diff --git a/blockstore_impl.h b/blockstore_impl.h
index e33ad00f..ee2cc2f8 100644
--- a/blockstore_impl.h
+++ b/blockstore_impl.h
@@ -194,6 +194,8 @@ class blockstore_impl_t
     // Sparse write tracking granularity. 4 KB is a good choice. Must be a multiple of disk_alignment
     uint64_t bitmap_granularity = 4096;
     bool readonly = false;
+    // By default, Blockstore locks all opened devices exclusively. This option can be used to disable locking
+    bool disable_flock = false;
     // It is safe to disable fsync() if drive write cache is writethrough
     bool disable_data_fsync = false, disable_meta_fsync = false, disable_journal_fsync = false;
     // Enable if you want every operation to be executed with an "implicit fsync"
diff --git a/blockstore_open.cpp b/blockstore_open.cpp
index f109f93a..19befbfa 100644
--- a/blockstore_open.cpp
+++ b/blockstore_open.cpp
@@ -1,3 +1,4 @@
+#include <sys/file.h>
 #include "blockstore_impl.h"
 
 static uint32_t is_power_of_two(uint64_t value)
@@ -34,6 +35,10 @@ void blockstore_impl_t::parse_config(blockstore_config_t & config)
     {
         disable_journal_fsync = true;
     }
+    if (config["disable_device_lock"] == "true" || config["disable_device_lock"] == "1" || config["disable_device_lock"] == "yes")
+    {
+        disable_flock = true;
+    }
     if (config["immediate_commit"] == "all")
     {
         immediate_commit = IMMEDIATE_ALL;
@@ -286,6 +291,10 @@ void blockstore_impl_t::open_data()
     {
         throw std::runtime_error("data_offset exceeds device size = "+std::to_string(data_size));
     }
+    if (!disable_flock && flock(data_fd, LOCK_EX) != 0)
+    {
+        throw std::runtime_error(std::string("Failed to lock data device: ") + strerror(errno));
+    }
 }
 
 void blockstore_impl_t::open_meta()
@@ -303,6 +312,10 @@ void blockstore_impl_t::open_meta()
         {
             throw std::runtime_error("meta_offset exceeds device size = "+std::to_string(meta_size));
         }
+        if (!disable_flock && flock(meta_fd, LOCK_EX) != 0)
+        {
+            throw std::runtime_error(std::string("Failed to lock metadata device: ") + strerror(errno));
+        }
     }
     else
     {
@@ -324,7 +337,11 @@ void blockstore_impl_t::open_journal()
         {
             throw std::runtime_error("Failed to open journal device");
         }
-        check_size(journal.fd, &journal.device_size, "metadata device");
+        check_size(journal.fd, &journal.device_size, "journal device");
+        if (!disable_flock && flock(journal.fd, LOCK_EX) != 0)
+        {
+            throw std::runtime_error(std::string("Failed to lock journal device: ") + strerror(errno));
+        }
     }
     else
     {
diff --git a/osd_peering_pg.cpp b/osd_peering_pg.cpp
index f208efa6..6cfa0a0d 100644
--- a/osd_peering_pg.cpp
+++ b/osd_peering_pg.cpp
@@ -357,6 +357,7 @@ void pg_t::calc_object_states()
 
 void pg_t::print_state()
 {
+    // FIXME Immediately report state on each change
     printf(
         "[PG %u] is %s%s%s%s%s%s%s%s%s (%lu objects)\n", pg_num,
         (state & PG_OFFLINE) ? "offline" : "",