[RFC] btrfs: Remove V0 extent support

Commit Message

Nikolay Borisov June 21, 2018, 6:45 a.m. UTC

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 <[e-mail]>
---
 fs/btrfs/ctree.c       |   6 +-
 fs/btrfs/ctree.h       |   2 -
 fs/btrfs/extent-tree.c | 209 +------------------------------------------------
 fs/btrfs/print-tree.c  |  30 +------
 fs/btrfs/relocation.c  | 151 +----------------------------------
 5 files changed, 4 insertions(+), 394 deletions(-)

Comments

David Sterba June 21, 2018, 9:22 a.m. UTC | #1

On Thu, Jun 21, 2018 at 09:45:00AM +0300, Nikolay Borisov wrote:
> 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.

Ack. Given the age of the format and nearly zero chance of such
filesystem to be still in use it should be ok to remove it directly and
not add some sort of warning when such filesystem is found.

> 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. 

I think there should be some verbose way to report what happened and
possibly do proper error handling and go to read-only eventually.
The type of checks for v0 do not seem to be something that could be done
at mount time.
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Chris Mason June 21, 2018, 5:50 p.m. UTC | #2

On 21 Jun 2018, at 5:22, David Sterba wrote:

> On Thu, Jun 21, 2018 at 09:45:00AM +0300, Nikolay Borisov wrote:
>> 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.
>
> Ack. Given the age of the format and nearly zero chance of such
> filesystem to be still in use it should be ok to remove it directly 
> and
> not add some sort of warning when such filesystem is found.

Agreed, it seems very unlikely to me that we have happy v0 users.

>
>> 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.
>
> I think there should be some verbose way to report what happened and
> possibly do proper error handling and go to read-only eventually.
> The type of checks for v0 do not seem to be something that could be 
> done
> at mount time.

Yeah, with the code we have right now, it's really obvious the BUG()s 
are for V0 extents.  With all the ifdefs removed its much less clear.  
I'd swap them out for a transaction abort with a message about the v0 
extents.

Also, there's at least one ASSERT() left over in a #else, which I would 
also turn into a more explicit abort or at least comment.

-chris
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Patch

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 6879697520d5..d1273ec2e0d5 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -888,11 +888,7 @@  int btrfs_block_can_be_shared(struct btrfs_root *root,
 	     btrfs_root_last_snapshot(&root->root_item) ||
 	     btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
 		return 1;
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
-	    btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
-		return 1;
-#endif
+
 	return 0;
 }
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e671a1fcbbec..bc52bf7ac572 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -55,8 +55,6 @@  struct btrfs_ordered_sum;
 
