */
if (atomic_dec_and_test(&rh->recovery_in_flight))
wake_up_all(&_kmirrord_recovery_stopped);
}
/*
* Returns any quiesced regions.
*/
static struct region *rh_recovery_start(struct region_hash *rh)
{
struct region *reg = NULL;
spin_lock_irq(&rh->region_lock);
if (!list_empty(&rh->quiesced_regions)) {
reg = list_entry(rh->quiesced_regions.next,
struct region, list);
list_del_init(&reg->list); /* remove from the quiesced list */
}
spin_unlock_irq(&rh->region_lock);
return reg;
}
static void rh_recovery_end(struct region *reg, int success)
{
struct region_hash *rh = reg->rh;
spin_lock_irq(&rh->region_lock);
if (success)
list_add(&reg->list, &reg->rh->recovered_regions);
else {
reg->state = RH_NOSYNC;
list_add(&reg->list, &reg->rh->failed_recovered_regions);
}
spin_unlock_irq(&rh->region_lock);
wake(rh->ms);
}
static int rh_flush(struct region_hash *rh)
{
return rh->log->type->flush(rh->log);
}
static void rh_delay(struct region_hash *rh, struct bio *bio)
{
struct region *reg;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, bio_to_region(rh, bio));
bio_list_add(&reg->delayed_bios, bio);
read_unlock(&rh->hash_lock);
}
static void rh_stop_recovery(struct region_hash *rh)
{
int i;
/* wait for any recovering regions */
for (i = 0; i < MAX_RECOVERY; i++)
down(&rh->recovery_count);
}
static void rh_start_recovery(struct region_hash *rh)
{
int i;
for (i = 0; i < MAX_RECOVERY; i++)
up(&rh->recovery_count);
wake(rh->ms);
}
#define MIN_READ_RECORDS 20
struct dm_raid1_read_record {
struct mirror *m;
struct dm_bio_details details;
};
/*
* 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;
}
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
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);
}
/* 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;
if (!errors_handled(ms))
return;
/*
* 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 (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;
}
for (new = ms->mirror; new < ms->mirror + ms->nr_mirrors; new++)
if (!atomic_read(&new->error_count)) {
set_default_mirror(new);
break;
}
if (unlikely(new == ms->mirror + ms->nr_mirrors))
DMWARN("All sides of mirror have failed.");
out:
schedule_work(&ms->trigger_event);
}
/*-----------------------------------------------------------------
* 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 region *reg = (struct region *)context;
struct mirror_set *ms = reg->rh->ms;
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++;
}
}
rh_recovery_end(reg, !(read_err || write_err));
}
static int recover(struct mirror_set *ms, struct region *reg)
{
int r;
unsigned int i;
struct io_region from, to[KCOPYD_MAX_REGIONS], *dest;
struct mirror *m;
unsigned long flags = 0;
/* fill in the source */
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
m = get_default_mirror(ms);
from.bdev = m->dev->bdev;
from.sector = m->offset + region_to_sector(reg->rh, reg->key);
if (reg->key == (ms->nr_regions - 1)) {
/*
* The final region may be smaller than
* region_size.
*/
from.count = ms->ti->len & (reg->rh->region_size - 1);
if (!from.count)
from.count = reg->rh->region_size;
} else
from.count = reg->rh->region_size;
/* fill in the destinations */
for (i = 0, dest = to; i < ms->nr_mirrors; i++) {
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
if (&ms->mirror[i] == get_default_mirror(ms))
continue;
m = ms->mirror + i;
dest->bdev = m->dev->bdev;
dest->sector = m->offset + region_to_sector(reg->rh, reg->key);
dest->count = from.count;
dest++;
}
/* hand to kcopyd */
set_bit(KCOPYD_IGNORE_ERROR, &flags);
r = 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)
{
int r;
struct region *reg;
struct dirty_log *log = ms->rh.log;
/*
* Start quiescing some regions.
*/
rh_recovery_prepare(&ms->rh);
/*
* Copy any already quiesced regions.
