diff --git a/check/main.c b/check/main.c
index 28310013..62824907 100644
--- a/check/main.c
+++ b/check/main.c
@@ -10287,6 +10287,14 @@ static int cmd_check(const struct cmd_struct *cmd, int argc, char **argv)
 	if (init_extent_tree || init_csum_tree) {
 		struct btrfs_trans_handle *trans;
 
+		/*
+		 * If we're rebuilding extent tree, we must keep the flag set
+		 * for the whole duration of btrfs check.  As we rely on later
+		 * extent tree check code to rebuild block group items, thus we
+		 * can no longer trust the free space for metadata.
+		 */
+		if (init_extent_tree)
+			gfs_info->rebuilding_extent_tree = 1;
 		trans = btrfs_start_transaction(gfs_info->tree_root, 0);
 		if (IS_ERR(trans)) {
 			ret = PTR_ERR(trans);
diff --git a/kernel-shared/ctree.h b/kernel-shared/ctree.h
index c1bd7503..a11961d2 100644
--- a/kernel-shared/ctree.h
+++ b/kernel-shared/ctree.h
@@ -376,6 +376,7 @@ struct btrfs_fs_info {
 	unsigned int hide_names:1;
 	unsigned int allow_transid_mismatch:1;
 	unsigned int skip_leaf_item_checks:1;
+	unsigned int rebuilding_extent_tree:1;
 
 	int transaction_aborted;
 
@@ -936,11 +937,15 @@ int btrfs_update_extent_ref(struct btrfs_trans_handle *trans,
 			    u64 root_objectid, u64 ref_generation,
 			    u64 owner_objectid);
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans);
+struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info, u64 flags);
 int update_space_info(struct btrfs_fs_info *info, u64 flags,
 		      u64 total_bytes, u64 bytes_used,
 		      struct btrfs_space_info **space_info);
 int btrfs_free_block_groups(struct btrfs_fs_info *info);
 int btrfs_read_block_groups(struct btrfs_fs_info *info);
+int btrfs_try_chunk_alloc(struct btrfs_trans_handle *trans,
+			  struct btrfs_fs_info *fs_info, u64 alloc_bytes,
+			  u64 flags);
 struct btrfs_block_group *
 btrfs_add_block_group(struct btrfs_fs_info *fs_info, u64 bytes_used, u64 type,
 		      u64 chunk_offset, u64 size);
diff --git a/kernel-shared/extent-tree.c b/kernel-shared/extent-tree.c
index 7022643a..93669c55 100644
--- a/kernel-shared/extent-tree.c
+++ b/kernel-shared/extent-tree.c
@@ -1623,8 +1623,7 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans)
 	return ret;
 }
 
-static struct btrfs_space_info *__find_space_info(struct btrfs_fs_info *info,
-						  u64 flags)
+struct btrfs_space_info *btrfs_find_space_info(struct btrfs_fs_info *info, u64 flags)
 {
 	struct btrfs_space_info *found;
 
@@ -1648,7 +1647,7 @@ static int free_space_info(struct btrfs_fs_info *fs_info, u64 flags,
 	if (bytes_used)
 		return -ENOTEMPTY;
 
-	found = __find_space_info(fs_info, flags);
+	found = btrfs_find_space_info(fs_info, flags);
 	if (!found)
 		return -ENOENT;
 	if (found->total_bytes < total_bytes) {
@@ -1669,7 +1668,7 @@ int update_space_info(struct btrfs_fs_info *info, u64 flags,
 {
 	struct btrfs_space_info *found;
 
-	found = __find_space_info(info, flags);
+	found = btrfs_find_space_info(info, flags);
 	if (found) {
 		found->total_bytes += total_bytes;
 		found->bytes_used += bytes_used;
@@ -1715,7 +1714,7 @@ static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
 	}
 }
 
-static int do_chunk_alloc(struct btrfs_trans_handle *trans,
+int btrfs_try_chunk_alloc(struct btrfs_trans_handle *trans,
 			  struct btrfs_fs_info *fs_info, u64 alloc_bytes,
 			  u64 flags)
 {
@@ -1725,7 +1724,7 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans,
 	u64 num_bytes;
 	int ret;
 
