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dm raid1: one kmirrord per mirror

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This patch replaces the single instance of kmirrord by one instance per mirror
set.  This change is required to avoid a deadlock in kmirrord when the
persistent dirty log of a mirror itself resides on a mirror.  The single
instance of kmirrord then issues a sync write to the dirty log in write_bits
which gets deferred to kmirrord itself later in the call chain.  But kmirrord
never does the deferred work because it is still waiting for the sync
write_bits.

_mirror_sets is removed as it no longer needed, and we always flush the
workqueue before destroying it to ensure all work is complete before
destroying it.

Signed-off-by: Holger Smolinski <smolinski@de.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Holger Smolinski 2007-05-09 02:32:50 -07:00 committed by Linus Torvalds
parent 8defab3377
commit 6ad36fe2b4
1 changed files with 27 additions and 54 deletions
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81
drivers/md/dm-raid1.c
View file

@ -22,15 +22,8 @@
#define DM_MSG_PREFIX "raid1"
static struct workqueue_struct *_kmirrord_wq;
static struct work_struct _kmirrord_work;
static DECLARE_WAIT_QUEUE_HEAD(_kmirrord_recovery_stopped);
static inline void wake(void)
{
queue_work(_kmirrord_wq, &_kmirrord_work);
}
/*-----------------------------------------------------------------
* Region hash
*
@ -136,6 +129,9 @@ struct mirror_set {
struct mirror *default_mirror; /* Default mirror */
struct workqueue_struct *kmirrord_wq;
struct work_struct kmirrord_work;
unsigned int nr_mirrors;
struct mirror mirror[0];
};
@ -153,6 +149,11 @@ 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);
@ -471,7 +472,7 @@ static void rh_dec(struct region_hash *rh, region_t region)
spin_unlock_irqrestore(&rh->region_lock, flags);
if (should_wake)
wake();
wake(rh->ms);
}
/*
@ -558,7 +559,7 @@ static void rh_recovery_end(struct region *reg, int success)
list_add(&reg->list, &reg->rh->recovered_regions);
spin_unlock_irq(&rh->region_lock);
wake();
wake(rh->ms);
}
static void rh_flush(struct region_hash *rh)
@ -592,7 +593,7 @@ static void rh_start_recovery(struct region_hash *rh)
for (i = 0; i < MAX_RECOVERY; i++)
up(&rh->recovery_count);
wake();
wake(rh->ms);
}
/*
@ -870,11 +871,10 @@ static void do_writes(struct mirror_set *ms, struct bio_list *writes)
/*-----------------------------------------------------------------
* kmirrord
*---------------------------------------------------------------*/
static LIST_HEAD(_mirror_sets);
static DECLARE_RWSEM(_mirror_sets_lock);
static void do_mirror(struct mirror_set *ms)
static void do_mirror(struct work_struct *work)
{
struct mirror_set *ms =container_of(work, struct mirror_set,
kmirrord_work);
struct bio_list reads, writes;
spin_lock(&ms->lock);
@ -890,16 +890,6 @@ static void do_mirror(struct mirror_set *ms)
do_writes(ms, &writes);
}
static void do_work(struct work_struct *ignored)
{
struct mirror_set *ms;
down_read(&_mirror_sets_lock);
list_for_each_entry (ms, &_mirror_sets, list)
do_mirror(ms);
up_read(&_mirror_sets_lock);
}
/*-----------------------------------------------------------------
* Target functions
*---------------------------------------------------------------*/
@ -978,23 +968,6 @@ static int get_mirror(struct mirror_set *ms, struct dm_target *ti,
return 0;
}
static int add_mirror_set(struct mirror_set *ms)
{
down_write(&_mirror_sets_lock);
list_add_tail(&ms->list, &_mirror_sets);
up_write(&_mirror_sets_lock);
wake();
return 0;
}
static void del_mirror_set(struct mirror_set *ms)
{
down_write(&_mirror_sets_lock);
list_del(&ms->list);
up_write(&_mirror_sets_lock);
}
/*
* Create dirty log: log_type #log_params <log_params>
*/
@ -1096,13 +1069,22 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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");
free_context(ms, ti, m);
return -ENOMEM;
}
INIT_WORK(&ms->kmirrord_work, do_mirror);
r = kcopyd_client_create(DM_IO_PAGES, &ms->kcopyd_client);
if (r) {
destroy_workqueue(ms->kmirrord_wq);
free_context(ms, ti, ms->nr_mirrors);
return r;
}
add_mirror_set(ms);
wake(ms);
return 0;
}
@ -1110,8 +1092,9 @@ static void mirror_dtr(struct dm_target *ti)
{
struct mirror_set *ms = (struct mirror_set *) ti->private;
del_mirror_set(ms);
flush_workqueue(ms->kmirrord_wq);
kcopyd_client_destroy(ms->kcopyd_client);
destroy_workqueue(ms->kmirrord_wq);
free_context(ms, ti, ms->nr_mirrors);
}
@ -1127,7 +1110,7 @@ static void queue_bio(struct mirror_set *ms, struct bio *bio, int rw)
spin_unlock(&ms->lock);
if (should_wake)
wake();
wake(ms);
}
/*
@ -1270,20 +1253,11 @@ static int __init dm_mirror_init(void)
if (r)
return r;
_kmirrord_wq = create_singlethread_workqueue("kmirrord");
if (!_kmirrord_wq) {
DMERR("couldn't start kmirrord");
dm_dirty_log_exit();
return r;
}
INIT_WORK(&_kmirrord_work, do_work);
r = dm_register_target(&mirror_target);
if (r < 0) {
DMERR("%s: Failed to register mirror target",
mirror_target.name);
dm_dirty_log_exit();
destroy_workqueue(_kmirrord_wq);
}
return r;
@ -1297,7 +1271,6 @@ static void __exit dm_mirror_exit(void)
if (r < 0)
DMERR("%s: unregister failed %d", mirror_target.name, r);
destroy_workqueue(_kmirrord_wq);
dm_dirty_log_exit();
}