*/
while ((reg = rh_recovery_start(&ms->rh))) {
r = recover(ms, reg);
if (r)
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)
{
region_t region = bio_to_region(&ms->rh, bio);
if (ms->rh.log->type->in_sync(ms->rh.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)
{
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 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;
}
/*-----------------------------------------------------------------
* 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 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);
(void) dm_io(&io_req, 1, &io, NULL);
}
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 = bio_to_region(&ms->rh, bio);
m = get_default_mirror(ms);
/*
* We can only read balance if the region is in sync.
*/
if (likely(rh_in_sync(&ms->rh, 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
*---------------------------------------------------------------*/
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
/* __bio_mark_nosync
* @ms
* @bio
* @done
* @error
*
* The bio was written on some mirror(s) but failed on other mirror(s).
* We can successfully endio the bio but should avoid the region being
* marked clean by setting the state RH_NOSYNC.
*
* This function is _not_ safe in interrupt context!
*/
static void __bio_mark_nosync(struct mirror_set *ms,
struct bio *bio, unsigned done, int error)
{
unsigned long flags;
struct region_hash *rh = &ms->rh;
struct dirty_log *log = ms->rh.log;
struct region *reg;
region_t region = bio_to_region(rh, bio);
int recovering = 0;
/* We must inform the log that the sync count has changed. */
log->type->set_region_sync(log, region, 0);
ms->in_sync = 0;
read_lock(&rh->hash_lock);
reg = __rh_find(rh, region);
read_unlock(&rh->hash_lock);
/* region hash entry should exist because write was in-flight */
BUG_ON(!reg);
BUG_ON(!list_empty(&reg->list));
spin_lock_irqsave(&rh->region_lock, flags);
/*
* Possible cases:
* 1) RH_DIRTY
* 2) RH_NOSYNC: was dirty, other preceeding writes failed
* 3) RH_RECOVERING: flushing pending writes
* Either case, the region should have not been connected to list.
*/
recovering = (reg->state == RH_RECOVERING);
reg->state = RH_NOSYNC;
BUG_ON(!list_empty(&reg->list));
spin_unlock_irqrestore(&rh->region_lock, flags);
bio_endio(bio, error);
if (recovering)
complete_resync_work(reg, 0);
}
static void write_callback(unsigned long error, void *context)
{
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
unsigned i, ret = 0;
struct bio *bio = (struct bio *) context;
struct mirror_set *ms;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
int uptodate = 0;
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.
*/
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
if (likely(!error))
goto out;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
for (i = 0; i < ms->nr_mirrors; i++)
if (test_bit(i, &error))
fail_mirror(ms->mirror + i, DM_RAID1_WRITE_ERROR);
else
uptodate = 1;
if (unlikely(!uptodate)) {
DMERR("All replicated volumes dead, failing I/O");
/* None of the writes succeeded, fail the I/O. */
ret = -EIO;
} else if (errors_handled(ms)) {
/*
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
* Need to raise event. Since raising
* events can block, we need to do it in
* the main thread.
*/
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
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)
wake(ms);
return;
}
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
out:
bio_endio(bio, ret);
}
static void do_write(struct mirror_set *ms, struct bio *bio)
{
unsigned int i;
struct io_region io[ms->nr_mirrors], *dest = io;
struct mirror *m;
struct dm_io_request io_req = {
.bi_rw = WRITE,
.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));
(void) 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;
if (!writes->head)
return;
/*
* Classify each write.
*/
bio_list_init(&sync);
bio_list_init(&nosync);
bio_list_init(&recover);
while ((bio = bio_list_pop(writes))) {
state = rh_state(&ms->rh, bio_to_region(&ms->rh, bio), 1);
switch (state) {
case RH_CLEAN:
case RH_DIRTY:
this_list = &sync;
break;
case RH_NOSYNC:
this_list = &nosync;
break;
case RH_RECOVERING:
this_list = &recover;
break;
}
bio_list_add(this_list, bio);
}
/*
* Increment the pending counts for any regions that will
* be written to (writes to recover regions are going to
* be delayed).
