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, 1 insertions, 0 deletions

diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 81c0444f37b6..3bf40591742a 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -32,6 +32,7 @@ struct btrfs_inode {
         struct extent_io_tree io_tree;
         struct extent_io_tree io_failure_tree;
         struct mutex csum_mutex;
+        struct mutex extent_mutex;
         struct inode vfs_inode;
         struct btrfs_ordered_inode_tree ordered_tree;