Add a per-inode lock around btrfs_drop_extents

btrfs_drop_extents is always called with a range lock held on the inode.
But, it may operate on extents outside that range as it drops and splits
them.

This patch adds a per-inode mutex that is held while calling
btrfs_drop_extents and while inserting new extents into the tree.  It
prevents races from two procs working against adjacent ranges in the tree.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 343d1101c31c..4036c62b6671 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1671,6 +1671,8 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
         ret = __free_extent(trans, root, bytenr, num_bytes, root_objectid,
                             ref_generation, owner_objectid, owner_offset,
                             pin, pin == 0);
+
+        finish_current_insert(trans, root->fs_info->extent_root);
         pending_ret = del_pending_extents(trans, root->fs_info->extent_root);
         return ret ? ret : pending_ret;
 }