*/
rh_inc_pending(&ms->rh, &sync);
rh_inc_pending(&ms->rh, &nosync);
ms->log_failure = rh_flush(&ms->rh) ? 1 : 0;
/*
* Dispatch io.
*/
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
if (unlikely(ms->log_failure)) {
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->failures, &sync);
spin_unlock_irq(&ms->lock);
} else
while ((bio = bio_list_pop(&sync)))
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
do_write(ms, bio);
while ((bio = bio_list_pop(&recover)))
rh_delay(&ms->rh, bio);
while ((bio = bio_list_pop(&nosync))) {
map_bio(get_default_mirror(ms), bio);
generic_make_request(bio);
}
}
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
static void do_failures(struct mirror_set *ms, struct bio_list *failures)
{
struct bio *bio;
if (!failures->head)
return;
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
if (!ms->log_failure) {
while ((bio = bio_list_pop(failures)))
__bio_mark_nosync(ms, bio, bio->bi_size, 0);
return;
}
/*
* If the log has failed, unattempted writes are being
* put on the failures 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.
*/
if (dm_noflush_suspending(ms->ti)) {
while ((bio = bio_list_pop(failures)))
bio_endio(bio, DM_ENDIO_REQUEUE);
return;
}
if (atomic_read(&ms->suspend)) {
while ((bio = bio_list_pop(failures)))
bio_endio(bio, -EIO);
return;
}
spin_lock_irq(&ms->lock);
bio_list_merge(&ms->failures, failures);
spin_unlock_irq(&ms->lock);
wake(ms);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
}
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
*---------------------------------------------------------------*/
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
static int _do_mirror(struct work_struct *work)
{
struct mirror_set *ms =container_of(work, struct mirror_set,
kmirrord_work);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
struct bio_list reads, writes, failures;
unsigned long flags;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
spin_lock_irqsave(&ms->lock, flags);
reads = ms->reads;
writes = ms->writes;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
failures = ms->failures;
bio_list_init(&ms->reads);
bio_list_init(&ms->writes);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
bio_list_init(&ms->failures);
spin_unlock_irqrestore(&ms->lock, flags);
rh_update_states(&ms->rh);
do_recovery(ms);
do_reads(ms, &reads);
do_writes(ms, &writes);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
do_failures(ms, &failures);
return (ms->failures.head) ? 1 : 0;
}
static void do_mirror(struct work_struct *work)
{
/*
* If _do_mirror returns 1, we give it
* another shot. This helps for cases like
* 'suspend' where we call flush_workqueue
* and expect all work to be finished. If
* a failure happens during a suspend, we
* couldn't issue a 'wake' because it would
* not be honored. Therefore, we return '1'
* from _do_mirror, and retry here.
*/
while (_do_mirror(work))
schedule();
}
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
/*-----------------------------------------------------------------
* Target functions
*---------------------------------------------------------------*/
static struct mirror_set *alloc_context(unsigned int nr_mirrors,
uint32_t region_size,
struct dm_target *ti,
struct dirty_log *dl)
{
size_t len;
struct mirror_set *ms = NULL;
if (array_too_big(sizeof(*ms), sizeof(ms->mirror[0]), nr_mirrors))
return NULL;
len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
2007-07-19 16:49:03 +08:00
ms = kzalloc(len, GFP_KERNEL);
if (!ms) {
ti->error = "Cannot allocate mirror context";
return NULL;
}
spin_lock_init(&ms->lock);
ms->ti = ti;
ms->nr_mirrors = nr_mirrors;
ms->nr_regions = dm_sector_div_up(ti->len, region_size);
ms->in_sync = 0;
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
ms->log_failure = 0;
atomic_set(&ms->suspend, 0);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
atomic_set(&ms->default_mirror, DEFAULT_MIRROR);
len = sizeof(struct dm_raid1_read_record);
ms->read_record_pool = mempool_create_kmalloc_pool(MIN_READ_RECORDS,
len);
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;
}
if (rh_init(&ms->rh, ms, dl, region_size, ms->nr_regions)) {
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);
rh_exit(&ms->rh);
mempool_destroy(ms->read_record_pool);
kfree(ms);
}
static inline int _check_region_size(struct dm_target *ti, uint32_t size)
{
return !(size % (PAGE_SIZE >> 9) || !is_power_of_2(size) ||
size > ti->len);
}
