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Commit d9abbf1c authored by Jan Schmidt's avatar Jan Schmidt Committed by Chris Mason
Browse files

Btrfs: fix locking on ROOT_REPLACE operations in tree mod log 



To resolve backrefs, ROOT_REPLACE operations in the tree mod log are
required to be tied to at least one KEY_REMOVE_WHILE_FREEING operation.
Therefore, those operations must be enclosed by tree_mod_log_write_lock()
and tree_mod_log_write_unlock() calls.

Those calls are private to the tree_mod_log_* functions, which means that
removal of the elements of an old root node must be logged from
tree_mod_log_insert_root. This partly reverts and corrects commit ba1bfbd5
(Btrfs: fix a tree mod logging issue for root replacement operations).

This fixes the brand-new version of xfstest 276 as of commit cfe73f71.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
Signed-off-by: default avatarChris Mason <chris.mason@fusionio.com>
parent 6113077c

fs/btrfs/ctree.c

+20 −10
Original line number Diff line number Diff line
@@ -651,6 +651,8 @@ tree_mod_log_insert_root(struct btrfs_fs_info *fs_info, 
	if (tree_mod_dont_log(fs_info, NULL))

		return 0;



	__tree_mod_log_free_eb(fs_info, old_root);



	ret = tree_mod_alloc(fs_info, flags, &tm);

	if (ret < 0)

		goto out;
@@ -736,7 +738,7 @@ tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq) 
static noinline void

tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,

		     struct extent_buffer *src, unsigned long dst_offset,

		     unsigned long src_offset, int nr_items)

		     unsigned long src_offset, int nr_items, int log_removal)

{

	int ret;

	int i;
@@ -750,10 +752,12 @@ tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst, 
	}



	for (i = 0; i < nr_items; i++) {

		if (log_removal) {

			ret = tree_mod_log_insert_key_locked(fs_info, src,

							i + src_offset,

							MOD_LOG_KEY_REMOVE);

			BUG_ON(ret < 0);

		}

		ret = tree_mod_log_insert_key_locked(fs_info, dst,

						     i + dst_offset,

						     MOD_LOG_KEY_ADD);
@@ -927,7 +931,6 @@ static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans, 
			ret = btrfs_dec_ref(trans, root, buf, 1, 1);

			BUG_ON(ret); /* -ENOMEM */

		}

		tree_mod_log_free_eb(root->fs_info, buf);

		clean_tree_block(trans, root, buf);

		*last_ref = 1;

	}
@@ -1046,6 +1049,7 @@ static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans, 
		btrfs_set_node_ptr_generation(parent, parent_slot,

					      trans->transid);

		btrfs_mark_buffer_dirty(parent);

		tree_mod_log_free_eb(root->fs_info, buf);

		btrfs_free_tree_block(trans, root, buf, parent_start,

				      last_ref);

	}
@@ -1750,7 +1754,6 @@ static noinline int balance_level(struct btrfs_trans_handle *trans, 
			goto enospc;

		}



		tree_mod_log_free_eb(root->fs_info, root->node);

		tree_mod_log_set_root_pointer(root, child);

		rcu_assign_pointer(root->node, child);
@@ -2995,7 +2998,7 @@ static int push_node_left(struct btrfs_trans_handle *trans, 
		push_items = min(src_nritems - 8, push_items);



	tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,

			     push_items);

			     push_items, 1);

	copy_extent_buffer(dst, src,

			   btrfs_node_key_ptr_offset(dst_nritems),

			   btrfs_node_key_ptr_offset(0),
@@ -3066,7 +3069,7 @@ static int balance_node_right(struct btrfs_trans_handle *trans, 
				      sizeof(struct btrfs_key_ptr));



	tree_mod_log_eb_copy(root->fs_info, dst, src, 0,

			     src_nritems - push_items, push_items);

			     src_nritems - push_items, push_items, 1);

	copy_extent_buffer(dst, src,

			   btrfs_node_key_ptr_offset(0),

			   btrfs_node_key_ptr_offset(src_nritems - push_items),
@@ -3218,12 +3221,18 @@ static noinline int split_node(struct btrfs_trans_handle *trans, 
	int mid;

	int ret;

	u32 c_nritems;

	int tree_mod_log_removal = 1;



	c = path->nodes[level];

	WARN_ON(btrfs_header_generation(c) != trans->transid);

	if (c == root->node) {

		/* trying to split the root, lets make a new one */

		ret = insert_new_root(trans, root, path, level + 1);

		/*

		 * removal of root nodes has been logged by

		 * tree_mod_log_set_root_pointer due to locking

		 */

		tree_mod_log_removal = 0;

		if (ret)

			return ret;

	} else {
@@ -3261,7 +3270,8 @@ static noinline int split_node(struct btrfs_trans_handle *trans, 
			    (unsigned long)btrfs_header_chunk_tree_uuid(split),

			    BTRFS_UUID_SIZE);



	tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);

	tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid,

			     tree_mod_log_removal);

	copy_extent_buffer(split, c,

			   btrfs_node_key_ptr_offset(0),

			   btrfs_node_key_ptr_offset(mid),