dm raid1: one kmirrord per mirror
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>
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 23a6426..c8b4c10 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -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 *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 @@
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 @@
spin_unlock_irqrestore(&rh->region_lock, flags);
if (should_wake)
- wake();
+ wake(rh->ms);
}
/*
@@ -558,7 +559,7 @@
list_add(®->list, ®->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 @@
for (i = 0; i < MAX_RECOVERY; i++)
up(&rh->recovery_count);
- wake();
+ wake(rh->ms);
}
/*
@@ -870,11 +871,10 @@
/*-----------------------------------------------------------------
* 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 @@
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 @@
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 @@
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 @@
{
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 @@
spin_unlock(&ms->lock);
if (should_wake)
- wake();
+ wake(ms);
}
/*
@@ -1270,20 +1253,11 @@
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 @@
if (r < 0)
DMERR("%s: unregister failed %d", mirror_target.name, r);
- destroy_workqueue(_kmirrord_wq);
dm_dirty_log_exit();
}