 #define BTRFS_OLDEST_GENERATION	0ULL
 
-#define BTRFS_COMPAT_EXTENT_TREE_V0
-
 /*
  * the max metadata block size.  This limit is somewhat artificial,
  * but the memmove costs go through the roof for larger blocks.
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0f7e797236dc..4129831523a2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -870,17 +870,7 @@  int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
 			num_refs = btrfs_extent_refs(leaf, ei);
 			extent_flags = btrfs_extent_flags(leaf, ei);
 		} else {
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-			struct btrfs_extent_item_v0 *ei0;
-			BUG_ON(item_size != sizeof(*ei0));
-			ei0 = btrfs_item_ptr(leaf, path->slots[0],
-					     struct btrfs_extent_item_v0);
-			num_refs = btrfs_extent_refs_v0(leaf, ei0);
-			/* FIXME: this isn't correct for data */
-			extent_flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
-#else
 			BUG();
-#endif
 		}
 		BUG_ON(num_refs == 0);
 	} else {
@@ -1039,89 +1029,6 @@  int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
  * tree block info structure.
  */
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-static int convert_extent_item_v0(struct btrfs_trans_handle *trans,
-				  struct btrfs_fs_info *fs_info,
-				  struct btrfs_path *path,
-				  u64 owner, u32 extra_size)
-{
-	struct btrfs_root *root = fs_info->extent_root;
-	struct btrfs_extent_item *item;
-	struct btrfs_extent_item_v0 *ei0;
-	struct btrfs_extent_ref_v0 *ref0;
-	struct btrfs_tree_block_info *bi;
-	struct extent_buffer *leaf;
-	struct btrfs_key key;
-	struct btrfs_key found_key;
-	u32 new_size = sizeof(*item);
-	u64 refs;
-	int ret;
-
-	leaf = path->nodes[0];
-	BUG_ON(btrfs_item_size_nr(leaf, path->slots[0]) != sizeof(*ei0));
-
-	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
-	ei0 = btrfs_item_ptr(leaf, path->slots[0],
-			     struct btrfs_extent_item_v0);
-	refs = btrfs_extent_refs_v0(leaf, ei0);
-
-	if (owner == (u64)-1) {
-		while (1) {
-			if (path->slots[0] >= btrfs_header_nritems(leaf)) {
-				ret = btrfs_next_leaf(root, path);
-				if (ret < 0)
-					return ret;
-				BUG_ON(ret > 0); /* Corruption */
-				leaf = path->nodes[0];
-			}
-			btrfs_item_key_to_cpu(leaf, &found_key,
-					      path->slots[0]);
-			BUG_ON(key.objectid != found_key.objectid);
-			if (found_key.type != BTRFS_EXTENT_REF_V0_KEY) {
-				path->slots[0]++;
-				continue;
-			}
-			ref0 = btrfs_item_ptr(leaf, path->slots[0],
-					      struct btrfs_extent_ref_v0);
-			owner = btrfs_ref_objectid_v0(leaf, ref0);
-			break;
-		}
-	}
-	btrfs_release_path(path);
-
-	if (owner < BTRFS_FIRST_FREE_OBJECTID)
-		new_size += sizeof(*bi);
-
-	new_size -= sizeof(*ei0);
-	ret = btrfs_search_slot(trans, root, &key, path,
-				new_size + extra_size, 1);
-	if (ret < 0)
-		return ret;
-	BUG_ON(ret); /* Corruption */
-
-	btrfs_extend_item(fs_info, path, new_size);
-
-	leaf = path->nodes[0];
-	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
-	btrfs_set_extent_refs(leaf, item, refs);
-	/* FIXME: get real generation */
-	btrfs_set_extent_generation(leaf, item, 0);
-	if (owner < BTRFS_FIRST_FREE_OBJECTID) {
-		btrfs_set_extent_flags(leaf, item,
-				       BTRFS_EXTENT_FLAG_TREE_BLOCK |
-				       BTRFS_BLOCK_FLAG_FULL_BACKREF);
-		bi = (struct btrfs_tree_block_info *)(item + 1);
-		/* FIXME: get first key of the block */
-		memzero_extent_buffer(leaf, (unsigned long)bi, sizeof(*bi));
-		btrfs_set_tree_block_level(leaf, bi, (int)owner);
-	} else {
-		btrfs_set_extent_flags(leaf, item, BTRFS_EXTENT_FLAG_DATA);
-	}
-	btrfs_mark_buffer_dirty(leaf);
-	return 0;
-}
-#endif
-
 /*
  * is_data == BTRFS_REF_TYPE_BLOCK, tree block type is required,
  * is_data == BTRFS_REF_TYPE_DATA, data type is requried,
@@ -1251,17 +1158,6 @@  static noinline int lookup_extent_data_ref(struct btrfs_trans_handle *trans,
 	if (parent) {
 		if (!ret)
 			return 0;
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		key.type = BTRFS_EXTENT_REF_V0_KEY;
-		btrfs_release_path(path);
-		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-		if (ret < 0) {
-			err = ret;
-			goto fail;
-		}
-		if (!ret)
-			return 0;
-#endif
 		goto fail;
 	}
 
