btrfs: Remove V0 extent support

The v0 compat code was introduced in commit 5d4f98a28c7d
("Btrfs: Mixed back reference  (FORWARD ROLLING FORMAT CHANGE)") 9
years ago, which was merged in 2.6.31. This means that the code is
there to support filesystems which are _VERY_ old and if you are using
btrfs on such an old kernel, you have much bigger problems. This coupled
with the fact that no one is likely testing/maintining this code likely
means it has bugs lurking. All things considered I think 43 kernel
releases later it's high time this remnant of the past got removed.

This patch removes all code wrapped in #ifdefs but leaves the BUG_ONs in case
we have a v0 with no support intact as a sort of safety-net.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 1 insertions, 29 deletions

diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index 59efcf2e0de8..c0dac9d7ce33 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -52,18 +52,8 @@ static void print_extent_item(struct extent_buffer *eb, int slot, int type)
 	u64 offset;
 	int ref_index = 0;
 
-	if (item_size < sizeof(*ei)) {
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		struct btrfs_extent_item_v0 *ei0;
-		BUG_ON(item_size != sizeof(*ei0));
-		ei0 = btrfs_item_ptr(eb, slot, struct btrfs_extent_item_v0);
-		pr_info("\t\textent refs %u\n",
-		       btrfs_extent_refs_v0(eb, ei0));
-		return;
-#else
+	if (item_size < sizeof(*ei))
 		BUG();
-#endif
-	}
 
 	ei = btrfs_item_ptr(eb, slot, struct btrfs_extent_item);
 	flags = btrfs_extent_flags(eb, ei);
@@ -133,20 +123,6 @@ static void print_extent_item(struct extent_buffer *eb, int slot, int type)
 	WARN_ON(ptr > end);
 }
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-static void print_extent_ref_v0(struct extent_buffer *eb, int slot)
-{
-	struct btrfs_extent_ref_v0 *ref0;
-
-	ref0 = btrfs_item_ptr(eb, slot, struct btrfs_extent_ref_v0);
-	printk("\t\textent back ref root %llu gen %llu owner %llu num_refs %lu\n",
-		btrfs_ref_root_v0(eb, ref0),
-		btrfs_ref_generation_v0(eb, ref0),
-		btrfs_ref_objectid_v0(eb, ref0),
-		(unsigned long)btrfs_ref_count_v0(eb, ref0));
-}
-#endif
-
 static void print_uuid_item(struct extent_buffer *l, unsigned long offset,
 			    u32 item_size)
 {
@@ -280,11 +256,7 @@ void btrfs_print_leaf(struct extent_buffer *l)
 			       btrfs_file_extent_ram_bytes(l, fi));
 			break;
 		case BTRFS_EXTENT_REF_V0_KEY:
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-			print_extent_ref_v0(l, i);
-#else
 			BUG();
-#endif
 			break;
 		case BTRFS_BLOCK_GROUP_ITEM_KEY:
 			bi = btrfs_item_ptr(l, i,