btrfs: remove the snapshot check from check_committed_ref()

At check_committed_ref() we have this check to see if the data extent was
created in a generation lower than or equals to the generation where the
last snapshot for the root was created, and if so we return immediately
with 1, since it's very likely the extent is shared, referenced by other
root.

The only call chain for check_committed_ref() is the following:

   can_nocow_file_extent()
      btrfs_cross_ref_exist()
         check_committed_ref()

And we already do that snapshot check at can_nocow_file_extent(), before
we call btrfs_cross_ref_exist(). This makes the check done at
check_committed_ref() redundant, so remove it.

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 46a3a4a4536b6fa43fb6404ef324a08c5fb0566f..e81f4615ccdfe66d2831adace84c318f1528785e 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2358,14 +2358,6 @@ static noinline int check_committed_ref(struct btrfs_root *root,
        if (item_size != expected_size)
                goto out;
 
-       /*
-        * If extent created before last snapshot => it's shared unless the
-        * snapshot has been deleted.
-        */
-       if (btrfs_extent_generation(leaf, ei) <=
-           btrfs_root_last_snapshot(&root->root_item))
-               goto out;
-
        /* If this extent has SHARED_DATA_REF then it's shared */
        type = btrfs_get_extent_inline_ref_type(leaf, iref, BTRFS_REF_TYPE_DATA);
        if (type != BTRFS_EXTENT_DATA_REF_KEY)