Btrfs: update nodatacow code v2

This patch simplifies the nodatacow checker. If all references
were created after the latest snapshot, then we can avoid COW
safely. This patch also updates run_delalloc_nocow to do more
fine-grained checking.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index ca5547af6090..8bf6a085a730 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -454,6 +454,7 @@ struct btrfs_root_item {
         __le64 bytenr;
         __le64 byte_limit;
         __le64 bytes_used;
+        __le64 last_snapshot;
         __le32 flags;
         __le32 refs;
         struct btrfs_disk_key drop_progress;
@@ -1413,6 +1414,8 @@ BTRFS_SETGET_STACK_FUNCS(root_refs, struct btrfs_root_item, refs, 32);
 BTRFS_SETGET_STACK_FUNCS(root_flags, struct btrfs_root_item, flags, 32);
 BTRFS_SETGET_STACK_FUNCS(root_used, struct btrfs_root_item, bytes_used, 64);
 BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
+BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
+                         last_snapshot, 64);
 
 /* struct btrfs_super_block */
 BTRFS_SETGET_STACK_FUNCS(super_bytenr, struct btrfs_super_block, bytenr, 64);
@@ -1564,9 +1567,8 @@ int btrfs_update_pinned_extents(struct btrfs_root *root,
                                 u64 bytenr, u64 num, int pin);
 int btrfs_drop_leaf_ref(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root, struct extent_buffer *leaf);
-int btrfs_cross_ref_exists(struct btrfs_trans_handle *trans,
-                           struct btrfs_root *root,
-                           struct btrfs_key *key, u64 bytenr);
+int btrfs_cross_ref_exist(struct btrfs_trans_handle *trans,
+                          struct btrfs_root *root, u64 bytenr);
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
                          struct btrfs_root *root);
 int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);