diff options
| -rw-r--r-- | drivers/md/dm-snap.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c index de302702ab3..f4fd0cee9c3 100644 --- a/drivers/md/dm-snap.c +++ b/drivers/md/dm-snap.c @@ -134,6 +134,27 @@ static void stop_tracking_chunk(struct dm_snapshot *s, mempool_free(c, s->tracked_chunk_pool); } +static int __chunk_is_tracked(struct dm_snapshot *s, chunk_t chunk) +{ + struct dm_snap_tracked_chunk *c; + struct hlist_node *hn; + int found = 0; + + spin_lock_irq(&s->tracked_chunk_lock); + + hlist_for_each_entry(c, hn, + &s->tracked_chunk_hash[DM_TRACKED_CHUNK_HASH(chunk)], node) { + if (c->chunk == chunk) { + found = 1; + break; + } + } + + spin_unlock_irq(&s->tracked_chunk_lock); + + return found; +} + /* * One of these per registered origin, held in the snapshot_origins hash */ @@ -840,6 +861,13 @@ static void pending_complete(struct dm_snap_pending_exception *pe, int success) } /* + * Check for conflicting reads. This is extremely improbable, + * so yield() is sufficient and there is no need for a wait queue. + */ + while (__chunk_is_tracked(s, pe->e.old_chunk)) + yield(); + + /* * Add a proper exception, and remove the * in-flight exception from the list. */ |