[PATCH] device-mapper raid1: drop mark_region spinlock fix

The spinlock region_lock is held while calling mark_region which can sleep.
Drop the spinlock before calling that function.

A region's state and inclusion in the clean list are altered by rh_inc and
rh_dec.  The state variable is set to RH_CLEAN in rh_dec, but only if
'pending' is zero.  It is set to RH_DIRTY in rh_inc, but not if it is already
so.  The changes to 'pending', the state, and the region's inclusion in the
clean list need to be atomicly.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 11 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 2375709a392c..6b0fc1670929 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -376,16 +376,18 @@ static void rh_inc(struct region_hash *rh, region_t region)
         read_lock(&rh->hash_lock);
         reg = __rh_find(rh, region);
 
+        spin_lock_irq(&rh->region_lock);
         atomic_inc(&reg->pending);
 
-        spin_lock_irq(&rh->region_lock);
         if (reg->state == RH_CLEAN) {
-                rh->log->type->mark_region(rh->log, reg->key);
-
                 reg->state = RH_DIRTY;
                 list_del_init(&reg->list);      /* take off the clean list */
-        }
-        spin_unlock_irq(&rh->region_lock);
+                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);
 }
@@ -408,21 +410,17 @@ static void rh_dec(struct region_hash *rh, region_t region)
         reg = __rh_lookup(rh, region);
         read_unlock(&rh->hash_lock);
 
+        spin_lock_irqsave(&rh->region_lock, flags);
         if (atomic_dec_and_test(&reg->pending)) {
-                spin_lock_irqsave(&rh->region_lock, flags);
-                if (atomic_read(&reg->pending)) { /* check race */
-                        spin_unlock_irqrestore(&rh->region_lock, flags);
-                        return;
-                }
                 if (reg->state == RH_RECOVERING) {
                         list_add_tail(&reg->list, &rh->quiesced_regions);
                 } else {
                         reg->state = RH_CLEAN;
                         list_add(&reg->list, &rh->clean_regions);
                 }
-                spin_unlock_irqrestore(&rh->region_lock, flags);
                 should_wake = 1;
         }
+        spin_unlock_irqrestore(&rh->region_lock, flags);
 
         if (should_wake)
                 wake();