btrfs: new inline ref storing owning subvol of data extents

In order to implement simple quota groups, we need to be able to
associate a data extent with the subvolume that created it. Once you
account for reflink, this information cannot be recovered without
explicitly storing it. Options for storing it are:

- a new key/item
- a new extent inline ref item

The former is backwards compatible, but wastes space, the latter is
incompat, but is efficient in space and reuses the existing inline ref
machinery, while only abusing it a tiny amount -- specifically, the new
item is not a ref, per-se.

Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index 75042a7fcf30..7e46aa8a0444 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -83,12 +83,20 @@ static void print_extent_data_ref(const struct extent_buffer *eb,
 	       btrfs_extent_data_ref_count(eb, ref));
 }
 
+static void print_extent_owner_ref(const struct extent_buffer *eb,
+				   const struct btrfs_extent_owner_ref *ref)
+{
+	ASSERT(btrfs_fs_incompat(eb->fs_info, SIMPLE_QUOTA));
+	pr_cont("extent data owner root %llu\n", btrfs_extent_owner_ref_root_id(eb, ref));
+}
+
 static void print_extent_item(const struct extent_buffer *eb, int slot, int type)
 {
 	struct btrfs_extent_item *ei;
 	struct btrfs_extent_inline_ref *iref;
 	struct btrfs_extent_data_ref *dref;
 	struct btrfs_shared_data_ref *sref;
+	struct btrfs_extent_owner_ref *oref;
 	struct btrfs_disk_key key;
 	unsigned long end;
 	unsigned long ptr;
@@ -164,6 +172,10 @@ static void print_extent_item(const struct extent_buffer *eb, int slot, int type
 			"\t\t\t(parent %llu not aligned to sectorsize %u)\n",
 				     offset, eb->fs_info->sectorsize);
 			break;
+		case BTRFS_EXTENT_OWNER_REF_KEY:
+			oref = (struct btrfs_extent_owner_ref *)(&iref->offset);
+			print_extent_owner_ref(eb, oref);
+			break;
 		default:
 			pr_cont("(extent %llu has INVALID ref type %d)\n",
 				  eb->start, type);