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;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
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 dirty_log *create_dirty_log(struct dm_target *ti,
unsigned int argc, char **argv,
unsigned int *args_used)
{
unsigned int param_count;
struct 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_create_dirty_log(argv[0], ti, param_count, argv + 2);
if (!dl) {
ti->error = "Error creating mirror dirty log";
return NULL;
}
if (!_check_region_size(ti, dl->type->get_region_size(dl))) {
ti->error = "Invalid region size";
dm_destroy_dirty_log(dl);
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 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 > KCOPYD_MAX_REGIONS + 1) {
ti->error = "Invalid number of mirrors";
dm_destroy_dirty_log(dl);
return -EINVAL;
}
argv++, argc--;
if (argc < nr_mirrors * 2) {
ti->error = "Too few mirror arguments";
dm_destroy_dirty_log(dl);
return -EINVAL;
}
ms = alloc_context(nr_mirrors, dl->type->get_region_size(dl), ti, dl);
if (!ms) {
dm_destroy_dirty_log(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 = ms->rh.region_size;
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);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
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 = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
if (r)
goto err_destroy_wq;
wake(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;
flush_workqueue(ms->kmirrord_wq);
kcopyd_client_destroy(ms->kcopyd_client);
destroy_workqueue(ms->kmirrord_wq);
free_context(ms, ti, ms->nr_mirrors);
}
static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
{
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
unsigned long flags;
int should_wake = 0;
struct bio_list *bl;
bl = (rw == WRITE) ? &ms->writes : &ms->reads;
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
spin_lock_irqsave(&ms->lock, flags);
should_wake = !(bl->head);
bio_list_add(bl, bio);
dm raid1: handle write failures This patch gives mirror the ability to handle device failures during normal write operations. The 'write_callback' function is called when a write completes. If all the writes failed or succeeded, we report failure or success respectively. If some of the writes failed, we call fail_mirror; which increments the error count for the device, notes the type of error encountered (DM_RAID1_WRITE_ERROR), and selects a new primary (if necessary). Note that the primary device can never change while the mirror is not in-sync (IOW, while recovery is happening.) This means that the scenario where a failed write changes the primary and gives recovery_complete a chance to misread the primary never happens. The fact that the primary can change has necessitated the change to the default_mirror field. We need to protect against reading garbage while the primary changes. We then add the bio to a new list in the mirror set, 'failures'. For every bio in the 'failures' list, we call a new function, '__bio_mark_nosync', where we mark the region 'not-in-sync' in the log and properly set the region state as, RH_NOSYNC. Userspace must also be notified of the failure. This is done by 'raising an event' (dm_table_event()). If fail_mirror is called in process context the event can be raised right away. If in interrupt context, the event is deferred to the kmirrord thread - which raises the event if 'event_waiting' is set. Backwards compatibility is maintained by ignoring errors if the DM_FEATURES_HANDLE_ERRORS flag is not present. Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:29 +08:00
spin_unlock_irqrestore(&ms->lock, flags);
if (should_wake)
wake(ms);
}
/*
* 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;
if (rw == WRITE) {
/* Save region for mirror_end_io() handler */
map_context->ll = bio_to_region(&ms->rh, bio);
queue_bio(ms, bio, rw);
return DM_MAPIO_SUBMITTED;
}
r = ms->rh.log->type->in_sync(ms->rh.log,
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) {
rh_dec(&ms->rh, map_context->ll);
return error;
}
if (error == -EOPNOTSUPP)
goto out;
if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio))
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;
}
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
static void mirror_presuspend(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dirty_log *log = ms->rh.log;
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
atomic_set(&ms->suspend, 1);
/*
* We must finish up all the work that we've
* generated (i.e. recovery work).