-	space_info = __find_space_info(fs_info, flags);
+	space_info = btrfs_find_space_info(fs_info, flags);
 	if (!space_info) {
 		ret = update_space_info(fs_info, flags, 0, 0, &space_info);
 		BUG_ON(ret);
@@ -2375,13 +2374,11 @@ int btrfs_reserve_extent(struct btrfs_trans_handle *trans,
 	if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
 	    root->root_key.objectid == BTRFS_CSUM_TREE_OBJECTID) {
 		if (!(profile & BTRFS_BLOCK_GROUP_METADATA)) {
-			ret = do_chunk_alloc(trans, info,
-					     num_bytes,
-					     BTRFS_BLOCK_GROUP_METADATA);
+			ret = btrfs_try_chunk_alloc(trans, info, num_bytes,
+						    BTRFS_BLOCK_GROUP_METADATA);
 			BUG_ON(ret);
 		}
-		ret = do_chunk_alloc(trans, info,
-				     num_bytes + SZ_2M, profile);
+		ret = btrfs_try_chunk_alloc(trans, info, num_bytes + SZ_2M, profile);
 		BUG_ON(ret);
 	}
 
@@ -2418,7 +2415,7 @@ static int alloc_reserved_tree_block(struct btrfs_trans_handle *trans,
 	u64 start, end;
 	int ret;
 
-	sinfo = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
+	sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
 	ASSERT(sinfo);
 
 	ins.objectid = node->bytenr;
@@ -2516,7 +2513,7 @@ static int alloc_tree_block(struct btrfs_trans_handle *trans,
 	if (!extent_op)
 		return -ENOMEM;
 
-	sinfo = __find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
+	sinfo = btrfs_find_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA);
 	if (!sinfo) {
 		error("Corrupted fs, no valid METADATA block group found");
 		return -EUCLEAN;
@@ -3706,7 +3703,7 @@ int cleanup_ref_head(struct btrfs_trans_handle *trans,
 		if (!head->is_data) {
 			struct btrfs_space_info *sinfo;
 
-			sinfo = __find_space_info(trans->fs_info,
+			sinfo = btrfs_find_space_info(trans->fs_info,
 					BTRFS_BLOCK_GROUP_METADATA);
 			ASSERT(sinfo);
 			sinfo->bytes_reserved -= head->num_bytes;
diff --git a/kernel-shared/transaction.c b/kernel-shared/transaction.c
index f86e1559..44104a39 100644
--- a/kernel-shared/transaction.c
+++ b/kernel-shared/transaction.c
@@ -29,24 +29,69 @@
 #include "kernel-shared/uapi/btrfs_tree.h"
 #include "common/messages.h"
 
-struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
-						   unsigned int num_items)
+/*
+ * The metadata reservation code is completely different from the kernel:
+ *
+ * - No need to support reclaim
+ * - No support for transaction join
+ *
+ * This is due to the fact that btrfs-progs is only single threaded, thus it
+ * always starts a transaction, does some tree operations, and commits the
+ * transaction.
+ *
+ * So here we only need to make sure we have enough metadata space, and there
+ * will be no metadata over-commit (allowing extra metadata operations as long
+ * as there is unallocated space).
+ *
+ * The only extra step we can really do to increase metadata space is to allocate
+ * new metadata chunks.
+ */
+
+static unsigned int calc_insert_metadata_size(const struct btrfs_fs_info *fs_info,
+					      unsigned int num_items)
+{
+	return fs_info->nodesize * BTRFS_MAX_LEVEL * num_items * 2;
+}
+
+static bool meta_has_enough_space(struct btrfs_fs_info *fs_info,
+				  u64 profile, unsigned int size)
+{
+	struct btrfs_space_info *sinfo;
+
+	profile &= BTRFS_BLOCK_GROUP_TYPE_MASK;
+
+	/*
+	 * The fs is temporary (still during mkfs), do not check free space
+	 * as we don't have all meta/sys chunks setup.
+	 */
+	if (btrfs_super_magic(fs_info->super_copy) != BTRFS_MAGIC)
+		return true;
+
+	/*
+	 * The fs is under extent tree rebuilding, do not do any free space check
+	 * as they are not reliable.
+	 */
+	if (fs_info->rebuilding_extent_tree)
+		return true;
+
+	sinfo = btrfs_find_space_info(fs_info, profile);
+	if (!sinfo) {
+		error("unable to find block group for profile 0x%llx", profile);
+		return false;
+	}
+
+	if (sinfo->bytes_used + sinfo->bytes_pinned + sinfo->bytes_reserved +
+	    size < sinfo->total_bytes)
+		return true;
+	return false;
+}
+
+static struct btrfs_trans_handle *alloc_trans_handle(struct btrfs_root *root,
+						     unsigned int num_items)
 {
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_trans_handle *h;
 
