Merge branch 'for-2.6.28' of git://linux-nfs.org/~bfields/linux

[linux-2.6-omap-h63xx.git] / drivers / md / dm-snap.c

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index b2d9d1ac28adb4554537fd3568ae4fe52e748a41..6c96db26b87c2ac4c3dd4ba6d29f99d60c24ac17 100644 (file)
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -229,19 +229,21 @@ static void __insert_origin(struct origin *o)
  */
 static int register_snapshot(struct dm_snapshot *snap)
 {
-       struct origin *o;
+       struct origin *o, *new_o;
        struct block_device *bdev = snap->origin->bdev;
 
+       new_o = kmalloc(sizeof(*new_o), GFP_KERNEL);
+       if (!new_o)
+               return -ENOMEM;
+
        down_write(&_origins_lock);
        o = __lookup_origin(bdev);
 
-       if (!o) {
+       if (o)
+               kfree(new_o);
+       else {
                /* New origin */
-               o = kmalloc(sizeof(*o), GFP_KERNEL);
-               if (!o) {
-                       up_write(&_origins_lock);
-                       return -ENOMEM;
-               }
+               o = new_o;
 
                /* Initialise the struct */
                INIT_LIST_HEAD(&o->snapshots);
@@ -368,6 +370,7 @@ static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snaps
        struct dm_snap_pending_exception *pe = mempool_alloc(s->pending_pool,
                                                             GFP_NOIO);
 
+       atomic_inc(&s->pending_exceptions_count);
        pe->snap = s;
 
        return pe;
@@ -375,7 +378,11 @@ static struct dm_snap_pending_exception *alloc_pending_exception(struct dm_snaps
 
 static void free_pending_exception(struct dm_snap_pending_exception *pe)
 {
-       mempool_free(pe, pe->snap->pending_pool);
+       struct dm_snapshot *s = pe->snap;
+
+       mempool_free(pe, s->pending_pool);
+       smp_mb__before_atomic_dec();
+       atomic_dec(&s->pending_exceptions_count);
 }
 
 static void insert_completed_exception(struct dm_snapshot *s,
@@ -600,6 +607,7 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 
        s->valid = 1;
        s->active = 0;
+       atomic_set(&s->pending_exceptions_count, 0);
        init_rwsem(&s->lock);
        spin_lock_init(&s->pe_lock);
        s->ti = ti;
@@ -726,6 +734,14 @@ static void snapshot_dtr(struct dm_target *ti)
        /* After this returns there can be no new kcopyd jobs. */
        unregister_snapshot(s);
 
+       while (atomic_read(&s->pending_exceptions_count))
+               yield();
+       /*
+        * Ensure instructions in mempool_destroy aren't reordered
+        * before atomic_read.
+        */
+       smp_mb();
+
 #ifdef CONFIG_DM_DEBUG
        for (i = 0; i < DM_TRACKED_CHUNK_HASH_SIZE; i++)
                BUG_ON(!hlist_empty(&s->tracked_chunk_hash[i]));