@@ -1406,13 +1302,6 @@  static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
 				      struct btrfs_shared_data_ref);
 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	} else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
-		struct btrfs_extent_ref_v0 *ref0;
-		ref0 = btrfs_item_ptr(leaf, path->slots[0],
-				      struct btrfs_extent_ref_v0);
-		num_refs = btrfs_ref_count_v0(leaf, ref0);
-#endif
 	} else {
 		BUG();
 	}
@@ -1428,14 +1317,6 @@  static noinline int remove_extent_data_ref(struct btrfs_trans_handle *trans,
 			btrfs_set_extent_data_ref_count(leaf, ref1, num_refs);
 		else if (key.type == BTRFS_SHARED_DATA_REF_KEY)
 			btrfs_set_shared_data_ref_count(leaf, ref2, num_refs);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		else {
-			struct btrfs_extent_ref_v0 *ref0;
-			ref0 = btrfs_item_ptr(leaf, path->slots[0],
-					struct btrfs_extent_ref_v0);
-			btrfs_set_ref_count_v0(leaf, ref0, num_refs);
-		}
-#endif
 		btrfs_mark_buffer_dirty(leaf);
 	}
 	return ret;
@@ -1475,13 +1356,6 @@  static noinline u32 extent_data_ref_count(struct btrfs_path *path,
 		ref2 = btrfs_item_ptr(leaf, path->slots[0],
 				      struct btrfs_shared_data_ref);
 		num_refs = btrfs_shared_data_ref_count(leaf, ref2);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	} else if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
-		struct btrfs_extent_ref_v0 *ref0;
-		ref0 = btrfs_item_ptr(leaf, path->slots[0],
-				      struct btrfs_extent_ref_v0);
-		num_refs = btrfs_ref_count_v0(leaf, ref0);
-#endif
 	} else {
 		WARN_ON(1);
 	}
@@ -1510,15 +1384,6 @@  static noinline int lookup_tree_block_ref(struct btrfs_trans_handle *trans,
 	ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
 	if (ret > 0)
 		ret = -ENOENT;
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (ret == -ENOENT && parent) {
-		btrfs_release_path(path);
-		key.type = BTRFS_EXTENT_REF_V0_KEY;
-		ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
-		if (ret > 0)
-			ret = -ENOENT;
-	}
-#endif
 	return ret;
 }
 
@@ -1684,22 +1549,6 @@  int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 
 	leaf = path->nodes[0];
 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (item_size < sizeof(*ei)) {
-		if (!insert) {
-			err = -ENOENT;
-			goto out;
-		}
-		ret = convert_extent_item_v0(trans, fs_info, path, owner,
-					     extra_size);
-		if (ret < 0) {
-			err = ret;
-			goto out;
-		}
-		leaf = path->nodes[0];
-		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-	}
-#endif
 	BUG_ON(item_size < sizeof(*ei));
 
 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
@@ -2433,17 +2282,6 @@  static int run_delayed_extent_op(struct btrfs_trans_handle *trans,
 
 	leaf = path->nodes[0];
 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (item_size < sizeof(*ei)) {
-		ret = convert_extent_item_v0(trans, fs_info, path, (u64)-1, 0);
-		if (ret < 0) {
-			err = ret;
-			goto out;
-		}
-		leaf = path->nodes[0];
-		item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-	}
-#endif
 	BUG_ON(item_size < sizeof(*ei));
 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
 	__run_delayed_extent_op(extent_op, leaf, ei);
@@ -3258,12 +3096,6 @@  static noinline int check_committed_ref(struct btrfs_root *root,
 
 	ret = 1;
 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (item_size < sizeof(*ei)) {
-		WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
-		goto out;
-	}
-#endif
 	ei = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_extent_item);
 
 	if (item_size != sizeof(*ei) +
@@ -6907,11 +6739,7 @@  static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 				break;
 			extent_slot--;
 		}
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		item_size = btrfs_item_size_nr(path->nodes[0], extent_slot);
-		if (found_extent && item_size < sizeof(*ei))
-			found_extent = 0;
-#endif
+
 		if (!found_extent) {
 			BUG_ON(iref);
 			ret = remove_extent_backref(trans, info, path, NULL,
@@ -6987,41 +6815,6 @@  static int __btrfs_free_extent(struct btrfs_trans_handle *trans,
 