-	if (fs_info->transaction_aborted)
-		return ERR_PTR(-EROFS);
-
-	if (root->commit_root) {
-		error("commit_root already set when starting transaction");
-		return ERR_PTR(-EINVAL);
-	}
-	if (fs_info->running_transaction) {
-		error("attempt to start transaction over already running one");
-		return ERR_PTR(-EINVAL);
-	}
-
 	h = kzalloc(sizeof(*h), GFP_NOFS);
 	if (!h)
 		return ERR_PTR(-ENOMEM);
@@ -66,6 +111,89 @@ struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 	return h;
 }
 
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+						   unsigned int num_items)
+{
+	struct btrfs_fs_info *fs_info = root->fs_info;
+	struct btrfs_trans_handle *h;
+	unsigned int rsv_bytes;
+	bool need_retry = false;
+	u64 profile;
+
+	if (root->root_key.objectid == BTRFS_CHUNK_TREE_OBJECTID)
+		profile = BTRFS_BLOCK_GROUP_SYSTEM |
+			  (fs_info->avail_system_alloc_bits &
+			   fs_info->system_alloc_profile);
+	else
+		profile = BTRFS_BLOCK_GROUP_METADATA |
+			  (fs_info->avail_metadata_alloc_bits &
+			   fs_info->metadata_alloc_profile);
+
+	if (fs_info->transaction_aborted)
+		return ERR_PTR(-EROFS);
+
+	if (root->commit_root) {
+		error("commit_root already set when starting transaction");
+		return ERR_PTR(-EINVAL);
+	}
+	if (fs_info->running_transaction) {
+		error("attempt to start transaction over already running one");
+		return ERR_PTR(-EINVAL);
+	}
+
+	/*
+	 * For those call sites, they are mostly delete items, in that case
+	 * just change it to 1.
+	 */
+	if (num_items == 0)
+		num_items = 1;
+
+	rsv_bytes = calc_insert_metadata_size(fs_info, num_items);
+
+	/*
+	 * We should not have so many items that it's larger than one metadata
+	 * chunk.
+	 */
+	if (rsv_bytes > SZ_1G) {
+		error("too much metadata space required: num_items %u reserved bytes %u",
+		      num_items, rsv_bytes);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!meta_has_enough_space(fs_info, profile, rsv_bytes))
+		need_retry = true;
+
+	h = alloc_trans_handle(root, num_items);
+	if (IS_ERR(h))
+		return ERR_PTR(PTR_ERR(h));
+
+	if (need_retry) {
+		int ret;
+
+		ret = btrfs_try_chunk_alloc(h, fs_info, rsv_bytes, profile);
+		if (ret < 0) {
+			btrfs_abort_transaction(h, ret);
+			errno = -ret;
+			error("failed to allocate new chunk: %m");
+			return ERR_PTR(ret);
+		}
+		ret = btrfs_commit_transaction(h, root);
+		if (ret < 0) {
+			errno = -ret;
+			error("failed to commit transaction for the new chunk: %m");
+			return ERR_PTR(ret);
+		}
+		if (!meta_has_enough_space(fs_info, profile, rsv_bytes)) {
+			errno = -ENOSPC;
+			error("failed to start transaction: %m");
+			return ERR_PTR(-ENOSPC);
+		}
+
+		h = alloc_trans_handle(root, num_items);
+	}
+	return h;
+}
+
 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 			       struct btrfs_root *root)
 {