*/
rh_stop_recovery(&ms->rh);
wait_event(_kmirrord_recovery_stopped,
!atomic_read(&ms->rh.recovery_in_flight));
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
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 dirty_log *log = ms->rh.log;
if (log->type->postsuspend && log->type->postsuspend(log))
/* FIXME: need better error handling */
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
DMWARN("log postsuspend failed");
}
static void mirror_resume(struct dm_target *ti)
{
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
struct mirror_set *ms = ti->private;
struct dirty_log *log = ms->rh.log;
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
atomic_set(&ms->suspend, 0);
if (log->type->resume && log->type->resume(log))
/* FIXME: need better error handling */
DMWARN("log resume failed");
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_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 dirty_log *log = ms->rh.log;
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(ms->rh.log),
(unsigned long long)ms->nr_regions, buffer);
sz += log->type->status(ms->rh.log, type, result+sz, maxlen-sz);
break;
case STATUSTYPE_TABLE:
sz = log->type->status(ms->rh.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,
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
(unsigned long long)ms->mirror[m].offset);
if (ms->features & DM_RAID1_HANDLE_ERRORS)
DMEMIT(" 1 handle_errors");
}
return 0;
}
static struct target_type mirror_target = {
.name = "mirror",
.version = {1, 0, 20},
.module = THIS_MODULE,
.ctr = mirror_ctr,
.dtr = mirror_dtr,
.map = mirror_map,
.end_io = mirror_end_io,
dm raid1: fix EIO after log failure This patch adds the ability to requeue write I/O to core device-mapper when there is a log device failure. If a write to the log produces and error, the pending writes are put on the "failures" list. Since the log is marked as failed, they will stay on the failures list until a suspend happens. Suspends come in two phases, presuspend and postsuspend. We must make sure that all the writes on the failures list are requeued in the presuspend phase (a requirement of dm core). This means that recovery must be complete (because writes may be delayed behind it) and the failures list must be requeued before we return from presuspend. The mechanisms to ensure recovery is complete (or stopped) was already in place, but needed to be moved from postsuspend to presuspend. We rely on 'flush_workqueue' to ensure that the mirror thread is complete and therefore, has requeued all writes in the failures list. Because we are using flush_workqueue, we must ensure that no additional 'queue_work' calls will produce additional I/O that we need to requeue (because once we return from presuspend, we are unable to do anything about it). 'queue_work' is called in response to the following functions: - complete_resync_work = NA, recovery is stopped - rh_dec (mirror_end_io) = NA, only calls 'queue_work' if it is ready to recover the region (recovery is stopped) or it needs to clear the region in the log* **this doesn't get called while suspending** - rh_recovery_end = NA, recovery is stopped - rh_recovery_start = NA, recovery is stopped - write_callback = 1) Writes w/o failures simply call bio_endio -> mirror_end_io -> rh_dec (see rh_dec above) 2) Writes with failures are put on the failures list and queue_work is called** ** write_callbacks don't happen during suspend ** - do_failures = NA, 'queue_work' not called if suspending - add_mirror (initialization) = NA, only done on mirror creation - queue_bio = NA, 1) delayed I/O scheduled before flush_workqueue is called. 2) No more I/Os are being issued. 3) Re-attempted READs can still be handled. (Write completions are handled through rh_dec/ write_callback - mention above - and do not use queue_bio.) Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
2008-02-08 10:11:35 +08:00
.presuspend = mirror_presuspend,
.postsuspend = mirror_postsuspend,
.resume = mirror_resume,
.status = mirror_status,
};
static int __init dm_mirror_init(void)
{
int r;
r = dm_dirty_log_init();
if (r)
return r;
r = dm_register_target(&mirror_target);
if (r < 0) {
DMERR("Failed to register mirror target");
dm_dirty_log_exit();
}
return r;
}
static void __exit dm_mirror_exit(void)
{
int r;
r = dm_unregister_target(&mirror_target);
if (r < 0)
DMERR("unregister failed %d", r);
dm_dirty_log_exit();
}
/* 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");