 	leaf = path->nodes[0];
 	item_size = btrfs_item_size_nr(leaf, extent_slot);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (item_size < sizeof(*ei)) {
-		BUG_ON(found_extent || extent_slot != path->slots[0]);
-		ret = convert_extent_item_v0(trans, info, path, owner_objectid,
-					     0);
-		if (ret < 0) {
-			btrfs_abort_transaction(trans, ret);
-			goto out;
-		}
-
-		btrfs_release_path(path);
-		path->leave_spinning = 1;
-
-		key.objectid = bytenr;
-		key.type = BTRFS_EXTENT_ITEM_KEY;
-		key.offset = num_bytes;
-
-		ret = btrfs_search_slot(trans, extent_root, &key, path,
-					-1, 1);
-		if (ret) {
-			btrfs_err(info,
-				  "umm, got %d back from search, was looking for %llu",
-				ret, bytenr);
-			btrfs_print_leaf(path->nodes[0]);
-		}
-		if (ret < 0) {
-			btrfs_abort_transaction(trans, ret);
-			goto out;
-		}
-
-		extent_slot = path->slots[0];
-		leaf = path->nodes[0];
-		item_size = btrfs_item_size_nr(leaf, extent_slot);
-	}
-#endif
 	BUG_ON(item_size < sizeof(*ei));
 	ei = btrfs_item_ptr(leaf, extent_slot,
 			    struct btrfs_extent_item);
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index a4e11cf04671..b03040b84fe9 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,
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 879b76fa881a..52c1e3e6802d 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -586,29 +586,6 @@  static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 	return btrfs_get_fs_root(fs_info, &key, false);
 }
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-static noinline_for_stack
-struct btrfs_root *find_tree_root(struct reloc_control *rc,
-				  struct extent_buffer *leaf,
-				  struct btrfs_extent_ref_v0 *ref0)
-{
-	struct btrfs_root *root;
-	u64 root_objectid = btrfs_ref_root_v0(leaf, ref0);
-	u64 generation = btrfs_ref_generation_v0(leaf, ref0);
-
-	BUG_ON(root_objectid == BTRFS_TREE_RELOC_OBJECTID);
-
-	root = read_fs_root(rc->extent_root->fs_info, root_objectid);
-	BUG_ON(IS_ERR(root));
-
-	if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
-	    generation != btrfs_root_generation(&root->root_item))
-		return NULL;
-
-	return root;
-}
-#endif
-
 static noinline_for_stack
 int find_inline_backref(struct extent_buffer *leaf, int slot,
 			unsigned long *ptr, unsigned long *end)
@@ -621,12 +598,6 @@  int find_inline_backref(struct extent_buffer *leaf, int slot,
 	btrfs_item_key_to_cpu(leaf, &key, slot);
 
 	item_size = btrfs_item_size_nr(leaf, slot);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (item_size < sizeof(*ei)) {
-		WARN_ON(item_size != sizeof(struct btrfs_extent_item_v0));
-		return 1;
-	}
-#endif
 	ei = btrfs_item_ptr(leaf, slot, struct btrfs_extent_item);
 	WARN_ON(!(btrfs_extent_flags(leaf, ei) &
 		  BTRFS_EXTENT_FLAG_TREE_BLOCK));
@@ -811,29 +782,8 @@  struct backref_node *build_backref_tree(struct reloc_control *rc,
 			goto next;
 		}
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		if (key.type == BTRFS_SHARED_BLOCK_REF_KEY ||
-		    key.type == BTRFS_EXTENT_REF_V0_KEY) {
-			if (key.type == BTRFS_EXTENT_REF_V0_KEY) {
-				struct btrfs_extent_ref_v0 *ref0;
-				ref0 = btrfs_item_ptr(eb, path1->slots[0],
-						struct btrfs_extent_ref_v0);
-				if (key.objectid == key.offset) {
-					root = find_tree_root(rc, eb, ref0);
-					if (root && !should_ignore_root(root))
-						cur->root = root;
-					else
-						list_add(&cur->list, &useless);
-					break;
-				}
-				if (is_cowonly_root(btrfs_ref_root_v0(eb,
-								      ref0)))
-					cur->cowonly = 1;
-			}
-#else
 		ASSERT(key.type != BTRFS_EXTENT_REF_V0_KEY);
 		if (key.type == BTRFS_SHARED_BLOCK_REF_KEY) {
-#endif
 			if (key.objectid == key.offset) {
 				/*
 				 * only root blocks of reloc trees use
@@ -3333,48 +3283,6 @@  int relocate_data_extent(struct inode *inode, struct btrfs_key *extent_key,
 	return 0;
 }
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-static int get_ref_objectid_v0(struct reloc_control *rc,
-			       struct btrfs_path *path,
-			       struct btrfs_key *extent_key,
-			       u64 *ref_objectid, int *path_change)
-{
-	struct btrfs_key key;
-	struct extent_buffer *leaf;
-	struct btrfs_extent_ref_v0 *ref0;
-	int ret;
-	int slot;
-
-	leaf = path->nodes[0];
-	slot = path->slots[0];
-	while (1) {
-		if (slot >= btrfs_header_nritems(leaf)) {
-			ret = btrfs_next_leaf(rc->extent_root, path);
-			if (ret < 0)
-				return ret;
-			BUG_ON(ret > 0);
-			leaf = path->nodes[0];
-			slot = path->slots[0];
-			if (path_change)
-				*path_change = 1;
-		}
-		btrfs_item_key_to_cpu(leaf, &key, slot);
-		if (key.objectid != extent_key->objectid)
-			return -ENOENT;
-
-		if (key.type != BTRFS_EXTENT_REF_V0_KEY) {
-			slot++;
-			continue;
-		}
-		ref0 = btrfs_item_ptr(leaf, slot,
-				struct btrfs_extent_ref_v0);
-		*ref_objectid = btrfs_ref_objectid_v0(leaf, ref0);
-		break;
-	}
-	return 0;
-}
-#endif
-
 /*
  * helper to add a tree block to the list.
  * the major work is getting the generation and level of the block
@@ -3408,22 +3316,7 @@  static int add_tree_block(struct reloc_control *rc,
 		}
 		generation = btrfs_extent_generation(eb, ei);
 	} else {
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		u64 ref_owner;
-		int ret;
-
-		BUG_ON(item_size != sizeof(struct btrfs_extent_item_v0));
-		ret = get_ref_objectid_v0(rc, path, extent_key,
-					  &ref_owner, NULL);
-		if (ret < 0)
-			return ret;
-		BUG_ON(ref_owner >= BTRFS_MAX_LEVEL);
-		level = (int)ref_owner;
-		/* FIXME: get real generation */
-		generation = 0;
-#else
 		BUG();
-#endif
 	}
 
