Btrfs: split the global ordered extents mutex

When we create a snapshot, we just need wait the ordered extents in
the source fs/file root, but because we use the global mutex to protect
this ordered extents list of the source fs/file root to avoid accessing
a empty list, if someone got the mutex to access the ordered extents list
of the other fs/file root, we had to wait.

This patch splits the above global mutex, now every fs/file root has
its own mutex to protect its own list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5a800986f416..5f4921554f0a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1814,6 +1814,8 @@ struct btrfs_root {
         struct list_head delalloc_inodes;
         struct list_head delalloc_root;
         u64 nr_delalloc_inodes;
+
+        struct mutex ordered_extent_mutex;
         /*
          * this is used by the balancing code to wait for all the pending
          * ordered extents