 	btrfs_release_path(path);
@@ -3781,12 +3674,7 @@  int add_data_references(struct reloc_control *rc,
 	eb = path->nodes[0];
 	ptr = btrfs_item_ptr_offset(eb, path->slots[0]);
 	end = ptr + btrfs_item_size_nr(eb, path->slots[0]);
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-	if (ptr + sizeof(struct btrfs_extent_item_v0) == end)
-		ptr = end;
-	else
-#endif
-		ptr += sizeof(struct btrfs_extent_item);
+	ptr += sizeof(struct btrfs_extent_item);
 
 	while (ptr < end) {
 		iref = (struct btrfs_extent_inline_ref *)ptr;
@@ -3832,13 +3720,8 @@  int add_data_references(struct reloc_control *rc,
 		if (key.objectid != extent_key->objectid)
 			break;
 
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-		if (key.type == BTRFS_SHARED_DATA_REF_KEY ||
-		    key.type == BTRFS_EXTENT_REF_V0_KEY) {
-#else
 		BUG_ON(key.type == BTRFS_EXTENT_REF_V0_KEY);
 		if (key.type == BTRFS_SHARED_DATA_REF_KEY) {
-#endif
 			ret = __add_tree_block(rc, key.offset, blocksize,
 					       blocks);
 		} else if (key.type == BTRFS_EXTENT_DATA_REF_KEY) {
@@ -4086,39 +3969,7 @@  static noinline_for_stack int relocate_block_group(struct reloc_control *rc)
 			BUG_ON(ret);
 
 		} else {
-#ifdef BTRFS_COMPAT_EXTENT_TREE_V0
-			u64 ref_owner;
-			int path_change = 0;
-
-			BUG_ON(item_size !=
-			       sizeof(struct btrfs_extent_item_v0));
-			ret = get_ref_objectid_v0(rc, path, &key, &ref_owner,
-						  &path_change);
-			if (ret < 0) {
-				err = ret;
-				break;
-			}
-			if (ref_owner < BTRFS_FIRST_FREE_OBJECTID)
-				flags = BTRFS_EXTENT_FLAG_TREE_BLOCK;
-			else
-				flags = BTRFS_EXTENT_FLAG_DATA;
-
-			if (path_change) {
-				btrfs_release_path(path);
-
-				path->search_commit_root = 1;
-				path->skip_locking = 1;
-				ret = btrfs_search_slot(NULL, rc->extent_root,
-							&key, path, 0, 0);
-				if (ret < 0) {
-					err = ret;
-					break;
-				}
-				BUG_ON(ret > 0);
-			}
-#else
 			BUG();
-#endif
 		}
 
 		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {